OvaScience, Inc. (Form: S-3, Received: 11/06/2018 17:34:48)

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As filed with the Securities and Exchange Commission on November 6, 2018

Registration No. 333-

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-3
REGISTRATION STATEMENT
Under
The Securities Act of 1933

OVASCIENCE, INC.
(Exact name of registrant as specified in its charter)


Delaware (State or other jurisdiction of incorporation or organization)		45-1472564 (I.R.S. Employer Identification Number)

9 Fourth Avenue
Waltham, MA 02451
(617) 500-2802
(Address, including zip code, and telephone number, including area code, of registrant's principal executive offices)

Christopher A. Kroeger, M.D., M.B.A.
President & Chief Executive Officer
OvaScience, Inc.
9 Fourth Avenue
Waltham, MA 02451
(617) 500-2802
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy to:
William C. Hicks, Esq.
Megan N. Gates, Esq.
Daniel A. Bagliebter, Esq.
Mintz, Levin, Cohn, Ferris, Glovsky & Popeo, P.C.
One Financial Center
Boston, MA 02111
(617) 542-6000

Approximate date of proposed sale to the public:
From time to time after the effective date of this Registration Statement.

If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. o

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box: ý

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. o

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company" and "emerging growth company" in Rule 12b-2 of the Exchange Act. (Check one):


Large accelerated filer o		Accelerated filer ý		Non-accelerated filer o		Smaller reporting company ý Emerging Growth Company o

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act o

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities to be Registered	Amount to be Registered(1)	Proposed Maximum Offering Price Per Share(2)	Proposed Maximum Aggregate Offering Price(2)	Amount of Registration Fee




Common stock, par value $0.001 per share	1,886,574 shares	$0.77	$1,452,661.98	$176.07

(1): Pursuant to Rule 416(a) of the Securities Act of 1933, as amended, this Registration Statement shall also cover any additional shares of the Registrant's common stock that become issuable by reason of any stock dividend, stock split, recapitalization or other similar transaction effected without receipt of consideration that increases the number of the Registrant's outstanding shares of common stock.
(2): Estimated in accordance with Rule 457(c) solely for purposes of calculating the registration fee on the basis of the average of the high and low prices of Registrant's common stock as reported on The Nasdaq Capital Market on November 5, 2018.

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

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EXPLANATORY NOTE

This registration statement relates to the resale by the selling stockholders of up to an aggregate of 1,886,574 shares of OvaScience's common stock (the "Shares"). OvaScience, Inc. ("OvaScience") is filing this registration statement in connection with its merger with Millendo Therapeutics, Inc. ("Millendo") pursuant to an Agreement and Plan of Merger and Reorganization, as may be amended from time to time (the "Merger Agreement"), pursuant to which a wholly owned subsidiary of OvaScience will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience (the "Merger"). At the closing of the Merger (the "Effective Time"), each share of Millendo common stock, par value $0.001 per share ("Millendo Common Stock") (excluding certain shares to be cancelled pursuant to the Merger Agreement, and shares held by stockholders who have exercised and perfected appraisal rights or dissenters' rights), outstanding immediately prior to the Effective Time will be converted into the right to receive shares of OvaScience common stock, par value $0.001 per share ("OvaScience Common Stock") equal to an exchange ratio set forth in the Merger Agreement and as described further in this registration statement.

The Shares registered for resale on this registration statement will be sold to the selling stockholders pursuant to a Stock Purchase Agreement, dated November 1, 2018 (as amended from time to time, the "Purchase Agreement"), by and among OvaScience, Millendo and the investors listed therein (the "Investors"). Pursuant to the terms of the Purchase Agreement, the Investors agreed to purchase shares of OvaScience Common Stock for an aggregate purchase price of approximately $20.0 million as part of a private placement financing (the "Post-Closing Financing"). The consummation of the Post-Closing Financing and the other transactions contemplated by the Purchase Agreement are conditioned upon the satisfaction or waiver of the conditions set forth in the Purchase Agreement. OvaScience and the Investors intend to complete the Post-Closing Financing after the Effective Time. Under the terms of the Post-Closing Financing, the Shares issued in the Post-Closing Financing will be issued pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended. The resale of the Shares by the Investors is being registered for resale on this registration statement.

OvaScience expects this registration statement to become effective promptly after the closing of the Post-Closing Financing. Following the Merger, the business of Millendo will continue as the business of the combined organization. Additionally, it has been determined that Millendo will be the accounting acquirer in the Merger, based upon the terms of the Merger Agreement and other factors including: (i) holders of Millendo stock and other persons holding securities convertible, exercisable or exchangeable directly or indirectly for Millendo Common Stock were initially estimated to own at least 82% of OvaScience immediately following the Effective Time, (ii) Millendo will hold the majority (seven of eight) of board seats of the combined company and (iii) Millendo's management will hold all key positions in the management of the combined company. Because of these factors, OvaScience has included herein and has incorporated by reference to information about the Millendo business and operations in this registration statement.

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The information in this prospectus is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission. The selling stockholders may not sell these securities until the Securities and Exchange Commission declares the registration statement effective. This prospectus is not an offer to sell these securities and the selling stockholders named in this prospectus are not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated November 6, 2018

Prospectus

1,886,574 Shares

Common Stock

The selling stockholders of OvaScience, Inc. ("OvaScience," "we," "us" or the "Company") listed beginning on page 14 may offer and resell up to 1,886,574 shares of OvaScience common stock, par value $0.001 per share ("OvaScience Common Stock") under this prospectus. The selling stockholders will acquire these shares pursuant to a Stock Purchase Agreement, dated November 1, 2018 (as amended from time to time, the "Purchase Agreement"), by and among OvaScience, Millendo Therapeutics, Inc. ("Millendo") and the investors listed therein (the "Investors").

Pursuant to the terms of the Purchase Agreement, the Investors agreed to purchase shares of OvaScience Common Stock. On August 9, 2018, the Company announced that it had entered into an Agreement and Plan of Merger and Reorganization, as may be amended from time to time (the "Merger Agreement"), pursuant to which a wholly owned subsidiary of OvaScience will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience (the "Merger"). At the closing of the Merger (the "Effective Time"), each share of Millendo common stock, par value $0.001 per share ("Millendo Common Stock") (excluding certain shares to be cancelled pursuant to the Merger Agreement, and shares held by stockholders who have exercised and perfected appraisal rights or dissenters' rights), outstanding immediately prior to the Effective Time will be converted into the right to receive shares of OvaScience Common Stock equal to an exchange ratio, as further discussed in the Merger Agreement (the "Exchange Ratio").

Pursuant to the terms of the Purchase Agreement, the Investors agreed to purchase shares of OvaScience Common Stock for an aggregate purchase price of approximately $20.0 million as part of a private placement financing (the "Post-Closing Financing"). The consummation of the Post-Closing Financing and the other transactions contemplated by the Purchase Agreement are conditioned upon the satisfaction or waiver of the conditions set forth in the Purchase Agreement. OvaScience and the Investors intend to complete the Post-Closing Financing after the Effective Time. Under the terms of the Post-Closing Financing, the Shares issued in the Post-Closing Financing will be issued pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended. The resale of the Shares by the Investors are being registered for resale on this registration statement.

The selling stockholders (which term as used herein includes their respective donees, transferees or other successors in interest) may sell these shares through public or private transactions at market prices prevailing at the time of sale or at negotiated prices. We will not receive any proceeds from the sale of the shares by the selling stockholders. In addition, the selling stockholders may sell or otherwise dispose of the shares of OvaScience Common Stock offered by this prospectus from time to time on terms to be determined at the time of sale through ordinary brokerage transactions or through any other means described in this prospectus under "Plan of Distribution."

Until October 31, 2018, the OvaScience Common Stock was listed on The Nasdaq Global Market under the symbol "OVAS"; effective October 31, 2018, the listing of the OvaScience Common Stock was transferred to The Nasdaq Capital Market under the symbol "OVAS." The last reported sale price of OvaScience Common Stock on November 5, 2018 was $0.78 per share. In connection with the Merger, OvaScience has filed an initial listing application with The Nasdaq Capital Market pursuant to Nasdaq's rules for companies conducting a business combination that results in a change of control. After completion of the Merger, OvaScience is expected to be renamed "Millendo Therapeutics, Inc." and is expected to trade on The Nasdaq Capital Market under the symbol "MLND."

The prices at which the selling stockholders may sell all or a portion of the shares will be determined by the prevailing market price for the shares or in negotiated transactions. You are urged to obtain current market quotations for the OvaScience Common Stock.

Investing in OvaScience Common Stock is highly speculative and involves a significant degree of risk. See "Risk Factors" beginning on page 11 of this prospectus for a discussion of information that should be considered before making a decision to purchase OvaScience Common Stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of the disclosures in this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is , 2018.

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INFORMATION INCORPORATED BY REFERENCE		2
PROSPECTUS SUMMARY		4
THE OFFERING		6
DESCRIPTION OF THE MERGER		7
DESCRIPTION OF THE PRIVATE PLACEMENT		10
RISK FACTORS		11
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		12
USE OF PROCEEDS		13
SELLING STOCKHOLDERS		14
PLAN OF DISTRIBUTION		16
LEGAL MATTERS		18
EXPERTS		19
WHERE YOU CAN FIND ADDITIONAL INFORMATION		20

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we have filed with the Securities and Exchange Commission (the "SEC") pursuant to which the selling stockholders named herein may, from time to time, offer and sell or otherwise dispose of the shares of our common stock covered by this prospectus. You should not assume that the information contained in this prospectus is accurate on any date subsequent to the date set forth on the front cover of this prospectus or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus is delivered or shares of common stock are sold or otherwise disposed of on a later date. It is important for you to read and consider all information contained in this prospectus, including the documents incorporated by reference therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you under the captions "Where You Can Find Additional Information" and "Information Incorporated by Reference" in this prospectus.

We have not authorized any dealer, salesman or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus. This prospectus does not constitute an offer to sell or the solicitation of an offer to buy any of our shares of common stock other than the shares of our common stock covered hereby, nor does this prospectus constitute an offer to sell or the solicitation of an offer to buy any securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. Persons who come into possession of this prospectus in jurisdictions outside the United States are required to inform themselves about, and to observe, any restrictions as to the offering and the distribution of this prospectus applicable to those jurisdictions.

Unless we have indicated otherwise, or the context otherwise requires, references in this prospectus supplement and the accompanying prospectus to "OvaScience," the "Company," "we," "us" and "our" refer to OvaScience, Inc. and its subsidiaries.

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INFORMATION INCORPORATED BY REFERENCE

We are allowed to incorporate by reference information contained in documents that we file with the SEC. This means that we can disclose important information to you by referring you to those documents and that the information in this prospectus is not complete and you should read the information incorporated by reference for more detail. Information in this prospectus supersedes information incorporated by reference that we filed with the Commission prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus.

We incorporate by reference the documents listed below and any future filings we will make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act (i) after the date of the initial filing of the registration statement of which this prospectus is a part and prior to effectiveness of such registration statement, and (ii) from the date of this prospectus but prior to the termination of the offering of the securities covered by this prospectus (other than Current Reports or portions thereof furnished under Item 2.02 or 7.01 of Form 8-K):

•: Our proxy statement filed on Schedule 14A dated November 5, 2018 in connection with the Company's special meeting of stockholders;
•: Our Annual Report on Form 10-K for the fiscal year ended December 31, 2017;
•: Our proxy statement on Schedule 14A filed on April 30, 2018 in connection with the Company's annual meeting of stockholders;
•: Our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2018 and June 30, 2018;
•: Our Current Reports on Form 8-K and 8-K/A filed with the SEC on January 3, 2018, January 8, 2018, February 1, 2018, March 15, 2018, May 3, 2018, June 26, 2018, August 9, 2018 and November 1, 2018 (other than any portions thereof deemed furnished and not filed); and
•: The description of our common stock set forth in the registration statement on Form 8-A registering our common stock under Section 12 of the Exchange Act, which was filed with the Commission on April 25, 2013, including any amendments or reports filed for purposes of updating such description.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, a copy of any or all of the information that is incorporated by reference in this prospectus but not delivered with this prospectus, including exhibits that are specifically incorporated by reference in such documents. You may request a copy of such documents, which will be provided to you at no cost, by writing or telephoning us at the following address or telephone number:

OvaScience, Inc.
9 Fourth Avenue
Waltham, MA 02451
(617) 500-2802
Attn: Jonathan Gillis

You should rely only on the information incorporated by reference or provided in this prospectus. We have not authorized anyone to provide you with different information. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front of this document. Any statement contained in a document incorporated in this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus modifies or supersedes that statement. Any statement that is modified or superseded will not constitute a part of this prospectus, except as modified or superseded.

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Copies of the documents incorporated by reference may also be found on our website at www.ovascience.com. Except with respect to the documents expressly incorporated by reference above which are accessible at our website, the information contained on our website is not a part of, and should not be construed as being incorporated by reference into, this prospectus.

The information incorporated herein by reference includes information about Millendo. Following the Effective Time, the business of Millendo will continue as the business of the combined organization. Additionally, it has been determined that Millendo will be the accounting acquirer in the Merger, based upon the terms of the Merger Agreement and other factors including: (i) holders of Millendo stock and other persons holding securities convertible, exercisable or exchangeable directly or indirectly for Millendo Common Stock were initially estimated to own at least 82% of OvaScience immediately following the Effective Time, (ii) Millendo will hold the majority (seven of eight) of board seats of the combined company and (iii) Millendo's management will hold all key positions in the management of the combined company. Because of these factors, OvaScience has incorporated by reference to information about the Millendo business and operations into this prospectus.

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PROSPECTUS SUMMARY

This summary description about us and our business highlights selected information contained elsewhere in this prospectus or incorporated by reference into this prospectus. It does not contain all the information you should consider before investing in our securities. Important information is incorporated by reference into this prospectus. To understand this offering fully, you should read carefully the entire prospectus, including "Risk Factors" and "Cautionary Note Regarding Forward-Looking Statements", together with the additional information described under "Information Incorporated By Reference".

ABOUT OVASCIENCE, INC. AND MILLENDO THERAPEUTICS, INC.

OvaScience, Inc.

OvaScience, Inc.
9 Fourth Avenue
Waltham, MA 02451
(617) 500-2802

OvaScience is a company focused on the discovery and development of new treatment options for women and families struggling with infertility. To date OvaScience has been leveraging the breakthrough discovery of egg precursor, or EggPC ^SM , cells to transform the treatment landscape for women's fertility. OvaScience's operations to date have been limited to organizing and staffing the company, business planning, raising capital, acquiring and developing our technology, identifying potential fertility treatments, developing the OvaPrime ^SM treatment, the OvaTure ^SM treatment and the AUGMENT ^SM treatment, introducing AUGMENT in select international in vitro fertilization ("IVF") clinics and determining the regulatory and development path for OvaScience's fertility treatments. OvaScience has generated limited revenues to date, and does not anticipate significant revenues in the near term. In June 2017, OvaScience announced that it would continue to focus on advancing OvaPrime in clinical development and OvaTure in preclinical development and would discontinue ongoing efforts related to the AUGMENT treatment outside of North America. To better align its organization with these strategic priorities, OvaScience restructured its workforce and reduced its workforce by approximately 50%. On January 3, 2018, OvaScience announced a further restructuring of its organization and a workforce reduction of approximately 50%. On May 3, 2018, OvaScience announced that its Board of Directors had approved a corporate restructuring plan furthering its on-going efforts to effectively align its resources.

Millendo Therapeutics, Inc.

Millendo Therapeutics, Inc.
301 N. Main Street
Suite 100
Ann Arbor, MI 48104
(734) 845-9000

Millendo is a late-stage biopharmaceutical company focused on developing novel treatments for orphan endocrine diseases where current therapies do not exist or are insufficient. The endocrine system is a collection of glands that secrete hormones into the blood stream to regulate a number of functions, including appetite, metabolism, growth, development and reproduction. Diseases of the endocrine system can cause multiple and varied symptoms, including appetite dysregulation, metabolic dysfunction, obesity, cardiovascular disease, menstrual irregularity, excessive facial and body hair growth, and infertility.

Millendo is currently advancing two product candidates to treat three indications. Millendo's most advanced product candidate, livoletide (AZP-531), is a potential treatment for Prader-Willi syndrome,

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or PWS, a rare and complex genetic endocrine disease characterized by hyperphagia, or insatiable hunger, that contributes to serious complications, a significant burden on patients and caregivers and early mortality. In a randomized, double-blind, placebo-controlled Phase 2 clinical trial in 47 patients with PWS, Millendo observed that administration of livoletide once daily was associated with a clinically meaningful improvement in hyperphagia, as well as a reduction in appetite. In a pre-specified analysis of 38 home-resident PWS patients from the Phase 2 trial, Millendo observed a larger and statistically significant decrease in hyperphagia following administration of livoletide as compared to placebo. Millendo expects to initiate a pivotal Phase 2b/3 clinical trial of livoletide in home-resident PWS patients in the first quarter of 2019, with results expected in the first half of 2020. Millendo is also developing nevanimibe (ATR-101) with a primary focus on treating patients with classic congenital adrenal hyperplasia, or CAH, a rare, monogenic adrenal disease that requires lifelong treatment with exogenous cortisol, often at high doses. These chronic high doses of cortisol can result in side effects that include diabetes, obesity, hypertension and psychological problems. When on suboptimal doses of cortisol, female CAH patients can experience male-pattern hair growth, male physical characteristics, infertility and menstrual irregularity, and male CAH patients can experience testicular atrophy, infertility and testicular tumors, making it difficult for physicians to appropriately treat CAH without causing adverse consequences. Millendo recently reported results from its Phase 2 clinical trial of nevanimibe in patients with CAH and initiated a Phase 2b trial in the third quarter of 2018. Millendo is also investigating nevanimibe in a Phase 2 clinical trial for the treatment of patients with endogenous Cushing's syndrome, or CS, a rare endocrine disease characterized by excessive cortisol production from the adrenal glands.

Orion Merger Sub, Inc.

Orion Merger Sub, Inc. ("Merger Sub") is a wholly owned subsidiary of OvaScience, and was formed solely for the purposes of carrying out the Merger.

Recent Events

On August 9, 2018, OvaScience announced that it had entered into an Agreement and Plan of Merger and Reorganization, as may be amended from time to time with Millendo Therapeutics, Inc. ("Millendo"), pursuant to which Merger Sub will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience (the "Merger"). The Shares registered for resale on this registration statement will be sold to the selling stockholders pursuant to a Stock Purchase Agreement, dated November 1, 2018 (as amended from time to time, the "Purchase Agreement"), by and among OvaScience, Millendo and the investors listed therein (the "Investors"). Pursuant to the terms of the Purchase Agreement, the Investors agreed to purchase shares of OvaScience Common Stock for an aggregate purchase price of approximately $20.0 million as part of a private placement financing (the "Post-Closing Financing"). The consummation of the Post-Closing Financing and the other transactions contemplated by the Purchase Agreement are conditioned upon the satisfaction or waiver of the conditions set forth in the Purchase Agreement. OvaScience and the Investors intend to complete the Post-Closing Financing after the Effective Time. Under the terms of the Post-Closing Financing, the Shares issued in the Post-Closing Financing will be issued pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended. The resale of the Shares by the Investors are being registered for resale on this registration statement.

Corporate Information

OvaScience was incorporated under the laws of the State of Delaware in April 2011 under the name Ovastem, Inc. and changed its name to OvaScience, Inc. in May 2011. OvaScience's principal executive offices are located at 9 4th Avenue, Waltham, Massachusetts 02451, and its telephone number is (617) 500-2802. OvaScience's website address is www.ovascience.com. The information contained on, or that can be accessed through, OvaScience's website is not a part of this registration statement. OvaScience has included OvaScience's website address in this registration statement solely as an inactive textual reference.

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THE OFFERING


Shares of common stock that may be offered by the selling stockholders		Up to 1,886,574 shares.
Use of Proceeds		We will not receive any proceeds from the sale of the common stock by the selling stockholders.
Offering Price		The selling stockholders may sell all or a portion of their shares through public or private transactions at prevailing market prices or at privately negotiated prices.
Nasdaq Capital Market symbol		Until October 31, 2018, the OvaScience Common Stock was listed on The Nasdaq Global Market under the symbol "OVAS"; effective October 31, 2018, the listing of the OvaScience Common Stock was transferred to The Nasdaq Capital Market under the symbol "OVAS." The last reported sale price of OvaScience Common Stock on November 5, 2018 was $0.78 per share.
		OvaScience has filed an initial listing application with The Nasdaq Capital Market pursuant to Nasdaq's rules for companies conducting a business combination that results in a change of control. After completion of the Merger, OvaScience will be renamed "Millendo Therapeutics, Inc." and expects to trade on The Nasdaq Capital Market under the symbol "MLND."
Risk Factors		Investing in our common stock involves a high degree of risk. See "Risk Factors" below.

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DESCRIPTION OF THE MERGER

On August 9, 2018, OvaScience announced that it had entered into an Agreement and Plan of Merger and Reorganization, as may be amended from time to time (the "Merger Agreement") with Millendo under which Millendo will merge with OvaScience in an all-stock transaction (the "Merger"). If the Merger is completed, a wholly owned subsidiary of OvaScience ("Merger Sub") will merge with and into Millendo, with Millendo surviving as a wholly owned subsidiary of OvaScience. In connection with the Merger, holders of OvaScience stock have been asked to approve an amendment to OvaScience's restated certificate of incorporation effecting a reverse stock split of OvaScience Common Stock at a ratio mutually agreed to between OvaScience and Millendo in the range of one new share for every 5 to 15 shares outstanding (the "Reverse Stock Split").

Immediately prior to closing of the Merger (the "Effective Time"), each share of Millendo preferred stock and Millendo class-1 common stock will be converted into Millendo Common Stock. At the Effective Time, each share of Millendo's common stock, par value $0.001 per share ("Millendo Common Stock") outstanding immediately prior to the Effective Time (excluding shares held by stockholders who have exercised and perfected appraisal rights or dissenters' rights, but including shares of Millendo Common Stock that will be issued pursuant to certain existing Millendo shareholders in a pre-closing private placement of Millendo Common Stock (the "Pre-Closing Financing")) will be converted into the right to receive a number of shares of OvaScience Common Stock based on an exchange ratio set forth in the Merger Agreement (the "Exchange Ratio"). OvaScience will assume all outstanding and unexercised options to purchase shares of Millendo Common Stock (each, a "Millendo Option," and each holder of a Millendo Option, a "Millendo Optionholder") and warrants to purchase Millendo Common Stock, and each such Millendo Options and warrants will be converted into an option or warrant, respectively, to purchase shares of OvaScience Common Stock, with the number of shares of OvaScience Common Stock subject to such option or warrant and the exercise price being appropriately adjusted to reflect the Exchange Ratio.

The final Exchange Ratio will be determined pursuant to a formula described in more detail in the Merger Agreement. As of the date of the execution of the Merger Agreement, it was estimated that immediately after the consummation of the Merger, based solely on the sample Exchange Ratio of 0.1173 set forth below, holders of shares of Millendo Common Stock, Millendo Optionholders and other persons holding securities and rights directly or indirectly convertible, exercisable or exchangeable for Millendo Common Stock (collectively, "Millendo Securityholders") would own approximately 82% of Fully Diluted Closing OvaScience Common Stock, and holders of shares of OvaScience Common Stock, holders of options to purchase shares of OvaScience Common Stock and other persons holding securities and rights directly or indirectly convertible, exercisable or exchangeable for OvaScience Common Stock (collectively, "OvaScience Securityholders") would own approximately 18% of Fully Diluted Closing OvaScience Common Stock (as defined below), subject to adjustment of the Exchange Ratio as set forth in the Merger Agreement.

The percentages set forth above assume that the initial estimate of the Exchange Ratio is not changed; however, the Exchange Ratio is subject to change as set forth in the Merger Agreement. The initial estimate of the Exchange Ratio set forth below assumed (i) that OvaScience would have between $40 million and $42 million in net cash immediately prior to Closing, (ii) a Pre-Closing Financing amount of $30.0 million, (iii) OvaScience outstanding shares and options as of the Closing would be equal to 3,721,460 (on a post reverse stock split basis), (iv) Millendo shares as of the Closing would be equal to 148,171,273 (on a fully-diluted, as-converted basis) and (v) a reverse stock split of every 10 shares of outstanding OvaScience Common Stock being combined and reclassified into one share of OvaScience Common Stock.

The Exchange Ratio is calculated using a formula intended to allocate a percentage of the combined organization to existing Millendo Securityholders. Based on the assumptions described above,

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the Exchange Ratio would have been equal to approximately 0.1173 post-reverse split shares of OvaScience Common Stock for each share of Millendo Common Stock, which Exchange Ratio is subject to change based on the amount of OvaScience net cash, changes in the capitalization of OvaScience or Millendo prior to the Closing and the amount raised by Millendo in the Pre-Closing Financing (and as a result, OvaScience Securityholders and Millendo Securityholders could own more or less of the combined organization). After the initial signing of the Merger Agreement, the valuations for Millendo and OvaScience were reduced.

OvaScience currently estimates that, assuming for this purpose a closing date of November 30, 2018, (i) it will have approximately $37.6 million in net cash immediately prior to Closing, (ii) the Pre-Closing Financing amount will be approximately $29.5 million, (iii) OvaScience outstanding shares and options as of the Closing will be equal to 3,727,669 (on a post reverse stock split basis) and (iv) the Millendo shares as of the Closing on a fully diluted and as-converted basis will be equal to 152,629,595. Accordingly, it is currently estimated that the Exchange Ratio at Closing will be approximately 0.1070 and, based solely on such Exchange Ratio, at Closing: (a) Millendo Securityholders as of immediately prior to the Merger (not including the shares issued in the Pre-Closing Financing) will own approximately 67.1% of the Fully Diluted Closing OvaScience Common Stock (as defined below), (b) the shares issued in the Pre-Closing Financing to Millendo Securityholders as of immediately prior to the Merger will represent approximately 13.1% of the Fully Diluted Closing OvaScience Common Stock, (c) the OvaScience Securityholders as of immediately prior to the Merger (excluding for this purpose certain out-of-the-money OvaScience Options) will own approximately 18.6% of the Fully Diluted Closing OvaScience Common Stock, and (d) the shares available for issuance under the Millendo Plan as of immediately prior to the Merger will represent approximately 1.2% of the Fully Diluted Closing OvaScience Common Stock, in each case, subject to adjustment of the Exchange Ratio as set forth in the Merger Agreement and described herein. Additionally, it is anticipated that the Post-Closing Financing (as defined below) will close shortly after the Closing, which would dilute, and thereby reduce, each then existing OvaScience Securityholder's proportionate holdings. Assuming that the Post-Closing Financing closes immediately after the Merger as well as the other aforementioned assumptions, it is expected that (a) Millendo Securityholders as of immediately prior to the Merger (not including the shares issued in the Pre-Closing Financing) will own approximately 61.7% of the Fully Diluted Post-Financing OvaScience Common Stock (as defined below), (b) the shares issued in the Pre-Closing Financing to Millendo Securityholders as of immediately prior to the Merger will represent approximately 12.0% of the Fully Diluted Post-Financing OvaScience Common Stock, (c) the OvaScience Securityholders as of immediately prior to the Merger (excluding for this purpose certain out-of-the-money OvaScience Options) will own approximately 17.1% of the Fully Diluted Post-Financing OvaScience Common Stock, (d) the shares issued in the Post-Closing Financing to the Post-Closing Financing Investor (as defined below) will represent approximately 8.1% of the Fully Diluted Post-Financing OvaScience Common Stock, and (e) the shares available for issuance under the Millendo Plan as of immediately prior to the Merger will represent approximately 1.1% of the Fully Diluted Post-Financing OvaScience Common Stock, in each case, subject to adjustment of the Exchange Ratio as set forth in the Merger Agreement and described herein. "Fully Diluted Closing OvaScience Common Stock" as used herein means (x) Orion Outstanding Shares (as defined in the Merger Agreement, which figure excludes the shares available for issuance under the 2012 Plan and a portion of the out-of-the-money OvaScience Options) plus (y) Company Outstanding Shares (as defined in the Merger Agreement, which figure includes the shares available for issuance under the Millendo Plan). "Fully Diluted Post-Financing OvaScience Common Stock" as used herein means (x) Orion Outstanding Shares (as defined in the Merger Agreement, which figure excludes the shares available for issuance under the 2012 Plan and a portion of the out-of-the-money OvaScience Options) plus (y) Company Outstanding Shares (as defined in the Merger Agreement, which figure includes the shares available for issuance under the Millendo Plan) plus (z) the Post-Closing Financing shares.

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The Closing will occur no later than the second business day after the last of the conditions to the Merger has been satisfied or waived (other than those conditions that by their nature are to be satisfied at the Closing, but subject to the satisfaction or waiver of each such conditions), or at such other time as OvaScience and Millendo agree. OvaScience and Millendo anticipate that the consummation of the Merger will occur in the fourth quarter of 2018. However, because the Merger is subject to a number of conditions, neither OvaScience nor Millendo can predict exactly when the Closing will occur or if it will occur at all. After completion of the Merger, assuming that OvaScience receives the required stockholder approval of its proposal to change the name of the company, OvaScience will be renamed "Millendo Therapeutics, Inc."

On September 25, 2018, OvaScience and Millendo entered into the First Amendment to the Merger Agreement (the "First Amendment"). The First Amendment provides, among other things, that shares of OvaScience Common Stock to be issued in exchange for shares of Millendo Common Stock to be issued in the Pre-Closing Financing would not be registered pursuant to the Registration Statement on Form S-4, originally filed by OvaScience on September 26, 2018. The First Amendment also increased the size of the board of directors of the combined company by one seat. Further, it provides, among other things, that shares of OvaScience Common Stock to be issued in exchange for shares of Millendo Common Stock to be issued to certain of the investors in the Pre-Closing Financing that were not previously stockholders of Millendo would be registered pursuant to a separate resale registration statement on Form S-3.

On November 1, 2018, OvaScience and Millendo entered into the Second Amendment to the Merger Agreement (the "Second Amendment"). The Second Amendment was proposed by Millendo in order to lower Millendo's valuation from $191.9 million to $155.0 million in connection with the Post-Closing Financing. The Second Amendment provides that as a result of the reduction in Millendo's valuation, the Pre-Closing Financing, including the conversion of any convertible promissory notes issued after the date of the Second Amendment, would be consummated at a price per share for Millendo Common Stock of not less than $1.2096. The Second Amendment also provides that Millendo's Valuation would equal the sum of $155 million plus any proceeds received in the Pre-Closing Financing, and that OvaScience's Valuation would be lowered to $45.5 million, subject to certain adjustments set forth in the Merger Agreement. The Second Amendment additionally (i) provides that the definition of Millendo outstanding shares used for purposes of the exchange ratio shall include shares of Millendo Common Stock available for issuance under its stock option plans, (ii) provides for an adjustment to the Company's net cash in connection with certain litigation matters, and (iii) revises the definition of the Company's outstanding lease obligations with respect to its principal office space. It also revises certain representations and warranties being made by Millendo.

The description of the Merger Agreement is not complete and is qualified in its entirety by reference to Merger Agreement, which has been filed as an annex to our proxy statement on Schedule 14A, filed with the SEC on November 5, 2018 and which is incorporated by reference herein. See "Where You Can Find Additional Information" and "Information Incorporated by Reference." The representations, warranties and covenants made by us in the Merger Agreement were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties thereto, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were made as of an earlier date. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

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DESCRIPTION OF THE PRIVATE PLACEMENT

On November 1, 2018, OvaScience and Millendo entered into a Stock Purchase Agreement (as may be amended from time to time, the "Purchase Agreement") with certain investors (the "Investors"), which provided for the sale and issuance of shares (the "Shares") of OvaScience Common Stock (the "Post-Closing Financing") for an aggregate purchase price of approximately $20 million at a per share purchase price of (i) $1.2096 divided by (ii) the Exchange Ratio. The consummation of the Post-Closing Financing and the other transactions contemplated by the Purchase Agreement are conditioned upon the satisfaction or waiver of the conditions set forth in the Purchase Agreement. OvaScience and the Investors intend to complete the Post-Closing Financing after the Effective Time. Under the terms of the Post-Closing Financing, the Shares issued in the Post-Closing Financing will be issued pursuant to an exemption from the registration requirements of the Securities Act of 1933, as amended. The resale of the Shares by the Investors are being registered for resale on this registration statement.

Concurrently with the execution of the Purchase Agreement, OvaScience entered into a Registration Rights Agreement (as may be amended from time to time, the "Registration Rights Agreement") with the Investors, pursuant to which OvaScience agreed to file, as promptly as reasonably possible after the execution of the Registration Rights Agreement, a registration statement (the "Resale Registration Shelf") with the SEC covering the resale of the shares sold to the Investors in the Post-Closing Financing and to use its reasonable best efforts to have the registration statement declared effective as promptly as practicable following the filing of the Resale Registration Shelf.

Under the Registration Rights Agreement, OvaScience also agreed to use its reasonable best efforts to maintain the effectiveness of the Resale Registration Shelf until the earliest of (a) the date as of which Investors may sell all of their securities covered by the Resale Registration Shelf without restriction pursuant to Rule 144 or (b) all Shares covered by the Resale Registration Shelf otherwise cease to be registrable securities, as defined in the Registration Rights Agreement.

The descriptions of the Purchase Agreement and the Registration Agreement are not complete and are qualified in their entirety by reference to the Purchase Agreement and the Registration Rights Agreement, each of which have been filed as an exhibit to the registration statement of which this prospectus is a part. See "Where You Can Find Additional Information" and "Information Incorporated by Reference." The representations, warranties and covenants made by us in such agreements were made solely for the benefit of the parties to such agreements, including, in some cases, for the purpose of allocating risk among the parties thereto, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were made as of an earlier date. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

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RISK FACTORS

An investment in our common stock involves a high degree of risk. Prior to making a decision about investing in our common stock, you should carefully consider the risks, uncertainties and assumptions discussed under (i) the section entitled "Risk Factors," in our proxy statement on Schedule 14A, filed with the SEC on November 5, 2018 and (ii) Item 1A, "Risk Factors," in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed with the SEC on March 15, 2018, as updated by our subsequent filings with the SEC under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), which are incorporated herein by reference, together with the information in this prospectus and any other information incorporated by reference into this prospectus. See "Where You Can Find Additional Information" and "Information Incorporated by Reference." Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our business, financial condition or results of operations. The occurrence of any of these known or unknown risks might cause you to lose all or part of your investment in our common stock.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This registration statement and the documents incorporated by reference into this registration statement contain forward-looking statements (including within the meaning of Section 21E of the United States Securities Exchange Act of 1934, as amended (the "Exchange Act"), and Section 27A of the Securities Act) concerning OvaScience, Millendo, the proposed Merger and other matters. These statements may discuss goals, intentions and expectations as to future plans, trends, events, results of operations or financial condition, or otherwise, based on current beliefs of the management of OvaScience, as well as assumptions made by, and information currently available to, management. Forward-looking statements generally include statements that are predictive in nature and depend upon or refer to future events or conditions, and include words such as "may," "will," "should," "would," "expect," "plan," "believe," "intend," "look forward," and other similar expressions among others. Statements that are not historical facts are forward-looking statements. Forward-looking statements are based on current beliefs and assumptions that are subject to risks and uncertainties and are not guarantees of future performance. Actual results could differ materially from those contained in any forward-looking statement as a result of various factors, including, without limitation: the risk that the conditions to the closing of the Merger are not satisfied, including the failure to timely or at all obtain stockholder approval for the Merger; uncertainties as to the timing of the consummation of the Merger and the ability of each of OvaScience and Millendo to consummate the Merger; risks and uncertainties as to the ability of the parties to consummate the Post-Closing Financing; risks related to OvaScience's ability to correctly estimate its operating expenses and its expenses associated with the Merger; risks related to the changes in market price of the OvaScience Common Stock relative to the Exchange Ratio; the ability of OvaScience or Millendo to protect their respective intellectual property rights; competitive responses to the Merger; unexpected costs, charges or expenses resulting from the Merger; potential adverse reactions or changes to business relationships resulting from the announcement or completion of the Merger; and legislative, regulatory, political and economic developments. The foregoing review of important factors that could cause actual events to differ from expectations should not be construed as exhaustive and should be read in conjunction with statements that are included herein and elsewhere. OvaScience can give no assurance that the conditions to the Merger will be satisfied. Except as required by applicable law, OvaScience undertakes no obligation to revise or update any forward-looking statement, or to make any other forward looking statements, whether as a result of new information, future events or otherwise.

For a discussion of the factors that may cause OvaScience, Millendo or the combined organization's actual results, performance or achievements to differ materially from any future results, performance or achievements expressed or implied in such forward-looking statements, or for a discussion of risks associated with the ability of OvaScience and Millendo to complete the Merger and the effect of the Merger on the business of OvaScience, Millendo and the combined organization, see (i) the section entitled "Risk Factors," in our proxy statement on Schedule 14A, filed with the SEC on November 5, 2018 and (ii) Item 1A, "Risk Factors," in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed with the SEC on March 15, 2018, as updated by our subsequent filings with the SEC under the Exchange Act.

Additional factors that could cause actual results to differ materially from those expressed in the forward-looking statements are discussed in reports filed with the SEC by OvaScience. See the section titled " Where You Can Find More Information " in this registration statement. There can be no assurance that the Merger will be completed, or if it is completed, that it will be completed within the anticipated time period or that the expected benefits of the Merger will be realized.

If any of these risks or uncertainties materialize or any of these assumptions prove incorrect, the results of operations of OvaScience, Millendo or the combined organization could differ materially from the forward-looking statements. All forward-looking statements in this registration statement are current only as of the date on which the statements were made. OvaScience and Millendo do not undertake any obligation to publicly update any forward-looking statement to reflect events or circumstances after the date on which any statement is made, the occurrence of unanticipated events or any new information that becomes available in the future.

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USE OF PROCEEDS

We will not receive any of the proceeds from the sale of the common stock by the selling stockholders named in this prospectus. All proceeds from the resale of the shares of our common stock offered by this prospectus will belong to the selling stockholders identified in this prospectus under "Selling Stockholders."

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SELLING STOCKHOLDERS

This prospectus covers the resale by the selling stockholders identified below of up to 1,886,574 shares of our common stock that will be issued to the selling stockholders. The selling stockholders will acquire our securities pursuant to the Post-Closing Financing following the closing of the Merger. See "Prospectus Summary—Description of the Merger" and "Prospectus Summary—Description of the Private Placement." We will not receive any proceeds from the resale of the common stock by the selling stockholders.

To our knowledge, none of the selling stockholders has been an officer or director of ours or any of our predecessors or affiliates within the past three years and no selling stockholder had a material relationship with OvaScience or any of its affiliates within the last three years. Our knowledge is based on information provided by the selling stockholders in connection with the filing of this prospectus, as well as information obtained from relevant Schedule 13D and 13G filings.

The shares registered for resale on this registration statement will be sold to the selling stockholders under the Purchase Agreement, pursuant to which the Investors agreed to purchase shares of OvaScience Common Stock following the closing of the Merger. The table below sets forth information, to our knowledge, for the selling stockholders and other information regarding the beneficial ownership (as determined under Section 13(d) of the Exchange Act and the rules and regulations thereunder) of the shares of OvaScience Common Stock that would be held by the selling stockholders, assuming the closing of the Merger occurred on November 30, 2018.

The percentage of ownership is based on 18,859,542 shares of OvaScience Common Stock expected to be outstanding upon the Closing, including the effect of the Reverse Stock Split, if approved and implemented at a 1:10 ratio, and the Pre-Closing Financing, adjusted as required by the rules promulgated by the SEC to determine beneficial ownership. The following table and the related notes assume that, at the Effective Time, each share of Millendo Common Stock will convert into the right to receive 0.1070 post-Reverse Stock Split shares of OvaScience Common Stock (which is the current estimate of the Exchange Ratio and is subject to change as described elsewhere in this prospectus) and to account for the occurrence of certain events.

The table and footnotes assume that the selling stockholders will sell all of the shares listed. However, because the selling stockholders may sell all or some of their shares under this prospectus from time to time, or in another permitted manner, we cannot assure you as to the actual number of shares that will be sold by the selling stockholders or that will be held by the selling stockholders after completion of any sales. We do not know how long the selling stockholders will hold the shares before selling them. The inclusion of any shares in this table does not constitute an admission of beneficial ownership by the persons named below. The selling stockholders listed below are sorted alphabetically by first name.

Information about the selling stockholders may change over time. Any changed information will be set forth in an amendment to the registration statement or supplement to this prospectus, to the extent required by law.

	Shares Beneficially Owned as of the date of this Prospectus								Shares Beneficially Owned After the Offering(2)

	Shares Beneficially Owned as of the date of this Prospectus					Shares Offered by this Prospectus			Shares Beneficially Owned After the Offering(2)
Name of Selling Stockholder	Number		Percent(1)			Shares Offered by this Prospectus			Number		Percent(1)
Great Point Partners, LLC		1,769,179		9.4	%		1,886,574	(3)		—		*

*: Less than 1%.

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(1): Applicable percentage ownership is based on 18,859,542 shares of our common stock outstanding as of November 30, 2018, which includes shares expected to be issued by Millendo as part of the Pre-Closing Financing and by OvaScience in the Post-Closing Financing.
(2): Assumes the sale of all shares offered pursuant to this prospectus.
(3): The number of shares offered for resale by this Prospectus is based on an estimated Exchange Ratio of 0.1141, which accounts for potential reductions in OvaScience cash. Currently, the Exchange Ratio is estimated to be 0.1070, which Exchange Ratio is subject to change as described elsewhere in this Prospectus.

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PLAN OF DISTRIBUTION

The selling stockholders, which as used herein includes donees, pledgees, transferees or other successors-in-interest selling shares of common stock or interests in shares of common stock received after the date of this prospectus from a selling stockholder as a gift, pledge, partnership distribution or other transfer, may, from time to time, sell, transfer or otherwise dispose of any or all of their shares of common stock or interests in shares of common stock on any stock exchange, market or trading facility on which the shares are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.

The selling stockholders may use any one or more of the following methods when disposing of shares or interests therein:

•: ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;
•: block trades in which the broker-dealer will attempt to sell the shares as agent, but may position and resell a portion of the block as principal to facilitate the transaction;
•: purchases by a broker-dealer as principal and resale by the broker-dealer for its account;
•: an exchange distribution in accordance with the rules of the applicable exchange;
•: privately negotiated transactions;
•: short sales effected after the date the registration statement of which this Prospectus is a part is declared effective by the SEC;
•: through the writing or settlement of options or other hedging transactions, whether through an options exchange or otherwise;
•: broker-dealers may agree with the selling stockholders to sell a specified number of such shares at a stipulated price per share;
•: a combination of any such methods of sale; and
•: any other method permitted by applicable law.

The selling stockholders may, from time to time, pledge or grant a security interest in some or all of the shares of common stock owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the shares of common stock, from time to time, under this prospectus, or under an amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act amending the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer the shares of common stock in other circumstances, in which case the transferees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

In connection with the sale of our common stock or interests therein, the selling stockholders may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of the common stock in the course of hedging the positions they assume. The selling stockholders may also sell shares of our common stock short and deliver these securities to close out their short positions, or loan or pledge the common stock to broker-dealers that in turn may sell these securities. The selling stockholders may also enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or other financial institution of shares offered by this prospectus, which shares such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

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The aggregate proceeds to the selling stockholders from the sale of the common stock offered by them will be the purchase price of the common stock less discounts or commissions, if any. Each of the selling stockholders reserves the right to accept and, together with their agents from time to time, to reject, in whole or in part, any proposed purchase of common stock to be made directly or through agents. We will not receive any of the proceeds from this offering. Upon any exercise of the warrants by payment of cash, however, we will receive the exercise price of the warrants.

The selling stockholders also may resell all or a portion of the shares in open market transactions in reliance upon Rule 144 under the Securities Act of 1933, provided that they meet the criteria and conform to the requirements of that rule.

The selling stockholders and any underwriters, broker-dealers or agents that participate in the sale of the common stock or interests therein may be "underwriters" within the meaning of Section 2(11) of the Securities Act. Any discounts, commissions, concessions or profit they earn on any resale of the shares may be underwriting discounts and commissions under the Securities Act. Selling stockholders who are "underwriters" within the meaning of Section 2(11) of the Securities Act will be subject to the prospectus delivery requirements of the Securities Act.

To the extent required, the shares of our common stock to be sold, the names of the selling stockholders, the respective purchase prices and public offering prices, the names of any agents, dealer or underwriter, any applicable commissions or discounts with respect to a particular offer will be set forth in an accompanying prospectus supplement or, if appropriate, a post-effective amendment to the registration statement that includes this prospectus.

In order to comply with the securities laws of some states, if applicable, the common stock may be sold in these jurisdictions only through registered or licensed brokers or dealers. In addition, in some states the common stock may not be sold unless it has been registered or qualified for sale or an exemption from registration or qualification requirements is available and is complied with.

We have advised the selling stockholders that the anti-manipulation rules of Regulation M under the Exchange Act may apply to sales of shares in the market and to the activities of the selling stockholders and their affiliates. In addition, to the extent applicable we will make copies of this prospectus (as it may be supplemented or amended from time to time) available to the selling stockholders for the purpose of satisfying the prospectus delivery requirements of the Securities Act. The selling stockholders may indemnify any broker-dealer that participates in transactions involving the sale of the shares against certain liabilities, including liabilities arising under the Securities Act.

We will pay all expenses of the registration of the shares of common stock pursuant to the registration rights agreement, including, without limitation, Securities and Exchange Commission filing fees and expenses of compliance with state securities or "blue sky" laws; provided , however , that each selling stockholder will pay all underwriting discounts and selling commissions, if any and any related legal expenses incurred by it. We will indemnify the selling stockholders against certain liabilities, including some liabilities under the Securities Act, in accordance with the registration rights agreement, or the selling stockholders will be entitled to contribution. We may be indemnified by the selling stockholders against civil liabilities, including liabilities under the Securities Act, that may arise from any written information furnished to us by the selling stockholders specifically for use in this prospectus, in accordance with the related registration rights agreement, or we may be entitled to contribution.

We have agreed with the selling stockholders to keep the registration statement of which this prospectus constitutes a part effective until the earlier of (1) such time as all of the shares covered by this prospectus have been disposed of pursuant to and in accordance with the registration statement or (2) the date on which all of the shares may be sold without restriction pursuant to Rule 144 of the Securities Act.

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LEGAL MATTERS

The validity of the shares of common stock offered in this prospectus has been passed upon for us by Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts.

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EXPERTS

The consolidated financial statements of OvaScience, Inc. appearing in OvaScience, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2017, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

The consolidated financial statements of Millendo Therapeutics, Inc. as of December 31, 2017 and 2016 and for each of the years then ended that are incorporated by reference in this prospectus and elsewhere in this registration statement have been audited by Ernst & Young LLP, independent auditors, as set forth in their report thereon (which contains an explanatory paragraph describing conditions that raise substantial doubt about the Company's ability to continue as a going concern as described in Note 1 to the consolidated financial statements), included therein, and incorporated herein by reference. Such financial statements are incorporated herein in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

The financial statements of Millendo Therapeutics SAS, which comprise the balance sheet as of December 31, 2016 and the related statements of income and cash flows for the year then ended, and the balance sheet as of December 19, 2017 and the related statements of income and cash flows for the period from January 1 to December 19, 2017, and the related notes to the financial statements that are incorporated by reference in this prospectus and elsewhere in this registration statement have been audited by RSM Rhône-Alpes, as set forth in their report thereon, included therein, and incorporated herein by reference. Such financial statements are incorporated by reference herein in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

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WHERE YOU CAN FIND ADDITIONAL INFORMATION

We are subject to the information requirements of the Exchange Act and we therefore file periodic reports, proxy statements and other information with the SEC relating to our business, financial statements and other matters. The reports, proxy statements and other information we file may be inspected and copied at prescribed rates at the SEC's Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the SEC's Public Reference Room by calling the SEC at 1-800-SEC-0330. The SEC also maintains web site that contains reports, proxy and information statements and other information regarding issuers like us that file electronically with the SEC. The address of the SEC's web site is http://www.sec.gov.

This prospectus constitutes part of a registration statement filed under the Securities Act with respect to the shares of common stock covered hereby. As permitted by the SEC's rules, this prospectus omits some of the information, exhibits and undertakings included in the registration statement. You may read and copy the information omitted from this prospectus but contained in the registration statement, as well as the periodic reports and other information we file with the SEC, at the public reference room and web site of the SEC referred to above. You may also access our filings with the SEC on our web site, which is located at http://www.ovascience.com. The information contained on our web site is not part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

Statements contained in this prospectus as to the contents of any contract or other document are not necessarily complete, and in each instance we refer you to the copy of the contract or other document filed or incorporated by reference as an exhibit to the registration statement or as an exhibit to our Exchange Act filings, each such statement being qualified in all respects by such reference.

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1,886,574 Shares

Common Stock

PROSPECTUS

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION

The following table sets forth the fees and expenses incurred and to be incurred in connection with the registration of the securities being registered hereby, all of which will be borne by us. Except for the SEC registration fee, all amounts are estimates.


SEC Registration Fee	$	176.07
Accounting Fees and Expenses	$	15,000.00
Legal Fees and Expenses	$	40,000.00
Printing Expenses	$	10,000.00
Miscellaneous Fees and Expenses	$	4,823.93
Total	$	70,000.00

ITEM 15. INDEMNIFICATION OF OFFICERS AND DIRECTORS

Subsection (a) of Section 145 of the General Corporation Law of the State of Delaware ("DGCL"), empowers a corporation to indemnify any person who was or is a party or who is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with such action, suit or proceeding if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable cause to believe the person's conduct was unlawful.

Subsection (b) of Section 145 empowers a corporation to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor by reason of the fact that the person acted in any of the capacities set forth above, against expenses (including attorneys' fees) actually and reasonably incurred by the person in connection with the defense or settlement of such action or suit if the person acted in good faith and in a manner the person reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or the court in which such action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem proper.

Section 145 further provides that to the extent a director or officer of a corporation has been successful on the merits or otherwise in the defense of any action, suit or proceeding referred to in subsections (a) and (b) of Section 145, or in defense of any claim, issue or matter therein, such person shall be indemnified against expenses (including attorneys' fees) actually and reasonably incurred by such person in connection therewith; that indemnification provided for by Section 145 shall not be deemed exclusive of any other rights to which the indemnified party may be entitled; and the indemnification provided for by Section 145 shall, unless otherwise provided when authorized or ratified, continue as to a person who has ceased to be a director, officer, employee or agent and shall inure to the benefit of such person's heirs, executors and administrators. Section 145 also empowers the

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corporation to purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against any liability asserted against such person and incurred by such person in any such capacity, or arising out of his status as such, whether or not the corporation would have the power to indemnify such person against such liabilities under Section 145.

Section 102(b)(7) of the DGCL provides that a corporation's certificate of incorporation may contain a provision eliminating or limiting the personal liability of a director to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director, provided that such provision shall not eliminate or limit the liability of a director (i) for any breach of the director's duty of loyalty to the corporation or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL or (iv) for any transaction from which the director derived an improper personal benefit.

OvaScience's restated certificate of incorporation provides that OvaScience shall indemnify and advance expenses to each person who was or is a party or threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether criminal, civil, administrative or investigative, by reason of the fact that he or she is or was, or has agreed to become, a director or officer of OvaScience, or is or was serving, or has agreed to serve, at the request of OvaScience, as a director, officer, partner, employee or trustee of, or in a similar capacity with, another corporation, partnership, joint venture, trust or other enterprise, or by reason of any action alleged to have been taken or omitted in such capacity, against all expenses (including attorneys' fees), liabilities, losses, judgments, fines, and amounts paid in settlement actually and reasonably incurred in connection with such action, suit or proceeding and any appeal therefrom.

OvaScience has indemnification agreements with its directors, in addition to the indemnification provided for in its restated certificate of incorporation, and intends to enter into indemnification agreements with any new directors in the future.

OvaScience has purchased and intends to maintain insurance on behalf of any person who is or was a director or officer of OvaScience against any loss arising from any claim asserted against him or her and incurred by him or her in any such capacity, subject to certain exclusions.

Pursuant to the terms of the Merger Agreement and subject to applicable law, from the Effective Time through the sixth anniversary of the date on which the Effective Time occurs, OvaScience shall indemnify and hold harmless each person who is now, or has been at any time prior to the date thereof, or who becomes prior to the Effective Time, a director or officer of OvaScience or Millendo, respectively, against all Costs incurred in connection with any claim, action, suit, proceeding or investigation, whether civil, criminal, administrative or investigative, arising out of or pertaining to the fact that such person is or was a director or officer of OvaScience or Millendo, whether asserted or claimed prior to, at or after the Effective Time, in each case, to the fullest extent permitted under the DGCL for directors or officers of Delaware corporations, provided that such officer or director acted in good faith and in a manner such party reasonable believed to be in or not opposed to the best interest of OvaScience or the Surviving Corporation, as applicable, and, with respect to any criminal proceeding, such officer or director had no reasonable cause to believe such conducted was unlawful; provided, further, that, if applicable law so provides, no indemnification against such Costs shall be made in respect of any claim, issue or matter in such proceeding as to which the director or officer shall have been adjudged to be liable to OvaScience or the Surviving Corporation unless and to the extent that the Court of Chancery of the State of Delaware shall determine that such indemnification may be made. Subject to applicable law, each such director and officer will be entitled to advancement of expenses incurred in the defense of any such claim, action, suit, proceeding or investigation from each of OvaScience and the Surviving Corporation, jointly and severally, upon receipt by OvaScience or

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the Surviving Corporation from such director or officer of a request therefor; provided that any such person to whom expenses are advanced provides an undertaking to OvaScience or the Surviving Corporation, as applicable, to the extent then required by the DGCL, to repay such advances if it is ultimately determined that such person is not entitled to indemnification. Such statement or statements shall reasonably evidence the expenses incurred by the directors and officers.

Further, pursuant to the Merger Agreement, the provisions of the OvaScience restated certificate of incorporation and the OvaScience by-laws with respect to indemnification, advancement of expenses and exculpation of present and former directors and officers of OvaScience shall not be amended, modified or repealed for a period of six years from the Effective Time in a manner that would adversely affect the rights thereunder of individuals who, at or prior to the Effective Time, were officers or directors of OvaScience, unless such modification is required by applicable law.

From and after the Effective Time, (i) the Surviving Corporation shall fulfill and honor in all respects the obligations of Millendo to each person who is or has served as a director or officer of Millendo as of immediately prior to the Closing pursuant to any indemnification provisions under the Millendo certificate of incorporation or Millendo bylaws and pursuant to any indemnification agreements between Millendo and such directors and officers, with respect to claims arising out of matters occurring at or prior to the Effective Time and (ii) OvaScience shall fulfill and honor in all respects the obligations of OvaScience to each person who is or has served as a director or officer of OvaScience as of immediately prior to the Closing pursuant to any indemnification provisions under the OvaScience Charter or OvaScience Bylaws and pursuant to any indemnification agreements between OvaScience and such directors and officers that were in effect prior to the date of the Merger Agreement, with respect to claims arising out of matters occurring at or prior to the Effective Time.

The Merger Agreement also provides that OvaScience shall maintain directors' and officers' liability insurance policies commencing at the closing time of the Merger, on commercially available terms and conditions with coverage limits customary for U.S. public companies similar situated to OvaScience. In addition, OvaScience shall purchase, prior to the Effective Time, a six-year prepaid "D&O tail policy" for the non-cancellable extension of the directors' and officers' liability coverage of OvaScience's existing directors' and officers' insurance policies and OvaScience's existing fiduciary liability insurance policies, in each case, for a claims reporting or discovery period of at least six years from and after the Effective Time.

From and after the Effective Time, OvaScience shall pay all expenses, including reasonable attorneys' fees, that are incurred by indemnified persons in connection with their successful enforcement of the rights provided to such persons in the Merger Agreement. The director and officer indemnification provisions of the Merger Agreement are intended to be in addition to the rights otherwise available to the current and former officers and directors of OvaScience and Millendo by law, charter, statute, bylaw or agreement, and shall operate for the benefit of, and shall be enforceable by, each of such indemnified persons, their heirs and their representatives.

In the event OvaScience or the Surviving Corporation or any of their respective successors or assigns (i) consolidates with or merges into any other person and shall not be the continuing or surviving corporation or entity of such consolidation or merger, or (ii) transfers all or substantially all of its properties and assets to any person, then, and in each such case, proper provision shall be made so that the successors and assigns of OvaScience or the Surviving Corporation, as the case may be, shall succeed to the indemnification obligations set forth in the Merger Agreement. OvaScience shall cause the Surviving Corporation to perform all of the director and officer indemnification obligations of the Surviving Corporation under the Merger Agreement.

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ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

A list of exhibits filed herewith is contained in the exhibit index that immediately precedes such exhibits and is incorporated herein by reference.

ITEM 17. UNDERTAKINGS

The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i): To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;
(ii): To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; and
(iii): To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

Provided however, that paragraphs (1)(i), (1)(ii) and (1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i)

If the registrant is relying on Rule 430B:

(A): Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and
(B): Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the

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information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date; or

(ii): If the registrant is subject to Rule 430C, each prospectus filed pursuant to Rule 424(b) as part of a registration statement relating to an offering, other than registration statements relying on Rule 430B or other than prospectuses filed in reliance on Rule 430A, shall be deemed to be part of and included in the registration statement as of the date it is first used after effectiveness. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such first use, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such date of first use.

The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant's annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by a director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

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EXHIBIT INDEX

The following exhibits are filed as part of this Registration Statement:

		Description

2.1		Agreement and Plan of Merger and Reorganization, dated as of August 8, 2018, by and among OvaScience, Inc., Orion Merger Sub, Inc. and Millendo Therapeutics, Inc. (incorporated by reference from Annex A to Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange Commission on November 1, 2018, File No. 333-227547)
2.2		First Amendment to Agreement and Plan of Merger and Reorganization, dated as of August 8, 2018, by and among OvaScience, Inc., Orion Merger Sub, Inc. and Millendo Therapeutics, Inc. (incorporated by reference from Annex A to Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange Commission on November 1, 2018, File No. 333-227547)
2.3		Second Amendment to Agreement and Plan of Merger and Reorganization, dated as of August 8, 2018, by and among OvaScience, Inc., Orion Merger Sub, Inc. and Millendo Therapeutics, Inc. (incorporated by reference from Annex A to Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange Commission on November 1, 2018, File No. 333-227547)
4.1		Restated Certificate of Incorporation of OvaScience, Inc. (incorporated by reference from the Current Report on Form 8-K filed by the Registrant on April 30, 2013, File No. 001-35890)
4.2		Third Amended and Restated Bylaws, as amended, of OvaScience, Inc. (incorporated by reference from the Current Report on Form 8-K filed by the Registrant on August 9, 2018, File No. 001-35890).
4.3		Specimen Stock Certificate evidencing shares of Common Stock of OvaScience, Inc. (incorporated by reference to the Registration Statement on Form S-1 filed by the registrant on August 29, 2012, File No. 333-183602)
4.4		Registration Rights Agreement, dated November 1, 2018, by and among OvaScience, Inc. and the persons listed on Schedule A thereto (incorporated by reference from Exhibit 10.46 to Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange Commission on November 1, 2018, File No. 333-227547).
4.5		Stock Purchase Agreement, dated November 1, 2018, by and among OvaScience, Inc., the purchasers set forth on Schedule I thereto and Millendo Therapeutics, Inc. (incorporated by reference from Exhibit 10.45 to Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange Commission on November 1, 2018, File No. 333-227547).
4.6	*	Second Amended and Restated Investor Rights Agreement by and among Millendo Therapeutics, Inc. and certain of its stockholders, dated December 19, 2017.
4.7	*	First Amendment to Second Amended and Restated Investor Rights Agreement, dated October 24, 2018.
4.8	*	Shareholders and Option Agreement, by and between Millendo Therapeutics, Inc. and Otonnale SAS, dated December 19, 2017.
4.9	*	First Amendment to Shareholders and Option Agreement, dated September 28, 2018.

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		Description

5.1	*	Opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. regarding the validity of the securities.
10.1	*	Lease Agreement, by and between Millendo Therapeutics, Inc. and 301 N. Main Street, L.L.C., dated December 31, 2015.
10.2	*	Lease Extension and Modification Agreement, by and between Millendo Therapeutics, Inc. and 301 N. Main Street, L.L.C., dated November 30, 2017.
10.3	*	Lease Extension and Modification Agreement, by and between Millendo Therapeutics, Inc. and 301 N. Main Street, L.L.C., dated October 22, 2018.
10.4	*#	Amendment No. 1 to the Atterocor, Inc. (n/k/a Millendo Therapeutics, Inc.) 2012 Stock Plan, dated December 17, 2015.
10.5	*#	Millendo Therapeutics, Inc. Amendment to 2012 Stock Plan, dated June 21, 2018.
23.1	*	Consent of Ernst & Young LLP, Independent Registered Public Accounting Firm to OvaScience, Inc.
23.2	*	Consent of Ernst & Young LLP, Independent Auditors to Millendo Therapeutics, Inc.
23.3	*	Consent of RSM Rhône-Alpes, Independent Auditors to Millendo Therapeutics SAS
23.4	*	Consent of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. (included in Exhibit 5.1)
24.1		Power of Attorney (included on the signature page of this Registration Statement)

*: Filed herewith.
#: Indicates a management contract or compensatory plan, contract or arrangement.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Waltham, Commonwealth of Massachusetts, on the 6th day of November, 2018.


		OvaScience, Inc.
		By:		/s/ CHRISTOPHER A. KROEGER, M.D., M.B.A. Christopher A. Kroeger, M.D., M.B.A. President and Chief Executive Officer

POWER OF ATTORNEY

Each person whose signature appears below hereby constitutes and appoints Christopher A. Kroeger, M.D., M.B.A. and Jonathan Gillis, and each of them, as his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments and registration statements filed pursuant to Rule 462) to this registration statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent or his substitutes or substitute, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement on Form S-3 has been signed by the following persons in the capacities and on the dates indicated.

Name	Title	Date


/s/ CHRISTOPHER A. KROEGER, M.D., M.B.A. Christopher A. Kroeger, M.D., M.B.A.	President and Chief Executive Officer (Principal Executive Officer)	November 6, 2018
/s/ JONATHAN GILLIS Jonathan Gillis	Senior Vice President, Finance (Principal Financial Officer)	November 6, 2018
/s/ JEFFREY D. CAPELLO Jeffrey D. Capello	Director	November 6, 2018
/s/ RICHARD ALDRICH Richard Aldrich	Director	November 6, 2018

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Name	Title	Date


/s/ MARY FISHER Mary Fisher	Director	November 6, 2018
/s/ JOHN P. HOWE, III, M.D. John P. Howe, III, M.D.	Director	November 6, 2018
/s/ MARC KOZIN Marc Kozin	Director	November 6, 2018
/s/ JOHN SEXTON, PH.D. John Sexton, Ph.D.	Director	November 6, 2018

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Exhibit 4.6

EXECUTION VERSION

MILLENDO THERAPEUTICS , INC.

SECOND AMENDED AND RESTATED
INVESTOR RIGHTS AGREEMENT

THIS SECOND AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT (the “ Agreement ”) is entered into as of the 19th day of December, 2017, by and among MILLENDO THERAPEUTICS, INC. , a Delaware corporation (formerly known as Atterocor, Inc.) (the “ Company ”), the persons or entities listed on Exhibit A hereto, referred to hereinafter as the “ Investors ” and each individually as an “ Investor ”.

RECITALS

WHEREAS , certain of the Investors (the “ Existing Investors ”) hold shares of the Company’s Series A Preferred Stock, par value $0.001 per share (the “ Series A Preferred Stock ”), Series B Preferred Stock, par value $0.001 per share (the “ Series B Preferred Stock ”), and/or shares of Common Stock issued upon conversion thereof and possess registration rights, information rights, rights of first offer and other rights pursuant to that certain Amended and Restated Investor Rights Agreement dated as of December 18, 2015 by and among the Company and such Existing Investors (the “ Prior Agreement ”);

WHEREAS , the Prior Agreement may be amended, and any provision therein waived, with the consent of the Company and the holders of a majority of the outstanding Registrable Securities (as such term is defined in the Prior Agreement);

WHEREAS , the Existing Investors as holders of a majority of the outstanding Registrable Securities (as such term is defined in the Prior Agreement) of the Company desire to terminate the Prior Agreement and to accept the rights created pursuant hereto in lieu of the rights granted to them under the Prior Agreement;

WHEREAS, certain Investors are acquiring shares of the Company’s Series A-1 Preferred Stock, par value $0.001 per share (the “ Series A-1 Preferred Stock ”) and Series B-1 Preferred Stock, par value $0.001 per share (the “ Series B-1 Preferred Stock ”) pursuant to that certain Share Sale and Contribution Agreement, by and among the Company, the shareholders of Alizé Pharma SAS (“ Alizé ”), Alizé, the Manager (as defined therein), the Contributing Holder Representative (as defined therein) and Eumedix FR S.À. R.L. (the “ Share Contribution Agreement ”) of even date herewith (the “ Transaction ”);

WHEREAS, the obligations in the Share Contribution Agreement are conditioned upon the execution and delivery of this Agreement; and

WHEREAS, in connection with the consummation of the Transaction, the parties desire to enter into this Agreement in order to grant registration rights, information rights and other rights to the Investors as set forth below.

NOW, THEREFORE, in consideration of these premises and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

AGREEMENT

SECTION 1. GENERAL.

1.1 Definitions . As used in this Agreement the following terms shall have the following respective meanings:

(a) “ Affiliate ” means, with respect to any specified Person, any other Person who, directly or indirectly, controls, is controlled by, or is under common control with such Person, including without limitation any general partner, managing member, officer or director of such Person or any venture capital fund now or hereafter existing that is controlled by one or more general partners or managing members of, or shares the same management company with, such Person.

(b) “ Anti-Corruption Laws ” means, in the case of U.S. persons or entities, the U.S. Foreign Corrupt Practices Act of 1977, as amended, and any foreign laws or regulations with an extraterritorial scope relating to anti-bribery applicable to such persons or entities, and, in the case of French persons or entities, any applicable French legislation relating to anti-bribery including but not limited to provisions of Titles III and IV, Book IV of the French Criminal Code, as amended, and any foreign laws or regulations with an extraterritorial scope relating to anti-bribery applicable to such persons or entities.

(c) “ Anti-Money Laundering Laws ” means, in the case of U.S. persons or entities, any US and foreign laws or regulations with an extraterritorial scope relating to anti-money laundering applicable to such persons or entities, and, in the case of French persons or entities, any applicable French legislation relating to anti-money laundering including but not limited to provisions of Title VI, Book V of the French Monetary and Financial Code, as amended, and any foreign laws or regulations with an extraterritorial scope relating to anti- money laundering applicable to such persons or entities.

(d) “Class Common-1 Stock” shall have the meaning ascribed to such term in the Charter.

(e) “Common Shares” shall have the meaning ascribed to such term in the Charter.

(f) “Common Stock” shall have the meaning ascribed to such term in the Charter.

(g) “Convertible Stock” shall have the meaning ascribed to such term in the Charter.

(h) “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

(i) “Form S-3” means such form under the Securities Act as in effect on the date hereof or any successor or similar registration form under the Securities Act subsequently adopted by the SEC which permits inclusion or incorporation of substantial information by reference to other documents filed by the Company with the SEC.

(j) “Holder” means any person owning of record Registrable Securities that have not been sold to the public or any assignee of record of such Registrable Securities in accordance with Section 2.9 hereof.

(k) “Initial Offering” means the Company’s first firm commitment underwritten public offering of its Common Stock registered under the Securities Act.

(l) “New Preferred Stock” means, collectively, the Series A-1 Preferred Stock and the Series B-1 Preferred Stock.

(m) “Preferred Stock” means, collectively, the Series A Preferred Stock, the Series A-1 Preferred Stock, the Series B Preferred Stock and the Series B-1 Preferred Stock.

(n) “Register,” “registered,” and “registration” refer to a registration effected by preparing and filing a registration statement in compliance with the Securities Act, and the declaration or ordering of effectiveness of such registration statement or document.

(o) “Registrable Securities” means (a) Common Stock of the Company issuable or issued upon conversion of the Shares and (b) any Common Stock of the Company issued as (or issuable upon the conversion or exercise of any warrant, right or other security which is issued as) a dividend or other distribution with respect to, or in exchange for or in replacement of, such above-described securities. Notwithstanding the foregoing, Registrable Securities shall not include any securities (i) sold by a person to the public either pursuant to a registration statement or Rule 144 or (ii) sold in a private transaction in which the transferor’s rights under Section 2 of this Agreement are not assigned.

(p) “Registrable Securities then outstanding” shall be the number of shares of the Company’s Common Stock that are Registrable Securities and either (a) are then issued and outstanding or (b) are issuable pursuant to then exercisable or convertible securities.

(q) “Registration Expenses” shall mean all expenses incurred by the Company in complying with Sections 2.2, 2.3 and 2.4 hereof, including, without limitation, all registration and filing fees, printing expenses, fees and disbursements of counsel for the Company, reasonable fees and disbursements not to exceed thirty-seven thousand five hundred dollars ($37,500) of a single special counsel for the Holders, blue sky fees and expenses and the expense of any special audits incident to or required by any such registration (but excluding the compensation of regular employees of the Company which shall be paid in any event by the Company).

(r) “SEC” or “Commission” means the Securities and Exchange Commission.

(s) “Securities Act” shall mean the Securities Act of 1933, as amended.

(t) “Selling Expenses” means all underwriting discounts, selling commissions, and stock transfer taxes applicable to the sale of Registrable Securities, and fees and disbursements of counsel for any Holder, except for the fees and disbursements of the Selling Holder Counsel borne and paid by the Company as provided in Section 2.5.

(u) “Shares” shall mean the Series A Preferred Stock, Series A-1 Preferred Stock, Series B Preferred Stock, Series B-1 Preferred Stock, the Class Common-1 Stock and any other Common Stock held from time to time by the Investors listed on Exhibit A hereto and their permitted assigns.

(v) “Special Registration Statement” shall mean (i) a registration statement relating to any employee benefit plan or (ii) with respect to any corporate reorganization or transaction under Rule 145 of the Securities Act, any registration statements related to the issuance or resale of securities issued in such a transaction or (iii) a registration related to stock issued upon conversion of debt securities.

SECTION 2. REGISTRATION; RESTRICTIONS ON TRANSFER.

2.1 Restrictions on Transfer.

(a) Each Holder agrees not to make any disposition of all or any portion of the Shares or Registrable Securities unless and until:

(i) there is then in effect a registration statement under the Securities Act covering such proposed disposition and such disposition is made in accordance with such registration statement; or

(ii) (A) the transferee has agreed in writing to be bound by the terms of this Agreement, (B) such Holder shall have notified the Company of the proposed disposition and shall have furnished the Company with a detailed statement of the circumstances surrounding the proposed disposition, and (C) if reasonably requested by the Company, such Holder shall have furnished the Company with an opinion of counsel, reasonably satisfactory to the Company, that such disposition will not require registration of such shares under the Securities Act. It is agreed that the Company will not require opinions of counsel for transactions made pursuant to Rule 144, except in unusual circumstances. After its Initial Offering, the Company will not require any transferee pursuant to Rule 144 to be bound by the terms of this Agreement if the shares so transferred do not remain Registrable Securities hereunder following such transfer.

(b) Notwithstanding the provisions of subsection (a) above, no such restriction shall apply to a transfer by a Holder that is (i) a partnership transferring to its partners or former partners in accordance with partnership interests, (ii) a partnership transferring to one or more affiliated partnerships or funds managed by it or any of its respective directors, officers or partners, (iii) a corporation transferring to a wholly-owned subsidiary or a parent corporation that owns all of the capital stock of the Holder, (iv) a limited liability company transferring to its members or former members in accordance with their interest in the limited liability company, or (v) an individual transferring to the Holder’s family member or trust for the benefit of an individual

Holder; provided that in each case the transferee will agree in writing to be subject to the terms of this Agreement to the same extent as if he were an original Holder hereunder.

(c) Each certificate representing Shares or Registrable Securities shall be stamped or otherwise imprinted with legends substantially similar to the following (in addition to any legend required under applicable state securities laws):

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE “ ACT ”) AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, ASSIGNED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT OR UNLESS THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY AND ITS COUNSEL THAT SUCH REGISTRATION IS NOT REQUIRED.

THE SALE, PLEDGE, HYPOTHECATION OR TRANSFER OF THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO THE TERMS AND CONDITIONS OF A CERTAIN INVESTOR RIGHTS AGREEMENT BY AND BETWEEN THE STOCKHOLDER AND THE COMPANY. COPIES OF SUCH AGREEMENT MAY BE OBTAINED UPON WRITTEN REQUEST TO THE SECRETARY OF THE COMPANY.

(d) The Company shall be obligated to reissue promptly unlegended certificates at the request of any Holder thereof if the Company has completed its Initial Offering and the Holder shall have obtained an opinion of counsel (which counsel may be counsel to the Company) reasonably acceptable to the Company to the effect that the securities proposed to be disposed of may lawfully be so disposed of without registration, qualification and legend, provided that the second legend listed above shall be removed only at such time as the Holder of such certificate is no longer subject to any restrictions hereunder.

(e) Any legend endorsed on an instrument pursuant to applicable state securities laws and the stop-transfer instructions with respect to such securities shall be removed upon receipt by the Company of an order of the appropriate blue sky authority authorizing such removal.

2.2 Demand Registration.

(a) Subject to the conditions of this Section 2.2, if the Company shall receive a written request from the Holders of at least twenty percent (20%) of the Registrable Securities (the “ Initiating Holders ”) that the Company file a registration statement under the Securities Act covering the registration of at least forty percent (40%) of the Registrable Securities then outstanding (or a lesser percent if the anticipated aggregate offering price, net of underwriting discounts and commissions, would exceed $10,000,000), then the Company shall, within fifteen (15) days of the receipt thereof, give written notice of such request to all Holders, and subject to

the limitations of this Section 2.2, as soon as practicable, and in any event within sixty (60) days after the date such request is given by the Initiating Holders, file a registration statement under the Securities Act covering all Registrable Securities that the Initiating Holders requested to be registered and any additional Registrable Securities requested to be included in such registration by any other Holders, and effect, as expeditiously as reasonably possible, the registration under the Securities Act of all Registrable Securities that all Holders request to be registered.

(b) If the Initiating Holders intend to distribute the Registrable Securities covered by their request by means of an underwriting, they shall so advise the Company as a part of their request made pursuant to this Section 2.2 or any request pursuant to Section 2.4 and the Company shall include such information in the written notice referred to in Section 2.2(a) or Section 2.4(a), as applicable. In such event, the right of any Holder to include its Registrable Securities in such registration shall be conditioned upon such Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting to the extent provided herein. All Holders proposing to distribute their securities through such underwriting shall enter into an underwriting agreement in customary form with the underwriter or underwriters selected for such underwriting by the Holders of a majority of the Registrable Securities held by all Initiating Holders (which underwriter or underwriters shall be reasonably acceptable to the Company). Notwithstanding any other provision of this Section 2.2 or Section 2.4, if the underwriter advises the Company in writing that marketing factors require a limitation of the number of securities to be underwritten (including Registrable Securities) then the Company shall so advise all Holders of Registrable Securities that would otherwise be underwritten pursuant hereto, and the number of shares that may be included in the underwriting shall be allocated to the Holders of such Registrable Securities on a pro rata basis based on the number of Registrable Securities held by all such Holders (including the Initiating Holders ) ; provided, however , that the number of shares of Registrable Securities to be included in such underwriting and registration shall not be reduced unless all other securities of the Company are first entirely excluded from the underwriting and registration. Any Registrable Securities excluded or withdrawn from such underwriting shall be withdrawn from the registration.

(c) The Company shall not be required to effect a registration pursuant to this Section 2.2:

(i) prior to the earlier of (A) the fifth (5 th ) anniversary of the date of this Agreement or (B) the expiration of the restrictions on transfer set forth in Section 2.11 following the Initial Offering;

(ii) after the Company has effected one (1) registration pursuant to this Section 2.2, and such registration have been declared or ordered effective;

(iii) during the period starting with the date of filing of, and ending on the date one hundred eighty (180) days following the effective date of the registration statement pertaining to the Initial Offering (or such longer period as may be determined pursuant to Section 2.11 hereof); provided that the Company makes reasonable good faith efforts to cause such registration statement to become effective;

(iv) if within thirty (30) days of receipt of a written request from Initiating Holders pursuant to Section 2.2(a), the Company gives notice to the Holders of the Company’s intention to file a registration statement for its Initial Offering within ninety (90) days;

(v) if the Company shall furnish to Holders requesting a registration statement pursuant to this Section 2.2 a certificate signed by the Chairman of the Board stating that in the good faith judgment of the Board of Directors of the Company (the “ Board ”), such registration would (i) materially interfere with a significant acquisition, corporate reorganization, or other similar transaction involving the Company; (ii) require premature disclosure of material information that the Company has a bona fide business purpose for preserving as confidential; or (iii) render the Company unable to comply with requirements under the Securities Act or Exchange Act, in which event the Company shall have the right to defer such filing for a period of not more than one hundred twenty (120) days after receipt of the request of the Initiating Holders; provided that such right to delay a request shall be exercised by the Company not more than once in any twelve (12) month period;

(vi) if the Initiating Holders propose to dispose of shares of Registrable Securities that may be immediately registered on Form S-3 pursuant to a request made pursuant to Section 2.4 below; or

(vii) in any particular jurisdiction in which the Company would be required to qualify to do business or to execute a general consent to service of process in effecting such registration, qualification or compliance.

2.3 Piggyback Registrations. The Company shall notify all Holders of Registrable Securities in writing at least fifteen (15) days prior to the filing of any registration statement under the Securities Act for purposes of a public offering of securities of the Company (including, but not limited to, registration statements relating to secondary offerings of securities of the Company, but excluding Special Registration Statements) and will afford each such Holder an opportunity to include in such registration statement all or part of such Registrable Securities held by such Holder. Each Holder desiring to include in any such registration statement all or any part of the Registrable Securities held by it shall, within fifteen (15) days after the above-described notice from the Company, so notify the Company in writing. Such notice shall state the intended method of disposition of the Registrable Securities by such Holder. If a Holder decides not to include all of its Registrable Securities in any registration statement thereafter filed by the Company, such Holder shall nevertheless continue to have the right to include any Registrable Securities in any subsequent registration statement or registration statements as may be filed by the Company with respect to offerings of its securities, all upon the terms and conditions set forth herein.

(a) Underwriting. If the registration statement of which the Company gives notice under this Section 2.3 is for an underwritten offering, the Company shall so advise the Holders of Registrable Securities. In such event, the right of any such Holder to include Registrable Securities in a registration pursuant to this Section 2.3 shall be conditioned upon such Holder’s participation in such underwriting and the inclusion of such Holder’s Registrable Securities in the underwriting to the extent provided herein. All Holders proposing to distribute their Registrable Securities through such underwriting shall enter into an underwriting agreement in customary form with the underwriter or underwriters selected for such underwriting by the

Company. Notwithstanding any other provision of this Agreement, if the Company determines in good faith, based on consultation with the underwriter, that marketing factors require a limitation of the number of shares to be underwritten, the number of shares that may be included in the underwriting shall be allocated, first, to the Company; second, to the Holders on a pro rata basis based on the total number of Registrable Securities held by the Holders; and third, to any stockholder of the Company (other than a Holder) on a pro rata basis; provided, however, that no such reduction shall reduce the amount of securities of the selling Holders included in the registration below thirty percent (30%) of the total amount of securities included in such registration, unless such offering is the Initial Offering and such registration does not include shares of any other selling stockholders, in which event any or all of the Registrable Securities of the Holders may be excluded in accordance with the immediately preceding clause. In no event will shares of any other selling stockholder be included in such registration that would reduce the number of shares which may be included by Holders without the written consent of Holders of a majority of the Registrable Securities proposed to be sold in the offering. If any Holder disapproves of the terms of any such underwriting, such Holder may elect to withdraw therefrom by written notice to the Company and the underwriter, delivered at least ten (10) business days prior to the effective date of the registration statement. Any Registrable Securities excluded or withdrawn from such underwriting shall be excluded and withdrawn from the registration. For any Holder which is a partnership, limited liability company or corporation, the partners, retired partners, members, retired members and stockholders of such Holder, or the estates and family members of any such partners, retired partners, members and retired members and any trusts for the benefit of any of the foregoing person shall be deemed to be a single “Holder,” and any pro rata reduction with respect to such “Holder” shall be based upon the aggregate amount of shares carrying registration rights owned by all entities and individuals included in such “Holder,” as defined in this sentence.

(b) Right to Terminate Registration. The Company shall have the right to terminate or withdraw any registration initiated by it under this Section 2.3 whether or not any Holder has elected to include securities in such registration, and shall promptly notify any Holder that has elected to include shares in such registration of such termination or withdrawal. The Registration Expenses of such withdrawn registration shall be borne by the Company in accordance with Section 2.5 hereof.

2.4 Form S-3 Registration. If at any time when it is eligible to use a Form S-3 registration statement, the Company shall receive from the Initiating Holders a written request or requests that the Company effect a registration on Form S-3 (or any successor to Form S-3) or any similar short-form registration statement and any related qualification or compliance with respect to all or a part of the Registrable Securities owned by such Holder or Holders, the Company will:

(a) promptly give written notice of the proposed registration, and any related qualification or compliance, to all other Holders of Registrable Securities; and

(b) as soon as practicable, and in any event within sixty (60) days after the date such request is given by the Initiating Holders, effect such registration and all such qualifications and compliances as may be so requested and as would permit or facilitate the sale and distribution of all or such portion of such Holder’s or Holders’ Registrable Securities as are specified in such request, together with all or such portion of the Registrable Securities of any other Holder or

Holders joining in such request as are specified in a written request given within fifteen (15) days after receipt of such written notice from the Company; provided, however , that the Company shall not be obligated to effect any such registration, qualification or compliance pursuant to this Section 2.4:

(i) if Form S-3 is not available for such offering by the Holders, or

(ii) if the Holders, together with the holders of any other securities of the Company entitled to inclusion in such registration, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public of less than one million dollars ($1,000,000), or

(iii) if within thirty (30) days of receipt of a written request from any Holder or Holders pursuant to this Section 2.4, the Company gives notice to such Holder or Holders of the Company’s intention to make a public offering within ninety (90) days, other than pursuant to a Special Registration Statement, or

(iv) if the Company shall furnish to the Holders a certificate signed by the Chairman of the Board stating that in the good faith judgment of the Board, such registration would (i) materially interfere with a significant acquisition, corporate reorganization, or other similar transaction involving the Company; (ii) require premature disclosure of material information that the Company has a bona fide business purpose for preserving as confidential; or (iii) render the Company unable to comply with requirements under the Securities Act or Exchange Act, in which event the Company shall have the right to defer the filing of the Form S-3 registration statement for a period of not more than one hundred twenty (120) days after receipt of the request of the Holder or Holders under this Section 2.4; provided , that such right to delay a request shall be exercised by the Company not more than once in any twelve (12) month period, or

(v) if the Company has, within the twelve (12) month period preceding the date of such request, already effected two (2) registrations on Form S-3 for the Holders pursuant to this Section 2.4, or

(vi) in any particular jurisdiction in which the Company would be required to qualify to do business or to execute a general consent to service of process in effecting such registration, qualification or compliance.

(c) Subject to the foregoing, the Company shall file a Form S-3 registration statement covering the Registrable Securities and other securities so requested to be registered as soon as practicable after receipt of the requests of the Holders. Registrations effected pursuant to this Section 2.4 shall not be counted as demands for registration or registrations effected pursuant to Section 2.2.

2.5 Expenses of Registration. All expenses (other than Selling Expenses) incurred in connection with registrations, filings, or qualifications pursuant to Section 2, including all registration, filing, and qualification fees; printers’ and accounting fees; fees and disbursements of counsel for the Company; and the reasonable fees and disbursements, not to exceed thirty-five thousand dollars ($35,000), of one counsel for the selling Holders (“ Selling Holder Counsel ”), shall be borne and paid by the Company. All Selling Expenses incurred in connection with any

registrations hereunder, shall be borne by the holders of the securities so registered pro rata on the basis of the number of shares so registered; provided , however , the Company shall not be required to pay for expenses of any registration proceeding begun pursuant to Section 2.2 or 2.4, the request of which has been subsequently withdrawn by the Initiating Holders unless (a) the withdrawal is based upon material adverse information concerning the Company of which the Initiating Holders were not aware at the time of such request or (b) the Holders of a majority of Registrable Securities agree to deem such registration to have been effected as of the date of such withdrawal for purposes of determining whether the Company shall be obligated pursuant to Section 2.2(c) or 2.4(b)(v), as applicable, to undertake any subsequent registration, in which event such right shall be forfeited by all Holders). If the Holders are required to pay the Registration Expenses, such expenses shall be borne by the holders of securities (including Registrable Securities) requesting such registration in proportion to the number of shares for which registration was requested. If the Company is required to pay the Registration Expenses of a withdrawn offering pursuant to clause (a) above, then such registration shall not be deemed to have been effected for purposes of determining whether the Company shall be obligated pursuant to Section 2.2(c) or 2.4(b)(v), as applicable, to undertake any subsequent registration.

2.6 Obligations of the Company. Whenever required to effect the registration of any Registrable Securities, the Company shall, as expeditiously as reasonably possible:

(a) prepare and file with the SEC a registration statement with respect to such Registrable Securities and use all reasonable efforts to cause such registration statement to become effective, and, upon the request of the Holders of a majority of the Registrable Securities registered thereunder, keep such registration statement effective for up to one hundred and twenty (120) days or, if earlier, until the Holder or Holders have completed the distribution related thereto; provided, however, that at any time, upon written notice to the participating Holders and for a period not to exceed sixty (60) days thereafter (the “ Suspension Period ”), the Company may delay the filing or effectiveness of any registration statement or suspend the use or effectiveness of any registration statement (and the Initiating Holders hereby agree not to offer or sell any Registrable Securities pursuant to such registration statement during the Suspension Period) if the Company reasonably believes that there is or may be in existence material nonpublic information or events involving the Company, the failure of which to be disclosed in the prospectus included in the registration statement could result in a Violation (as defined below). In the event that the Company shall exercise its right to delay or suspend the filing or effectiveness of a registration hereunder, the applicable time period during which the registration statement is to remain effective shall be extended by a period of time equal to the duration of the Suspension Period. The Company may extend the Suspension Period for an additional consecutive thirty (30) days with the consent of the holders of at least a majority of the Registrable Securities registered under the applicable registration statement, which consent shall not be unreasonably withheld. No more than two such Suspension Periods shall occur in any twelve (12) month period. If so directed by the Company, all Holders registering shares under such registration statement shall (i) not offer to sell any Registrable Securities pursuant to the registration statement during the period in which the delay or suspension is in effect after receiving notice of such delay or suspension; and (ii) use their reasonable efforts to deliver to the Company (at the Company’s expense) all copies, other than permanent file copies then in such Holders’ possession, of the prospectus relating to such Registrable Securities current at the time of receipt of such notice. Notwithstanding the foregoing, the Company shall not be required to file, cause to become effective or maintain the effectiveness

of any registration statement other than a registration statement on Form S-3 that contemplates a distribution of securities on a delayed or continuous basis pursuant to Rule 415 under the Securities Act.

(b) Prepare and file with the SEC such amendments and supplements to such registration statement and the prospectus used in connection with such registration statement as may be necessary to comply with the provisions of the Securities Act with respect to the disposition of all securities covered by such registration statement for the period set forth in subsection (a) above.

(c) Furnish to the Holders such number of copies of a prospectus, including a preliminary prospectus, in conformity with the requirements of the Securities Act, and such other documents as they may reasonably request in order to facilitate the disposition of Registrable Securities owned by them.

(d) Use its commercially reasonable efforts to register and qualify the securities covered by such registration statement under such other securities or Blue Sky laws of such jurisdictions as shall be reasonably requested by the Holders; provided that the Company shall not be required in connection therewith or as a condition thereto to qualify to do business or to file a general consent to service of process in any such states or jurisdictions.

(e) In the event of any underwritten public offering, enter into and perform its obligations under an underwriting agreement, in usual and customary form, with the managing underwriter(s) of such offering. Each Holder participating in such underwriting shall also enter into and perform its obligations under such an agreement.

(f) Notify each Holder of Registrable Securities covered by such registration statement at any time when a prospectus relating thereto is required to be delivered under the Securities Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, includes an untrue statement of a material fact or omits to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing. The Company will use reasonable efforts to amend or supplement such prospectus in order to cause such prospectus not to include any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing.

(g) Use its reasonable efforts to furnish, on the date that such Registrable Securities are delivered to the underwriters for sale, if such securities are being sold through underwriters, (i) an opinion, dated as of such date, of the counsel representing the Company for the purposes of such registration, in form and substance as is customarily given to underwriters in an underwritten public offering, addressed to the underwriters, if any, and (ii) a letter, dated as of such date, from the independent certified public accountants of the Company, in form and substance as is customarily given by independent certified public accountants to underwriters in an underwritten public offering addressed to the underwriters.

2.7 Delay of Registration; Furnishing Information.

(a) No Holder shall have any right to obtain or seek an injunction restraining or otherwise delaying any such registration as the result of any controversy that might arise with respect to the interpretation or implementation of this Section 2.

(b) It shall be a condition precedent to the obligations of the Company to take any action pursuant to Sections 2.2, 2.3 or 2.4 that the selling Holders shall furnish to the Company such information regarding themselves, the Registrable Securities held by them and the intended method of disposition of such securities as shall be required to effect the registration of their Registrable Securities.

(c) The Company shall have no obligation with respect to any registration requested pursuant to Section 2.2 or Section 2.4 if the number of shares or the anticipated aggregate offering price of the Registrable Securities to be included in the registration does not equal or exceed the number of shares or the anticipated aggregate offering price required to originally trigger the Company’s obligation to initiate such registration as specified in Section 2.2 or Section 2.4, whichever is applicable.

2.8 Indemnification. In the event any Registrable Securities are included in a registration statement under Sections 2.2, 2.3 or 2.4:

(a) To the extent permitted by law, the Company will indemnify and hold harmless each Holder, the partners, members, officers and directors of each Holder; any underwriter (as defined in the Securities Act) for such Holder and each person, if any, who controls such Holder or underwriter within the meaning of the Securities Act or the Exchange Act, against any losses, claims, damages, or liabilities (joint or several) to which they may become subject under the Securities Act, the Exchange Act or other federal or state law, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any of the following statements, omissions or violations (collectively a “ Violation ”) by the Company: (i) any untrue statement or alleged untrue statement of a material fact contained in such registration statement or incorporated reference therein, including any preliminary prospectus or final prospectus contained therein or any amendments or supplements thereto, (ii) the omission or alleged omission to state therein a material fact required to be stated therein, or necessary to make the statements therein not misleading, or (iii) any violation or alleged violation by the Company of the Securities Act, the Exchange Act, any state securities law or any rule or regulation promulgated under the Securities Act, the Exchange Act or any state securities law in connection with the offering covered by such registration statement; and the Company will reimburse each such Holder, partner, member, officer, director, underwriter or controlling person for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however , that the indemnity agreement contained in this Section 2.8(a) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such settlement is effected without the consent of the Company, which consent shall not be unreasonably withheld, nor shall the Company be liable in any such case for any such loss, claim, damage, liability or action to the extent that it arises out of or is based upon a Violation which occurs in reliance upon and in conformity with written information furnished expressly for use in connection with such registration by such Holder, partner, member, officer, director, underwriter or controlling person of such Holder.

(b) To the extent permitted by law, each Holder will, if Registrable Securities held by such Holder are included in the securities as to which such registration qualifications or compliance is being effected, indemnify and hold harmless the Company, each of its directors, its officers and each person, if any, who controls the Company within the meaning of the Securities Act, any underwriter and any other Holder selling securities under such registration statement or any of such other Holder’s partners, directors or officers or any person who controls such Holder, against any losses, claims, damages or liabilities (joint or several) to which the Company or any such director, officer, controlling person, underwriter or other such Holder, or partner, director, officer or controlling person of such other Holder may become subject under the Securities Act, the Exchange Act or other federal or state law, insofar as such losses, claims, damages or liabilities (or actions in respect thereto) arise out of or are based upon any of the following statements: (i) any untrue statement or alleged untrue statement of a material fact contained in such registration statement or incorporated reference therein, including any preliminary prospectus or final prospectus contained therein or any amendments or supplements thereto, (ii) the omission or alleged omission to state therein a material fact required to be stated therein, or necessary to make the statements therein not misleading, or (iii) any violation or alleged violation by the Company of the Securities Act (collectively, a “ Holder Violation ”), in each case to the extent (and only to the extent) that such Holder Violation occurs in reliance upon and in conformity with written information furnished by such Holder under an instrument duly executed by such Holder and stated to be specifically for use in connection with such registration; and each such Holder will reimburse any legal or other expenses reasonably incurred by the Company or any such director, officer, controlling person, underwriter or other Holder, or partner, officer, director or controlling person of such other Holder in connection with investigating or defending any such loss, claim, damage, liability or action if it is judicially determined that there was such a Holder Violation; provided, however, that the indemnity agreement contained in this Section 2.8(b) shall not apply to amounts paid in settlement of any such loss, claim, damage, liability or action if such settlement is effected without the consent of the Holder, which consent shall not be unreasonably withheld; provided further , that in no event shall any indemnity under this Section 2.8 exceed the net proceeds from the offering received by such Holder.

(c) Promptly after receipt by an indemnified party under this Section 2.8 of notice of the commencement of any action (including any governmental action), such indemnified party will, if a claim in respect thereof is to be made against any indemnifying party under this Section 2.8, deliver to the indemnifying party a written notice of the commencement thereof and the indemnifying party shall have the right to participate in, and, to the extent the indemnifying party so desires, jointly with any other indemnifying party similarly noticed, to assume the defense thereof with counsel mutually satisfactory to the parties; provided, however, that an indemnified party shall have the right to retain its own counsel, with the fees and expenses thereof to be paid by the indemnifying party, if representation of such indemnified party by the counsel retained by the indemnifying party would be inappropriate due to actual or potential differing interests between such indemnified party and any other party represented by such counsel in such proceeding. The failure to deliver written notice to the indemnifying party within a reasonable time of the commencement of any such action shall relieve such indemnifying party of any liability to the indemnified party under this Section 2.8 to the extent, and only to the extent, prejudicial to its ability to defend such action, but the omission so to deliver written notice to the indemnifying party will not relieve it of any liability that it may have to any indemnified party otherwise than under this Section 2.8.

(d) If the indemnification provided for in this Section 2.8 is held by a court of competent jurisdiction to be unavailable to an indemnified party with respect to any loses, claims, damages or liabilities referred to herein, the indemnifying party, in lieu of indemnifying such indemnified party thereunder, shall to the extent permitted by applicable law contribute to the amount paid or payable by such indemnified party as a result of such loss, claim, damage or liability in such proportion as is appropriate to reflect the relative fault of the indemnifying party on the one hand and of the indemnified party on the other in connection with the Violation(s) or Holder Violation(s) that resulted in such loss, claim, damage or liability,as well as any other relevant equitable considerations. The relative fault of the indemnifying party and of the indemnified party shall be determined by a court of law by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission to state a material fact relates to information supplied by the indemnifying party or by the indemnified party and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission; provided that in no event shall any contribution by a Holder hereunder exceed the proceeds from the offering received by such Holder.

(e) The obligations of the Company and Holders under this Section 2.8 shall survive completion of any offering of Registrable Securities in a registration statement and, with respect to liability arising from an offering to which this Section 2.8 would apply that is covered by a registration filed before termination of this Agreement, such termination. No indemnifying party, in the defense of any such claim or litigation, shall, except with the consent of each indemnified party, consent to entry of any judgment or enter into any settlement which does not include as an unconditional term thereof the giving by the claimant or plaintiff to such Indemnified Party of a release from all liability in respect to such claim or litigation.

2.9 Assignment of Registration Rights. The rights to cause the Company to register Registrable Securities pursuant to this Section 2 may be assigned by a Holder to a transferee or assignee of Registrable Securities (for so long as such shares remain Registrable Securities) that (a) is a subsidiary, parent, general partner, limited partner, retired partner, member or retired member, or stockholder of a Holder that is a corporation, partnership or limited liability company, (b) is a Holder’s family member or trust for the benefit of an individual Holder, (c) acquires at least five hundred thousand (500,000) shares of Registrable Securities (as adjusted for stock splits and combinations), or (d) is an entity affiliated by common control (or other related entity) with such Holder; provided, however, (i) the transferor shall, within ten (10) days after such transfer, furnish to the Company written notice of the name and address of such transferee or assignee and the securities with respect to which such registration rights are being assigned and (ii) such transferee shall agree to be subject to all restrictions set forth in this Agreement.

2.10 Limitation on Subsequent Registration Rights. Other than as provided in Section 5.10, after the date of this Agreement, the Company shall not enter into any agreement with any holder or prospective holder of any securities of the Company that would grant such holder rights to demand the registration of shares of the Company’s capital stock, or to include such shares in a registration statement that would reduce the number of shares includable by the Holders.

2.11 Market Stand-Off Agreement. To the extent required (and such requirement is made in writing to the Holders) by the Company or the underwriters, each Holder hereby agrees

that such Holder shall not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale, any shares of Common Stock (or other securities) of the Company held by such Holder (other than those included in the registration) (i) during the 180-day period following the effective date of the Initial Offering (or such longer period, not to exceed 34 days after the expiration of the 180-day period, as the underwriters or the Company shall request in order to facilitate compliance with NASD Rule 2711 or NYSE Member Rule 472 or any successor or similar rule or regulation); provided that all officers and directors of the Company and holders of at least one percent (1%) of the Company’s voting securities are bound by and have entered into similar agreements, and provided that, such agreements shall provide that any discretionary waiver or termination of the restrictions of such agreements by the Company or the underwriters shall apply to all Holders equally on a pro rata basis (as such term is defined in Section 4.1). The foregoing provisions of this Section 2.11 shall not apply to the sale of any shares to an underwriter pursuant to an underwriting agreement.

2.12 Agreement to Furnish Information. Each Holder agrees to execute and deliver such other agreements as may be reasonably requested by the Company or the managing underwriters that are consistent with the Holder’s obligations under Section 2.11 or that are necessary to give further effect thereto. In addition, if reasonably requested by the Company or the representative of the underwriters of Common Stock (or other securities) of the Company, each Holder shall provide, within ten (10) days of such request, such information as may be required by the Company or such representative in connection with the completion of any public offering of the Company’s securities pursuant to a registration statement filed under the Securities Act. The obligations described in Section 2.11 and this Section 2.12 shall not apply to a Special Registration Statement. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to such shares of Common Stock (or other securities) subject to the foregoing restriction until the end of such period. Each Holder agrees that any transferee of any shares of Registrable Securities shall be bound by Sections 2.11 and 2.12. The underwriters of the Company’s stock are intended third party beneficiaries of Sections 2.11 and 2.12 and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto.

2.13 Rule 144 Reporting. With a view to making available to the Holders the benefits of certain rules and regulations of the SEC which may permit the sale of the Registrable Securities to the public without registration, the Company agrees to use its best efforts to:

(a) Make and keep public information available, as those terms are understood and defined in SEC Rule 144 or any similar or analogous rule promulgated under the Securities Act, at all times after the effective date of the first registration filed by the Company for an offering of its securities to the general public;

(b) File with the SEC, in a timely manner, all reports and other documents required of the Company under the Exchange Act; and

(c) So long as a Holder owns any Registrable Securities, furnish to such Holder forthwith upon request: a written statement by the Company as to its compliance with the reporting requirements of said Rule 144 of the Securities Act, and of the Exchange Act (at any time after it has become subject to such reporting requirements); a copy of the most recent annual or quarterly

report of the Company filed with the Commission; and such other reports and documents as a Holder may reasonably request in connection with availing itself of any rule or regulation of the SEC allowing it to sell any such securities without registration.

2.14 Termination of Registration Rights. The right of any Holder to request registration or inclusion of Registrable Securities in any registration pursuant to Section 2.2, Section 2.3, or Section 2.4 hereof shall terminate upon the earlier of: (i) the date three (3) years following an initial public offering that results in the conversion of all outstanding shares of Preferred stock; or (ii) such time as such Holder, holds less than one percent (1%) of the Company’s outstanding Common Stock (treating all shares of Preferred Stock on an as converted basis), the Company has completed its Initial Offering and all Registrable Securities of the Company issuable or issued upon conversion of the Shares held by and issuable to such Holder (and its Affiliates) may be sold pursuant to Rule 144 during any ninety (90) day period. Upon such termination, such shares shall cease to be “Registrable Securities” hereunder for all purposes.

SECTION 3. COVENANTS OF THE COMPANY.

3.1 Basic Financial Information and Reporting.

(a) The Company will maintain true books and records of account in which full and correct entries will be made of all its business transactions pursuant to a system of accounting established and administered in accordance with generally accepted accounting principles consistently applied (except as noted therein), and will set aside on its books all such proper accruals and reserves as shall be required under generally accepted accounting principles consistently applied.

(b) So long as an Investor (with its Affiliates) shall own not less than two hundred fifty thousand (250,000) shares of Preferred Stock (as adjusted for stock splits and combinations) (a “ Major Investor ”), the Company will furnish each Major Investor, as soon as practicable after the end of each fiscal year of the Company, and in any event within one hundred twenty (120) days thereafter, an unaudited balance sheet of the Company, as at the end of such fiscal year, and an unaudited statement of income and a statement of cash flows of the Company, for such year, all prepared in accordance with generally accepted accounting principles consistently applied (except as noted therein) and setting forth in each case in comparative form the figures for the previous fiscal year, all in reasonable detail.

(c) The Company will furnish each Major Investor, as soon as practicable after the end of the first, second and third quarterly accounting periods in each fiscal year of the Company, and in any event within forty-five (45) days thereafter, an unaudited balance sheet of the Company as of the end of each such quarterly period, and an unaudited statement of income and a statement of cash flows of the Company for such period and for the current fiscal year to date, prepared in accordance with generally accepted accounting principles consistently applied (except as noted therein), with the exception that no notes need be attached to such statements and year-end audit adjustments may not have been made, as well as an up-to-date capitalization table of the Company.

(d) The Company will furnish each Major Investor, as soon as practicable, but in any event within thirty (30) days of the end of each month, a balance sheet of the Company as of the end of each such month, and a statement of income and a statement of cash flows of the Company for such month and for the current fiscal year to date, including a comparison to plan figures for such period, prepared in accordance with generally accepted accounting principles consistently applied (except as noted thereon), with the exception that no notes need be attached to such statements and year-end audit adjustments may not have been made.

(e) The Company will furnish each such Major Investor to the extent requested by such Major Investor no earlier than thirty (30) days after the beginning of each fiscal year an annual budget for such fiscal year (and as soon as available, any subsequent written revisions thereto).

3.2 Inspection Rights. Each Major Investor shall have the right to visit and inspect any of the properties of the Company or any of its subsidiaries, and to discuss the affairs, finances and accounts of the Company or any of its subsidiaries with its officers, and to review such information as is reasonably requested all at such reasonable times and as often as may be reasonably requested; provided, however, that the Company shall not be obligated under this Section 3.2 with respect to a competitor of the Company or with respect to information which the Board reasonably determines in good faith is confidential or attorney-client privileged and should not, therefore, be disclosed.

3.3 Confidentiality of Records. Each Investor agrees to use the same degree of care as such Investor uses to protect its own confidential information to keep confidential any information furnished to such Investor hereof that the Company identifies as being confidential or proprietary (so long as such information is not in the public domain), except that such Investor may disclose such proprietary or confidential information (i) to any former partners who retained an economic interest in such Investor, current or prospective partner of the partnership or any subsequent partnership under common investment management, limited partner, general partner, member or management company of such Investor, employee or representative of such Investor having a need to know the contents of such information, such Investor’s legal counsel, accountants or other professional advisors, subsidiary or parent of such Investor, in each case as long as such party is advised of and agrees or has agreed to be bound by the confidentiality provisions of this Section 3.3 or comparable restrictions; (ii) at such time as it enters the public domain through no fault of such Investor; (iii) that is communicated to it free of any obligation of confidentiality; (iv) that is developed by such Investor or its agents independently of and without reference to any confidential information communicated by the Company; or (v) as required by applicable law.

3.4 Reservation of Common Stock. The Company will at all times reserve and keep available, solely for issuance and delivery upon the conversion of the Preferred Stock, all Common Stock issuable from time to time upon such conversion.

3.5 Stock Vesting. Unless otherwise approved by the Board (including a majority of the Preferred Directors, as defined in that certain Second Amended and Restated Voting Agreement dated as of the date hereof, as the same may be amended from time to time), all stock options and other stock equivalents issued after the date of this Agreement to employees, directors, consultants and other service providers (“ Stock Awards ”) shall be subject to vesting as follows:

(a) twenty-five percent (25%) of such stock shall vest at the end of the first year following the earlier of the date of issuance or such person’s services commencement date with the Company, and (b) the remaining seventy-five percent (75%) of such stock shall vest monthly over the remaining three (3) years. All unvested stock subject to such Stock Awards shall be subject to repurchase at cost by the Company upon termination of employment or service of such director, officer, employee or consultant for any reason. No transfer of unvested stock subject to such Stock Awards shall be allowed. The Company shall have a right of first refusal on all transfers of vested stock, which right of first refusal shall terminate upon a Qualified IPO (as defined in the Company’s Amended and Restated Certificate of Incorporation (as may be amended from time to time, the “ Charter ”)).

3.6 Directors’ Liability and Indemnification; Director and Officer Insurance. The Charter and bylaws shall provide (a) for elimination of the liability of directors to the maximum extent permitted by law and (b) for indemnification of directors for acts on behalf of the Company to the maximum extent permitted by law; provided that such insurance coverage shall be in an amount no less than $4,000,000 (inclusive of main and “Side A” policies). In addition, the Company shall enter into and use its best efforts to at all times maintain indemnification agreements with each of its directors to indemnify such directors to the maximum extent permissible under applicable law. Further, in the event the Company merges with another entity and is not the surviving corporation, or transfers all of its assets, the Company shall use its best effort to provide that successors of the Company shall assume the Company’s obligations with respect to indemnification of the directors. The Company will use its best efforts to obtain promptly after the date hereof and maintain in full force and effect director and officer liability insurance in an amount to be determined and approved by the Board, including the Preferred Directors.

3.7 Observer Rights.

(a) The Company shall allow (i) one (1) representative designated by New Enterprise Associates 15, L.P., or its Affiliates (“ NEA ”), who shall initially be Sara Nayeem, (ii) one (1) representative designated by Osage University Partners I, L.P., or its Affiliates (“ Osage ”), who shall initially be Bill Harrington, (iii) one (1) representative designated by Frazier Healthcare VI, L.P., or its Affiliates (“ Frazier ”), who shall initially be Dan Estes, (iv) one (1) representative designated by Altitude Life Science Ventures, or its Affiliates (“ Altitude ”), who shall initially be Dave Maki, (v) one (1) representative designated by Roche Finance Ltd., or its Affiliates (“ Roche ”), who shall initially be Carole Nuetcherlein, (vi) one (1) representative designated by Adams Street Partners, LLC, or its Affiliates (“ Adams Street ”), who shall initially be Elisha P. Gould III and (vii) one (1) representative from Longwood Fund III GP, LLC, or its Affiliates (“ Longwood ”), who shall initially be David Donabedian, to attend all meetings of the Board in a nonvoting capacity, so long such designating entity is a Major Investor. The Company shall give such representative copies of all notices, minutes, consents and other materials, financial or otherwise, which the Company provides to its Board; provided, however, that the Company reserves the right to exclude such representative from access to any material or meeting or portion thereof if the Company in good faith believes, with advice of counsel, that such exclusion is reasonably necessary to preserve the attorney-client privilege, to protect highly confidential information or for other similar reasons. The decision of the Board with respect to the privileged or confidential nature of such information shall be final and binding.

(b) The Company shall allow one (1) representative designated by AstraZeneca AB who shall initially be Kumar Srinivasan, to attend all meetings of the Board in a nonvoting capacity. The Company shall give such representative copies of all notices, minutes, consents and other materials, financial or otherwise, which the Company provides to its Board; provided, however, that the Company reserves the right to exclude such representative from access to any material or meeting or portion thereof if the Company in good faith believes, with advice of counsel, that such exclusion is reasonably necessary to preserve the attorney-client privilege, to protect highly confidential information or for other similar reasons (including actual or potential conflicts of interest). The decision of the Board with respect to the privileged or confidential nature of such information shall be final and binding. Notwithstanding any other provision contained herein, this Section 3.7(b) shall expire and terminate as to AstraZeneca AB upon the earliest of (i) AstraZeneca AB’s disposition of fifty percent (50%) or more of the Series B Preferred Stock issued to AstraZeneca AB pursuant to that certain License Agreement between the Company and AstraZeneca AB dated August 25, 2015, (ii) the effective date of the Company’s initial public offering of its Common Stock or any other transaction that results in the Company or any successor being a publicly traded company, (iii) upon an Acquisition (as defined in the Charter) or (iv) at such time AstraZeneca AB holds less than one percent (1%) of the Company’s outstanding Common Stock (treating all shares of Convertible Stock on an as converted basis).

(c) For so long as any shares of New Preferred Stock remain outstanding, the Company shall allow two (2) representatives designated by the holders of a majority of shares of New Preferred Stock, who shall initially be Gilles Alberici and Olivier Martinez, to attend all meetings of the Board in a nonvoting capacity. The Company shall give such representative copies of all notices, minutes, consents and other materials, financial or otherwise, which the Company provides to its Board; provided, however, that the Company reserves the right to exclude such representative from access to any material or meeting or portion thereof if the Company in good faith believes, with advice of counsel, that such exclusion is reasonably necessary to preserve the attorney-client privilege, to protect highly confidential information or for other similar reasons (including actual or potential conflicts of interest). The decision of the Board with respect to the privileged or confidential nature of such information shall be final and binding. Notwithstanding any other provision contained herein, this Section 3.7(c) shall expire and terminate as to the holders of New Preferred Stock upon the earliest of (i) at such time as the holders of New Preferred Stock collectively hold less than five percent (5%) of the Company’s outstanding Common Stock (treating all shares of Convertible Stock on an as converted basis), (ii) the effective date of the Company’s initial public offering of its Common Stock or any other transaction that results in the Company or any successor being a publicly traded company or (iii) upon an Acquisition (as defined in the Charter).

3.8 Board Meetings. The Company will use its best efforts to hold at least four (4) meetings of the Board each year or as otherwise approved by the Board.

3.9 Compensation Committee. The Company shall establish a compensation committee of the Board (“ Compensation Committee ”) consisting of at least two (2) directors designated by the holders of Preferred Stock, for the purpose of, among other things, reviewing and determining the compensation of the Company’s executive officers.

3.10 Reimbursement of Expenses. The Company shall reimburse each director of the Company for all reasonable travel or other out-of-pocket expenses incurred in connection with attending meetings of the Board.

3.11 Proprietary Information and Inventions Agreement. The Company shall require all employees and consultants to execute and deliver a Proprietary Information and Inventions Agreement substantially in a form approved by the Board.

3.12 Qualified Small Business. For so long as any of the Shares are held by an Investor (or a transferee in whose hands such Shares are eligible to qualify as “Qualified Small Business Stock” as defined in Section 1202(c) of the Internal Revenue Code of 1986, as amended (the “ Code ”)), the Company will use its reasonable efforts to comply with the reporting and recordkeeping requirements of Section 1202 of the Code, any regulations promulgated thereunder and any similar state laws and regulations.

3.13 Non-Competition and Non-Solicitation Agreement. The Company shall require that all key employees and key consultants (as determined by the Board or the Compensation Committee) execute and deliver a Non-Competition and Non-Solicitation Agreement substantially in a form approved by the Board.

3.14 Investor Covenants on Anti Money Laundering and Anti-Corruption.

(a) Each Investor represents and warrants, for purposes of all applicable Anti-Money Laundering Laws, that:

i. the origin and source of the funds that it/he/she paid to the Company to acquire or subscribe for any Shares or make any shareholder’s loan to the Company do not result from any activity in breach of any applicable Anti-Money Laundering Laws.

(b) Until the consummation of a Qualified IPO, the Company will use its best efforts to inform the Investors of any new shareholder of the Company (with indication of its identity and, for closely-held legal entities, of its shareholders or beneficial owners) before the relevant individual or entity becomes a shareholder of the Company and to use its best efforts to cause any new shareholder of the Company to comply with the parties’ undertakings set forth in this Section. In particular, in the event of issuance of equity or other voting securities, the Company will use its best efforts to obtain appropriate representations and warranties or other reasonably sufficient evidence from the relevant subscribing third party that such third party complies with all applicable Anti-Money Laundering Laws.

3.15 Company Covenants on Anti Money Laundering and Anti-Corruption .

(a) The Company represents and warrants that it does not participate and has never participated in any transactions in violation of applicable Anti-Money Laundering Laws.

(b) The Company undertakes to comply with all applicable Anti-Corruption Laws and not to participate in any activities in violation of applicable Anti-Corruption Laws. The

Company has adopted and implemented appropriate internal policies and/or rules in order to prevent the violation of applicable Anti-Corruption Laws.

3.16 Additional Undertakings and Acknowledgements on Anti Money Laundering and Anti-Corruption.

(a) The parties hereto acknowledge that InnoBio and its management company ( société de gestion ), Bpifrance Investissement, are subject to certain filing and reporting obligations to prevent money laundering activities and financing of terrorism provided for in sections 2 to 7 of Chapter 1 of Title VI, Book V of the French Monetary and Financial Code and of the provisions of the General Rules ( Réglement Général ) of the French Stock Market Regulator ( Autorité des Marchés Financiers ) and, in particular, are required to report to competent regulatory authorities: (i) any transaction involving money transfers which they are aware, assume or have good reasons to believe that: (a) relates to the commission of an crime or offence which can result in the imprisonment of its authors for a duration exceeding one year or (b) participates to the financing of terrorism, as well as (ii) any transaction for which the identity of the relevant instructing party, the effective beneficiary, the settlor in a trust or any other asset management vehicle involved in the relevant transaction remains unclear despite all investigations InnoBio and its management company have to carry out. Under applicable French laws, InnoBio and its management company also have to refrain from carrying out any operation they believe is linked to money laundering activities or financing of terrorism.

3.17 Termination of Covenants. All covenants of the Company contained in Section 3 of this Agreement (other than the provisions of Section 3.3 and 3.6) shall expire and terminate as to each Investor upon the earlier of (i) the effective date of a Qualified IPO (as defined in the Charter) or (ii) upon an Acquisition (as defined in the Charter).

SECTION 4. RIGHTS OF FIRST REFUSAL.

4.1 Subsequent Offerings. Subject to applicable securities laws, each Major Investor shall have a right of first refusal to purchase its pro rata share of all Equity Securities, as defined below, that the Company may, from time to time, propose to sell and issue after the date of this Agreement, other than the Equity Securities excluded by Section 4.6 hereof. Each Major Investor’s pro rata share is equal to the ratio of (a) the number of Common Shares (including all shares of Common Stock issuable or issued upon conversion of the Shares or upon the exercise of outstanding warrants or options) of which such Major Investor is deemed to be a holder immediately prior to the issuance of such Equity Securities to (b) the total number of the Company’s outstanding Common Shares (including all shares of Common Stock issued or issuable upon conversion of the Shares or upon the exercise of any outstanding warrants or options) immediately prior to the issuance of the Equity Securities. The term “ Equity Securities ” shall mean (i) any Common Stock, Preferred Stock or other security of the Company, (ii) any security convertible into or exercisable or exchangeable for, with or without consideration, any Common Stock, Preferred Stock or other security (including any option to purchase such a convertible security), (iii) any security carrying any warrant or right to subscribe to or purchase any Common Stock, Preferred Stock or other security, or (iv) any such warrant or right.

4.2 Exercise of Rights. If the Company proposes to issue any Equity Securities, it shall give each Major Investor written notice of its intention, describing the Equity Securities, the price and the terms and conditions upon which the Company proposes to issue the same. Each Major Investor shall have fifteen (15) days from the giving of such notice to agree to purchase its pro rata share of the Equity Securities for the price and upon the terms and conditions specified in the notice by giving written notice to the Company and stating therein the quantity of Equity Securities to be purchased. Notwithstanding the foregoing, the Company shall not be required to offer or sell such Equity Securities to any Major Investor if such offer or sale would cause the Company to be in violation of applicable federal securities laws by virtue of such offer or sale.

4.3 Issuance of Equity Securities to Other Persons . If not all of the Major Investors elect to purchase their pro rata share of the Equity Securities, then the Company shall promptly notify in writing the Major Investors who do so elect and shall offer such Major Investors the right to acquire such unsubscribed shares on a pro rata basis. The Major Investors shall have five (5) days after receipt of such notice to notify the Company of its election to purchase all or a portion thereof of the unsubscribed shares. The Company shall have ninety (90) days thereafter to sell the Equity Securities in respect of which the Major Investor’s rights were not exercised, at a price not lower and upon general terms and conditions not materially more favorable to the purchasers thereof than specified in the Company’s notice to the Major Investors pursuant to Section 4.2 hereof. If the Company has not sold such Equity Securities within ninety (90) days of the notice provided pursuant to Section 4.2, the Company shall not thereafter issue or sell any Equity Securities, without first offering such securities to the Major Investors in the manner provided above.

4.4 Termination of Rights of First Refusal. The rights of first refusal established by this Section 4 shall not apply to, and shall terminate upon the earlier of (i) the effective date of a Qualified IPO or (ii) upon a Liquidation Event (as defined in the Charter).

4.5 Assignment of Rights of First Refusal. The rights of first refusal of each Major Investor under this Section 4 may be assigned to the same parties, subject to the same restrictions as any transfer of registration rights pursuant to Section 2.9; provided further that Regents of the University of Michigan shall also have the right to apportion its right of first refusal among itself and any Osage University Partners, including any investment fund managed by Osage University Partners that is an “accredited investor” with the meaning of Regulation D under the Securities Act.

4.6 Excluded Securities. The rights of first refusal established by this Section 4 shall have no application to any of the following Equity Securities:

(a) any Equity Securities that fall within one of the enumerated exceptions to the definition of Excluded Securities (as defined in the Charter);

(b) any Equity Securities issued pursuant to the Share Contribution Agreement; and

(c) any Equity Securities that are specifically deemed not to be subject to the rights of first refusal in this Section 4 by the written consent or affirmative vote of the Major Investors holding a majority of the Preferred Stock then held by all Major Investors.

SECTION 5. MISCELLANEOUS.

5.1 Governing Law. This Agreement shall be governed by and construed under the laws of the State of Delaware in all respects as such laws are applied to agreements among Delaware residents entered into and performed entirely within Delaware, without giving effect to conflict of law principles thereof.

5.2 Successors and Assigns. Except as otherwise expressly provided herein, the provisions hereof shall inure to the benefit of, and be binding upon, the parties hereto and their respective successors, assigns, heirs, executors, and administrators and shall inure to the benefit of and be enforceable by each person who shall be a holder of Registrable Securities from time to time; provided, however , that prior to the receipt by the Company of adequate written notice of the transfer of any Registrable Securities specifying the full name and address of the transferee, the Company may deem and treat the person listed as the holder of such shares in its records as the absolute owner and holder of such shares for all purposes, including the payment of dividends or any redemption price.

5.3 Entire Agreement. This Agreement, the Exhibits and Schedules hereto, the Share Contribution Agreement and the other documents delivered pursuant thereto constitute the full and entire understanding and agreement between the parties with regard to the subjects hereof and no party shall be liable or bound to any other in any manner by any oral or written representations, warranties, covenants and agreements except as specifically set forth herein and therein. Each party expressly represents and warrants that it is not relying on any oral or written representations, warranties, covenants or agreements outside of this Agreement.

5.4 Severability. In the event one or more of the provisions of this Agreement should, for any reason, be held to be invalid, illegal or unenforceable in any respect, such invalidity, illegality, or unenforceability shall not affect any other provisions of this Agreement, and this Agreement shall be construed as if such invalid, illegal or unenforceable provision had never been contained herein.

5.5 Amendment and Waiver.

(a) Except as otherwise expressly provided, this Agreement may be amended or modified, and the obligations of the Company and the rights of the Holders under this Agreement may be waived, only upon the written consent of the Company and the holders of a majority of the then-outstanding Registrable Securities. Notwithstanding the foregoing, this Agreement may not be amended or terminated and the observance of any term hereof may not be waived with respect to any Investor without the written consent of such Investor, unless such amendment, termination, or waiver applies to all Investors in the same fashion (it being agreed that a waiver of the provisions of Section 4 with respect to a particular transaction shall be deemed to apply to all Investors in the same fashion if such waiver does so by its terms, notwithstanding the fact that certain Investors may nonetheless, by agreement with the Company, purchase

securities in such transaction). The Company shall give prompt notice of any amendment or termination hereof or waiver hereunder to any party hereto that did not consent in writing to such amendment, termination, or waiver. Any amendment, termination, or waiver effected in accordance with this Section 5.5 shall be binding on all parties hereto, regardless of whether any such party has consented thereto provided , however , that notwithstanding the foregoing, (i) Section 3.7(a) of this Agreement shall not be amended or waived without the written consent of any of NEA, Osage, Frazier, Altitude, Roche, Longwood or Adams Street so long as such party is entitled to designate an observer pursuant to Section 3.7(a), (ii) Section 3.7(b) shall not be amended or waived without the written consent of AstraZeneca so long as such party is entitled to designate an observer pursuant to Section 3.7(b) and (iii) Section 3.7(c) shall not be amended or waived without the written consent of the holders of a majority of the shares of New Preferred Stock so long as such holders are entitled to designate an observer pursuant to Section 3.7(c). No waivers of or exceptions to any term, condition, or provision of this Agreement, in any one or more instances, shall be deemed to be or construed as a further or continuing waiver of any such term, condition, or provision.

(b) For the purposes of determining the number of Holders or Investors entitled to vote or exercise any rights hereunder, the Company shall be entitled to rely solely on the list of record holders of its stock as maintained by or on behalf of the Company.

5.6 Delays or Omissions. It is agreed that no delay or omission to exercise any right, power, or remedy accruing to any party, upon any breach, default or noncompliance by another party under this Agreement shall impair any such right, power, or remedy, nor shall it be construed to be a waiver of any such breach, default or noncompliance, or any acquiescence therein, or of any similar breach, default or noncompliance thereafter occurring. It is further agreed that any waiver, permit, consent, or approval of any kind or character on any party’s part of any breach, default or noncompliance under this Agreement or any waiver on such party’s part of any provisions or conditions of this Agreement must be in writing and shall be effective only to the extent specifically set forth in such writing. All remedies, either under this Agreement, by law, or otherwise afforded to any party, shall be cumulative and not alternative.

5.7 Notices. All notices required or permitted hereunder shall be in writing and shall be deemed effectively given: (a) upon personal delivery to the party to be notified, (b) when sent by confirmed electronic mail or facsimile if sent during normal business hours of the recipient; if not, then on the next business day, (c) five (5) days after having been sent by registered or certified mail, return receipt requested, postage prepaid, or (d) two (2) days after deposit with a nationally recognized overnight courier, specifying next day delivery, with written verification of receipt. All communications shall be sent to the party to be notified at the address as set forth on the signature pages hereof or Exhibit A hereto or at such other address or electronic mail address as such party may designate by ten (10) days advance written notice to the other parties hereto.

5.8 Attorneys’ Fees. In the event that any suit or action is instituted under or in relation to this Agreement, including without limitation to enforce any provision in this Agreement, the prevailing party in such dispute shall be entitled to recover from the losing party all fees, costs and expenses of enforcing any right of such prevailing party under or with respect to this Agreement, including without limitation, such reasonable fees and expenses of attorneys and accountants, which shall include, without limitation, all fees, costs and expenses of appeals.

5.9 Titles and Subtitles. The titles of the sections and subsections of this Agreement are for convenience of reference only and are not to be considered in construing this Agreement.

5.10 Additional Investors. Notwithstanding anything to the contrary contained herein, if the Company shall issue additional shares of its Preferred Stock pursuant to the Share Contribution Agreement, any purchaser of such shares of Preferred Stock shall become a party to this Agreement by executing and delivering an additional counterpart signature page to this Agreement and shall be deemed an “ Investor ,” a “ Holder ” and a party hereunder.

5.11 Counterparts. This Agreement may be executed in any number of counterparts, each of which shall be an original, but all of which together shall constitute one instrument.

5.12 Aggregation of Stock. All shares of Registrable Securities held or acquired by Affiliates shall be aggregated together for the purpose of determining the availability of any rights under this Agreement.

5.13 Pronouns. All pronouns contained herein, and any variations thereof, shall be deemed to refer to the masculine, feminine or neutral, singular or plural, as to the identity of the parties hereto may require.

5.14 Termination. This Agreement shall terminate and be of no further force or effect upon the earlier of (i) a Liquidation Event; or (ii) the date three (3) years following the effective date of a Qualified IPO.

5.15 Right to Conduct Activities. The Company hereby agrees and acknowledges that NEA, 5AM Co-Investors III, L.P., 5AM Ventures III, L.P., Adams Street, Roche, Longwood, Frazier, Osage,Altitude, CEMA Inc. (“ CEMA ”), Otannale SAS (“ Otannale ”), SHAM Innovation Sante SAS (“ SHAM ”) and InnoBio FPCI (“ InnoBio ”) (such Investors, collectively, the “ Fund Investors ”) are professional investment funds, and as such invest in numerous portfolio companies, some of which may be deemed competitive with the Company’s business (as currently conducted or as currently propose to be conducted). The Company hereby agrees that, to the extent permitted under applicable law, no Fund Investor shall be liable to the Company for any claim arising out of, or based upon, (i) the investment by such Fund Investor in any entity competitive with the Company, or (ii) actions taken by any partner, officer or other representative of such Fund Investor to assist any such competitive company, whether or not such action was taken as a member of the board of directors of such competitive company or otherwise, and whether or not such action has a detrimental effect on the Company; provided, however, that the foregoing shall not relieve (x) any of the Investors from liability associated with the unauthorized disclosure of the Company’s confidential information obtained pursuant to this Agreement, or (y) any director or officer of the Company from any liability associated with his or her fiduciary duties to the Company.

5.16 Amendment of Prior Agreement. The Prior Agreement is hereby amended and superseded in its entirety and restated herein. Such amendment and restatement is effective upon the execution of this Agreement by the Company and the parties required for an amendment pursuant to Section 5.5 of the Prior Agreement. Upon such execution, all provisions of, rights

granted and covenants made in the Prior Agreement are hereby waived, released and superseded in their entirety by the provisions hereof and shall have no further force or effect.

5.17 Dispute Resolution . The parties (a) hereby irrevocably and unconditionally submit to the jurisdiction of the state courts of Delaware and to the jurisdiction of the United States District Court for the District of Delaware for the purpose of any suit, action or other proceeding arising out of or based upon this Agreement, (b) agree not to commence any suit, action or other proceeding arising out of or based upon this Agreement except in the state courts of Delaware or the United States District Court for the District of Delaware, and (c) hereby waive, and agree not to assert, by way of motion, as a defense, or otherwise, in any such suit, action or proceeding, any claim that it is not subject personally to the jurisdiction of the above-named courts, that its property is exempt or immune from attachment or execution, that the suit, action or proceeding is brought in an inconvenient forum, that the venue of the suit, action or proceeding is improper or that this Agreement or the subject matter hereof may not be enforced in or by such court.

WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT, THE OTHER TRANSACTION DOCUMENTS, THE SECURITIES OR THE SUBJECT MATTER HEREOF OR THEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT MATTER OF THIS TRANSACTION, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS BEEN FULLY DISCUSSED BY EACH OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH PARTY KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL.

5.18 Acknowledgment . The Company acknowledges that the Investors are in the business of venture capital investing and therefore review the business plans and related proprietary information of many enterprises, including enterprises which may have products or services which compete directly or indirectly with those of the Company. Nothing in this Agreement shall preclude or in any way restrict the Investors from investing or participating in any particular enterprise whether or not such enterprise has products or services which compete with those of the Company.

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