6,840,000 Shares RETROPHIN, INC. CommonStock, Par Value $0.0001 Per Share UNDERWRITING AGREEMENT

Exhibit 1.1

6,840,000 Shares

RETROPHIN, INC.

Common Stock, Par Value $0.0001 Per Share

UNDERWRITING AGREEMENT

March 18, 2015

Leerink Partners LLC

Deutsche Bank Securities Inc.

  as Representatives of the several Underwriters

c/o Leerink Partners LLC

One Federal Street, 37th Floor

Boston, MA 02110

c/o Deutsche Bank Securities Inc.

60 Wall Street, 2nd Floor

New York, NY 10005

Ladies and Gentlemen:

Retrophin, Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the several underwriters named in Schedule I hereto (the “Underwriters”) for whom you are acting as representatives (the “Representatives”) 6,840,000 shares of its common stock, par value $0.0001 per share (the “Firm Shares”). The Company also proposes to issue and sell to the several Underwriters not more than an additional 1,026,000 shares of its common stock, par value $0.0001 per share (the “Additional Shares”) if and to the extent that you, as Representatives of the offering, shall have determined to exercise, on behalf of the Underwriters, the right to purchase such shares of common stock granted to the Underwriters in Section 2 hereof. The Firm Shares and the Additional Shares are hereinafter collectively referred to as the “Shares.” The shares of common stock, par value $0.0001 per share, of the Company to be outstanding after giving effect to the sales contemplated hereby are hereinafter referred to as the “Common Stock.”

The Company has filed with the Securities and Exchange Commission (the “Commission”) a registration statement, including a prospectus, on Form S-3 (file no. 333-198648) relating to securities (the “Shelf Securities”), including the Shares, to be issued from time to time by the Company. The registration statement as amended to the date of this Agreement, including the information (if any) deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A or Rule 430B under the Securities Act of 1933, as amended (the “Securities Act”), is hereinafter referred to as the “Registration Statement”,

and the related prospectus covering the Shelf Securities dated March 13, 2015 in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Base Prospectus.” If the Company has filed an abbreviated registration statement to register additional shares of Common Stock pursuant to Rule 462(b) under the Securities Act (the “Rule 462 Registration Statement”), then any reference herein to the term “Registration Statement” shall be deemed to include such Rule 462 Registration Statement. The Base Prospectus, as supplemented by the prospectus supplement specifically relating to the Shares in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 of the Securities Act) is hereinafter referred to as the “Prospectus,” and the term “preliminary prospectus” means any preliminary form of the Prospectus.

For purposes of this Agreement, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act, “Time of Sale Prospectus” means the Base Prospectus and the preliminary prospectus together with the free writing prospectuses, if any, each identified in Schedule II hereto and the pricing information set forth in Schedule II hereto, and “broadly available road show” means a “bona fide electronic road show” as defined in Rule 433(h)(5) under the Securities Act that has been made available without restriction to any person. As used herein, the terms “Registration Statement,” “Base Prospectus,” “preliminary prospectus,” “Time of Sale Prospectus” and “Prospectus” shall include the documents, if any, incorporated by reference therein. The terms “supplement,” “amendment,” and “amend” as used herein with respect to the Registration Statement, the Base Prospectus, the Time of Sale Prospectus, any preliminary prospectus or free writing prospectus shall include all documents subsequently filed by the Company with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the “Exchange Act”), that are deemed to be incorporated by reference therein.

1. Representations and Warranties. The Company represents and warrants to and agrees with each of the Underwriters that:

(a) The Registration Statement has become effective under the Securities Act. The Company has complied, to the Commission’s satisfaction, with all requests of the Commission for additional or supplemental information, if any, regarding the Registration Statement. No stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose are pending before or, to the knowledge of the Company, threatened by the Commission. At the time the Company’s Annual Report on Form 10-K for the year ended December 31, 2014, was filed with the Commission, or, if later, at the time the Registration Statement was originally filed with the Commission, the Company met the then-applicable requirements for use of Form S-3 under the Securities Act. The Company is eligible to offer and sell securities under the Registration Statement (including the offer and sale of the Shares) without reliance on General Instruction I.B.6 of Form S-3. The Company meets the requirements for use of Form S-3 under the Securities Act specified in the Financial Industry Regulatory Authority, Inc. (“FINRA”) Conduct Rule 5110(b)(7)(C)(i).

(b) (i) Each document, if any, filed or to be filed pursuant to the Exchange Act and incorporated by reference in the Time of Sale Prospectus or the Prospectus complied or will comply when so filed in all material respects with the Exchange Act and the applicable rules and

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regulations of the Commission thereunder, (ii) the Registration Statement does not contain, and each part of the Registration Statement, when such part became effective, did not contain, and each such part, as amended or supplemented, if applicable, will not contain as of the date of such amendment or supplement, any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (iv) the Registration Statement and the Prospectus comply, and as amended or supplemented, if applicable, will comply in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder, (v) the Time of Sale Prospectus does not, and at the time of each sale of the Shares in connection with the offering when the Prospectus is not yet available to prospective purchasers and at the Closing Date (as defined in Section 4), the Time of Sale Prospectus, as then amended or supplemented by the Company, if applicable, will not, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, (vi) each broadly available road show, if any, when considered together with the Time of Sale Prospectus, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading and (vii) the Prospectus, as of its date, does not contain and, as amended or supplemented, if applicable, will not contain as of the date of such amendment or supplement or as of the Closing Date, as hereinafter defined, any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, except that the representations and warranties set forth in this paragraph do not apply to statements or omissions in the Registration Statement, the Time of Sale Prospectus or the Prospectus based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through you expressly for use therein.

(c) As of the determination date referenced in Rule 164(h) under the Securities Act, the Company was not, is not or will not be (as applicable) an “ineligible issuer” in connection with the offering pursuant to Rules 164, 405 and 433 under the Securities Act. Any free writing prospectus that the Company is required to file pursuant to Rule 433(d) under the Securities Act has been, or will be, filed with the Commission in accordance with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Each free writing prospectus that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act or that was prepared by or behalf of or used or referred to by the Company complies or will comply in all material respects with the requirements of the Securities Act and the applicable rules and regulations of the Commission thereunder. Except for the free writing prospectuses, if any, identified in Schedule II hereto forming part of the Time of Sale Prospectus, and electronic road shows, if any, each furnished to you before first use, the Company has not prepared, used or referred to, and will not, without your prior consent, prepare, use or refer to, any free writing prospectus.

(d) The Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own and lease its property and to conduct its business as described in the Registration Statement, Time of Sale Prospectus and the Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the

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failure to be so qualified or be in good standing would not reasonably be expected to have a material adverse effect in the condition, financial or otherwise, or in the earnings, business, prospects or operations, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries, taken as a whole (a “Material Adverse Effect”).

(e) Each of the Company’s “subsidiaries” (for purposes of this Agreement, as defined in Rule 405 under the Securities Act) has been duly incorporated or organized, as the case may be, and is validly existing as a corporation, partnership or limited liability company, as applicable, in good standing, if applicable, under the laws of the jurisdiction of its incorporation or organization, except to the extent that the failure to be in good standing would not result, singularly or in the aggregate, in a Material Adverse Effect, and has the power and authority (corporate or other) to own or lease its properties and to conduct its business as described in the Registration Statement, the Time of Sale Prospectus and the Prospectus. Each of the Company’s subsidiaries is duly qualified as a foreign corporation, partnership or limited liability company, as applicable, to transact business and is in good standing in each jurisdiction in which the conduct of its business or its leasing of property requires such qualification (to the extent such concepts are applicable under such laws), except to the extent that the failure to be so qualified or be in good standing would not have a Material Adverse Effect. All of the issued and outstanding capital stock or other equity or ownership interests of each of the Company’s subsidiaries have been duly authorized and validly issued, are fully paid and nonassessable and are owned directly or indirectly by the Company free and clear of all liens, encumbrances, equities or claims, except to the extent that such liens, encumbrances, equities or claims would not be reasonably likely to have a Material Adverse Effect. The Company’s only subsidiaries are as described in Exhibit 21.1 of the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2014.

(f) Prior to the later of (i) the expiration or termination of the option granted to the several Underwriters in Section 2 and (ii) the completion of the Underwriters’ distribution of the Shares, the Company has not distributed and will not distribute any offering material in connection with the offering and sale of the Shares other than the Registration Statement, the Time of Sale Prospectus, the Prospectus or any free writing prospectus reviewed and consented to by the Representatives, or the free writing prospectuses, if any, identified on Schedule II hereto

(g) This Agreement has been duly authorized, executed and delivered by the Company.

(h) The authorized capital stock of the Company conforms as to legal matters to the description thereof contained in each of the Time of Sale Prospectus and the Prospectus.

(i) The shares of Common Stock outstanding prior to the issuance of the Shares have been duly authorized and are validly issued, fully paid and non-assessable.

(j) The Shares have been duly authorized and, when issued, delivered and paid for in accordance with the terms of this Agreement, will be validly issued, fully paid and non-assessable, and the issuance of such Shares will not be subject to any preemptive rights or other similar rights to subscribe for or purchase the Shares, which have not otherwise been waived.

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(k) The Common Stock are registered pursuant to Section 12(b) or 12(g) of the Exchange Act and are listed on The NASDAQ Global Market (the “NASDAQ”), and the Company has taken no action designed to terminate the registration of the Shares under the Exchange Act or delist the Common Stock from the NASDAQ, nor has the Company received any notification that the Commission or the NASDAQ is contemplating terminating such registration or listing. To the Company’s knowledge, it is in compliance with all applicable listing requirements of the NASDAQ.

(l) The execution and delivery by the Company of, and the performance by the Company of its obligations under, this Agreement will not (i) contravene any provision of applicable law, (ii) violate the terms of the certificate of incorporation or by-laws of the Company, (iii) conflict with or result in a breach of any agreement or other instrument binding upon the Company or any of its subsidiaries or (iv) result in a violation of any judgment, order or decree of any governmental body, agency or court having jurisdiction over the Company or any subsidiary, except in the cases of clauses (i), (iii) and (iv) such as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect or materially adversely affect the power or ability of the Company to perform its obligations under this Agreement, and no consent, approval, authorization or order of, or qualification with, any governmental body or agency is required to be obtained for the performance by the Company of its obligations under this Agreement, except (i) such as may have previously been obtained, (ii) such as may be required by the securities or Blue Sky laws of the various states or foreign jurisdictions or the rules and regulations of FINRA in connection with the offer and sale of the Shares and (iii) any such consents, approvals, authorizations, orders or qualifications, the absence of which would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect or a material adverse effect on the ability of the Company to perform its obligations under this Agreement.

(m) Except as otherwise disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, subsequent to the respective dates as of which information is given in the Registration Statement, the Time of Sale Prospectus and the Prospectus: (i) there has not occurred any material adverse change in the condition, financial or otherwise, or in the earnings, business, prospects or operations, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries, taken as a whole, have not incurred any material or interference with its business from fire, explosion, flood, earthquakes, accident or other calamity, whether or not covered by insurance, or from any strike, labor dispute or court or governmental action, order or decree, that are material, individually or in the aggregate, to the Company and its subsidiaries, considered as one entity, or has entered into any transactions not in the ordinary course of business; and (iii) there has not been any material decrease in the capital stock or any material increase in any short-term or long-term indebtedness of the Company or its subsidiaries and there has been no dividend or distribution of any kind declared, paid or made by the Company or, except for dividends paid to the Company or other subsidiaries, by any of the Company’s subsidiaries on any class of capital stock, or any repurchase or redemption by the Company or any of its subsidiaries of any class of capital stock.

(n) Except as disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, there is no action, suit, proceeding, inquiry or investigation brought by or before any governmental entity now pending or, to the knowledge of the Company, threatened to which

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the Company or any of its subsidiaries is a party or to which any of the properties of the Company or any of its subsidiaries is subject (i) other than proceedings that would not reasonably be expected to have a Material Adverse Effect or materially and adversely affect the consummation of the transactions contemplated by this Agreement or the performance by the Company of its obligations hereunder; and the aggregate of all pending legal or governmental proceedings to which the Company or any such subsidiary is a party or of which any of their respective properties or assets is the subject, including ordinary routine litigation incidental to the business, if determined adversely to the Company, would not be expected to have a Material Adverse Effect. There are no statutes, regulations, contracts or other documents to which the Company or its subsidiaries is subject or by which the Company or its subsidiaries is bound that are required to be described in the Registration Statement or the Prospectus or to be filed as exhibits to the Registration Statement that are not described in all material respects or filed as required.

(o) Each preliminary prospectus filed as part of the Registration Statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the Securities Act, complied when so filed in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder and, if filed by electronic transmission pursuant to EDGAR, was identical (except as may be permitted by Regulation S-T under the Securities Act) to the copy thereof delivered to the Underwriters for use in connection with the offer and sale of the Shares.

(p) The Company is not, and after giving effect to the offering and sale of the Shares and the application of the proceeds thereof as described in the Registration Statement, Time of Sale Prospectus or the Prospectus, will not be, required to register as an “investment company” as such term is defined in the Investment Company Act of 1940, as amended.

(q) The Company and its subsidiaries, taken as a whole, (i) are in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) are in compliance with all terms and conditions of any such permit, license or approval, except where such noncompliance with Environmental Laws, failure to receive required permits, licenses or other approvals or failure to comply with the terms and conditions of such permits, licenses or approvals would not, singly or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(r) There are no costs or liabilities associated with Environmental Laws (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties) which would, singly or in the aggregate, reasonably be expected to have a Material Adverse Effect on the Company and its subsidiaries, taken as a whole.

(s) Each of the Company and, to the Company’s knowledge, its subsidiaries is, and at all times has been, in compliance in all material respects with all applicable Health Care Laws, and

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has not engaged in activities which are, as applicable, cause for false claims liability, civil penalties, or mandatory or permissive exclusion from Medicare, Medicaid, or any other state health care program or federal health care program. For purposes of this Agreement, “Health Care Laws” means: (i) the Federal Food, Drug, and Cosmetic Act (21 U.S.C. §§ 301 et seq.)and the regulations promulgated thereunder; (ii) all applicable federal, state, local and all applicable foreign health care related fraud and abuse laws, including, without limitation, the U.S. Anti-Kickback Statute (42 U.S.C. Section 1320a-7b(b)), the U.S. Physician Payment Sunshine Act (42 U.S.C. § 1320a-7h), the U.S. Civil False Claims Act (31 U.S.C. Section 3729 et seq.), the criminal False Claims Law (42 U.S.C. § 1320a-7b(a)), all criminal laws relating to health care fraud and abuse, including but not limited to 18 U.S.C. Sections 286 and 287, and the health care fraud criminal provisions under the U.S. Health Insurance Portability and Accountability Act of 1996 (“HIPAA”) (42 U.S.C. Section 1320d et seq.), the exclusion laws (42 U.S.C. § 1320a-7), the civil monetary penalties law (42 U.S.C. § 1320a-7a), HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act (42 U.S.C. Section 17921 et seq.), and the regulations promulgated pursuant to such statutes; (iii) Medicare (Title XVIII of the Social Security Act); (iv) Medicaid (Title XIX of the Social Security Act); and (v) any and all other applicable health care laws and regulations, including the collection and reporting requirements, and the processing of any applicable rebate, chargeback or adjustment, under applicable rules and regulations relating to the Medicaid Drug Rebate Program (42 U.S.C. § 1396r-8) and any state supplemental rebate program, Medicare average sales price reporting (42 U.S.C. § 1395w-3a), the Public Health Service Act (42 U.S.C. § 256b), the VA Federal Supply Schedule (38 U.S.C. § 8126) or under any state pharmaceutical assistance program or U.S. Department of Veterans Affairs agreement, and any successor government programs. Neither the Company nor, to the knowledge of the Company, any subsidiary has received written notice of any claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action from any court or arbitrator or governmental or regulatory authority or third party alleging that any product operation or activity is in material violation of any Health Care Laws, and, to the Company’s knowledge, no such claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action is threatened. Neither the Company nor, to the knowledge of the Company, any subsidiary is a party to or has any ongoing reporting obligations pursuant to any corporate integrity agreements, deferred prosecution agreements, monitoring agreements, consent decrees, settlement orders, plans of correction or similar agreements with or imposed by the Food and Drug Administration of the U.S. Department of Health and Human Services or any committee thereof or from any other U.S. or foreign government or drug or medical device regulatory agency, or health care facility Institutional Review Board or other governmental or regulatory authority. Additionally, neither the Company, its subsidiaries nor, to the knowledge of the Company, any of the employees, officers or directors of the Company or its subsidiaries have been excluded, suspended or debarred from participation in any U.S. federal health care program or human clinical research or, to the knowledge of the Company, is subject to a governmental inquiry, investigation, proceeding, or other similar action that could reasonably be expected to result in debarment, suspension, or exclusion.

(t) Except as described in the Time of Sale Prospectus and the Prospectus or as set forth on Schedule III hereto, there are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Securities Act with respect to any securities of the Company or

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to require the Company to include such securities with the Shares registered pursuant to the Registration Statement, other than rights that have been complied with or waived.

(u) Neither the Company nor any of its subsidiaries or affiliates, nor any director or officer, nor, to the Company’s knowledge, any employee, agent or representative of the Company or of any of its subsidiaries or affiliates (i) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expenses relating to political activity; (ii) made any direct or indirect unlawful payment to any domestic government official, “foreign official” (as defined in the U.S. Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder (collectively, the “FCPA”) or employee from corporate funds; (iii) violated or is in violation of any provision of the FCPA or any applicable non-U.S. anti-bribery statute or regulation; or (iv) made any unlawful bribe, rebate, payoff, influence payment, kickback or other unlawful payment to any domestic government official, such foreign official or employee; and the Company and its subsidiaries and, to the knowledge of the Company, the Company’s affiliates have conducted their respective businesses in compliance with the FCPA and have instituted and are maintaining (and have no present or currently foreseeable intend to discontinue) policies and procedures designed to ensure, and which are reasonably expected to continue to ensure, continued compliance therewith.

(v) The operations of the Company and its subsidiaries are and have been conducted at all times in material compliance with applicable financial recordkeeping and reporting requirements, including those of the Bank Secrecy Act of 1970, as amended by Title III of the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act of 2001 (USA PATRIOT Act), and the applicable anti-money laundering statutes of jurisdictions where the Company and its subsidiaries conduct business, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Anti-Money Laundering Laws”), and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Anti-Money Laundering Laws is pending or, to the best knowledge of the Company, threatened.

(w) Neither the Company nor any of its subsidiaries (collectively, the “Entity”) or, to the knowledge of the Entity, any director, officer, employee, agent, controlled affiliate or representative of the Entity, is an individual or entity (“Person”) that is, or is owned or controlled by a Person that is: (i) the subject of any sanctions administered or enforced by the U.S. Department of Treasury’s Office of Foreign Assets Control (“OFAC”), the United Nations Security Council (“UNSC”), the European Union (“EU”), Her Majesty’s Treasury (“HMT”) or other relevant sanctions authority (collectively, “Sanctions”), nor (ii) located, organized or resident in a country or territory that is the subject of Sanctions (including, without limitation, Burma/Myanmar, Cuba, Iran, Libya, North Korea, Sudan and Syria). For the past 5 years, the Company has not knowingly engaged in, is not now knowingly engaged in, and will not engage in, any dealings or transactions with any Person, or in any country or territory, that at the time of the dealing or transaction is or was the subject of Sanctions.

(x) The Company and its subsidiaries do not own any real property. The Company and its subsidiaries have good title to all personal property owned by them which is material to the

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business of the Company and its subsidiaries, taken as a whole, in each case free and clear of all liens, encumbrances and defects except such as are described in the Time of Sale Prospectus or such as do not materially diminish the value of such property and do not materially interfere with the use made and proposed to be made of such property by the Company and its subsidiaries, taken as a whole; and any real property and buildings held under lease by the Company and its subsidiaries are held by them under valid, subsisting and, to the Company’s knowledge, enforceable leases with such exceptions as are not material and do not materially interfere with the use made and proposed to be made of such property and buildings by the Company and its subsidiaries, taken as a whole, in each case except as described in the Time of Sale Prospectus.

(y) The Company owns, possesses, licenses or has other rights to use all patents, patent applications, trade and service marks, trade and service mark registrations, trade names, copyrights, licenses, inventions, trade secrets, technology, know-how and other intellectual property that, to the knowledge of the Company, is necessary for the conduct of the Company’s business as now conducted (as described in the Registration Statement, Time of Sale Prospectus and the Prospectus, collectively, the “Intellectual Property”), and, to the Company’s knowledge, the patents, trademarks, and copyrights included within the Intellectual Property are valid, enforceable, and subsisting. Except as set forth in the Registration Statement, Time of Sale Prospectus and the Prospectus (exclusive of any supplement thereto) or except in each case as would not reasonably be expected to have a material adverse effect on the Company: (a) to the Company’s knowledge, there are no material rights of third parties to any such Intellectual Property; (b) to the Company’s knowledge, there is no material infringement by third parties of any such Intellectual Property; (c) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others challenging the Company’s rights in or to any such Intellectual Property; (d) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others challenging the validity or scope of any such Intellectual Property; (e) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others that the Company infringes or otherwise violates any patent, trademark, copyright, trade secret or other proprietary rights of others; (f) to the Company’s knowledge, there is no third-party U.S. patent which contains claims that would present an obstacle to the Company’s commercialization of any product or product candidate described in the Registration Statement, Time of Sale Prospectus and the Prospectus or that interferes under 35 U.S.C. §102(g) with the pending claims of any Intellectual Property; (g) to the Company’s knowledge, there is no prior art of which the Company is aware that would render any U.S. patent held by the Company invalid which has not been disclosed to the U.S. Patent and Trademark Office (the “PTO”); and (h) except as disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, the Company is not obligated to pay a material royalty, grant a license, or provide other material consideration to any third party in connection with the Intellectual Property. The Company and its subsidiaries are in compliance with the terms of each agreement pursuant to which Intellectual Property has been licensed to the Company or any subsidiary, and all such agreements are in full force and effect. To the Company’s knowledge, all patents and patent applications owned by the Company and filed with the PTO or any foreign or international patent authority (the “Company Patent Rights”) and all patents and patent applications in-licensed by the Company and filed with the PTO or any foreign or international patent authority (the “In-licensed Patent Rights”) have been duly and properly filed; the Company believes it has complied with their duty of candor and disclosure to the PTO for the Company Patent Rights and, to the Company’s knowledge, the licensors of the

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In-licensed Patent Rights have complied with their duty of candor and disclosure to the PTO for the In-licensed Patent Rights.

(z) No material labor dispute with the employees of the Company or any of its subsidiaries that is material to the business of the Company and its subsidiaries, taken as a whole, exists, except as described in the Time of Sale Prospectus, or, to the knowledge of the Company, is imminent; and the Company is not aware of any existing, threatened or imminent labor disturbance by the employees of any of its principal suppliers, manufacturers or contractors that would reasonably be expected to have a Material Adverse Effect.

(aa) The Company and each of its subsidiaries are insured by recognized, financially sound and reputable institutions with policies in such amounts and with such deductibles and covering such risks as are generally deemed adequate and customary for their businesses including, but not limited to, policies covering real and personal property owned or leased by the Company and its subsidiaries against theft, damage, destruction, acts of vandalism and earthquakes and policies covering the Company and its subsidiaries for product liability claims and clinical trial liability claims; neither the Company nor any of its subsidiaries has been refused any insurance coverage sought or applied for; and neither the Company nor any of its subsidiaries has any reason to believe that it will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain comparable coverage from similar insurers as may be necessary to continue its business at a cost that would not have a material adverse effect on the Company and its subsidiaries, taken as a whole, except as described in the Time of Sale Prospectus.

(bb) Except as described in the Registration Statement, the Time of Sale Prospectus and the Prospectus, the Company and each of its subsidiaries: (A) is and at all times has been in compliance with all statutes, rules or regulations of the U.S. Food and Drug Administration (“FDA”) and other comparable federal, state, local or foreign governmental and regulatory authorities (“Governmental Authority”) applicable to the ownership, testing, development, manufacture, packaging, processing, use, marketing, distribution, storage, import, export or disposal of any product under development, manufactured or distributed by the Company or each such subsidiary (“Applicable Laws”), except where such noncompliance would not, individually or in the aggregate, reasonably be expected to have a material adverse effect; (B) has not had any product or manufacturing site (whether Company- or subsidiary-owned or that of a contract manufacturer for Company or subsidiary products) subject to a Governmental Authority (including the FDA) shutdown or import or export prohibition, nor received any FDA Form 483 or other Governmental Authority nor received any FDA Form 483 or other Governmental Authority notice of inspectional observations, warning letter, untitled letter or other correspondence or notice from the FDA or any Governmental Authority alleging or asserting material noncompliance with any Applicable Laws or any licenses, certificates, approvals, clearances, exemptions, authorizations, permits and supplements or amendments thereto required by any such Applicable Laws (“Authorizations”); (C) possesses all Authorizations, except where failure to possess an Authorization would not, individually or in the aggregate, reasonably be expected to have a material adverse effect, and such Authorizations are valid and in full force and effect and the Company or such subsidiary is in compliance with the terms of such Authorizations and has fulfilled and performed all of its obligations with respect to such Authorizations, except where such noncompliance or failure to fulfill or perform such

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obligations would not, individually or in the aggregate, reasonably be expected to have a material adverse effect; (D) has not received notice that the FDA or any Governmental Authority has taken, is taking or intends to take action to limit, suspend, modify or revoke any material Authorizations, has no knowledge that the FDA or any Governmental Authority is considering such action and has no knowledge that any event has occurred which allows, or after notice or lapse of time would allow, revocation or termination thereof or results in any other material impairment of the rights of the holder of any Authorizations; and (E) has filed, obtained, maintained or submitted all reports, documents, forms, notices, applications, records, claims, data, submissions and supplements or amendments as required by any Applicable Laws or Authorizations except where failure to do so would not, individually or in the aggregate, reasonably be expected to have a material adverse effect and that all such reports, documents, forms, notices, applications, records, claims, data, submissions and supplements or amendments were materially complete, true and correct on the date filed (or were corrected or supplemented by a subsequent submission).

(cc) The studies, tests and preclinical and clinical trials conducted by, sponsored by or, to the Company’s knowledge, conducted on behalf of the Company and its subsidiaries that are described in the Registration Statement, the Time of Sale Prospectus and the Prospectus, or the results of which are referred to in the Registration Statement, the Time of Sale Prospectus and the Prospectus, as applicable, were and, if still ongoing, are being conducted in all material respects in accordance with standard medical and scientific research standards and Applicable Laws, including, without limitation, the Federal Food, Drug and Cosmetic Act and the rules and regulations promulgated thereunder at 21 C.F.R. Parts 50, 54, 56, 58 and 312; the descriptions of such studies, tests and trials, including any related results and regulatory status, contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus are accurate and complete in all material respects and fairly present the data derived from such studies, tests and trials; except to the extent disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, the Company is not aware of any studies, tests or trials, the results of which reasonably call into question the study, test, or trial results described or referred to in the Registration Statement, the Time of Sale Prospectus and the Prospectus when viewed in the context in which such results are described and the clinical state of development; and, except to the extent disclosed in the Registration Statement, the Time of Sale Prospectus or the Prospectus, the Company has not received any notices or correspondence from the FDA or any other Governmental Authority requiring the termination or suspension of any studies, tests or preclinical or clinical trials conducted by, sponsored by, or conducted on behalf of the Company that are described in the Registration Statement, the Time of Sale Prospectus and the Prospectus or the results of which are referred to in the Registration Statement, the Time of Sale Prospectus and the Prospectus, other than ordinary course communications with respect to modifications in connection with the design and implementation of such trials, and neither the FDA nor any other Governmental Authority has commenced, or, to the Company’s knowledge, threatened to initiate, any action to place a clinical hold order on, or otherwise terminate, delay or suspend such studies, tests or preclinical or clinical trials.

(dd) Except as described in the Registration Statement, the Time of Sale Prospectus and the Prospectus: (i) there have been no recalls, field notifications, field corrections, market withdrawals or replacements, warnings, “dear doctor” letters, investigator notices, safety alerts or other notices of action relating to an alleged lack of safety, efficacy or regulatory compliance of

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the Company products (“Safety Notices”) that remain unresolved or open; and (ii) to the Company’s knowledge, there are no material complaints with respect to the Company products that are currently unresolved. To the Company’s knowledge, there are no facts that would be reasonably likely to result in: (i) a material Safety Notice with respect to the Company products; (ii) a material change in labeling of any the Company products; or (iii) a termination or suspension of marketing or testing of any the Company products.

(ee) The Company and its subsidiaries and any “employee benefit plan” (as defined under the Employee Retirement Income Security Act of 1974, as amended, and the regulations and published interpretations thereunder (collectively, “ERISA”)) established or maintained by the Company, its subsidiaries or their “ERISA Affiliates” (as defined below) are in compliance in all material respects with ERISA. “ERISA Affiliate” means, with respect to the Company or any of its subsidiaries, any member of any group of organizations described in Sections 414(b), (c), (m) or (o) of the Internal Revenue Code of 1986, as amended, and the regulations and published interpretations thereunder (the “Code”) of which the Company or such subsidiary is a member. No “reportable event” (as defined under ERISA) has occurred or is reasonably expected to occur with respect to any “employee benefit plan” subject to Title IV of ERISA established or maintained by the Company, its subsidiaries or any of their ERISA Affiliates. No “employee benefit plan” subject to Title IV of ERISA established or maintained by the Company, its subsidiaries or any of their ERISA Affiliates, if such “employee benefit plan” were terminated, would have any “amount of unfunded benefit liabilities” (as defined under ERISA). Neither the Company, its subsidiaries nor any of their ERISA Affiliates has incurred or reasonably expects to incur any liability under (i) Title IV of ERISA with respect to termination of, or withdrawal from, any “employee benefit plan” or (ii) Sections 412, 4971, 4975 or 4980B of the Code. Each employee benefit plan established or maintained by the Company, its subsidiaries or any of their ERISA Affiliates that is intended to be qualified under Section 401(a) of the Code is so qualified and nothing has occurred, whether by action or failure to act, which would cause the loss of such qualification.

(ff) Each of BDO USA LLP, which has expressed its opinion with respect to the audited financial statements for the year ended December 31, 2014 (which term as used in this Agreement includes the related notes thereto) and Marcum LLP, which has expressed its opinion with respect to the audited financial statements for the year ended December 31, 2013 (which term as used in this Agreement includes the related notes thereto), in each case filed with the Commission as a part of the Registration Statement, the Time of Sale Prospectus and the Prospectus, is (i) an independent registered public accounting firm as required by them Exchange Act, and the rules of the Public Company Accounting Oversight Board (“PCAOB”), (ii) in compliance with the applicable requirements relating to the qualification of accountants under Rule 2-01 of Regulation S-X under the Securities Act and (iii) a registered public accounting firm as defined by the PCAOB whose registration has not been suspended or revoked and who has not requested such registration to be withdrawn.

(gg) The financial statements filed with the Commission as a part of, or incorporated by reference into, the Registration Statement, the Time of Sale Prospectus and the Prospectus present fairly in all material respects the consolidated financial position of the Company and its subsidiaries on the basis stated as of the dates indicated and the results of their operations, changes in stockholders’ equity and cash flows for the periods specified. Such financial

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statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) applied on a consistent basis throughout the periods involved, except as may be expressly stated in the related notes thereto and except in the case of unaudited financial statements, which are subject to normal and recurring year-end adjustments and do not contain certain footnotes as permitted by the applicable rules of the Commission. No other financial statements or supporting schedules are required to be included in the Registration Statement, the Time of Sale Prospectus or the Prospectus. The financial data set forth in the Registration Statement, and any financial data set forth in the each of the Time of Sale Prospectus and the Prospectus fairly present in all material respects the information set forth therein on a basis consistent with that of the audited financial statements contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus. All disclosures contained the Registration Statement, any preliminary prospectus or the Prospectus and any free writing prospectus, that constitute non-GAAP financial measures (as defined by the rules and regulations under the Securities Act and the Exchange Act comply with Regulation G under the Exchange Act and Item 10 of Regulation S-K under the Securities Act, as applicable. To the Company’s knowledge, no person who has been suspended or barred from being associated with a registered public accounting firm, or who has failed to comply with any sanction pursuant to Rule 5300 promulgated by the PCAOB, has participated in or otherwise aided the preparation of, or audited, the financial statements, supporting schedules or other financial data filed with the Commission as a part of the Registration Statement, the Time of Sale Prospectus and the Prospectus.

(hh) Except as described in the Time of Sale Prospectus or the Registration Statement, the Company and each of its subsidiaries, taken as a whole, maintain a system of internal accounting controls sufficient to provide reasonable assurance that: (i) transactions are executed in accordance with management’s general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with GAAP and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences.

(ii) The Company has established and maintains disclosure controls and procedures (as defined in Rules 13a-15 and 15d-15 under the Exchange Act), which (i) are designed to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to the Company’s principal executive officer and its principal financial officer by others within those entities, particularly during the periods in which the periodic reports required under the Exchange Act are being prepared; (ii) have been evaluated by management of the Company for effectiveness as of the end of the Company’s most recent fiscal quarter; and (iii) are effective in all material respects to perform the functions for which they were established. Since the end of the Company’s most recent audited fiscal year, there have been no significant deficiencies or material weakness in the Company’s internal control over financial reporting (as defined in Rule 13a-15(f) under the Exchange Act) (whether or not remediated) and no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting. The Company is not aware of any change in its internal control over financial reporting that has occurred during its most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

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(jj) There are no business relationships or related-party transactions involving the Company or any of its subsidiaries or any other person required to be described in the Registration Statement, the Time of Sale Prospectus or the Prospectus that have not been described as required.

(kk)All statistical, demographic and market related data included in the Registration Statement, the Time of Sale Prospectus or the Prospectus are based on or derived from sources that the Company believes, after reasonable inquiry, to be reliable and accurate. To the extent required, the Company has obtained the written consent to the use of such data from such sources.

(ll) The statements set forth in the Time of Sale Prospectus and Prospectus under the caption “Material U.S. Federal Income Tax Consequences to Non-U.S. Holders,” insofar as such statements purport to constitute summaries of United States federal income or estate tax law and the regulations or legal conclusions with respect thereto, constitute accurate summaries of the matters described therein in all material respects. The section entitled “Management’s Discussion and Analysis of Financial Condition and Results of Operations–Critical Accounting Policies” incorporated by reference in the Time of Sale Prospectus and the Prospectus accurately describes in all material respects and to the extent required under applicable rules and regulations: (i) the accounting policies which the Company believes are the most important in the portrayal of the Company’s financial condition and results of operations and which require management’s most difficult, subjective or complex judgments (“Critical Accounting Policies”); (ii) the judgments and uncertainties affecting the application of Critical Accounting Policies; and (iii) the likelihood that materially different amounts would be reported under different conditions or using different assumptions.

(mm) Except pursuant to this Agreement, there is no broker, finder or other party that is entitled to receive from the Company any brokerage or finder’s fee or other fee or commission as a result of any transactions contemplated by this Agreement.

(nn) Neither the Company nor any of its subsidiaries has sent or received any written communication regarding termination of, or intent not to renew, any of the contracts or agreements referred to or described in any preliminary prospectus, the Prospectus or any free writing prospectus, or referred to or described in, or filed as an exhibit to, the Registration Statement, or any document incorporated by reference therein, and no such termination or non-renewal has been threatened by the Company or any of its subsidiaries or, to the Company’s knowledge, any other party to any such contract or agreement, which threat of termination or non-renewal has not been rescinded as of the date hereof.

(oo) Except as described in the Time of Sale Prospectus or the Registration Statement, the Company has not sold, issued or distributed any shares of Common Stock during the six month period preceding the date hereof, including any sales pursuant to Rule 144A under, or Regulation D or S of, the Securities Act, other than shares issued pursuant to employee benefit plans, qualified stock option plans or other employee compensation plans or pursuant to outstanding options, rights or warrants.

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(pp) Except as disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, no subsidiary of the Company is prohibited or restricted, directly or indirectly, from paying dividends to the Company, or from making any other distribution with respect to such subsidiary’s equity securities or from repaying to the Company or any other subsidiary of the Company any amounts that may from time to time become due under any loans or advances to such subsidiary from the Company or from transferring any property or assets to the Company or to any other subsidiary.

(qq) Each financial or operational projection or other “forward-looking statement” (as defined by Section 27A of the Securities Act or Section 21E of the Exchange Act) contained in the Registration Statement, the Time of Sale Prospectus or the Prospectus (i) was so included by the Company in good faith and with reasonable basis after due consideration by the Company of the underlying assumptions, estimates and other applicable facts and circumstances and (ii) is accompanied by meaningful cautionary statements identifying those factors that could cause actual results to differ materially from those in such forward looking statement. No such statement was made with the knowledge of an executive officer or director of the Company that is was false or misleading.

(rr) All United States federal, state and foreign income and franchise tax returns and other material tax returns of the Company and its subsidiary required by law to be filed have been filed and such tax returns are true, complete and correct in all material respects. All taxes and any related or similar assessments or fines shown by such returns or otherwise assessed, which are due and payable, have been paid, except assessments against which appeals have been or will be promptly taken and as to which adequate reserves have been provided in conformity with GAAP. The charges, accruals and reserves on the books of the Company in respect of any tax liability for any years not finally determined are, in conformity with GAAP, adequate to meet any assessments or re-assessments for additional income tax for any years not finally determined.

(ss) The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act (an “Emerging Growth Company”).

2. Agreements to Sell and Purchase. The Company hereby agrees to sell to the several Underwriters, and each Underwriter, upon the basis of the representations and warranties herein contained, but subject to the conditions hereinafter stated, agrees, severally and not jointly, to purchase from the Company the respective numbers of Firm Shares set forth in Schedule I hereto opposite its name at $17.86 a share (the “Purchase Price”).

On the basis of the representations and warranties contained in this Agreement, and subject to its terms and conditions, the Company agrees to sell to the Underwriters the Additional Shares, and the Underwriters shall have the right to purchase, severally and not jointly, up to 1,026,000 Additional Shares at the Purchase Price. You may exercise this right on behalf of the Underwriters in whole or, from time to time, in part by giving written notice not later than 30 days after the date of this Agreement. Any exercise notice shall specify the number of Additional Shares to be purchased by the Underwriters and the date on which such shares are to be purchased. If the exercise notice is given before the Closing Date, and the purchase of the Additional Shares shall take place simultaneously with the purchase of the Firm Shares, the exercise notice may be given any time. If the exercise notice is given on or after the Closing

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Date, each purchase date must be at least two business days after the written notice is given and may not be earlier than the Closing Date nor later than ten business days after the date of such notice. Additional Shares may be purchased as provided in Section 4 hereof. On each day, if any, that Additional Shares are to be purchased (an “Option Closing Date”), each Underwriter agrees, severally and not jointly, to purchase the number of Additional Shares (subject to such adjustments to eliminate fractional shares as you may determine) that bears the same proportion to the total number of Additional Shares to be purchased on such Option Closing Date as the number of Firm Shares set forth in Schedule I hereto opposite the name of such Underwriter bears to the total number of Firm Shares.

3. Terms of Public Offering. The Company is advised by you that the Underwriters propose to make a public offering of their respective portions of the Shares as soon after the Registration Statement and this Agreement have become effective as in your judgment is advisable. The Company is further advised by you that the Shares are to be offered to the public initially at $19.00 a share (the “Public Offering Price”) and to certain dealers selected by you at a price that represents a concession not in excess of $0.684 a share under the Public Offering Price.

4. Payment and Delivery. Payment for the Firm Shares shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Firm Shares for the respective accounts of the several Underwriters at 10:00 a.m., New York City time, on March 24, 2015, or at such other time on the same or such other date, not later than the fifth business day thereafter, as shall be designated in writing by you. The time and date of such payment are hereinafter referred to as the “Closing Date.”

Payment for any Additional Shares shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Additional Shares for the respective accounts of the several Underwriters at 10:00 a.m., New York City time, on the date specified in the corresponding notice described in Section 2 or at such other time on the same or on such other date, in any event not later than the tenth business day thereafter, as shall be designated in writing by you.

The Firm Shares and Additional Shares shall be registered in such names and in such denominations as you shall request in writing not later than one full business day prior to the Closing Date or the applicable Option Closing Date, as the case may be. The Firm Shares and Additional Shares shall be delivered to you on the Closing Date or an Option Closing Date, as the case may be, for the respective accounts of the several Underwriters, with any transfer taxes payable in connection with the transfer of the Shares to the Underwriters duly paid, against payment of the Purchase Price therefor.

5. Conditions to the Underwriters’ Obligations. The several obligations of the Underwriters are subject to the following conditions:

(a) Subsequent to the execution and delivery of this Agreement and prior to the Closing Date and, with respect to any Additional Shares purchased after the Closing Date, each Option Closing Date:

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(i) there shall not have occurred any downgrading, nor shall any notice have been given of any intended or potential downgrading or of any review for a possible change that does not indicate the direction of the possible change, in the rating accorded any of the securities of the Company or any of its subsidiaries by any “nationally recognized statistical rating organization,” as such term is defined for purposes of Section 3(A)(62) of the Exchange Act.; and

(ii) there shall not have occurred any change in the condition, financial or otherwise, or in the earnings, business, prospects or operations, whether or not arising from transactions in the ordinary course of business, of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus as of the date of this Agreement that, in your reasonable judgment, is material and adverse and that makes it, in your reasonable judgment, impracticable to market the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus.

(b) The Underwriters shall have received on the Closing Date and each Option Closing Date a certificate, dated as of such date and signed on behalf of the Company by an executive officer of the Company, to the effect set forth in Section 5(a)(i) above and to the effect that (i) the representations and warranties of the Company contained in this Agreement are true and correct in all material respects as of such date and (ii) that the Company has complied with all of the agreements and satisfied all of the conditions on its part to be performed or satisfied hereunder on or before such date.

The officer signing and delivering such certificate may rely upon the best of his or her knowledge as to proceedings threatened.

(c) The Underwriters shall have received on the Closing Date and each Option Closing Date an opinion and negative assurance letter of Cooley LLP, securities counsel for the Company, dated as of such date, in form and substance reasonably satisfactory to the Representatives, together with signed or reproduced copies of such opinion and letter for each of the other Underwriters, substantially to the effect as set forth in Exhibit A hereto.

(d) The Underwriters shall have received on the Closing Date and each Option Closing Date an opinion of Seed Intellectual Property Law Group PLLC, intellectual property counsel to the Company, dated as of such date, in form and substance satisfactory to the Representatives, together with signed or reproduced copies of such opinion for each of the other Underwriters substantially to the effect set forth in Exhibit B hereto.

(e) The Underwriters shall have received on the Closing Date and each Option Closing Date an opinion of Latham & Watkins LLP, counsel for the Underwriters, dated as of such date, in form and substance satisfactory to the Representatives.

The opinion of Cooley LLP, described in Section 5(c) above and in Exhibit A attached hereto shall be rendered to the Underwriters at the request of the Company and shall so state therein.

(f) The Underwriters shall have received on the Closing Date and each Option Closing Date, a letter dated such date, in form and substance satisfactory to the Underwriters, from

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Marcum LLP, independent public accountants, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to certain of the financial statements and certain financial information contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

(g) The Underwriters shall have received on the Closing Date and each Option Closing Date, a letter dated such date, in form and substance satisfactory to the Underwriters, from BDO USA LLP, independent public accountants, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to certain of the financial statements and certain financial information contained in the Registration Statement, the Time of Sale Prospectus and the Prospectus; provided that the letter delivered on the Closing Date shall use a “cut-off date” not earlier than the date hereof.

(h) The letter agreements (each, a “Lock-up Agreement”), each substantially in the form of Exhibit C hereto, between you and each of the executives and directors of the Company listed on Exhibit D hereto relating to sales and certain other dispositions of shares of Common Stock or certain other securities, delivered to you on or before the date hereof, shall be in full force and effect on the Closing Date and each Option Closing Date.

The several obligations of the Underwriters to purchase Additional Shares hereunder are subject to the delivery to you on the applicable Option Closing Date of such documents as you may reasonably request with respect to the good standing of the Company, the due authorization and issuance of the Additional Shares to be sold on such Option Closing Date and other matters related to the issuance of such Additional Shares.

6. Covenants of the Company. The Company covenants with each Underwriter as follows:

(a) To furnish to you, without charge, a signed copy of the Registration Statement (including exhibits thereto) and for delivery to each other Underwriter a conformed copy of the Registration Statement (without exhibits thereto) and to furnish to you in New York City, without charge, prior to 10:00 a.m. New York City time on the business day next succeeding the date of this Agreement and during the period mentioned in Section 6(e) or 6(f) below, as many copies of the Time of Sale Prospectus, the Prospectus and any supplements and amendments thereto or to the Registration Statement as you may reasonably request.

(b) Before amending or supplementing the Registration Statement, the Time of Sale Prospectus or the Prospectus, to furnish to you a copy of each such proposed amendment or supplement and not to file any such proposed amendment or supplement to which you reasonably object, and to file with the Commission within the applicable period specified in Rule 424(b) under the Securities Act any prospectus required to be filed pursuant to such Rule.

(c) To furnish to you a copy of each proposed free writing prospectus to be prepared by or on behalf of, used by, or referred to by the Company and not to use or refer to any proposed free writing prospectus to which you reasonably object.

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(d) Not to take any action that would result in an Underwriter or the Company being required to file with the Commission pursuant to Rule 433(d) under the Securities Act a free writing prospectus prepared by or on behalf of the Underwriter that the Underwriter otherwise would not have been required to file thereunder.

(e) If the Time of Sale Prospectus is being used to solicit offers to buy the Shares at a time when the Prospectus is not yet available to prospective purchasers and any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Time of Sale Prospectus in order to make the statements therein, in the light of the circumstances, not misleading, or if any event shall occur or condition exist as a result of which the Time of Sale Prospectus conflicts with the information contained in the Registration Statement then on file, or if, in the opinion of counsel for the Company or the Underwriters, it is necessary to amend or supplement the Time of Sale Prospectus to comply with applicable law, promptly to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to any dealer upon request, either amendments or supplements to the Time of Sale Prospectus so that the statements in the Time of Sale Prospectus as so amended or supplemented will not, in the light of the circumstances under which they were made, when the Time of Sale Prospectus is delivered to a prospective purchaser, be misleading or so that the Time of Sale Prospectus, as amended or supplemented, will no longer conflict with the Registration Statement, or so that the Time of Sale Prospectus, as amended or supplemented, will comply with applicable law.

(f) If, during such period after the first date of the public offering of the Shares as in the opinion of counsel for the Company or the Underwriters the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is required by law to be delivered in connection with sales by an Underwriter or dealer, any event shall occur or condition exist as a result of which it is necessary to amend or supplement the Prospectus in order to make the statements therein, in the light of the circumstances under which they were made, when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is delivered to a purchaser, not misleading, or if, in the opinion of counsel for the Company or the Underwriters, it is necessary to amend or supplement the Prospectus to comply with applicable law, promptly to prepare, file with the Commission and furnish, at its own expense, to the Underwriters and to the dealers (whose names and addresses you will furnish to the Company) to which Shares may have been sold by you on behalf of the Underwriters and to any other dealers upon request, either amendments or supplements to the Prospectus so that the statements in the Prospectus as so amended or supplemented will not, in the light of the circumstances under which they were made, when the Prospectus (or in lieu thereof the notice referred to in Rule 173(a) under the Securities Act) is delivered to a purchaser, be misleading or so that the Prospectus, as amended or supplemented, will comply with applicable law.

(g) To endeavor to qualify the Shares for offer and sale under the securities or Blue Sky laws of such jurisdictions as you shall reasonably request; provided, that in no event shall the Company or any of its subsidiaries be obligated to qualify to do business as a foreign corporation in any jurisdiction in which it is not now so qualified or to file any general consent to service of process.

(h) To make generally available to the Company’s security holders and to you as soon as practicable an earnings statement covering a period of at least 12 months beginning with the first

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fiscal quarter of the Company occurring after the date of this Agreement which shall satisfy the provisions of Section 11(a) of the Securities Act and the rules and regulations of the Commission thereunder.

(i) To promptly notify the Representatives if the Company ceases to be an Emerging Growth Company at any time prior to the later of (i) completion of the distribution of the Shares within the meaning of the Securities Act and (ii) expiration of the Lock-Up Period (as defined below).

(j) Whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, to pay or cause to be paid all expenses incident to the performance of the Company’s obligations under this Agreement, including: (i) the fees, disbursements and expenses of the Company’s counsel and the Company’s accountants in connection with the registration and delivery of the Shares under the Securities Act and all other fees or expenses in connection with the preparation and filing of the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company and amendments and supplements to any of the foregoing, including all printing costs associated therewith, and the mailing and delivering of copies thereof to the Underwriters and dealers, in the quantities hereinabove specified, (ii) all costs and expenses related to the transfer and delivery of the Shares to the Underwriters, including any transfer or other taxes payable thereon, (iii) the reasonable, documented cost of printing or producing any Blue Sky or Legal Investment memorandum in connection with the offer and sale of the Shares under state securities laws and all expenses in connection with the qualification of the Shares for offer and sale under state securities laws as provided in Section 6(g) hereof, including filing fees and the reasonable, documented fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky or Legal Investment memorandum, (iv) all filing fees and the reasonable, documented fees and disbursements of counsel to the Underwriters incurred in connection with the review and qualification of the offering of the Shares by the FINRA, (v) all costs and expenses incident to listing the Shares on the NASDAQ Capital Market, (vi) the cost of printing certificates representing the Shares, (vii) the costs and charges of any transfer agent, registrar or depositary, (viii) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the offering of the Shares, including, without limitation, expenses associated with the preparation or dissemination of any electronic road show, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations with the prior approval of the Company, travel and lodging expenses of the representatives and officers of the Company and any such consultants, and 50% of the cost of any aircraft chartered in connection with any road show (provided, that the prior approval of the Company is obtained prior to the chartering of any such aircraft), (ix) the document production charges and expenses associated with printing this Agreement, and (x) all other costs and expenses incident to the performance of the obligations of the Company hereunder for which provision is not otherwise made in this Section. It is understood, however, that except as provided in this Section, Section 8 entitled “Indemnity and Contribution,” and the last paragraph of Section 10 below, the Underwriters will pay all of their costs and expenses, including fees and disbursements of their counsel, stock transfer taxes payable on resale of any of the Shares by them, travel and lodging expenses of their representatives in connection with any road show (including 50% of the cost of

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any aircraft chartered with the prior approval of the Representatives in connection with any road show), and any advertising expenses connected with any offers they may make, it being further understood, however, that the fees and disbursements of counsel for the Underwriters contemplated by clauses (iii) and (iv) above shall not exceed $25,000, in the aggregate.

The Company also covenants with each Underwriter that, without the prior written consent of the Representatives on behalf of the Underwriters, it will not, during the period ending 90 days after the date of the Prospectus (the “Lock-Up Period”), (A) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock or (B) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (A) or (B) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (C) file any registration statement (other than on Form S-8) with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock.

The restrictions contained in the preceding paragraph shall not apply to (1) the Shares to be sold hereunder, (2) the issuance by the Company of shares of Common Stock upon the exercise of outstanding stock options or warrants or grants of stock options or other stock-based awards or the conversion or vesting of a security outstanding on the date hereof described in the Registration Statement or of which the Underwriters have been advised in writing, (3) the grant of options to purchase or the issuance of shares of Common Stock or other equity awards by the Company to employees, officers, directors, advisors or consultants of the Company pursuant to employee benefit plans in effect on the date hereof and described in the Time of Sale Prospectus and Prospectus or pursuant to an employee stock purchase plan described in the Time of Sale Prospectus and Prospectus, or (4) the sale or issuance of or entry into an agreement to sell or issue shares of Common Stock or securities convertible into or exercisable for Common Stock in connection with any (a) mergers, (b) acquisition of securities, businesses, property, technologies or other assets, (c) joint ventures, (d) strategic alliances, commercial relationships or other collaborations, (e) equipment leasing arrangements, (f) debt financing or (g) the assumption of employee benefit plans in connection with mergers or acquisitions; provided, that the aggregate number of shares of Common Stock or securities convertible into or exercisable for Common Stock (on an as-converted or as-exercised basis, as the case may be) that the Company may sell or issue or agree to sell or issue pursuant to this clause (4) shall not exceed 5% of the total number of shares of the Company’s Common Stock issued and outstanding immediately following the completion of the transactions contemplated by this Agreement (determined on a fully-diluted basis and as adjusted for stock splits, stock dividends and other similar events after the date hereof).

The Company also covenants that if any persons other than those listed on Exhibit E shall become directors or executive officers of the Company prior to the end of the Company Lock-up Period, the Company shall cause each such person, prior to or contemporaneously with their appointment or election as a director or executive officer of the Company, to execute and deliver to the Representatives a Lock-up Agreement.

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7. Covenants of the Underwriters. Each Underwriter severally covenants with the Company not to take any action that would result in the Company being required to file with the Commission under Rule 433(d) a free writing prospectus prepared by or on behalf of such Underwriter that otherwise would not be required to be filed by the Company thereunder, but for the action of the Underwriter.

8. Indemnity and Contribution.

(a) The Company agrees to indemnify and hold harmless each Underwriter, each person, if any, who controls any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act and each affiliate of any Underwriter within the meaning of Rule 405 under the Securities Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof, any preliminary prospectus, the Time of Sale Prospectus or any amendment or supplement thereto, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any Company information that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act, any road show as defined in Rule 433(h) under the Securities Act (a “road show”) or the Prospectus or any amendment or supplement thereto, or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading, except insofar as such losses, claims, damages or liabilities are caused by any such untrue statement or omission or alleged untrue statement or omission based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through you expressly for use therein.

(b) Each Underwriter agrees, severally and not jointly, to indemnify and hold harmless the Company, its directors, its officers who sign the Registration Statement and each person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act to the same extent as the foregoing indemnity from the Company to such Underwriter, but only with reference to information relating to such Underwriter furnished to the Company in writing by such Underwriter through you expressly for use in the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, any issuer free writing prospectus, road show or the Prospectus or any amendment or supplement thereto.

(c) In case any proceeding (including any governmental investigation) shall be instituted involving any person in respect of which indemnity may be sought pursuant to Section 8(a) or 8(b), such person (the “indemnified party”) shall promptly notify the person against whom such indemnity may be sought (the “indemnifying party”) in writing and the indemnifying party, upon request of the indemnified party, shall retain counsel reasonably satisfactory to the indemnified party to represent the indemnified party and any others the indemnifying party may designate in such proceeding and shall pay the reasonably incurred and documented fees and disbursements of such counsel related to such proceeding. In any such proceeding, any indemnified party shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such indemnified party unless (i) the indemnifying party and the indemnified party shall have mutually agreed in writing to the retention of such counsel or (ii) the named parties to

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any such proceeding (including any impleaded parties) include both the indemnifying party and the indemnified party and representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood that the indemnifying party shall not, in respect of the legal expenses of any indemnified party in connection with any proceeding or related proceedings in the same jurisdiction, be liable for the fees and expenses of more than one separate firm (in addition to any local counsel) for all such indemnified parties and that all such fees and expenses shall be reimbursed as they are incurred. Such firm shall be designated in writing by the Representatives, in the case of parties indemnified pursuant to Section 8(a), and by the Company, in the case of parties indemnified pursuant to Section 8(b). The indemnifying party shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent or if there be a final judgment for the plaintiff, the indemnifying party agrees to indemnify the indemnified party from and against any loss or liability by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second and third sentences of this paragraph, the indemnifying party agrees that it shall be liable for any settlement of any proceeding effected without its written consent if (A) such settlement is entered into more than 30 days after receipt by such indemnifying party of the aforesaid request and (B) such indemnifying party shall not have reimbursed the indemnified party in accordance with such request prior to the date of such settlement (other than reimbursement for fees and expenses that the indemnifying party is contesting in good faith). No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened proceeding in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party, unless such settlement includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such proceeding and does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of any indemnified party.

(d) To the extent the indemnification provided for in Section 8(a) or Section 8(b) is unavailable to an indemnified party or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each indemnifying party under such paragraph, in lieu of indemnifying such indemnified party thereunder, shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other hand from the offering of the Shares or (ii) if the allocation provided by Section 8(d)(i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in Section 8(d)(i) above but also the relative fault of the Company on the one hand and of the Underwriters on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other hand in connection with the offering of the Shares shall be deemed to be in the same respective proportions as the net proceeds from the offering of the Shares (before deducting expenses but after deducting underwriting discounts and commissions) received by the Company and the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover of the Prospectus, bear to the aggregate Public Offering Price of the Shares. The relative fault of the Company on the one hand and the Underwriters on the other

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hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Underwriters’ respective obligations to contribute pursuant to this Section 8 are several in proportion to the respective number of Shares they have purchased hereunder, and not joint.

(e) The Company and the Underwriters agree that it would not be just or equitable if contribution pursuant to this Section 8 were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in Section 8(d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages and liabilities referred to in Section 8(d) shall be deemed to include, subject to the limitations set forth above, any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this Section 8, no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Shares underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages that such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The remedies provided for in this Section 8 are not exclusive and shall not limit any rights or remedies which may otherwise be available to any indemnified party at law or in equity.

(f) The indemnity and contribution provisions contained in this Section 8 and the representations, warranties and other statements of the Company contained in this Agreement shall remain operative and in full force and effect regardless of (i) any termination of this Agreement, (ii) any investigation made by or on behalf of any Underwriter, any person controlling any Underwriter or any affiliate of any Underwriter or by or on behalf of the Company, its officers or directors or any person controlling the Company and (iii) acceptance of and payment for any of the Shares.

9. Termination. The Underwriters may terminate this Agreement by notice given by you to the Company, if after the execution and delivery of this Agreement and prior to the Closing Date (a) trading generally shall have been suspended or materially limited on, or by, as the case may be, any of the New York Stock Exchange, or the NASDAQ Global Market, (b) trading of any securities of the Company shall have been suspended on any exchange or in any over-the-counter market, which, for the avoidance of doubt, shall not include secondary markets for privately held securities, (c) a material disruption in securities settlement, payment or clearance services in the United States shall have occurred, (d) any moratorium on commercial banking activities shall have been declared by Federal or New York state authorities or (e) there shall have occurred any outbreak or escalation of hostilities, or any change in financial markets or any calamity or crisis that, in your judgment, is material and adverse and which, singly or together with any other event specified in this clause (e), makes it, in your judgment,

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impracticable or inadvisable to proceed with the offer, sale or delivery of the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus or the Prospectus.

10. Effectiveness; Defaulting Underwriters. This Agreement shall become effective upon the execution and delivery hereof by the parties hereto.

If, on the Closing Date or an Option Closing Date, as the case may be, any one or more of the Underwriters shall fail or refuse to purchase Shares that it has or they have agreed to purchase hereunder on such date, and the aggregate number of Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate number of the Shares to be purchased on such date, the other Underwriters shall be obligated severally in the proportions that the number of Firm Shares set forth opposite their respective names in Schedule I bears to the aggregate number of Firm Shares set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as you may specify, to purchase the Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date; provided that in no event shall the number of Shares that any Underwriter has agreed to purchase pursuant to this Agreement be increased pursuant to this Section 10 by an amount in excess of one-ninth of such number of Shares without the written consent of such Underwriter. If, on the Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Firm Shares and the aggregate number of Firm Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Firm Shares to be purchased on such date, and arrangements satisfactory to you and the Company for the purchase of such Firm Shares are not made within 36 hours after such default, this Agreement shall terminate. In the event of such termination, the Company shall have no liability to any Underwriter (except to the extent provided in Sections 6(k) and 8 hereof) nor shall any Underwriter (other than an Underwriter who shall have failed otherwise than for some reason permitted under this Agreement to purchase the amount of Firm Shares agreed by such Underwriter to be purchased hereunder) be under any liability to the Company (except to the extent provided under Sections 6(k) and 8 hereof). In any such case either you or the Company shall have the right to postpone the Closing Date, but in no event for longer than seven days, in order that the required changes, if any, in the Registration Statement, in the Time of Sale Prospectus, in the Prospectus or in any other documents or arrangements may be effected. If, on an Option Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Additional Shares and the aggregate number of Additional Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Additional Shares to be purchased on such Option Closing Date, the non-defaulting Underwriters shall have the option to (a) terminate their obligation hereunder to purchase the Additional Shares to be sold on such Option Closing Date or (b) purchase not less than the number of Additional Shares that such non-defaulting Underwriters would have been obligated to purchase in the absence of such default. Any action taken under this paragraph shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

If this Agreement shall be terminated by the Underwriters, or any of them, pursuant to Section 9 hereof or because of any failure or refusal on the part of the Company to comply with the terms or to fulfill any of the conditions of this Agreement, or if for any reason the Company shall be unable to perform its obligations under this Agreement (unless such failure to comply or inability to perform is due primarily to any default of any Underwriter the Company will

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reimburse the Underwriters or such Underwriters as have so terminated this Agreement with respect to themselves, severally, for all documented out-of-pocket accountable expenses (including the fees and disbursements of their counsel) reasonably incurred by such Underwriters in connection with this Agreement or the offering contemplated hereunder.

11. Entire Agreement.

(a) This Agreement, together with any contemporaneous written agreements and any prior written agreements (to the extent not superseded by this Agreement) that relate to the offering of the Shares, represents the entire agreement between the Company and the Underwriters with respect to the preparation of any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, the conduct of the offering, and the purchase and sale of the Shares.

(b) The Company acknowledges that in connection with the offering of the Shares: (i) the Underwriters have acted at arm’s length, are not agents of, and owe no fiduciary duties to, the Company or any other person, (ii) the Underwriters owe the Company only those duties and obligations set forth in this Agreement and prior written agreements (to the extent not superseded by this Agreement), if any, and (iii) the Underwriters may have interests that differ from those of the Company. The Company waives to the full extent permitted by applicable law any claims it may have against the Underwriters arising from an alleged breach of fiduciary duty in connection with the offering of the Shares.

12. Counterparts. This Agreement may be signed in two or more counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

13. Applicable Law. This Agreement shall be governed by and construed in accordance with the internal laws of the state of New York.

14. Headings. The headings of the sections of this Agreement have been inserted for convenience of reference only and shall not be deemed a part of this Agreement.

15. Notices. All communications hereunder shall be in writing and effective only upon receipt and if to the Underwriters shall be delivered, mailed or sent to (i) Leerink Partners LLC, 255 California St., 12^th Floor, San Francisco, California 94111, Attention: Bryan Giraudo, fax: (415)  ###-###-####, with a copy to John I. Fitzgerald, Esq., Managing Director, One Federal Street, 37th Floor, Boston, Massachusetts 02110, fax: (617)  ###-###-#### and (ii) Deutsche Bank Securities Inc., 60 Wall Street, 2nd Floor, New York, New York 10005, Attention: Equity Capital Markets – Syndicate Desk, fax: (212)  ###-###-#### , with a copy to Deutsche Bank Securities Inc., 60 Wall Street, 36th Floor, New York, New York 10005, Attention: General Counsel, fax: (212)  ###-###-####; and if to the Company shall be delivered, mailed or sent to 12255 El Camino Real, Suite 250, San Diego, California 92130, Attention: Margaret Valeur-Jensen, Ph.D., General Counsel, fax: (858)  ###-###-####, with a copy to Cooley LLP, 4401 Eastgate Mall, San Diego, California, Attention: Jason Kent, fax: (858)  ###-###-####.

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SCHEDULE I

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SCHEDULE II

Time of Sale Prospectus

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SCHEDULE III

None.

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EXHIBIT C

Form of Lock-Up Agreement

                    , 2015

Leerink Partners LLC

Deutsche Bank Securities Inc.

  as Representatives of the several Underwriters

c/o Leerink Partners LLC

299 Park Avenue

New York, NY 10171

c/o Deutsche Bank Securities Inc.

60 Wall Street, 4^th Floor

New York, NY 10005

Ladies and Gentlemen:

The undersigned understands that Leerink Partners LLC and Deutsche Bank Securities Inc. (the “Representatives”) propose to enter into an Underwriting Agreement (the “Underwriting Agreement”) with Retrophin, Inc., a Delaware corporation (the “Company”), providing for the public offering (the “Public Offering”) by the several Underwriters listed on Schedule I to the Underwriting Agreement (the “Underwriters”), of shares of the Common Stock, $0.0001 par value per share, of the Company (the “Common Stock”).

To induce the Underwriters that may participate in the Public Offering to continue their efforts in connection with the Public Offering, the undersigned hereby agrees that, without the prior written consent of the Representatives on behalf of the Underwriters, it will not, during the period commencing on the date hereof and ending 90 days after the date of the final prospectus relating to the Public Offering (the “Restricted Period”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise.

The foregoing sentence shall not apply to (a) transfers of shares of Common Stock or any security convertible into Common Stock as a bona fide gift or by will, other testamentary document or intestate succession, (b) distributions of shares of Common Stock or any security convertible into Common Stock to limited partners, members, stockholders, or wholly-owned subsidiaries of the undersigned, (c) transfers of shares of Common Stock or any security convertible into Common Stock to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, (d) transfers of shares of Common Stock or any

C-1

security convertible into Common Stock to any corporation, partnership, limited liability company or similar entity of which all of the beneficial ownership interests are held by the undersigned or the immediate family of the undersigned; provided that in the case of any transfer or distribution pursuant to clauses (a)-(d), each donee, distributee or transferee shall sign and deliver to the Representatives a lock-up letter substantially in the form of this letter and no public announcement or filing under the Exchange Act shall be required or voluntarily made during the Restricted Period, (e) the establishment of a new trading plan pursuant to Rule 10b5-1 under the Exchange Act providing for dispositions or sales of Common Stock; provided that such plan does not permit dispositions or sales of shares of Common Stock or any security convertible into Common Stock during the Restricted Period and no public announcement or filing under the Exchange Act regarding the establishment of such plan shall be required or voluntarily made during the Restricted Period, (f) the exercise of options to purchase Common Stock outstanding as of the date hereof or granted under equity incentive plans in effect as of the date hereof or described in the registration statement with respect to the Public Offering, provided that the underlying Common Stock continues to be subject to the terms of this agreement, (g) transfers of shares of Common Stock or any security convertible into Common Stock pursuant to a bona fide third party tender offer, merger, consolidation or other similar transaction made to holders of the Common Stock involving a change of control of the Company, provided that in the event that the tender offer, merger, consolidation or other such transaction is not completed, the undersigned shall remain subject to the restrictions contained herein, (h) the repurchase or forfeiture of securities by the Company in connection with termination of the undersigned’s employment with the Company, (i) the settlement of restricted stock, restricted stock units or options on a “net” basis or any other withholding of shares of Common Stock by the Company upon vesting and/or settlement of restricted stock, restricted stock units and/or options provided that (x) the underlying shares of Common Stock received by the undersigned shall continue to be subject to the restrictions on transfer set forth in this agreement and (y) the Company becomes the owner of the shares of Common Stock surrendered in the net exercise, (j) the transfer or sale of any shares of Common Stock or other securities solely to satisfy tax obligations related to the delivery of shares pursuant to the vesting of restricted stock units or restricted shares granted to the undersigned; provided that, any filing made under the Exchange Act or other public announcement shall indicate (in the notes thereto or otherwise) that the filing or announcement relates to the circumstances described in this clause (j); and (k) transfers of shares of Common Stock or any security convertible into Common Stock pursuant to any order or settlement agreement not involving any public sale of shares of Common Stock or other securities and approved by any court of competent jurisdiction, provided that the undersigned shall cause the transferee to sign and deliver to the Representatives a lock-up letter substantially in the form of this letter, and provided further, that any filing or public announcement under the Exchange Act or otherwise that is required to be made during the Restricted Period as a result of such transfer shall include a statement that such transfer has occurred by operation of law.

In addition, the undersigned agrees that, without the prior written consent of the Representatives on behalf of the Underwriters, it will not, during the Restricted Period, make any demand for or exercise any right with respect to, the registration of any shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock. The undersigned also agrees and consents to the entry of stop transfer instructions with the

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Company’s transfer agent and registrar against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

The undersigned understands that the Company and the Underwriters are relying upon this agreement in proceeding toward consummation of the Public Offering. The undersigned further understands that this agreement is irrevocable and shall be binding upon the undersigned’s heirs, legal representatives, successors and assigns.

Whether or not the Public Offering actually occurs depends on a number of factors, including market conditions. Any Public Offering will only be made pursuant to an Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Underwriters. If (i) the closing of the Public Offering has not occurred prior to June 30, 2015, (ii) the Company notifies you in writing that it does not intend to proceed with the Public Offering, (iii) the registration statement filed with respect to the Public Offering is withdrawn or (iv) for any reason the Underwriting Agreement shall be terminated prior to the Closing Date (as defined in the Underwriting Agreement), this agreement shall be of no further force or effect.

This agreement shall be governed by and construed in accordance with the laws of the State of New York, without regard to the conflict of laws principles thereof.

[Signature page follows]

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EXHIBIT D

Directors and Executive Officers

Signing Lock-up Agreement

Directors:

Steven Richardson

Stephen Aselage

Cornelius Golding

Gary Lyons

Jeffrey Meckler

Executive Officers:

Laura M. Clague

Alvin Shih

Margaret Valeur-Jensen

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