NOTICE OF ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON NOVEMBER 3, 2017

To the Stockholders of Cempra, Inc.:

The 2017 annual meeting of the stockholders, or the 2017 Annual Meeting, of Cempra, Inc., or Cempra, will be held at 8:00 a.m., local time, on November 3, 2017, at the offices of Wyrick Robbins Yates & Ponton LLP located at 4101 Lake Boone Trail, Suite 300, Raleigh, NC 27607, to consider and act upon the following matters:

Cempra common stock is the only type of security entitled to vote at the 2017 Annual Meeting. The board of directors has fixed September 29, 2017 as the record date for the determination of stockholders entitled to notice of, and to vote at, the 2017 Annual Meeting and any adjournment or postponement thereof. Only holders of record of shares of Cempra common stock at the close of business on the record date are entitled to notice of, and to vote at, the 2017 Annual Meeting. At the close of business on the record date, Cempra had 52,509,281 shares of common stock outstanding and entitled to vote at the 2017 Annual Meeting. Each holder of record of shares of common stock on the record date will be entitled to one vote for each share held on all matters to be voted upon at the 2017 Annual Meeting.

Your vote is important. The affirmative vote of the holders of a majority of the shares of Cempra common stock present in person or represented by proxy and entitled to vote on the matter at the 2017 Annual Meeting is

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required for approval of Proposal 1, Proposal 5, Proposal 6 and Proposal 7 above. The affirmative vote of the holders of a majority of the outstanding shares of Cempra common stock as of the record date for the 2017 Annual Meeting is required for approval of Proposal 2a, Proposal 2b, Proposal 2c and Proposal 3 above. Proposal 4, the election of the Class III directors, will be determined by a plurality of the votes cast at the 2017 Annual Meeting.

Whether or not you plan to attend the 2017 Annual Meeting in person, please complete, date, sign and promptly return the accompanying proxy card in the enclosed postage paid envelope to ensure that your shares will be represented and voted at the 2017 Annual Meeting. If you date, sign and return your proxy card without indicating how you wish to vote, your proxy will be counted as a vote in favor of Proposals 1 through 7. The failure to return your proxy card or to vote in person at the 2017 Annual Meeting will have the same effect as a vote against Proposal 2a, Proposal 2b, Proposal 2c and Proposal 3. If you attend the 2017 Annual Meeting, you may, upon your written request, withdraw your proxy and vote in person.

By Order of the Board of Directors of Cempra, Inc.

Mark W. Hahn

Secretary

October 5, 2017

Chapel Hill, North Carolina

CEMPRA’S BOARD OF DIRECTORS HAS DETERMINED AND BELIEVES THAT EACH OF THE PROPOSALS OUTLINED ABOVE IS ADVISABLE, FAIR AND IN THE BEST INTERESTS OF CEMPRA AND ITS STOCKHOLDERS AND HAS UNANIMOUSLY APPROVED EACH SUCH PROPOSAL. CEMPRA’S BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT CEMPRA STOCKHOLDERS VOTE “FOR” EACH SUCH PROPOSAL.

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REFERENCES TO ADDITIONAL INFORMATION

This proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and the rules thereunder, contains a notice of meeting with respect to the 2017 annual meeting of stockholders, or the 2017 Annual Meeting, at which Cempra stockholders will consider and vote on the proposals to approve the issuance of common stock, par value $0.001 per share, of Cempra, or Cempra common stock, issuable to the holders of common stock, par value $0.001, of Melinta, or Melinta common stock, pursuant to the merger agreement described in this proxy statement; to approve amendments to Cempra’s certificate of incorporation to: (a) increase the number of authorized shares of Cempra common stock from 80,000,000 to 250,000,000, the approval of which is necessary to enable Cempra to issue the required number of shares of Cempra common stock to Melinta stockholders in connection with the merger; (b) change the name of Cempra to “Melinta Therapeutics, Inc.;” (c) elect for Cempra not to be governed by or subject to Section 203 of the Delaware General Corporation Law, or the DGCL; and (d) to effect a reverse stock split of Cempra common stock and related matters, referred to in this proxy statement as the reverse stock split; to elect three Class III directors for a three-year term expiring in 2020; to approve on a non-binding advisory basis Cempra’s 2016 executive compensation; to ratify the appointment of PricewaterhouseCoopers LLP as Cempra’s registered public accounting firm for the fiscal year ending December 31, 2017; and to consider and vote on a proposal to adjourn the 2017 Annual Meeting, if necessary, if a quorum is present, to solicit additional proxies, in the event that there are not sufficient votes at the time of the 2017 Annual Meeting in favor of Proposals 1, 2a, 2b, 2c or 3 above.

Additional business and financial information about Cempra can be found in documents previously filed by Cempra with the U.S. Securities and Exchange Commission, or the SEC. This information is available to you without charge at the SEC’s website at www.sec.gov.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE SHAREHOLDER MEETING TO BE HELD ON NOVEMBER 3, 2017:

In addition to receiving the proxy statement from Cempra in the mail or obtaining the information on the SEC’s website, Cempra stockholders will also be able to obtain the proxy statement, free of charge, from Cempra by requesting copies in writing using the following contact information:

CEMPRA, INC.

Attn: Investor Relations

6320 Quadrangle Drive, Suite 360

Chapel Hill, North Carolina 27517

Tel: (919) 313-6601

A copy of the proxy statement is also available, free of charge, at www.investorvote.com /CEMP and under the Investor Relations— Financial Information section of Cempra’s website at www.cempra.com .

You may also request additional copies from our proxy solicitor, Georgeson, LLC, or Georgeson, using the following contact information:

1290 Avenue of the Americas, 9th Floor

New York, NY 10104

(866) 821-2550

IF YOU WOULD LIKE TO REQUEST MATERIALS, PLEASE DO SO BY OCTOBER 25, 2017 IN ORDER TO RECEIVE THEM BEFORE THE 2017 ANNUAL MEETING.

See “Where You Can Find More Information” beginning on page 217 of this proxy statement.

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Except as otherwise specifically noted in this proxy statement “Cempra,” “we,” “our,” “us” and similar words refer to Cempra, Inc., including in certain cases, our subsidiaries. Throughout this proxy statement, we refer to Melinta Therapeutics, Inc. as “Melinta” and we refer to the Agreement and Plan of Merger and Reorganization, dated as of August 8, 2017, as amended on September 6, 2017, among Cempra, Castle Acquisition Corp., and Melinta, as it may be further amended from time to time, as the “merger agreement.” References in this proxy statement to the “combined company” refer to Cempra and Melinta, together with their respective subsidiaries, following the completion of the merger.

In addition, throughout this proxy statement, we refer to the stockholders of Cempra as the “Cempra stockholders,” the stockholders of Melinta as the “Melinta stockholders” and the transactions contemplated by the merger agreement, including the issuance of Cempra common stock to the Melinta stockholders, as, collectively, the “merger.”

Except as specifically indicated, the following information and all other information in this proxy statement does not give effect to the reverse stock split described in Proposal 3.

NOTE REGARDING TRADEMARKS

Cempra™ is Cempra’s trade name, the Cempra logo is Cempra’s trademark and Taksta ^® is Cempra’s registered trademark.

Melinta is Melinta’s trade name and MELINTA ^® , MELINTA THERAPEUTICS ^® and MELINTA THE ANTIBIOTICS COMPANY ^® are registered trademarks of Melinta. BAXDELA™ is a trademark and pending trademark application of Melinta.

The other trademarks, trade names and service marks appearing in this proxy statement are the property of their respective holders.

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QUESTIONS AND ANSWERS ABOUT THE 2017 ANNUAL MEETING

AND THE MERGER

Except as specifically indicated, the following information and all other information in this proxy statement does not give effect to the reverse stock split described in Proposal 3.

The following section provides answers to frequently asked questions about the 2017 Annual Meeting and the merger. This section, however, only provides summary information. These questions and answers may not address all issues that may be important to you as a stockholder. For a more complete response to these questions and for additional information, please refer to the cross-referenced pages below. You should carefully read this entire proxy statement, including each of the Annexes attached hereto.

Only stockholders of record as of the close of business on September 29, 2017, or the record date, will be entitled to vote at the 2017 Annual Meeting. As of the close of business on the record date, there were 52,509,281 shares of Cempra common stock issued and outstanding and entitled to vote, held by 22 stockholders of record. Each stockholder is entitled to one vote for each share of Cempra common stock held by such stockholder on the record date on each of the proposals presented in this proxy statement.

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For a more complete description of the merger, please see the section entitled “The Merger Agreement” beginning on page 103 of this proxy statement. For a discussion of the accounting treatment for the merger, see the section entitled “The Merger—Anticipated Accounting Treatment” beginning on page 99 of this proxy statement.

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For a more complete discussion of Cempra’s reasons for the merger, please see the section entitled “The Merger—Cempra’s Reasons for the Merger” beginning on page 65 of this proxy statement.

For a more complete description of the closing conditions under the merger agreement, please see the section entitled “The Merger Agreement—Conditions to the Completion of the Merger” beginning on page 108 of this proxy statement.

In the United States, Cempra must comply with applicable federal and state securities laws and NASDAQ rules and regulations in connection with the issuance of shares of Cempra common stock in the merger,

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including the filing with the SEC of this proxy statement. Prior to consummation of the merger, Cempra intends to file an initial listing application with the NASDAQ Global Market pursuant to NASDAQ Rule 5110(a) and to effect the initial listing of Cempra common stock issuable in connection with the merger or upon exercise of Melinta’s outstanding stock options or warrants.

At the effective time of the merger, each share of Melinta common stock will be converted into and exchanged for the right to receive a number of shares of Cempra common stock equal to the exchange ratio calculated in accordance with the merger agreement, except that shares held by stockholders who do not meet the definition of an “accredited investor” under Rule 501(a) of Regulation D promulgated under the Securities Act of 1933, as amended, or the Securities Act, will receive a per-share cash payment based on the closing price of Cempra common stock on the closing date of the merger multiplied by the exchange ratio. The exact exchange ratio per share of Melinta common stock will be based in part on the number of Melinta’s and Cempra’s common stock outstanding or issuable pursuant to outstanding options and warrants immediately prior to the effective time of the merger and the volume weighted average closing price of Cempra common stock on the NASDAQ Global Market for the ten trading days preceding the closing of the merger and will not be calculated until the closing date of the merger.

For a more complete discussion of the exchange ratio at the effective time of the merger, please see the section entitled “The Merger Agreement—Merger Consideration” beginning on 103 of this proxy statement.

At least ten days prior to the closing of the merger, Cempra intends to file an information statement with the SEC pursuant to Section 14(f) of the Exchange Act and Rule 14(f)-1 thereunder setting forth information regarding the Cempra and Melinta designees who will be appointed to the combined company’s board of directors at the effective time of the merger.

Additionally, the merger agreement provides that, immediately after the effective time of the merger, Cempra shall terminate the employment of its Acting Chief Executive Officer as an officer of Cempra and its subsidiaries, to be replaced by the successor Chief Executive Officer (or interim Chief Executive Officer,

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as applicable). The remainder of the combined company’s officers have not yet been identified, but the parties expect to identify these individuals prior to the closing of the merger.

Cempra stockholders will not sell, exchange or dispose of any shares of Cempra common stock as a result of the merger. Therefore, there will be no material U.S. federal income tax consequences to Cempra stockholders as a result of the merger.

For a more complete description of the tax consequences of the reverse stock split and the merger, please see the section entitled “The Merger—Certain U.S. Federal Income Tax Considerations” beginning on page 98 of this proxy statement.

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Cempra stockholders will also receive a cash payment for any fractional shares resulting from the reverse stock split.

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In addition, in connection with the execution of the merger agreement, holders beneficially owning, as of August 8, 2017, approximately 91.5% of the shares of Melinta’s outstanding capital stock, including Melinta’s directors and executive officers, have entered into voting and lock-up agreements with Cempra that provide, among other things, that such stockholders shall vote in favor of the adoption of the merger agreement and against any proposal made in opposition to, or in any competition with, the merger.

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If your shares of Cempra common stock are held by a bank, broker or other nominee, you are considered the beneficial owner of shares held in “street name,” and the proxy materials are being forwarded to you together with a voting instruction card by such bank, broker or other nominee. As the beneficial owner, you are also invited to attend the 2017 Annual Meeting. Since a beneficial owner is not the stockholder of record, you may not vote these shares in person at the 2017 Annual Meeting unless you obtain a proxy from your broker issued in your name giving you the right to vote the shares at the 2017 Annual Meeting.

If your shares are held by your broker or other agent as your nominee, you will need to obtain a proxy form from the institution that holds your shares and follow the instructions included on that form regarding how to instruct your broker or other agent to vote your shares.

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If you are a beneficial owner of shares registered in the name of your broker, bank, dealer or other similar organization, you should have received a proxy card and voting instructions with these proxy materials from that organization rather than from Cempra. Simply complete and mail the proxy card to ensure that your vote is counted. Alternatively, you may vote by telephone or over the internet as instructed by your broker or other agent. To vote in person at the 2017 Annual Meeting, you must obtain a valid proxy from your broker or other agent. Follow the instructions from your broker or other agent included with these proxy materials, or contact your broker or bank to request a proxy form.

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Proposals 1 and 2a are conditioned upon each other, and the approval of each such proposal is a condition to the completion of the merger. Therefore, the completion of the merger cannot proceed without the approval of Proposals 1 and 2a.

The Notice of Annual Meeting, this proxy statement and the Annexes attached hereto (including Cempra’s Annual Report on Form 10-K for the year ended December 31, 2016, as amended by Amendment No. 1 on Form 10-K/A, attached as Annexes B-1 and B-2 hereto) are also available, free of charge, in PDF and HTML format under the Investor Relations—Financial Information section of Cempra’s website at www.cempra.com and will remain posted on such website at least until the conclusion of the meeting.

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Melinta is a private company and its common stock is not publicly traded. There has never been, nor is there expected to be in the future, a public market for Melinta common stock. Following the merger, Melinta will be renamed and become a wholly owned subsidiary of Cempra, and Cempra will, in turn, be renamed “Melinta Therapeutics, Inc.”

On August 8, 2017, the last full trading day prior to the public announcement of the proposed merger, the closing price per share of Cempra common stock as reported on the NASDAQ Global Market was $3.80, for an aggregate market value of Cempra of approximately $205.3 million based on Cempra’s fully diluted shares outstanding as of August 8, 2017, as calculated under the treasury stock method. Accordingly, if the merger had been consummated on that day, the value attributable to the shares of Cempra common stock issued to holders of Melinta common stock and issuable to holders of Melinta’s outstanding options and warrants in connection with the merger would have been approximately $237.5 million, based on approximately 62.5 million shares of Cempra common stock issued or issuable to Melinta securityholders in the merger, multiplied by $3.80.

On September 29, 2017 the last practicable date before the printing of this proxy statement, the closing price per share of Cempra common stock as reported on the NASDAQ Global Market was $3.25, for an aggregate market value of Cempra of approximately $174.2 million based on Cempra’s fully diluted shares outstanding as of September 29, 2017, as calculated under the treasury stock method. Accordingly, if the merger had been consummated on that day, the value attributable to the shares of Cempra common stock issued to holders of Melinta common stock and issuable to holders of Melinta’s outstanding options and warrants in connection with the merger would have been approximately $201.5 million, based on approximately 62.0 million shares of Cempra common stock issued or issuable to Melinta stockholders in the merger multiplied by $3.25.

Because the market price of Cempra common stock is subject to fluctuation, the market value of the shares of Cempra common stock that holders of Melinta common stock will be entitled to receive in the merger may increase or decrease.

Following the consummation of the merger, and subject to successful application for initial listing with the NASDAQ Global Market, Cempra common stock will continue to be listed on the NASDAQ Global Market, but

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will trade under the symbol “MLNT” and under the combined company’s new name, “Melinta Therapeutics, Inc.”

Holders of Record

As of September 29, 2017, Cempra had 22 stockholders of record, which excludes stockholders whose shares were held in nominee or street name by brokers. Cempra believes that, when its record holders and stockholders whose shares are held in nominee or street name by brokers are combined, it has in excess of 15,000 stockholders.

As of September 29, 2017, Melinta had approximately 100 stockholders of record of Melinta common stock and 39 stockholders of record of Melinta’s preferred stock.

Dividends

Cempra has never declared or paid any cash dividends on its common stock. Cempra currently does not plan to declare dividends on shares of its common stock in the foreseeable future. Cempra expects to retain its future earnings, if any, for use in the operation and expansion of its business. The payment of cash dividends in the future, if any, will be at the discretion of Cempra’s board of directors and will depend upon such factors as earnings levels, capital requirements, its overall financial condition and any other factors Cempra’s board deems relevant. Pursuant to the terms of the Loan and Security Agreement, dated as of July 10, 2015, among Comerica Bank, Cempra and certain subsidiaries of Cempra, for as long as such agreement is outstanding, Cempra may not pay any cash dividends on its common stock.

Melinta has never paid or declared any cash dividends on its common stock.

Securities Authorized for Issuance under Equity Compensation Plans

For information about Cempra’s equity compensation plans, see Item 12 of Part III of Cempra’s Annual Report on Form 10-K for the year ended December 31, 2016, as amended by Amendment No. 1 on Form 10-K/A, which documents are attached as Annexes B-1 and B-2 to this proxy statement.

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RISK FACTORS

If the merger is consummated, the combined company will be faced with a market environment that cannot be predicted and that involves significant risks, many of which will be beyond its control. In addition to the other information contained in this proxy statement, you should carefully consider the risks described below before deciding how to vote your shares of common stock. In addition, you should read and consider the risks associated with the business of Cempra because these risks may also affect the combined company—these risks can be found in Cempra’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016, as amended by Amendment No. 1 on Form 10-K/A, which documents are attached as Annexes B-1 and B-2 to this proxy statement. You should also read and consider the other information in this proxy statement, including the other Annexes attached hereto.

Risks Related to the Merger

If the proposed merger with Melinta is not consummated, Cempra’s business could suffer materially and Cempra’s stock price could decline.

The consummation of the proposed merger with Melinta is subject to a number of closing conditions, including the approval of the stock issuance pursuant to the merger agreement by Cempra stockholders, expiration or termination of the applicable waiting period under the HSR Act and other customary closing conditions. Cempra is targeting a closing of the transaction in the fourth quarter of 2017.

If the proposed merger is not consummated, Cempra may be subject to a number of material risks, and its business and stock price could be adversely affected, as follows:

In addition, if the merger agreement is terminated and Cempra’s board of directors determines to seek another business combination, it may not be able to find a third party willing to provide equivalent or more attractive consideration than the consideration to be provided by each party in the merger. In such circumstances, Cempra’s board of directors may elect to, among other things, divest all or a portion of Cempra’s business, or

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take the steps necessary to liquidate all of Cempra’s business and assets, and in either such case, the consideration that Cempra receives may be less attractive than the consideration to be received by Cempra pursuant to the merger agreement.

The announcement and pendency of the proposed merger with Melinta could adversely affect Cempra’s business.

The announcement and pendency of the proposed merger could adversely affect Cempra’s business for a number of different reasons, many of which are not within Cempra’s control, including as follows:

Some of Cempra’s and Melinta’s officers and directors have conflicts of interest that may influence them to support or approve the merger.

Officers and directors of Cempra and Melinta participate in arrangements that provide them with interests in the merger that are different from yours, including, among others, to the extent applicable, their continued service as an officer or director of the combined company, retention and severance benefits, the acceleration of restricted stock and stock option vesting and continued indemnification. These interests, among others, may influence the officers and directors of Cempra and Melinta to support or approve the merger. For a more detailed discussion see “The Merger—Interests of Cempra’s Directors and Executive Officers in the Merger” and “The Merger—Interests of Melinta’s Directors and Executive Officers in the Merger” beginning on pages 92 and 96, respectively, of this proxy statement.

The merger may be completed even though material adverse changes may result from the announcement of the merger, industry-wide changes and other causes.

In general, either party can refuse to complete the merger if there is a material adverse change affecting the other party between August 8, 2017, the date of the merger agreement, and the closing. However, some types of changes do not permit either party to refuse to complete the merger, even if such changes would have a material adverse effect on Cempra or Melinta, to the extent they resulted from the following (unless, in some cases, they have a materially disproportionate effect on Cempra or Melinta, as the case may be):

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If adverse changes occur but Cempra and Melinta must still complete the merger, the combined company’s stock price may suffer.

During the pendency of the merger, Cempra may not be able to enter into a business combination with another party because of restrictions in the merger agreement.

Covenants in the merger agreement impede the ability of Cempra or Melinta to make acquisitions or complete other transactions that are not in the ordinary course of business pending completion of the merger. As a result, if the merger is not completed, the parties may be at a disadvantage to their competitors. In addition, while the merger agreement is in effect and subject to limited exceptions, each party is prohibited from soliciting, initiating, encouraging or taking actions designed to facilitate any inquiries or the making of any proposal or offer that could lead to the entering into certain extraordinary transactions with any third party, such as a sale of assets, an acquisition of Cempra common stock, a tender offer for Cempra common stock or a merger or other business combination outside the ordinary course of business, which transactions could be favorable to such party’s stockholders.

Cempra common stock could be delisted from the NASDAQ Global Market if Cempra does not comply with its initial listing standards at the time of the merger.

Pursuant to the NASDAQ Listing Rules, consummation of the merger requires the combined company to submit an initial listing application and, at the time of the merger, meet all of the criteria applicable to a company initially requesting listing (including a $4.00 per share minimum bid price for Cempra common stock). Cempra intends to apply for listing on the NASDAQ Global Market and is seeking stockholder approval of a reverse stock split in order to satisfy the initial listing criteria. While Cempra intends to obtain listing status for the combined company and maintain the same, no guarantees can be made about its ability to do so. In the event the merger is approved by Cempra stockholders but the reverse stock split is not, the merger could still be consummated and shares of Cempra common stock would not be listed on a national securities exchange.

If Cempra common stock is unable to be listed on NASDAQ or another national securities exchange, the common stock may be eligible to trade on the OTC Bulletin Board or another over-the-counter market. Any such alternative would likely result in it being more difficult for the company to raise additional capital through the public or private sale of equity securities and for investors to dispose of, or obtain accurate quotations as to the market value of, the common stock. In addition, there can be no assurance that the common stock would be eligible for trading on any such alternative exchange or markets.

The market price of the combined company’s common stock may decline as a result of the merger.

The market price of the combined company’s common stock may decline as a result of the merger for a number of reasons including if:

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Cempra stockholders may not realize a benefit from the merger commensurate with the ownership dilution they will experience in connection with the merger.

If the combined company is unable to realize the strategic and financial benefits currently anticipated from the merger, Cempra stockholders will have experienced substantial dilution of their ownership interest without receiving any commensurate benefit. Significant management attention and resources will be required to integrate the two companies. Delays in this process could adversely affect the combined company’s business, financial results, financial condition and stock price following the merger. Even if the combined company were able to integrate the business operations successfully, there can be no assurance that this integration will result in the realization of the full benefits of synergies, innovation and operational efficiencies that may be possible from this integration and that these benefits will be achieved within a reasonable period of time.

Because the lack of a public market for the Melinta shares makes it difficult to evaluate the fairness of the merger, Melinta stockholders may receive consideration in the merger that is greater than or less than the fair market value of the Melinta shares.

The outstanding capital stock of Melinta is privately held and is not traded in any public market. The lack of a public market makes it extremely difficult to determine the fair market value of Melinta. Since the percentage of Cempra’s equity to be issued to Melinta stockholders was determined based on negotiations between the parties, it is possible that the value of the Cempra common stock to be issued in connection with the merger will be greater than the fair market value of Melinta. Alternatively, it is possible that the value of the shares of Cempra common stock to be issued in connection with the merger will be less than the fair market value of Melinta.

The combined company will incur significant transaction costs as a result of the merger, including investment banking, legal and accounting fees. In addition, the combined company will incur significant consolidation and integration expenses which cannot be accurately estimated at this time. These costs could include the possible relocation of certain operations from North Carolina to other offices of the combined company as well as costs associated with shut down costs for certain operations, employee severance, terminating existing office leases and the loss of benefits of certain favorable office leases. Actual transaction costs may substantially exceed Cempra’s estimates and may have an adverse effect on the combined company’s financial condition and operating results.

Melinta’s principal stockholders, executive officers and directors will own a significant percentage of Cempra common stock and will be able to exert a significant control over matters submitted to the stockholders for approval.

Immediately following the effective time of the merger between Melinta and Cempra, Melinta stockholders are expected to own, on a fully-diluted basis as calculated under the treasury stock method, approximately 51.9%, and Cempra’s current stockholders are expected to own approximately 48.1%, of Cempra common stock. The final number of shares and the resulting ownership split between Cempra stockholders and Melinta stockholders will be subject to adjustments at the closing of the merger based on Cempra’s cash levels (net of debt and transaction expenses) and Melinta’s debt levels (above a permitted amount) and transaction expenses as described further in the section entitled “The Merger Agreement—Merger Consideration” beginning on page 103 of this proxy statement.

After the merger with Cempra, Melinta’s officers and directors, and stockholders who own more than 5% of Melinta common stock will beneficially own a significant percentage of Cempra common stock. This is further described below in the section entitled “Security Ownership of Principal Stockholders and Management of

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Melinta” beginning on page 214 of this proxy statement. This significant concentration of share ownership may adversely affect the trading price for Cempra common stock because investors often perceive disadvantages in owning stock in companies with controlling stockholders. These stockholders, if they acted together, could significantly influence all matters requiring approval by the stockholders following the merger, including the election of directors and the approval of mergers or other business combination transactions. The interests of these stockholders may not always coincide with the interests of other stockholders.

The merger may limit the use of the NOL carryforwards and other tax attributes of both Cempra and Melinta to offset future taxable income of the combined company.

Under Section 382 of the Code, if a corporation undergoes an “ownership change” (generally defined as a greater than 50% change (by value) in its equity ownership over a three-year period), the corporation’s ability to use its pre-change net operating loss, which is referred to as NOL, carryforwards and other pre-change tax attributes (such as research tax credits) to offset its post-change income may be limited.

As of December 31, 2016, Cempra had federal NOL carryforwards of approximately $353.5 million and state NOL carryforwards of approximately $244.8 million. As of December 31, 2016 Melinta had federal NOL carryforwards of approximately $278.2 million, state NOL carryforwards of approximately $275.9 million, and federal research and development credits of approximately $6.2 million. As of June 30, 2017, Cempra had estimated federal NOL carryforwards of approximately $377.7 million and estimated state NOL carryforwards of approximately $269.1 million, which amounts are estimates only and subject to change. As of June 30, 2017, Melinta had estimated federal NOL carryforwards of approximately $300 million and estimated state NOL carryforwards of approximately $300 million, which amounts are estimates only and subject to change. The merger may result in an ownership change for both Cempra and Melinta under Section 382 of the Code and may limit the use of the NOL carryforwards and other tax attributes of both Cempra and Melinta to offset future taxable income of the combined company for both federal and state income tax purposes. These tax attributes are subject to expiration at various times in the future to the extent that they have not been applied to offset the taxable income of the combined company. These limitations may affect the combined company’s effective tax rate in the future.

If any of the events described in “Risks Related to Melinta” occur, those events could cause the potential benefits of the merger not to be realized.

Following the effective time of the merger, it is expected that certain of Cempra’s and Melinta’s officers and directors will direct the business and operations of the combined company. Melinta’s business is expected to constitute most, if not all, of the business of the combined company following the merger. As a result, the risks described below in the section entitled “Risks Related to Melinta’s Business” beginning on page 37 are among the most significant risks to the combined company if the merger is completed. To the extent any of the events in the risks described below in the sections entitled “Risks Related to Melinta’s Financial Position and Need for Additional Capital,” “Risks Related to Regulatory Review and Approval of Melinta’s Product Candidates,” and “Risks Related to Melinta’s Intellectual Property” beginning on page 33 occur, those events could cause the potential benefits of the merger not to be realized and the market price of the combined company’s common stock to decline.

The financial projections included in this proxy statement involve risks, uncertainties and assumptions, many of which are beyond the control of Cempra and Melinta. As a result, they may not prove to be accurate and are not necessarily indicative of current values or future performance.

The financial projections contained in this proxy statement involve risks, uncertainties and assumptions and are not a guarantee of future performance. The future financial results of Cempra and, if the merger is completed, the combined company, may materially differ from those expressed in the financial projections due to factors that are beyond Cempra’s or Melinta’s ability to control or predict. Neither Cempra nor Melinta can provide any assurance that any of the financial projections will be realized or that Cempra’s or, if the merger is completed, the combined company’s, future financial results will not materially vary from the financial projections. The financial projections cover multiple years, and the information by its nature becomes subject to greater

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uncertainty with each successive year. The financial projections do not take into account any circumstances or events occurring after the date on which they were prepared. More specifically, the financial projections:

Risks Related to the Reverse Stock Split

The reverse stock split may not increase Cempra’s stock price over the long-term.

The principal purpose of the reverse stock split is to increase the per-share market price of Cempra common stock above the minimum bid price requirement under the NASDAQ Listing Rules so that the listing of the combined company and the shares of Cempra common stock being issued in the merger on NASDAQ Global Market (or, alternatively, the NASDAQ Capital Market) will be approved. It cannot be assured, however, that the reverse stock split will accomplish this objective for any meaningful period of time. While it is expected that the reduction in the number of outstanding shares of common stock will proportionally increase the market price of Cempra common stock, it cannot be assured that the reverse stock split will increase the market price of Cempra common stock by a multiple of the reverse stock split ratio chosen by Cempra’s board of directors in its sole discretion, or result in any permanent or sustained increase in the market price of Cempra common stock, which is dependent upon many factors, including Cempra’s business and financial performance, general market conditions, and prospects for future success. Thus, while the stock price of the combined company might meet the continued listing requirements for the NASDAQ Global Market initially, it cannot be assured that it will continue to do so.

The reverse stock split may decrease the liquidity of the common stock.

Although Cempra’s board of directors believes that the anticipated increase in the market price of Cempra common stock could encourage interest in its common stock and possibly promote greater liquidity for its stockholders, such liquidity could also be adversely affected by the reduced number of shares outstanding after the reverse stock split. The reduction in the number of outstanding shares may lead to reduced trading and a smaller number of market makers for Cempra common stock.

The reverse stock split may lead to a decrease in Cempra’s overall market capitalization.

Should the market price of Cempra common stock decline after the reverse stock split, the percentage decline may be greater, due to the smaller number of shares outstanding, than it would have been prior to the reverse stock split. A reverse stock split is often viewed negatively by the market and, consequently, can lead to a decrease in Cempra’s overall market capitalization. If the per share market price does not increase in proportion to the reverse stock split ratio, then the value of the combined company, as measured by its stock capitalization, will be reduced. In some cases, the per-share stock price of companies that have effected reverse stock splits subsequently declined back to pre-reverse split levels, and accordingly, it cannot be assured that the total market value of Cempra common stock will remain the same after the reverse stock split is effected, or that the reverse stock split will not have an adverse effect on Cempra’s stock price due to the reduced number of shares outstanding after the reverse stock split.

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Risks Related to Cempra

For risks related to the business of Cempra, please refer to the section entitled “Item 1A. Risk Factors” set forth in Cempra’s Annual Report on Form 10-K for the year ended December 31, 2016, as amended by Amendment No. 1 on Form 10-K/A, which documents are attached as Annexes B-1 and B-2 to this proxy statement.

Risks Related to Melinta

Because Cempra and Melinta operate similar businesses and both are pharmaceutical companies in the anti-infectives space, many of the risks related to the business of Cempra, disclosed in the section Risk Factors—Risks Related to Cempra are applicable to Melinta as well. It is noted and acknowledged that Melinta’s product Baxdela has received approval from the FDA, whereas no product of Cempra has reached this stage and that certain risks may differ as to their likelihood of occurring or the impact of such an occurrence as between Melinta and Cempra. This section should be read in conjunction with the section “Risk Factors—Risks Related to Cempra.”

Risks Related to Melinta’s Financial Position and Need for Additional Capital

Melinta has incurred net losses since inception and anticipates that it will continue to incur net losses for the foreseeable future.

Melinta has until recently been a development stage company and has incurred losses since its inception. Based on its operating plans, Melinta does not currently have sufficient working capital to fund planned operating expenses through the next 12 months without additional sources of cash. Pursuant to the terms of the merger agreement, Melinta is permitted to incur up to $15.0 million in additional debt prior to the close of the merger before adjustment of the exchange ratio. As of June 30, 2017, Melinta had an accumulated deficit of $534.2 million. Melinta recorded net losses of $73.9 million and $78.7 million during the years ended December 31, 2016 and 2015, respectively. Melinta anticipates that a substantial portion of its capital resources and efforts in the foreseeable future will be focused on commercialization of Baxdela. As a result, Melinta expects to continue to incur significant and increasing operating losses and negative cash flows for the foreseeable future. These losses have had and will continue to have an adverse effect on stockholders’ deficit and working capital.

Melinta will need to obtain additional financing to fund its operations.

Melinta will need to obtain additional financing to fund future operations, including the commercialization of Baxdela and the development and commercialization of its product candidates and to support sales and marketing activities. Moreover, Melinta’s fixed expenses such as rent, license payments, interest expense and other contractual commitments are substantial.

Melinta’s future funding requirements will depend on many factors, including, but not limited to:

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Melinta has to date not generated any revenue from the sale of any products and does not know when, or if, it will generate any revenue. Until Melinta can generate a sufficient amount of revenue, it may raise additional funds through collaborations and public or private debt or equity financings. Additional funds may not be available when needed on terms that are acceptable, or at all. To the extent that Melinta raises additional capital through the sale of equity or convertible debt securities, the ownership interest of existing stockholders will be diluted, and the terms may include liquidation or other preferences that adversely affect the rights of existing stockholders. Debt financing, if available, would result in increased fixed payment obligations and may involve agreements that include covenants limiting or restricting its ability to take specific actions such as incurring debt, making capital expenditures or declaring dividends. Further, as of June 30, 2017, Melinta had $30.0 million aggregate principal amount outstanding under a Loan and Security Agreement with Oberland Capital and, under the terms of the merger agreement, may borrow an additional $15.0 million prior to closing of the merger. In August 2017, Melinta borrowed an additional $10.0 million under the Loan and Security Agreement. The underlying terms of the Loan and Security Agreement may limit the ability of Melinta to raise additional capital or its capacity to incur more debt or service additional debt payments.

If Melinta is unable to obtain funding on a timely basis, Melinta will be unable to fund the commercialization of Baxdela or complete ongoing and planned clinical trials for Baxdela, radezolid and any of its other product candidates and Melinta may be required to significantly curtail some or all of its activities. Melinta also could be required to seek funds through arrangements with collaborative partners or otherwise that may require Melinta to relinquish rights to its product candidates or some of its technologies or otherwise agree to terms unfavorable to Melinta.

The timing of milestone, royalty and other payments Melinta is required to make under its license agreements is uncertain and could adversely affect its cash flows and results of operations.

Melinta has the following licensing agreements in place: an exclusive license and supply agreement with CyDex Pharmaceuticals, Inc. (now a wholly owned subsidiary of Ligand Pharmaceuticals Incorporated), an exclusive license agreement with Wakunaga Pharmaceutical Co., Ltd., or Wakunaga, an exclusive license agreement with Medical Research Council, and an exclusive license agreement with Yale University, in each case pursuant to which it is obligated to make milestone payments and pay royalties and other fees in connection with the development and commercialization of its product candidates. The timing of Melinta’s achievement of these milestones and the corresponding milestone payments is subject to factors relating to the clinical and regulatory development and commercialization of its product candidates, which are difficult to predict and for which many are beyond its control. Melinta may become obligated to make a milestone or other payment at a time when it does not have sufficient funds to make such payment, which could result in the loss of required intellectual property rights to further develop or commercialize one or more product candidates, or at a time that would otherwise require Melinta to use funds needed to continue to operate its business, which could delay Melinta’s clinical trials, curtail its operations, necessitate a scaling back of its commercialization and marketing efforts or cause Melinta to seek funds to meet these obligations on terms unfavorable to it. In addition, disputes with a licensor regarding compliance with the requirements of its agreements could result in its making milestone, royalty or other payments when it does not believe such payments are due to avoid potentially expensive litigation or termination of or a loss of rights under the agreement. If Melinta is unable to make any payment when due or if it fails to use commercially reasonable efforts to achieve certain development and commercialization milestones within the timeframes required by these agreements, the other party may have the right to terminate the agreement and all of Melinta’s rights to develop and commercialize product candidates using the applicable technology.

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Furthermore, the counterparty to a license agreement may fail to properly maintain or defend the intellectual property subject to the license agreement, leading to the potential invalidation of Melinta’s intellectual property or subjecting it to litigation or arbitration, any of which would be time-consuming and expensive. Additionally, in the event the counterparty commits a material breach of the license agreement, Melinta’s recourse is to terminate the agreement. If Melinta terminates its collaboration, the development or commercialization of the product or product candidate subject to the license agreement could be materially delayed or harmed. If disputes with the counterparty prevent or impair Melinta’s ability to maintain its current licensing and development arrangements on acceptable terms, Melinta may be unable to successfully develop and commercialize its products or product candidates.

Risks Related to Regulatory Review and Approval of Melinta’s Product Candidates

Melinta cannot be certain that Baxdela, radezolid, its ESKAPE pathogen program product candidates or any of its other product candidates will receive regulatory approval for additional uses, and without regulatory approval it will not be able to market its product candidates.

Melinta’s lead product, Baxdela, is a commercial-stage fluoroquinolone antibiotic that received FDA approval for both IV and tablet formulations in June 2017 for the treatment of adults with serious skin infections known as acute bacterial skin and skin structure infections. Melinta is evaluating Baxdela in a Phase 3 clinical program for serious CABP and plans to initiate a clinical trial in patients with cUTI. Beyond the commercial launch and potential label expansion of Baxdela, Melinta will continue to pursue other pipeline opportunities. Melinta is conducting clinical studies for radezolid for the treatment of acne vulgaris, plans to deliver compounds of antibiotics for bacterial “superbugs” for human clinical trials under its ESKAPE pathogen program, and is in pre-clinical phase for its compounds in the macrolide program, which have potential to treat the bacteria typically identified in skin and lung infections. Melinta’s business is substantially dependent on its ability to complete the development of, obtain regulatory approval for, and successfully commercialize such current and future products and product candidates in a timely manner. The process to develop, obtain regulatory approval for and commercialize product candidates is long, complex, uncertain and costly.

The development of a product candidate and issues relating to its approval and sale are subject to extensive regulation by the FDA in the U.S. and regulatory authorities in other countries, with regulations differing from country to country. Melinta is not permitted to commercialize, market or sell Melinta’s product candidates in the U.S. until it receives approval of an NDA from the FDA. An NDA must include extensive preclinical and clinical data and supporting information to establish the product candidate’s safety and effectiveness for each desired indication. The NDA must also include significant information regarding the chemistry, manufacturing and controls for the product. Melinta is currently dependent on the work conducted by contract organizations for these activities. Obtaining approval of an NDA is a lengthy, expensive and uncertain process, and may not be obtained. The FDA review process typically has defined timelines, but may take significantly longer if additional development work is required by the FDA. FDA approvals are never guaranteed. If Melinta submits an NDA to the FDA, the FDA must decide whether to accept or reject the submission for filing. Melinta cannot be certain that any submissions will be accepted for filing and review by the FDA. Even if a product is approved, the FDA may limit the indications for which the product may be marketed, include extensive warnings on the product labeling or require expensive and time-consuming post-approval clinical trials or reporting as conditions of approval. Foreign regulatory authorities also have requirements for approval of drug candidates with which Melinta must comply prior to marketing. Obtaining regulatory approval for marketing of a product candidate in one country does not ensure that Melinta will be able to obtain regulatory approval in other countries. In addition, delays in approvals or rejections of marketing applications in the U.S. or foreign countries may be based upon many factors, including:

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Compounds developed in the ESKAPE pathogen program and the macrolide program are still under preclinical development and may never advance to clinical testing or be successfully commercialized. The failure to enter clinical development and ultimately successfully commercialize one or more of the compounds could adversely affect the business and prospects of Melinta.

If Melinta fails to develop Baxdela for additional indications, its commercial opportunities will be limited.

To date, Melinta has focused primarily on the development of Baxdela for the treatment of ABSSSI. A key element of its strategy is to pursue clinical development of Baxdela for other indications, including CABP and/or cUTI. Melinta’s ability to broaden its revenue mix will be highly dependent on its ability to successfully develop and commercialize Baxdela for the treatment of additional indications. The development of Baxdela for additional indications will require additional funding beyond that needed to commercialize Baxdela for the treatment of ABSSSI and will face the same risks of failure inherent in drug development. Melinta cannot provide assurance that it will be successful in advancing any of these programs through the development process. Even if it is able to gain FDA approval to market Baxdela for the treatment of any of these additional indications, Melinta cannot provide assurance that any such additional indications will be successfully commercialized or widely accepted in the marketplace. If Melinta is unable to successfully develop and commercialize Baxdela for these additional indications, its commercial opportunities will be limited and its business prospects will suffer.

Melinta’s approved products or product candidates may have undesirable side effects which may delay or prevent marketing approval, or if approval is received, require them to be taken off the market, require them to include safety warnings, become subject to FDA required Risk Evaluation and Mitigation Strategies or other remediation activities .

If any of Melinta’s approved products or product candidates that receive marketing approval and Melinta or another party later identifies undesirable or unacceptable side effects caused by such products:

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Risks Related to Melinta’s Business

The commercial success of Baxdela for treatment of ABSSSI and any additional indications and of any future product of Melinta will depend upon the degree of market acceptance among physicians, patients, patient advocacy groups, health care payors and the medical community.

It cannot be assured that Baxdela for treatment of ABSSSI or any additional indication or any Melinta product candidate that may be approved in the future will gain market acceptance among physicians, patients, health care payors and the medical community. The degree of market acceptance for Melinta’s products will depend on a number of factors, including:

If Melinta fails to achieve market acceptance for its products, its revenue will be more limited and it will be more difficult to achieve profitability.

If Melinta fails to obtain and sustain an adequate level of reimbursement for its products by third-party payors, sales would be adversely affected.

There will be no commercially viable market for Melinta’s products, without reimbursement from third-party payors. Even if there is a commercially viable market, if the level of reimbursement is below its expectations, its revenue and gross margins will be adversely affected.

Third-party payors, such as government or private health care insurers, carefully review and increasingly question the coverage of, and challenge the prices charged for, drugs. Reimbursement rates from private health insurance companies vary depending on the company, the insurance plan and other factors. A current trend in the U.S. health care industry is toward cost containment. Large public and private payors, managed care organizations, group purchasing organizations and similar organizations are exerting increasing influence on decisions regarding the use of, and reimbursement levels for, particular treatments. Such third-party payors, including Medicare, are questioning the coverage of, and challenging the prices charged for, medical products and services, and many third-party payors limit coverage of or reimbursement for newly approved health care products. In particular, third-party payors may limit the covered indications. Cost-control initiatives could decrease the price Melinta might establish for products, which could result in product revenues being lower than anticipated. If the prices for its products decrease or if governmental and other third-party payors do not provide adequate coverage and reimbursement levels, its revenue and prospects for profitability will suffer. Reimbursement systems in international markets vary significantly by country and by region, and reimbursement approvals must be obtained on a country-by-country basis.

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Reimbursement in the European Union must be negotiated on a country-by-country basis and in many countries the product cannot be commercially launched until reimbursement is approved. The negotiation process in some countries can exceed 12 months.

Melinta is subject to existing and potential additional regulation and government inquiry, which can impose burdens on its operations and narrow the markets for its products .

Melinta is subject, both directly and indirectly, to the adverse impact of existing and potential future government regulation of its operations and markets. Its product candidates are, and any future approved product candidates will be, subject to regulation by the FDA and equivalent foreign regulatory authorities. These regulations govern a wide variety of product related activities, from quality management, design and development to labeling, manufacturing, promotion, sales and distribution. If Melinta or any of its suppliers or distributors fail to comply with the FDA and other applicable regulatory requirements, or are perceived to potentially have failed to comply, it may face, among other things, warning letters; adverse publicity affecting both Melinta and its customers; investigations or notices of non-compliance, fines, injunctions, and civil penalties; import or export restrictions; partial suspensions or total shutdown of production facilities or the imposition of operating restrictions; increased difficulty in obtaining required FDA clearances or approvals or foreign equivalents; seizures or recalls of its products or those of its customers; or the inability to sell such products. Any such FDA actions could disrupt Melinta’s business and operations, lead to significant remedial costs and have a material adverse impact on Melinta’s financial position and results of operations.

If Melinta is unable to establish a direct sales force for its products and product candidates, if approved, in the United States, its business may be harmed.

Melinta currently does not have an established sales organization. Melinta may market Baxdela and any product candidates that may be approved in the future directly to physicians in the United States through its own sales force. Melinta will need to incur significant additional expenses and commit significant additional management resources to establish and train a sales force to market and sell. Melinta may not be able to successfully establish these capabilities despite these additional expenditures. Melinta will also have to compete with other pharmaceutical and life sciences companies to recruit, hire, train and retain sales and marketing personnel. In the event Melinta is unable to successfully market and promote its products, its business may be harmed.

The successful commercialization of Melinta’s product candidates will depend on the pricing it is able to achieve for its product candidates, both inside and outside the U.S.

Melinta’s ability to successfully commercialize its product candidates will be dependent on whether it can obtain adequate pricing for any particular product candidate. Pricing may be substantially dependent on Melinta’s ability to obtain reimbursement from third-party payors, both in the U.S. and in foreign countries. Outside the U.S., certain countries, including a number of European Union members, set prices and reimbursement for pharmaceutical products, or medicinal products as they are commonly referred to in the E.U., with limited participation from those marketing the products. Melinta cannot be sure that any prices and reimbursement will be acceptable to it or its strategic commercial partners. If the regulatory authorities in these foreign jurisdictions set prices or reimbursement that are not commercially attractive for Melinta or its strategic commercial partners, its revenues from sales by Melinta or its collaborators, and the potential profitability of its product candidates, in those countries would be negatively affected. Further, through contractual or other arrangements, the price Melinta may be able to obtain in foreign countries may be dependent on the price it can achieve in the U.S.

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Melinta’s estimates of the market for and commercialization of Baxdela as a treatment for ABSSSI, CABP or cUTI or for any other product candidate may be inaccurate or vary significantly in regard to the potential market size.

The potential market opportunities for Baxdela and any other product candidate are difficult to estimate precisely. Melinta’s estimates of the potential market opportunities are predicated on many assumptions, including industry knowledge and publications, third-party research reports and other surveys. While Melinta believes that its internal assumptions are reasonable, these assumptions involve the exercise of significant judgment on the part of Melinta’s management, are inherently uncertain and the reasonableness of these assumptions has not been assessed by an independent source. If any of the assumptions proves to be inaccurate, the actual markets for Melinta’s product candidates could be smaller than its estimates of the potential market opportunities.

In addition, Melinta’s estimates regarding the timing and amount of acceptance of any product candidate, and the pricing achievable for any product candidate, may prove incorrect. Further, Melinta’s plans for commercialization of any product candidate may not materialize in the time or manner it anticipates and may be adversely impacted by any required label warnings, as will be the case for ABSSSI, and if Baxdela is approved for CABP or cUTI, or any perceived safety or efficacy concerns. Finally, Melinta may underestimate the demand for a product candidate, which could lead to lack of commercial quantities when needed and result in market backlash against the product candidate. Any of these occurrences could have a material adverse effect on its plans for commercialization of and the generation of any revenue from any product candidate.

Bacteria might develop resistance to Baxdela and any of Melinta’s product candidates, which could decrease the efficacy and commercial viability of Baxdela and those product candidates.

Bacteria develop resistance to antibiotics over time due to the genetic mutation of the bacteria. Many current and previous antibiotics have suffered reduced efficacy over time due to the development of resistance to such drugs. It is probable that, over time, bacteria will also develop resistance to Baxdela and Melinta’s drug candidates. If resistance were to develop rapidly to Baxdela or Melinta’s drug candidates, this would reduce the commercial potential for Melinta’s business.

Melinta is building its own marketing and sales organization for Baxdela for ABSSSI, which may expand to CABP and cUTI, if approved, but has no experience as a company in marketing drug products. If it is unable to successfully establish its own marketing and sales capabilities, or enter into agreements with third parties to market and sell its products after they are approved, it may not be able to generate product revenues.

If Melinta receives regulatory approval of Baxdela for CABP and cUTI and a sufficient market for Baxdela for ABSSSI, CABP, or cUTI is likely, it would expect to build its U.S. sales organization for the marketing, sales and distribution of Baxdela as a treatment for ABSSSI, CABP, or cUTI, the size and nature of which would be determined by approved labeling and the potential market for Baxdela in light of that label. The establishment and development of Melinta’s own sales force will be expensive and time consuming and could delay the planned launch of Baxdela, and Melinta cannot be certain that it will be able to successfully develop this capability. The timing of building any sales force will be dependent on many factors, including the anticipated approval date and its financial resources. Melinta may seek one or more licensing partners to handle some or all of the sales and marketing of Baxdela for ABSSSI, CABP, or cUTI in the U.S. In order to successfully commercialize any other products, Melinta must develop these capabilities on its own or make arrangements with third parties for the marketing, sales and distribution of its products. There also may be certain markets within the U.S. for Baxdela for which Melinta may seek a co-promotion arrangement. If Melinta is not successful in building its own sales force, it may not be able to enter into arrangements with third parties to sell Baxdela on favorable terms or at all. Melinta would not have control over a third-party sales organization and would be dependent on that organization for successfully selling any of its products. Such a third-party organization may not devote the necessary manpower, time, resources or priority to Melinta’s products, which would negatively

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impact its results of operations. In the event Melinta is unable to develop its own marketing and sales force or collaborate with a third-party marketing and sales organization, it would not be able to commercialize Baxdela or any other product candidates that it develops, which would negatively impact its ability to generate product revenues. Further, whether Melinta commercializes products on its own or relies on a third party to do so, its ability to generate revenue will be dependent on the effectiveness of the sales force. In addition, to the extent Melinta relies on third parties to commercialize its approved products, it will likely receive less revenues than if it commercialized these products itself.

A failure to maintain optimal inventory levels to meet commercial demand for any product that may be approved, including Baxdela, could harm Melinta’s reputation and subject it to financial losses.

Because accurate product planning is necessary to ensure that Melinta maintains optimal inventory levels for any product candidate that might be approved, including Baxdela, significant differences between its estimates and judgments and future actual demand for any approved products and the shelf life of inventory may result in significant charges for excess inventory or purchase commitments in the future. If Melinta is required to recognize charges for excess inventories, such charges could have a material adverse effect on its financial condition and results of operations. Melinta’s ability to maintain optimal inventory levels also depends on the performance of third-party contract manufacturers. If its manufacturers are unsuccessful in either obtaining raw materials, if Melinta is unable to release inventory on a timely and consistent basis, if Melinta fails to maintain an adequate level of product inventory, if inventory is destroyed or damaged, or if Melinta’s inventory reaches its expiration date, patients might not have access to Melinta’s products, sales could be lost, its reputation and brands could be harmed, and physicians may be less likely to prescribe its products in the future, each of which could have a material adverse effect on Melinta’s business, financial condition, results of operations and cash flows.

If Melinta obtains approval to commercialize any of its product candidates outside of the United States, a variety of risks associated with international operations could materially adversely affect its business.

If any of Melinta’s product candidates are approved outside the United States, Melinta has entered into and will likely enter into additional agreements with third parties to commercialize such product outside the United States. Melinta expects that it will be subject to additional risks related to entering into or maintaining these international business relationships, including:

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If Melinta markets any of its product candidates that receive approval in a manner that violates applicable health care laws, including laws prohibiting off-label promotion, disclosure laws or other similar laws, it may be subject to civil or criminal penalties.

Any regulatory approval of drug products is limited to those specific diseases and indications for which a product is deemed to be safe and effective by the FDA. In addition to the FDA approval required for new formulations, any new indication for an approved product also requires FDA approval. While physicians may choose to prescribe drugs for uses that are not described in the product’s labeling and for uses that differ from those tested in clinical studies and approved by the regulatory authorities, Melinta’s ability to promote the products is limited to those indications that are specifically approved by the FDA. Regulatory authorities in the United States generally do not regulate the behavior of physicians in their choice of treatments, and such off-label uses by healthcare professionals are common. Regulatory authorities do, however, restrict communications by pharmaceutical companies on the subject of off-label use. If Melinta is not able to obtain FDA approval for any desired future indications for solithromycin, fusidic acid or any other product candidates that may be approved, its ability to market and sell such products will be limited and Melinta’s business may be adversely affected.

In addition, in recent years, several states and localities have enacted legislation requiring pharmaceutical companies to establish marketing compliance programs, file periodic reports with the state or make periodic public disclosures on sales, marketing, pricing, clinical trials, health care provider payments and other activities. Additionally, the federal government has enacted the Physician Payment Sunshine Act which requires pharmaceutical manufacturers to report annually to the Secretary of Health and Human Services payments or other transfers of value made by that entity to physicians and teaching hospitals. If any of Melinta’s product candidates are approved, it will be required to report certain information with respect to such payments. Melinta also expects to have to comply with similar reporting obligations in foreign countries. Melinta will need to expend significant efforts to establish, maintain and enhance such reporting systems and processes in order to comply with these regulations. Failure to comply with the reporting requirements would result in significant civil monetary penalties. The Affordable Care Act also includes various provisions designed to strengthen significantly fraud and abuse enforcement, such as increased funding for enforcement efforts and the lowering of the intent requirement of the federal anti-kickback statute and criminal health care fraud statute such that a person or entity no longer needs to have actual knowledge of this statute or specific intent to violate it.

Melinta is subject to extensive and costly government regulation.

Antibiotics, including those Melinta is developing and plans to develop in the future, are subject to extensive and rigorous domestic government regulation including regulation by the FDA, the Centers for Medicare and Medicaid Services, other divisions of the U.S. Department of Health and Human Services, the U.S. Department of Justice, state and local governments and their respective foreign equivalents. The FDA regulates the research, development, pre-clinical and clinical testing, manufacture, safety, effectiveness, record keeping, reporting, labeling, storage, approval, advertising, promotion, sale, distribution, import and export of pharmaceutical products. If any products Melinta develops are tested or marketed abroad, they will also be subject to extensive regulation by foreign governments, whether or not Melinta has obtained FDA approval for a given product and its uses. Such foreign regulation may be equally or more demanding than corresponding U.S. regulation. Government regulation substantially increases the cost and risk of researching, developing, manufacturing and selling products. Melinta’s failure to comply with these regulations could result in significant fines or the inability of its product candidates to obtain and maintain regulatory approval, which would have a materially adverse effect on Melinta’s business, financial condition, results of operations and prospects.

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Melinta expects to rely upon third-party manufacturers for the commercial supply of Baxdela for ABSSSI and any of its product candidates that may be approved in the future. If third-party manufacturers fail to comply with manufacturing regulations, Melinta’s financial results and financial condition will be adversely affected.

Melinta does not have its own manufacturing facilities. Melinta expects to rely upon third-parties for the manufacture and supply of the active pharmaceutical ingredients contained in its products, as well as the preparation of finished products and their packaging. Even if Melinta receives approval for the commercialization of its product candidates, it will not be able to launch such product until Melinta has the appropriate commercial and manufacturing arrangements in place.

Before they can begin commercial manufacture of Melinta’s products, contract manufacturers must obtain regulatory approval of their manufacturing facilities, processes and quality systems. In addition, pharmaceutical manufacturing facilities are continuously subject to inspection by the FDA and foreign regulatory authorities, before and after product approval. Due to the complexity of the processes used to manufacture pharmaceutical products and product candidates, any potential third-party manufacturer may be unable to continue to pass or initially pass federal, state or international regulatory inspections in a cost-effective manner.

If a third-party manufacturer with whom Melinta contracts is unable to comply with manufacturing regulations, Melinta may be subject to fines, unanticipated compliance expenses, recall or seizure of its products, total or partial suspension of production and/or enforcement actions, including injunctions, and criminal or civil prosecution. These possible sanctions would adversely affect its financial results and financial condition.

If Melinta’s competitors are able to develop and market products that are preferred over Baxdela or any future approved products, its commercial opportunity for such products will be reduced.

Melinta faces competition from established pharmaceutical and biotechnology companies, as well as from academic institutions, government agencies and private and public research institutions, which may in the future develop products to treat ABSSSI, CABP, cUTI or other diseases or conditions that Melinta’s product candidates target. With respect to Baxdela for treatment of ABSSSI, Melinta faces competition from both established and early-stage pharmaceutical and biotechnology companies, among them, Paratek Pharmaceuticals, Inc., Motif Bio plc and Basilea Pharmaceutica Ltd., each of which currently have drugs in Phase 3 development for treatment of ABSSSI. In addition, researchers are continually learning more about treatments and new discoveries may lead to new therapies. As a result, Baxdela and any of Melinta’s future products may be rendered less competitive. Other early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.

Melinta’s commercial opportunity will be reduced if its competitors develop and commercialize products that are safer, more effective, have fewer side effects, are more convenient or are less expensive than Melinta’s products. Melinta expects that its ability to compete effectively will depend upon, among other things, its ability to:

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Melinta may not be successful in establishing and maintaining development and commercialization collaborations, which could adversely affect Melinta’s ability to develop certain of its product candidates and its financial condition and operating results.

Developing pharmaceutical products, conducting clinical trials, obtaining regulatory approval, establishing manufacturing capabilities and marketing approved products is expensive. Melinta has established significant commercial relationships to market Baxdela outside the United States with Menarini, Eurofarma, and Malin Life Sciences Holdings Limited, or Malin. Melinta has also entered into a collaboration agreement with a clinical research organization for the development of radezolid. Melinta plans to establish additional collaborations for development and commercialization of product candidates and research programs, including funding the continued development of Baxdela, radezolid and potentially other products and indications. Additionally, Melinta intends to enter into sales and marketing arrangements with third parties for international sales, and to develop its own sales force in the U.S. If Melinta is unable to maintain its existing arrangements or enter into any new such arrangements on acceptable terms, if at all, Melinta may be unable to effectively market and sell its products in its target markets. Melinta expects to face competition in seeking appropriate collaborators. Moreover, collaboration arrangements are complex and time consuming to negotiate, document and implement and may require substantial resources to maintain. Melinta may not be successful in its efforts to establish and implement collaborations or other alternative arrangements for the development of its product candidates.

If Melinta partners with a third party for development and commercialization of a product candidate, Melinta can expect to relinquish some or all of the control over the future success of that product candidate to the third party. Melinta’s collaboration partner may not devote sufficient resources to the commercialization of its product candidates or may otherwise fail in its commercialization. The terms of any collaboration or other arrangement that Melinta establishes may not be favorable to Melinta. In addition, any collaboration that Melinta enters into may be unsuccessful in the development and commercialization of its product candidates. In some cases, Melinta may be responsible for continuing preclinical and initial clinical development of a partnered product candidate or research program, and the payment Melinta receives from its collaboration partner may be insufficient to cover the cost of this development. If Melinta is unable to reach agreements with suitable collaborators for its product candidates, it would face increased costs, it may be forced to limit the number of its product candidates it can commercially develop or the territories in which it commercializes them and it might fail to commercialize products or programs for which a suitable collaborator cannot be found. If Melinta fails to achieve successful collaborations, its operating results and financial condition will be materially and adversely affected.

If Melinta fails to comply with environmental, health and safety laws and regulations, it could become subject to fines or penalties or incur costs that could have a material adverse effect on the success of its business.

Melinta is subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. From time to time and in the future, its operations may involve the use of hazardous and flammable materials, including chemicals and biological materials, and may also produce hazardous waste products. Even if it contracts with third parties for the disposal of these materials and wastes, Melinta cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from its use of hazardous materials, Melinta could be held liable for any resulting damages, and any liability could exceed its resources. Melinta also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

Although Melinta maintains workers’ compensation insurance to cover it for costs and expenses it may incur due to injuries to its employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. Melinta does not maintain insurance for environmental liability or toxic tort claims.

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In addition, Melinta may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair its research, development or production efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Melinta relies on certain third-party software in its business, including in the operation of its research and development operations, and the loss of such rights or the disruption of the software could result in a material disruption of its product development programs.

Melinta licenses and uses certain third-party software, including but not limited to programs licensed from Cemcomco LLC, which Melinta uses in its research and development operations. Cemcomco LLC may terminate the license should Melinta fail to pay licenses fees, which could cause material disruption to Melinta’s research operations. Furthermore, any such third-party software may include bugs or failures, may fail to continue to be compatible with Melinta’s systems, as necessary, or may be found to infringe other third-party rights, such that Melinta may be unable to continue to use the software for its current purposes. While alternative software is commercially available, implementing new software and related systems could have a material impact on Melinta’s business and specifically its research and development operations.

Melinta’s internal computer systems, or those of its CROs or other contractors or consultants, may fail or suffer security breaches, which could result in a material disruption of its product development programs.

Despite the implementation of security measures, Melinta’s internal computer systems and those of its CROs and other contractors and consultants are vulnerable to damage or disruption from computer viruses, software bugs, unauthorized access, natural disasters, terrorism, war, and telecommunication, equipment and electrical failures. While Melinta has not, to its knowledge, experienced any significant system failure, accident or security breach to date, if such an event were to occur and cause interruptions in its operations, it could result in a material disruption of its programs. For example, the loss of clinical trial data from completed or ongoing clinical trials for any of its product candidates could result in delays in its regulatory approval efforts and significantly increase its costs to recover or reproduce the data. To the extent that any disruption or security breach results in a loss of or damage to its data or applications, or inappropriate disclosure or theft of confidential or proprietary information, Melinta could incur liability, the further development of its product candidates could be delayed or its competitive position could be compromised.

Risks Related to Melinta’s Intellectual Property

Melinta’s ability to pursue the development and commercialization of Baxdela depends upon the continuation of its license from Wakunaga.

Melinta relies on certain licenses to certain patent rights and proprietary technology from third parties that are important or necessary to the development of its technology and products. For example, its license agreement with Wakunaga provides it with a worldwide exclusive license to develop and sell Baxdela. In particular, Melinta obtained an exclusive license to certain patents, patent applications and proprietary information, including patents and proprietary information owned by AbbVie Inc. and licensed to Wakunaga, covering the composition of matter to Baxdela, its manufacturing process, salt forms, pharmaceutical compositions containing Baxdela, methods of using Baxdela, and other proprietary information. Melinta’s license agreement with Wakunaga further grants it non-exclusive rights to other patents and applications. The license requires Melinta to make certain milestone and royalty payments to Wakunaga. If Melinta is unable to make any of these required payments under the license agreement, or if Melinta does not use commercially reasonable efforts to achieve certain development and commercialization milestones for Baxdela within the timeframes required by the license agreement, Melinta’s rights to develop and commercialize Baxdela could be terminated. In addition, Wakunaga may terminate the license agreement on a product-by-product and country-by-country basis based upon Melinta’s material breach of the license agreement if not cured within 90 days from written notice of breach. If Melinta’s

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license agreement with Wakunaga were terminated, it would lose its rights to develop and commercialize Baxdela, and would have to grant Wakunaga a perpetual, non-royalty bearing, exclusive license to its proprietary information reasonably necessary to commercialize Baxdela. Loss of its license agreement would materially and adversely affect its business, results of operations and future prospects.

In addition, disputes may arise regarding intellectual property subject to a licensing agreement, including:

If disputes over intellectual property that Melinta has licensed prevent or impair its ability to maintain its current licensing arrangements on acceptable terms, Melinta may be unable to successfully develop and commercialize the affected product candidates.

In addition, the agreements under which Melinta currently licenses intellectual property or technology from third parties are complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any contract interpretation disagreement that may arise could narrow what Melinta believes to be the scope of its rights to the relevant intellectual property or technology, or increase what it believes to be its financial or other obligation under the relevant agreement, either of which could have a material adverse effect on its business, financial condition, results of operations and prospects.

Melinta has not yet registered its trademarks in all of its potential markets, and failure to secure those registrations could adversely affect its business.

Melinta has filed trademark applications with the United States Patent and Trademark Office (“USPTO”) for its marks, including “MELINTA,” “MELINTA THERAPEUTICS,” “MELINTA THE ANTIBIOTICS COMPANY” and “BAXDELA” for use in connection with its goods and services. The MELINTA, MELINTA THERAPEUTICS and MELINTA THE ANTIBIOTICS COMPANY marks have matured to registration in the U.S. Melinta also anticipates filing foreign trademark applications for the same marks for goods and services outside the United States. Melinta has obtained registrations for the MELINTA THERAPEUTICS mark in Mexico, the European Union, Canada and Japan. The registrations will be subject to use and maintenance requirements. Melinta has not yet registered all of its trademarks in all of its potential markets, and it is also possible that there are names or symbols other than “MELINTA,” “MELINTA THERAPEUTICS,” “MELINTA THE ANTIBIOTICS COMPANY” and “BAXDELA” that may be protectable marks for which Melinta has not sought registration, and failure to secure those registrations could adversely affect its business. Melinta cannot assure you that opposition or cancellation proceedings will not be filed against its trademarks or that its trademarks would survive such proceedings.

Melinta has not yet registered trademarks for any of its product candidates in jurisdictions outside of the United States. The “BAXDELA” and any other future trademark applications for its product candidates in the U.S., its trademark applications in the U.S. and any other jurisdictions where it may file may not be allowed for registration, and registered trademarks may not be obtained, maintained or enforced. During trademark registration proceedings, Melinta may receive rejections. Although Melinta is given an opportunity to respond to those rejections, it may be unable to overcome such rejections. In addition, in the USPTO and in comparable agencies in many foreign jurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. Opposition or cancellation proceedings may be filed against its trademarks, and its trademarks may not survive such proceedings.

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FORWARD-LOOKING STATEMENTS

This proxy statement includes forward-looking statements within the meaning of Section 21E of the Exchange Act. For this purpose, any statements contained herein, other than statements of historical fact, including statements regarding the proposed merger with Melinta, including the expected timetable for completing the transaction; future financial and operating results, including targeted product milestones and potential revenues; benefits and synergies of the transaction; future opportunities of the combined company; the progress and timing of product development programs and related trials; the potential efficacy of products and product candidates; and the strategy, projected costs, prospects, plans and objectives of management of either Cempra, Melinta or the combined company, may be forward-looking statements under the provisions of The Private Securities Litigation Reform Act of 1995. In this proxy statement, words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “project,” “should,” “target,” “will,” “would” or other words that convey uncertainty of future events or outcomes are used to identify these forward-looking statements. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including “critical accounting estimates” and risks relating to (with respect to Cempra, Melinta and/or the combined company, as applicable): the ability to consummate the proposed merger; the ability to maintain compliance with NASDAQ listing standards; the liquidity and trading market for shares prior to and following the consummation of the proposed merger; clinical trials, including difficulties or delays in the completion of patient enrollment, data collection or data analysis; uncertainties in obtaining successful pre-clinical and clinical results for product candidates and unexpected costs that may result therefrom; ability to obtain required regulatory approvals for product candidates; costs, timing and regulatory review of the combined company’s studies and clinical trials, including its ability to address the issues identified by the FDA in the CRL relating to Cempra’s NDAs for solithromycin for CABP; failure to realize any value of certain product candidates developed and being developed, in light of inherent risks and difficulties involved in successfully bringing product candidates to market; the ability to develop new product candidates and support existing products; the ability to commercialize and launch any product candidate that receives regulatory approval, including Baxdela; the risk that the market for the combined company’s products, including Baxdela, may not be as large as expected; the ability to attain market acceptance among physicians, patients, patient advocacy groups, health care payors and the medical community for Baxdela and any future products of the combined company; the ability to continue marketing Baxdela or any approved drug successfully or at all once it is on the market in light of challenges relating to regulatory compliance, pricing, market acceptance and competition; the ability to obtain the substantial additional funding required to conduct development and commercialization activities; and the ability to obtain, maintain and enforce patent and other intellectual property protection for currently marketed products and product candidates. These and other risks are described in greater detail in the section entitled “Risk Factors” beginning on page 27 of this proxy statement. Many of these factors that will determine actual results are beyond Cempra’s, Melinta’s, or the combined company’s ability to control or predict. If one or more of these factors materialize, or if any underlying assumptions prove incorrect, actual results, performance or achievements may vary materially from any future results, performance or achievements expressed or implied by these forward-looking statements. In addition, any forward-looking statements in this proxy statement represent Cempra’s views only as of the date of this proxy statement and should not be relied upon as representing Cempra’s views as of any subsequent date. Cempra anticipates that subsequent events and developments will cause its views to change. However, while Cempra may elect to update these forward-looking statements publicly at some point in the future, Cempra specifically disclaims any obligation to do so, except as may be required by law, whether as a result of new information, future events or otherwise. Cempra’s forward-looking statements generally do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments it may make. In particular, unless otherwise stated or the context otherwise requires, Cempra has prepared this proxy statement as if it were going to remain an independent, standalone company. If Cempra consummates the merger with Melinta, the descriptions of its strategy, future operations and financial position, future revenues, projected costs and prospects and the plans and objectives of management in this proxy statement may no longer be applicable.

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THE 2017 ANNUAL MEETING

Cempra is furnishing this proxy statement to its stockholders as part of the solicitation of proxies by Cempra’s board of directors for use at the 2017 Annual Meeting and at any adjournments or postponements thereof.

Date, Time and Place

The 2017 Annual Meeting will be held at 8:00 a.m., local time, on November 3, 2017, at the offices of Wyrick Robbins Yates & Ponton LLP located at 4101 Lake Boone Trail, Suite 300, Raleigh, NC 27607.

If you are a holder of record and plan to attend the 2017 Annual Meeting, please bring your proxy or a photo identification to confirm your identity. If you are a beneficial owner of common stock held by a bank or broker, i.e., in “street name,” you will need proof of ownership to be admitted to the meeting. A recent brokerage statement or letter from a bank or broker are examples of proof of ownership. If you want to vote in person your common stock held in “street name,” you must get a proxy in your name from the registered holder.

Purposes of the 2017 Annual Meeting

The purposes of the 2017 Annual Meeting are to consider and act upon the following matters:

Proposals 1 and 2a are conditioned upon each other, and the approval of each such proposal is a condition to the completion of the merger. Therefore, the completion of the merger cannot proceed without the approval of Proposals 1 and 2a.

The merger agreement is attached as Annex A-1 and the merger agreement amendment is attached as Annex A-2 to this proxy statement.

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Recommendation of Cempra’s Board of Directors

After careful consideration, Cempra’s board of directors unanimously recommends that Cempra stockholders vote:

Record Date and Stockholders Entitled to Vote

Only holders of record of shares of Cempra common stock at the close of business on September 29, 2017, the record date for the 2017 Annual Meeting, are entitled to vote the shares of Cempra common stock they held on the record date at the 2017 Annual Meeting. At the close of business on the record date, there were 52,509,281 shares of common stock outstanding and entitled to vote at the 2017 Annual Meeting, held by 22 stockholders of record. Each holder of record is entitled to one vote for each share of Cempra common stock held by such stockholder on the record date on each of the proposals presented in this proxy statement.

Voting Procedures

If your common stock is held by a broker, bank or other nominee, they should send you instructions that you must follow in order to have your shares voted. If you hold shares in your own name, you may vote by proxy in any one of the following ways:

The internet and telephone voting procedures are designed to authenticate stockholders’ identities by use of a control number to allow stockholders to vote their shares and to confirm that stockholders’ instructions have been properly recorded. Voting via the internet or telephone must be completed by 1:00 a.m., Eastern time on November 3, 2017. Of course, you can always come to the meeting and vote your shares in person. If you submit or return a proxy card without giving specific voting instructions, your shares will be voted as recommended by Cempra’s board of directors.

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Cempra is not aware of any other matters to be presented at the meeting except for those described in this proxy statement. If any matters not described in this proxy statement are presented at the meeting, your proxyholder (one of the individuals named on your proxy card) will use their own judgment to determine how to vote your shares. If the meeting is adjourned, your proxyholder may vote your shares on the new meeting date as well, unless you revoke your proxy instructions before then.

Whether or not you plan to attend the 2017 Annual Meeting in person, please vote as soon as possible to ensure your vote is counted.

Revoking Your Proxy Instructions

If you are a stockholder of record, you can revoke your proxy before your shares are voted at the meeting by:

If you are a beneficial owner of shares held in “street name,” you may submit new voting instructions by contacting your bank, broker, nominee or trustee. You may also vote in person at the meeting if you obtain a legal proxy from them.

Counting Votes

Consistent with state law and Cempra’s bylaws, the presence, in person or by proxy, of at least a majority of the shares outstanding and entitled to vote at the meeting will constitute a quorum for purposes of voting on a particular matter at the meeting. On the record date, there were 52,509,281 shares of common stock outstanding and entitled to vote. Accordingly, the holders of 26,254,641 shares must be present at the 2017 Annual Meeting to have a quorum.

Once a share is represented for any purpose at the meeting, it is deemed present for quorum purposes for the remainder of the meeting and any adjournment thereof unless a new record date is set for the adjournment. Shares held of record by stockholders or their nominees who do not vote by proxy or attend the meeting in person will not be considered present or represented and will not be counted in determining the presence of a quorum. Signed proxies that withhold authority or reflect abstentions or “broker non-votes” will be counted for purposes of determining whether a quorum is present. “Broker non-votes” are proxies received from brokerage firms or other nominees holding shares on behalf of their clients who have not been given specific voting instructions from their clients with respect to non-routine matters. If there is no quorum, the chairperson of the meeting or any officer entitled to preside at or to act as secretary of the meeting may adjourn the 2017 Annual Meeting to another date.

Assuming the presence of a quorum at the meeting:

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With respect to “routine” matters, such as the ratification of the selection of Cempra’s independent registered public accounting firm, a bank, brokerage firm, or other nominee has the authority (but is not required) under the rules governing self-regulatory organizations, or the SRO rules, including NASDAQ, to vote its clients’ shares if the clients do not provide instructions. When a bank, brokerage firm, or other nominee votes its clients’ shares on routine matters without receiving voting instructions, these shares are counted both for establishing a quorum to conduct business at the meeting and in determining the number of shares voted FOR, AGAINST or ABSTAINING with respect to such routine matters.

With respect to “non-routine” matters, a bank, brokerage firm, or other nominee is not permitted under the SRO rules to vote its clients’ shares if the clients do not provide instructions. The bank, brokerage firm, or other nominee will so note on the voting instruction form, and this constitutes a “broker non-vote.” “Broker non-votes” will be counted for purposes of establishing a quorum to conduct business at the meeting, but not for determining the number of shares voted FOR, AGAINST, ABSTAINING or WITHHELD FROM with respect to such non-routine matters.

In summary, if you do not vote your proxy, your bank, brokerage firm, or other nominee may either:

Cempra encourages you to provide instructions to your bank, brokerage firm, or other nominee by voting your proxy. This action ensures that your shares will be voted in accordance with your wishes at the meeting.

No Dissenters’ Rights or Appraisal Rights

Holders of Cempra common stock will not be entitled to any dissenters’ rights or appraisal rights with respect to any of the proposals to be voted on at the 2017 Annual Meeting.

Solicitation of Proxies

Cempra will pay the cost of this proxy solicitation. You will need to obtain your own internet access if you choose to access the proxy materials and/or vote over the internet. In addition to soliciting proxies by mail, Cempra’s directors, executive officers and employees and Melinta’s directors and executive officers might solicit proxies personally and by telephone. None of these individuals will receive any additional compensation for this. Cempra has engaged Georgeson to assist Cempra in the distribution of proxy materials and the solicitation of votes described above for a fee of $15,000, plus additional fees based on the amount and types of services rendered and reimbursement of reasonable expenses. Cempra will, upon request, reimburse brokers, banks and other nominees for their expenses in sending proxy materials to their principals and obtaining their proxies.

Adjournments and Postponements

The 2017 Annual Meeting may be adjourned, recessed or postponed if a quorum is not present.

If the time, date and place of an adjourned meeting are announced at the original convening of the 2017 Annual Meeting, no notice of an adjourned meeting need be given unless, after the adjournment, a new record date is fixed for the adjourned meeting, in which case notice of the adjourned meeting will be given to each stockholder of record entitled to vote at the meeting. At any subsequent reconvening of the 2017 Annual Meeting at which a quorum is present in person or represented by proxy, any business may be transacted that might have

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been transacted at the original meeting, and all proxies will be voted in the same manner as they would have been voted at the original convening of the 2017 Annual Meeting, except for any proxies that have been validly revoked or withdrawn prior to the reconvened meeting.