Exhibit 10.1

AMENDMENT NO. ONE TO LOAN AND SECURITY AGREEMENT

THIS AMENDMENT NO. ONE TO LOAN AND SECURITY AGREEMENT (this “ Amendment ”) is made as of this 19 ^th day of June, 2013, by and among KALOBIOS PHARMACEUTICALS, INC. , a Delaware corporation (“ Borrower ”), and MIDCAP FINANCIAL SBIC, LP , a Delaware limited partnership (as Agent for Lenders, “ Agent ”, and individually, as a Lender), and the other financial institutions or other entities from time to time parties to the Loan Agreement referenced below, each as a Lender.

RECITALS

A. Pursuant to that certain Loan and Security Agreement dated as of September 5, 2012 by and among Borrower, Agent and Lenders (as amended hereby and as it may be further amended, modified and restated from time to time, the “ Loan Agreement ”), Agent and Lenders agreed to make available to Borrower a secured term loan in the original principal amount of $15,000,000 (as amended, modified, supplemented, extended and restated from time to time, the “ Term Loan ”). Capitalized terms used but not otherwise defined in this Amendment shall have the meanings set forth in the Loan Agreement.

B. Borrower has requested that Agent and the Lenders amend certain provisions of the Loan Agreement, and Agent and Lenders have agreed to do so, in accordance with the terms and subject to the conditions set forth herein.

AGREEMENT

NOW, THEREFORE , in consideration of the foregoing, the terms and conditions set forth in this Amendment, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Agent, Lenders and Borrower hereby agree as follows:

1. Recitals . This Amendment shall constitute a Loan Document and the Recitals set forth above shall be construed as part of this Amendment as if set forth fully in the body of this Agreement.

2. Amendment to Loan Agreement .

(a) Section 2.2(a) – Availability . Section 2.2(a) of the Loan Agreement is hereby amended and restated in its entirety as follows:

(a) Availability . Subject to the terms and conditions of this Agreement, during the Draw Period, the Lenders agree, severally and not jointly, to make one or more term loans to Borrower in an aggregate amount up to Fifteen Million Dollars ($15,000,000) according to each Lender’s Term Loan Commitment as set forth on Schedule 1 hereto (such term loans are hereinafter referred to singly as a “ Term Loan ”, and collectively as the “ Term Loans ”). After repayment, no Term Loan may be re-borrowed. The Term Loans shall be available in three (3) tranches. The first tranche (“ Tranche One ”) shall be in an amount not less than Five Million Dollars ($5,000,000), but not to exceed Ten

Million Dollars ($10,000,000), and shall be advanced on the Closing Date. The second tranche (“ Tranche Two ”) shall be in an amount equal to Ten Million Dollars ($10,000,000) less the amount advanced under Tranche One, and shall be available to be advanced in a single advance during the Draw Period. The Third Tranche (“ Tranche Three ”) shall be in amount equal to Five Million Dollars ($5,000,000) and shall be available in a single advance during the Draw Period. Notwithstanding anything set forth herein to the contrary, it is understood and agreed that Borrower is required to draw not less than Fifteen Million Dollars ($15,000,000) on or prior to the Draw Period Termination Date. Subject to the terms and conditions set forth in Section 12.1, Borrower may not assign its right to request the Term Loans.

(b) Section 2.2(b) – Interest Payments and Repayment . Section 2.2(b) of the Loan Agreement is hereby amended and restated in its entirety as follows:

(b) Interest Payments and Repayment . Commencing on the first (1 ^st ) Payment Date following the Funding Date of Tranche One, of Tranche Two and Tranche Three, respectively, and continuing on the Payment Date of each successive month thereafter through and including the Maturity Date, Borrower shall make monthly payments of interest to Agent, for payment to each Lender in accordance with its respective Pro Rata Share, in arrears, and calculated as set forth in Section 2.3. Commencing on the Amortization Date, and continuing on the Payment Date of each successive month thereafter through and including the Maturity Date, Borrower shall make consecutive monthly payments of principal to Agent, for payment to each Lender in accordance with its respective Pro Rata Share, as calculated by Agent based upon: (i) the amount of such Lender’s Term Loans and (ii) a straight-line amortization schedule for each Credit Extension (other than under Tranche Three) beginning on the Amortization Date and ending on the Maturity Date. Notwithstanding the preceding sentence, the payments of principal for Tranche Three shall commence on the Tranche Three Amortization Date and shall be calculated based on a straight-line amortization schedule beginning on the Tranche Three Amortization Date and ending on the Maturity Date. All unpaid principal and accrued interest with respect to the Term Loans is due and payable in full on the Maturity Date. The Term Loans may be prepaid only in accordance with Sections 2.2(c) and 2.2(d).

(c) Section 14—Definitions .

(i) The definitions of “Draw Period Termination Date” and “Warrants” in Section 14 of the Loan Agreement are hereby amended and restated in their entirety as follows:

“Draw Period Termination Date ” means May 30, 2014.

“Warrants ” means those certain Warrants to Purchase Stock now or hereafter executed by Borrower in favor of each Lender or such Lender’s Affiliates.

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(ii) The following term and definition are hereby added in alphabetical order to Section 14 of the Loan Agreement as follows:

“Tranche Three Amortization Date ” means that date which is the later of (i) first Payment Date following the Funding Date of Tranche Three or (ii) the Amortization Date.

(d) Exhibit E-1 – Warrants . Exhibit E-1 attached hereto is hereby added to the Loan Agreement as Exhibit E-1 thereto.

3. Confirmation of Representations and Warranties; Reaffirmation of Security Interest . Borrower hereby (a) confirms that all of the representations and warranties set forth in the Loan Agreement are true and correct with respect to Borrower as of the date hereof, and (b) covenants to perform its respective obligations under the Loan Agreement. Borrower confirms and agrees that all security interests and Liens granted to Agent continue in full force and effect, and all Collateral remains free and clear of any Liens, other than those granted to Agent and Permitted Liens. Nothing herein is intended to impair or limit the validity, priority or extent of Agent’s security interests in and Liens on the Collateral.

4. Enforceability . This Amendment constitutes the legal, valid and binding obligation of Borrower, and is enforceable against Borrower in accordance with its terms, except as the enforceability thereof may be limited by bankruptcy, insolvency or other similar laws relating to the enforcement of creditors’ rights generally and by general equitable principles.

5. Costs and Fees . Borrower shall be responsible for the payment of all reasonable costs and fees of Agent’s counsel incurred in connection with the preparation of this Amendment and any related documents. If Agent or any Lender uses in-house counsel for any of these purposes, Borrower further agrees that the Obligations include reasonable charges for such work commensurate with the fees that would otherwise be charged by outside legal counsel selected by Agent or such Lender for the work performed. Borrower hereby authorizes Agent to deduct all of such fees set forth in this Section 5 from the proceeds of one or more Term Loans made under the Loan Agreement.

6. Conditions to Effectiveness . This Amendment shall become effective as of the date on which each of the following conditions has been satisfied (the “ Effective Date ”):

(a) Borrower shall have delivered to Agent this Amendment, duly executed by an authorized officer of Borrower;

(b) Borrower has duly authorized and issued to Lenders warrants, the form of which is attached hereto as Exhibit E-1 (collectively, the “ 2013 Warrants ”), evidencing Lenders’ (or their respective affiliates or designees) right to acquire their respective Pro Rata Share of the class of stock of Borrower, on the terms and conditions set forth in the 2013 Warrants, as necessary to comply with the requirements of the Loan Documents.

(c) all representations and warranties of Borrower contained herein shall be true and correct in all material respects as of the Effective Date (and such parties’ delivery of their respective signatures hereto shall be deemed to be its certification thereof);

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(d) the secretary of Borrower shall have delivered to Agent a duly executed secretary’s and incumbency certificate identifying the current officers of Borrower who are duly authorized by Borrower’s board of directors to execute and deliver this Amendment and any related documents, together with resolutions of the governing board or body of Borrower authorizing the transactions contemplated by this Amendment and the issuance of the Warrant; and

(e) Agent shall have received from Borrower of all of the fees owing pursuant to this Amendment and Agent’s reasonable out-of-pocket legal fees and expenses.

7. No Waiver or Novation . The execution, delivery and effectiveness of this Amendment shall not, except as expressly provided in this Amendment, operate as a waiver of any right, power or remedy of Agent, nor constitute a waiver of any provision of the Loan Agreement, the Loan Documents or any other documents, instruments and agreements executed or delivered in connection with any of the foregoing. Nothing herein is intended or shall be construed as a waiver of any existing Defaults or Events of Default under the Loan Agreement or other Loan Documents or any of Agent’s rights and remedies in respect of such Defaults or Events of Default. This Amendment (together with any other document executed in connection herewith) is not intended to be, nor shall it be construed as, a novation of the Loan Agreement.

8. Affirmation . Except as specifically amended pursuant to the terms hereof, the Loan Agreement and all other Loan Documents (and all covenants, terms, conditions and agreements therein) shall remain in full force and effect, and are hereby ratified and confirmed in all respects by Borrower. Borrower covenants and agrees to comply with all of the terms, covenants and conditions of the Loan Agreement (as amended hereby) and the Loan Documents, notwithstanding any prior course of conduct, waivers, releases or other actions or inactions on Agent’s or any Lender’s part which might otherwise constitute or be construed as a waiver of or amendment to such terms, covenants and conditions.

9. Confidentiality . Borrower will not disclose the contents of this Amendment, the Loan Agreement or any of the other Loan Documents to any third party (including, without limitation, any financial institution or intermediary) without Agent’s prior written consent, other than to Borrower’s officers and advisors on a need-to-know basis. Borrower agrees to inform all such persons who receive information concerning this Amendment, the Loan Agreement and the other Loan Documents that such information is confidential and may not be disclosed to any other Person.

10. Miscellaneous .

(a) Reference to the Effect on the Loan Agreement. Upon the effectiveness of this Amendment, each reference in the Loan Agreement to “this Agreement,” “hereunder,” “hereof,” “herein,” or words of similar import shall mean and be a reference to the Loan Agreement, as amended by this Amendment. Except as specifically amended above, the Loan Agreement, and all other Loan Documents (and all covenants, terms, conditions and agreements therein), shall remain in full force and effect, and are hereby ratified and confirmed in all respects by Borrower.

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(b) Incorporation of Loan Agreement Provisions . The provisions contained in Section 12.2 (Indemnification), Section 11 (Choice of Law, Venue and Jury Trial Waiver) and Section 12.9 (Waiver of Jury Trial) of the Loan Agreement are incorporated herein by reference to the same extent as if reproduced herein in their entirety.

(c) Headings . Section headings in this Amendment are included for convenience of reference only and shall not constitute a part of this Amendment for any other purpose.

(d) Counterparts . This Amendment may be signed in any number of counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument. Signatures by facsimile or by electronic mail delivery of an electronic version (e.g., .pdf or .tif file) of an executed signature page shall be treated as delivery of an original and shall bind the parties hereto. This Amendment constitutes the entire agreement and understanding among the parties hereto and supersede any and all prior agreements and understandings, oral or written, relating to the subject matter hereof.

[SIGNATURES APPEAR ON FOLLOWING PAGES]

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IN WITNESS WHEREOF , intending to be legally bound, and intending that this document constitute an agreement executed under seal, the undersigned have executed this Amendment under seal as of the day and year first hereinabove set forth.

[Signature Page to Amendment No. 1 to Loan and Security Agreement]

Exhibit 10.2

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW, OR SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION CAN BE MADE IN COMPLIANCE WITH RULE 144 OF THE ACT, OR IN THE OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE REASONABLY SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS EXEMPT FROM REGISTRATION.

THIS WARRANT CERTIFIES THAT, for good and valuable consideration, including without limitation the mutual promises contained in the Loan Agreement, MIDCAP FINANCIAL SBIC, LP, a Delaware limited partnership (together with any successor or permitted assignee or transferee of this Warrant or any holder of the Shares issuable or issued upon exercise of this Warrant, “Holder”) is entitled to purchase up to the Number of Shares of fully paid and nonassessable capital stock of the Company of the Class of Stock and at the Warrant Price, as adjusted pursuant to the terms of this Warrant, subject to the provisions and upon the terms and conditions set forth in this Warrant. As used herein, “Share” or “Shares” (a) shall refer to either (i) the shares of stock issuable upon the exercise or conversion of this Warrant and any shares of capital stock into which such shares may be converted or exchanged, or (ii) the authorized or issued and outstanding shares of capital stock of the Company which are of the same class and series as the shares of stock issuable upon the exercise or conversion of this Warrant, in either case as the specific provisions of this Warrant or the context may require.

This Warrant shall be exercisable for the Initial Shares. The “Initial Shares” means the Number of Shares of the Class of Stock of the Company’s capital stock each set forth above and as adjusted pursuant to the terms of this Warrant.

ARTICLE 1. EXERCISE.

1.1 Method of Exercise . Holder may at any time and from time to time exercise this Warrant, in whole or in part, by delivering a duly completed and executed Notice of Exercise in substantially the form attached as Appendix 1 to the principal office of the Company

(which notice may be delivered by facsimile or pdf). Unless Holder is exercising the conversion right set forth in Section 1.2, Holder shall also deliver to the Company a check, wire transfer (to an account designated by the Company), or other form of payment acceptable to the Company for the aggregate Warrant Price for the Shares being purchased.

1.2 Conversion Right . In lieu of exercising this Warrant as specified in Article 1.1, Holder may at any time and from time to time after the Issue Date convert this Warrant, in whole or in part, into a number of Shares determined by dividing (a) the aggregate fair market value of the number of Shares or the securities otherwise issuable upon exercise of this Warrant with respect to which Holder elects to convert this Warrant minus the aggregate Warrant Price of such Shares by (b) the fair market value of one Share. The “fair market value” of one Share shall be determined pursuant to Section 1.3.

1.3 Fair Market Value . (a) If the Company’s common stock is then listed or quoted on a Trading Market, the fair market value of each Share shall be the average of the daily volume weighted average trading price of a Share for the fifteen (15) Trading Days immediately prior to the date on which Holder delivers its Notice of Exercise to the Company (the “ 15-Day Trailing Average Price ”) on the principal Trading Market on which the Shares are then listed or quoted as reported by Bloomberg L.P. (based on a Trading Day from 9:30 a.m. (New York City time) to 4:00 p.m. (New York City time)), (b) if the National Association of Securities Dealers, Inc. OTC Bulletin Board (the “ OTC Bulletin Board ”) is not a Trading Market, the fair market value of each Share shall be the 15-Day Trailing Average Price on the OTC Bulletin Board, (c) if the Shares are not then listed or quoted for trading on the OTC Bulletin Board and if prices for the Shares are then reported in the “Pink Sheets” published by Pink OTC Markets, Inc. (or a similar organization or agency succeeding to its functions of reporting prices), the fair market value of each Share shall be the most recent bid price per share of Shares so reported. “Trading Market” means any of the following markets or exchanges on which the Shares are or have most recently been listed or quoted for trading on the date in question: the NYSE AMEX, the Nasdaq Capital Market, the Nasdaq Global Market, the Nasdaq Global Select Market, the New York Stock Exchange or the OTC Bulletin Board (or any successors to any of the foregoing). In the event of an exercise in connection with an Acquisition, the fair market value of a Share shall be the value to be received per Share by all holders of such Shares in such transaction. If the Company’s common stock is not traded in a public market and other than in the event of an exercise in connection with an Acquisition, the Board of Directors of the Company shall determine the fair market value in its reasonable good faith judgment.

1.4 Delivery of Certificate and New Warrant . Promptly after Holder exercises or converts this Warrant pursuant to Article 1.1 or 1.2, respectively, and, if applicable, the Company receives payment of the aggregate Warrant Price, the Company shall promptly deliver to Holder certificates for the Shares acquired and, if this Warrant has not been fully exercised or converted and has not expired, a new Warrant representing the Shares not so acquired. This Warrant shall be deemed to have been exercised and such certificates deemed issued, and Holder shall become the holder of record of the Shares for all purposes, as of the date of Holder’s delivery of the exercise notice pursuant to Article 1.1 and payment of the Warrant Price, if applicable. If an exercise or conversion is to be made in connection with an Acquisition, such exercise may at the election of Holder be conditioned upon the consummation of such transaction, in which case such exercise shall not be deemed to be effective until immediately prior to the consummation of such transaction.

1.5 Replacement of Warrants . On receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Warrant and, in the case of

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loss, theft or destruction, on delivery of an indemnity agreement reasonably satisfactory in form and amount to the Company or, in the case of mutilation on surrender and cancellation of this Warrant, the Company shall execute and deliver, in lieu of this Warrant, a new warrant of like tenor and amount.

1.6 Treatment of Warrant Upon Acquisition of Company .

1.6.1 “ Acquisition ”. For the purpose of this Warrant, “Acquisition” means (a) any sale, assignment, transfer, license, or other disposition of all or substantially all of the assets of the Company, or (b) any reorganization, consolidation, share exchange or merger of the Company with or into another person or entity, or sale of outstanding securities of the Company by the holders thereof, in each case where any “person” (as such term is defined in Sections 3(a)(9) and 13(d)(3) of the Exchange Act), other than a trustee or other fiduciary holding securities under an employee benefit plan of Company, is or becomes a beneficial owner (within the meaning Rule 13d-3 promulgated under the Exchange Act), directly or indirectly, of securities of the Company, representing fifty percent (50%) or more of the combined voting power of Company’s then outstanding securities.

1.6.2 Treatment of Warrant Upon Acquisition .

A) Upon the written request of the Company, Holder agrees that, in the event of an Acquisition that (i) is not described in Section 1.6.1(a), (ii) in which the sole consideration is cash, and (iii) in connection with or as a result of which all holders of the Shares will receive or have the right to receive solely cash in respect of all of their Shares, then either (a) Holder shall exercise its conversion or purchase right under this Warrant and such exercise will be deemed effective immediately prior to the consummation of such Acquisition, or (b) if Holder does not elect to exercise the Warrant, this Warrant will expire upon the consummation of such Acquisition, subject to Section 5.9. The Company shall provide Holder with written notice of its request relating to the foregoing (together with such reasonable information as Holder may reasonably request in connection with such contemplated Acquisition giving rise to such notice), which notice is to be delivered to Holder not less than twenty (20) days prior to the closing of the proposed Acquisition.

B) Upon the written request of the Company, Holder agrees that, in the event of an Acquisition that is described in Section 1.6.1(a) and is an “arms’-length” transaction with a third party that is not an Affiliate (as defined below) of the Company (a “True Asset Sale”), Holder may (a) exercise its conversion or purchase right under this Warrant and such exercise will be deemed effective immediately prior to the consummation of such True Asset Sale, (b) if Holder does not elect to exercise the Warrant, permit this Warrant to continue (unless exercised in the interim) until the earlier of the Expiration Date or the dissolution and/or liquidation of the Company following the closing of any such True Asset Sale, subject to Section 5.9, or (c) if Holder does not elect to exercise the Warrant, elect to have the terms of Section 1.6.2(D) below apply. The Company shall provide Holder with written notice of its request relating to the foregoing (together with such reasonable information as Holder may request in connection with such contemplated Acquisition giving rise to such notice), which notice is to be delivered to Holder not less than twenty (20) days prior to the closing of the proposed True Asset Sale.

C) Upon the written request of the Company, Holder agrees that, in the event of an Acquisition (i) in which the consideration is a combination of cash and equity securities of the acquirer listed for trading on a U.S. national securities exchange and

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which may be freely resold pursuant to a resale registration statement or under Rule 144 of the Act without any restriction or limitation (including without limitation volume and manner of sale restrictions), (ii) in connection with or as a result of which all holders of the shares are or have the right to receive solely cash and/or such securities in the same proportions in respect of all of their Shares, and (iii) on the record date for which the fair market value of one Share (or other securities issuable upon exercise of this Warrant) is greater than the Warrant Price, Holder may (a) exercise its conversion or purchase right under this Warrant and such exercise will be deemed effective immediately prior to the consummation of such Acquisition, or (b) if Holder does not elect to exercise the Warrant, this Warrant will expire upon the consummation of such Acquisition, subject to Section 5.9.

D) Upon the closing of any Acquisition other than those particularly described in subsections (A), (B) and (C) above (or in the case of an Acquisition described in Section 1.6.2(B) above if Holder elects to have the terms of this Section 1.6.2(D) apply), the successor, surviving or acquiring entity, if applicable, shall assume in writing the obligations of this Warrant, including agreements to deliver to Holder in exchange for this Warrant a written instrument issued by the successor, surviving or acquiring entity pursuant to which this Warrant shall thereafter be exercisable for the kind, amount and value of securities, cash, and property as would have been payable for the Shares issuable upon exercise of the unexercised portion of this Warrant had such Shares been outstanding on the record date for the Acquisition and subsequent closing. The Warrant Price and/or number of Shares shall be adjusted accordingly.

As used herein “ Affiliate ” shall mean any person or entity that owns or controls directly or indirectly ten percent (10%) or more of the voting securities of the Company, any person or entity that controls, is controlled by or is under common control with any such person or entity, and each of such person’s or entity’s officers, directors, members, managers, joint venturers or partners, as applicable (whether as a result of the ownership of voting securities, by contract or otherwise).

ARTICLE 2. ADJUSTMENTS TO THE SHARES .

2.1 Share Dividends, Subdivisions and Combinations . If the Company declares or pays a dividend on the Shares payable in common stock or other securities, then upon exercise of this Warrant, for each Share acquired, Holder shall receive, without cost to Holder, the total number and kind of securities to which Holder would have been entitled had Holder owned the Shares of record as of the date the dividend occurred. If the Company subdivides the Shares by reclassification or otherwise into a greater number of shares or takes any other action which increases the number of shares of any class or series of capital stock into which the Shares are convertible, the number of Shares purchasable hereunder shall be proportionately increased and the Warrant Price shall be proportionately decreased. If the outstanding Shares are combined or consolidated, by reclassification or otherwise, into a lesser number of shares, the Warrant Price shall be proportionately increased and the number of Shares shall be proportionately decreased.

2.2 Reclassification, Exchange, Combinations or Substitution . Upon any reclassification, exchange, substitution, reorganization, merger, consolidation or other event that results in a change of the number and/or class of the underlying securities as to which purchase rights under this Warrant exist, Holder shall be entitled to receive, upon exercise or conversion of this Warrant, the number, amount and kind of securities, money and property that Holder would have ultimately received upon the completion of such reclassification, exchange,

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substitution, reorganization, merger, consolidation or other event if this Warrant had been exercised immediately before such reclassification, exchange, substitution, reorganization, merger, consolidation or other event. The Company or its successor shall promptly issue to Holder an amendment to this Warrant setting forth the number and kind of such new securities or other property issuable upon exercise or conversion of this Warrant as a result of such reclassification, exchange, substitution, reorganization, merger, consolidation or other event that results in a change of the number and/or class of securities issuable upon exercise or conversion of this Warrant. The amendment to this Warrant shall provide for adjustments which shall be as nearly equivalent as may be practicable to the adjustments provided for in this Article 2 including, without limitation, adjustments to the Warrant Price and to the number of securities or property issuable upon exercise of the new Warrant. The provisions of this Article 2.2 shall similarly apply to successive reclassifications, exchanges, substitutions, reorganizations, mergers, consolidations or other events.

2.3 Reserved .

2.4 Reserved .

2.5 No Impairment . Without the prior written consent of Holder, the Company shall not, by amendment of the Company’s Certificate of Incorporation, any shareholders agreement or its by-laws, or through any reorganization, recapitalization, share exchange, transfer of assets, consolidation, merger, dissolution, issuance or sale of securities, or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, and shall at all times in good faith assist in carrying out of all such terms and in taking all such action as may be necessary or appropriate to protect Holder’s rights against such avoidance or impairment.

2.6 Fractional Shares . No fractional Shares shall be issuable upon exercise or conversion of this Warrant and the number of Shares to be issued shall be rounded down to the nearest whole Share. If a fractional share interest arises upon any exercise or conversion of the Warrant, the Company shall eliminate such fractional share interest by paying Holder the amount computed by multiplying the fractional interest by the fair market value of a full Share.

2.7 Certificate as to Adjustments . Upon each adjustment of the Warrant Price or the kind or number of securities issuable under this Warrant pursuant to this Article 2, the Company shall promptly notify Holder in writing, and, at the Company’s expense, promptly compute such adjustment, and furnish Holder with a certificate of its Chief Executive Officer, Corporate Secretary or a senior financial officer setting forth such adjustment and the facts upon which such adjustment is based. The Company shall, upon written request, furnish Holder a certificate setting forth the Warrant Price and the number and kind of securities issuable under this Warrant in effect upon the date thereof and the series of adjustments leading to such Warrant Price and such number and kind of securities.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY .

3.1 Representations and Warranties . The Company represents and warrants and covenants to Holder as follows:

(a) The Company has all requisite legal and corporate power and authority, and has taken all corporate action on the part of itself, its officers, directors and stockholders necessary, to execute, issue and deliver this Warrant, to issue the Shares issuable

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upon exercise or conversion of this Warrant, and to carry out and perform its obligations under this Warrant, and this Warrant constitutes the legally binding and valid obligation of the Company enforceable in accordance with its terms, except as enforceability may be limited by applicable bankruptcy, insolvency, reorganization, or similar laws relating to or affecting the enforcement of creditors’ rights, or to principles of equity.

(b) This Warrant has been validly issued and is free of restrictions on transfer other than restrictions on transfer set forth herein and under applicable state and federal securities laws. All Shares which may be issued upon the exercise of the purchase or conversion right represented by this Warrant shall, upon issuance, be duly authorized, validly issued, fully paid and nonassessable, and free of any liens and encumbrances (including preemptive or other similar rights) except for restrictions on transfer provided for herein or under applicable federal and state securities laws.

(c) The execution, delivery, and performance of this Warrant will not result in an violation of, be in conflict with, or constitute a default under, with or without the passage of time or giving of notice, any provision of the Company’s Certificate of Incorporation or the Company’s by-laws, any provision of any judgment, decree, or order to which the Company is a party, by which it is bound, or to which any of its material assets are subject, any contract, obligation, or commitment to which the Company is a party or by which it is bound, or any statute, rule, or governmental regulation applicable to the Company, or the creation of any lien, charge, or encumbrance upon any assets of the Company.

3.2 Notice of Certain Events; Information . If the Company proposes at any time (a) to declare any dividend or distribution upon any of its stock, whether in cash, property, stock, or other securities and whether or not a regular cash dividend; (b) to effect any reclassification or recapitalization of any of its stock; (c) to merge or consolidate with or into any other corporation, or sell, lease, license, or convey all or substantially all of its assets, (d) to approve or participate in any Acquisition, (e) to liquidate, dissolve or wind up, or (f) to take any action or to effect any transaction which requires the Company to provide notice to other holders of the Shares, then, in connection with each such event, the Company shall give Holder: (1) at least twenty (20) days prior written notice of the date on which a record will be taken for such dividend or distribution (and specifying the date on which the holders of stock will be entitled thereto) or for determining rights to vote, if any, in respect of the matters referred to in (a) above; and (2) in the case of the matters referred to in (b), (c), (d), (e) or (f) above, at least twenty (20) days prior written notice of the date when the same will take place (and, if applicable, specifying the date on which the holders of stock will be entitled to exchange their common stock for securities or other property deliverable upon the occurrence of such event).

3.3 Reports . With a view to making available to Holder the benefits of Securities and Exchange Commission (“ SEC ”) Rule 144 and any other rule or regulation of the SEC that may at any time permit Holder to sell securities of the Company to the public without registration or pursuant to a registration on Form S-3, the Company shall, so long as it is subject to the reporting requirements of the Act (and the rules and regulations promulgated thereunder) and the Exchange Act, (A) use commercially reasonable efforts to make and keep available adequate current public information, as those terms are understood and defined in SEC Rule 144, at all times; (B) use commercially reasonable efforts to file with the SEC in a timely manner all reports and other documents required of the Company under the Act and the Exchange Act; and (C) furnish to Holder in connection with a proposed sale of the Shares pursuant to Rule 144, upon request (1) a written statement by the Company that it has complied with the reporting requirements of SEC Rule 144, and (2) such other information as may be reasonably requested in availing Holder of any rule or regulation of the SEC that permits the sale of any securities without registration or pursuant to Form S-3.

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3.4 No Shareholder Rights. Except as provided in this Warrant, Holder will not have any rights as a shareholder of the Company until the exercise or conversion of this Warrant.

3.5 Certain Information . The Company agrees to provide Holder at any time and from time to time with such information as Holder may reasonably request for purposes of Holder’s compliance with regulatory, accounting and reporting requirements applicable to Holder. Holder acknowledges that it is a violation of law to trade in securities of the Company while in possession of material non-public information received from the Company and agrees that it shall hold and treat all such information in confidence in accordance with the provisions of Section 12.9 of the Loan Agreement, which provisions are hereby incorporated herein by reference and agreed to apply to such information.

ARTICLE 4. REPRESENTATIONS, WARRANTIES OF THE HOLDER . Holder represents and warrants to the Company as follows:

4.1 Purchase for Own Account . This Warrant and the securities to be acquired upon exercise of this Warrant by Holder will be acquired for investment for Holder’s account, not as a nominee or agent, and not with a view to the public resale or distribution within the meaning of the Act and Holder has no present intention of selling or engaging in any public distribution of the same except pursuant to a registration or exemption. Holder also represents that Holder has not been formed for the specific purpose of acquiring this Warrant or the Shares.

4.2 Disclosure of Information . Holder has received or has had full access to all the information it considers necessary or appropriate to make an informed investment decision with respect to the acquisition of this Warrant and its underlying securities. Holder further has had an opportunity to ask questions and receive answers from the Company regarding the terms and conditions of the offering of this Warrant and its underlying securities and to obtain additional information (to the extent the Company possessed such information or could acquire it without unreasonable effort or expense) necessary to verify any information furnished to Holder or to which Holder has access.

4.3 Investment Experience . Holder understands that the purchase of this Warrant and its underlying securities involves substantial risk. Holder has experience as an investor in securities of companies in the development stage and acknowledges that Holder can bear the economic risk of Holder’s investment in this Warrant and its underlying securities and has such knowledge and experience in financial or business matters that Holder is capable of evaluating the merits and risks of its investment in this Warrant and its underlying securities and/or has a preexisting personal or business relationship with the Company and certain of its officers, directors or controlling persons of a nature and duration that enables Holder to be aware of the character, business acumen and financial circumstances of such persons.

4.4 Accredited Investor Status . Holder is an “accredited investor” within the meaning of Regulation D promulgated under the Act.

4.5 The Act . Holder understands that this Warrant and the Shares issuable upon exercise or conversion hereof have not been registered under the Act in reliance upon a

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specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of Holder’s investment intent as expressed herein. Holder understands that this Warrant and the Shares issued upon any exercise or conversion hereof must be held indefinitely unless subsequently registered under the Act and qualified under applicable state securities laws, or unless exemption from such registration and qualification are otherwise available.

4.6 Reserved.

ARTICLE 5. MISCELLANEOUS .

5.1 Term . This Warrant is exercisable in whole or in part at any time and from time to time on or before the Expiration Date. The conditions under which the Warrant shall automatically convert on the Expiration Date are set forth in Section 5.9 below.

5.2 Legends .

(a) This Warrant and the Shares (and the securities issuable, directly or indirectly, upon conversion of the Shares, if any) shall be imprinted with a legend in substantially the following form:

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW, OR UNLESS SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION CAN BE MADE IN COMPLIANCE WITH RULE 144 OF THE ACT, OR UNLESS, IN THE OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE REASONABLY SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS EXEMPT FROM REGISTRATION.

(b) Notwithstanding the foregoing, neither this Warrant nor any certificate or instrument evidencing this Warrant or the Shares shall bear, and the Company hereby agrees to remove, within ten (10) days of any written request (together with such evidence or documentation described in the following provisions) by Holder, pursuant to the following provisions of this Section 5.2(b), or not to affix, as applicable, any restrictive or other legend, notice or provision restricting the sale or transfer of this Warrant or the Shares, in each case provided that the Holder has provided reasonable evidence to the Company (including any customary broker’s or transferring stockholder’s letters but expressly excluding an opinion of counsel other than with respect to clause (D) below) that: (A) a transfer of this Warrant or the Shares, as applicable, has been made pursuant to SEC Rule 144 (assuming the transferor is not an “affiliate” (as defined in SEC Rule 144) of the Company); (B) the Warrant or the Shares, as applicable, are then eligible for transfer pursuant to SEC Rule 144(b)(i); (C) a transfer of this Warrant or the Shares has been made for no consideration to an affiliate of Holder or has otherwise been made to any affiliate of Holder who is an “accredited investor” as defined in Regulation D promulgated under the Act, and that is otherwise in compliance with all applicable securities laws; or (D) in connection with any other sale or transfer, provided that upon the

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request of the Company, such Holder provides the Company with an opinion of counsel to such Holder, in a reasonably acceptable form to the Company, to the effect that either such sale or transfer may be made without registration under the applicable requirements of the Act or that such a legend, notice or provision is not required by, and is not required in order to establish compliance with any provisions of, the Act. For all purposes of Section 1.4, the Company shall not be deemed to have delivered to Holder Shares unless and until the Company shall have fully complied with all of the terms and conditions of this Section 5.2(b) (if removal has been requested by the Holder in compliance with this Section 5.2(b)).

5.3 Compliance with Securities Laws on Transfer . This Warrant and the Shares issuable upon exercise of this Warrant (and the securities issuable, directly or indirectly, upon conversion of the Shares, if any) may not be transferred or assigned in whole or in part without compliance with applicable federal and state securities laws by the transferor and the transferee (including, without limitation, the delivery of investment representation letters and, subject to Section 5.2(b), legal opinions reasonably satisfactory to the Company, as reasonably requested by the Company). The Company shall not require Holder to provide an opinion of counsel if the transfer is to an Affiliate of Holder.

5.4 Transfer Procedure . Subject to the provisions of Article 5.3 and upon and effective immediately as of providing Company with written notice substantially in the form attached as Appendix 2, Holder and any permitted transferee may transfer all or part of this Warrant or the Shares issuable upon exercise of this Warrant (or the Shares issuable directly or indirectly, upon conversion of the Shares, if any) to any transferee, provided, however, in connection with any such transfer, Holder or such transferee will give the Company notice of the portion of the Warrant being transferred with the name, address and taxpayer identification number of the transferee and Holder or such transferee promptly thereafter surrenders this Warrant to the Company for reissuance to the transferee(s) (and Holder if applicable).

5.5 Notices . All notices, requests, documents and other communications (collectively, “Notices”) from the Company to Holder, or vice versa, shall be in writing and deemed validly delivered effective as of the earliest to occur of (a) when actually received, or (b) the third business day after mailing by first-class registered or certified mail, postage prepaid, or the first business day after deposit with a reputable overnight courier with all charges paid, in each case other than actual receipt at such mailing, facsimile or electronic mail address as may have been furnished to the Company or Holder, as the case may be. As used in this Warrant, “business days” shall refer to all days other than any Saturday, Sunday or day on which the Company’s primary depository bank is closed. All notices to the Holder shall be addressed as follows until the Company receives notice of a change of address in connection with a transfer or otherwise:

MidCap Financial SBIC, LP

7255 Woodmont Avenue, Suite 200

Bethesda, Maryland 20814

Attention: Portfolio Management- Life Sciences

Telephone No: (301) 841-6438

E-Mail: lviera@midcapfinancial.com

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Notice to the Company shall be addressed as follows until the Holder receives notice of a change in address:

KaloBios Pharmaceuticals, Inc.

260 East Grand Avenue

South San Francisco, California 94080

Attention: Chief Financial Officer

Telephone No: (650) 243-3100

E-Mail: jcooper@kalobios.com

With a copy to:

Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP

1200 Seaport Blvd

Redwood City, CA 94063

Attention: Bennett L. Yee

Telephone No: (650) 463-5244

E-Mail: byee@gunder.com

5.6 Waiver . This Warrant and any term hereof may be changed, waived, discharged or terminated only by an instrument in writing signed by the party against which enforcement of such change, waiver, discharge or termination is sought.

5.7 Reserved .

5.8 Attorneys’ Fees . In the event of any dispute between the parties concerning the terms and provisions of this Warrant, the party prevailing in such dispute shall be entitled to collect from the other party all costs incurred in such dispute, including reasonable attorneys’ fees and disbursements.

5.9 Automatic Conversion upon Expiration . Unless Holder notifies the Company in writing to the contrary prior to such automatic conversion, in the event that, upon the earliest to occur of the Expiration Date or any expiration, involuntary termination or cancellation of this Warrant, the fair market value of one Share as determined in accordance with Section 1.3 above is greater than the Warrant Price in effect on such date, then this Warrant shall automatically be deemed as of immediately before such date to have been converted pursuant to Section 1.2 above as to all Shares for which it shall not previously have been exercised or converted, and the Company shall promptly deliver a certificate representing the Shares issued upon such conversion to the Holder.

5.10 Counterparts . This Warrant may be executed in counterparts, all of which together shall constitute one and the same agreement.

5.11 Governing Law . This Warrant shall be governed by and construed and interpreted in accordance with the laws of the State of New York, without reference to its conflict of law provisions (other than Section 5-1401 of the General Obligations Law).

5.12 Headings . The various headings in this Warrant are inserted for convenience only and shall not affect the meaning or interpretation of this Warrant or any provisions hereof.

5.13 Severability . In the event any one or more of the provisions of this Warrant shall for any reason be held invalid, illegal or unenforceable, the remaining provisions of this Warrant shall be unimpaired, and the invalid, illegal or unenforceable provision shall be replaced by a mutually acceptable valid, legal and enforceable provision.

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[ Remainder of Page Intentionally Left Blank; Signature Page Follows ]

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IN WITNESS WHEREOF, the parties have executed this Warrant to Purchase Stock by their duly authorized representatives as of June 19, 2013.

COMPANY

KALOBIOS PHARMACEUTICALS, INC.

HOLDER

MIDCAP FINANCIAL SBIC, LP

WARRANT SIGNATURE PAGE

APPENDIX 1

NOTICE OF EXERCISE

1. Holder elects to purchase                      shares of the Common Stock of KALOBIOS PHARMACEUTICALS, INC. pursuant to the terms of the attached Warrant, and tenders payment of the purchase price of the shares in full.

[or]

1. Holder elects to convert the attached Warrant into Shares/cash [strike one] in the manner specified in the Warrant. This conversion is exercised for                      of the Shares covered by the Warrant.

[Strike paragraph that does not apply.]

2. Please issue a certificate or certificates representing the shares in the name specified below:

3. By its execution below and for the benefit of the Company, Holder hereby restates each of the representations and warranties in Article 4 of the Warrant as the date hereof.

APPENDIX 2

ASSIGNMENT

For value received, [                    ] hereby sells, assigns and transfers unto

Name:

Address:

Tax ID:

that certain Warrant to Purchase Stock issued by KALOBIOS PHARMACEUTICALS, INC. (the “Company”), on June     , 2013 (the “Warrant”) together with all rights, title and interest therein.

By its execution below, and for the benefit of the Company,                      makes each of the representations and warranties set forth in Article 4 of the Warrant and agrees to all other provisions of the Warrant as of the date hereof.