Flexion Therapeutics, Inc. 5,500,000 Shares Common Stock ($0.001 par value) Underwriting Agreement

Exhibit 1.1

Flexion Therapeutics, Inc.

5,500,000 Shares

Common Stock

($0.001 par value)

Underwriting Agreement

New York, New York

June 8, 2016

▇▇▇▇▇ Fargo Securities, LLC

RBC Capital Markets, LLC

As Representatives of the several Underwriters,

c/o Wells Fargo Securities, LLC

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▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇

c/o RBC Capital Markets, LLC

▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇

▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇

Ladies and Gentlemen:

Flexion Therapeutics, Inc., a corporation organized under the laws of the State of Delaware (the “Company”), proposes to sell to the several underwriters named in Schedule II hereto (the “Underwriters”), for whom you (the “Representatives”) are acting as representatives, the number of shares of its common stock, $0.001 par value (“Common Stock”) set forth in Schedule I hereto opposite the heading “Number of Underwritten Securities to be sold by the Company” (said shares to be issued and sold by the Company being hereinafter called the “Underwritten Securities”). The Company also proposes to grant to the Underwriters an option to purchase up to the number of additional shares of Common Stock set forth in Schedule I hereto opposite the heading “Number of Option Securities to be sold by the Company” (the “Option Securities”; the Option Securities, together with the Underwritten Securities, being hereinafter called the “Securities”). To the extent there are no additional Underwriters listed on Schedule II other than you, the term Representatives as used herein shall mean you, as Underwriters, and the terms Representatives and Underwriters shall mean either the singular or plural as the context requires. Any reference herein to the Registration Statement, the Base Prospectus, any Preliminary Prospectus or the Final Prospectus shall be deemed to refer to and include the documents incorporated by reference therein pursuant to Item 12 to the Registration Statement on Form S-3 which were filed under the Exchange Act on or before the Effective Date of the Registration Statement or the issue date of the Base Prospectus, any Preliminary Prospectus or the Final Prospectus, as the case may be; and any reference herein to the terms

“amend,” “amendment” or “supplement” with respect to the Registration Statement, the Base Prospectus, any Preliminary Prospectus or the Final Prospectus shall be deemed to refer to and include the filing of any document under the Exchange Act after the Effective Date of the Registration Statement or the issue date of the Base Prospectus, any Preliminary Prospectus or the Final Prospectus, as the case may be, deemed to be incorporated by reference therein. Certain terms used herein are defined in Section 20 hereof.

1. Representations and Warranties. The Company represents and warrants to, and agrees with, each Underwriter as set forth below in this Section 1.

(a) The Company has prepared and filed with the Commission a shelf registration statement on Form S-3 (File No. 333-203706), including a related Base Prospectus, for registration under the Act of the offering and sale of the Securities. Such Registration Statement, including any amendments thereto filed prior to the Execution Time, has become effective. At the time such shelf registration statement became effective, the Company met the requirements for use of Form S-3 under the Act. No stop order suspending the effectiveness of the Registration Statement has been issued under the 1933 Act and no proceedings for that purpose have been instituted or are pending or, to the knowledge of the Company, are contemplated by the Commission, and any request on the part of the Commission for additional information has been complied with. The Company may have filed with the Commission, as part of an amendment to the Registration Statement or pursuant to Rule 424(b), one or more preliminary prospectus supplements relating to the Securities, each of which has previously been furnished to the Representatives. The Company will file with the Commission a final prospectus supplement relating to the Securities in accordance with Rule 424(b). As filed, such final prospectus supplement, together with the Base Prospectus, shall contain all information required by the Act and the Exchange Act and the respective rules thereunder with respect to the offer and sale of the Securities and, except to the extent the Representatives shall agree in writing to a modification, shall be in all substantive respects in the form furnished to the Representatives prior to the Execution Time or, to the extent not completed at the Execution Time, shall contain only such specific additional information and other changes (beyond that contained in the Base Prospectus and any Preliminary Prospectus) as the Company has advised the Representatives, prior to the Execution Time, will be included or made therein. The Registration Statement, at the Execution Time, meets the requirements set forth in Rule 415(a)(1)(x). The initial Effective Date of the Registration Statement was not earlier than the date three years before the Execution Time.

(b) On each Effective Date, the Registration Statement did, and when the Final Prospectus is first filed in accordance with Rule 424(b) and on the Closing Date (as defined herein) and on any date on which Option Securities are purchased, if such date is not the Closing Date (a “settlement date”), the Final Prospectus (and any supplement thereto) will, comply in all material respects with the applicable requirements of the Act and the Exchange Act and the respective rules thereunder; on each Effective Date, at the Execution Time and on the Closing Date, the Registration Statement did not and will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein not misleading;

and on the date of any filing pursuant to Rule 424(b) and on the Closing Date and any settlement date, the Final Prospectus (together with any supplement thereto) will not include any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the Company makes no representations or warranties as to the information contained in or omitted from the Registration Statement, or the Final Prospectus (or any supplement thereto) in reliance upon and in conformity with information furnished in writing to the Company by or on behalf of any Underwriter through the Representatives specifically for inclusion in the Registration Statement or the Final Prospectus (or any supplement thereto), it being understood and agreed that the only such information furnished by or on behalf of any Underwriter consists of the information described as such in Section 8 hereof.

(c) Except as disclosed in the Company’s Current Report on Form 8-K filed with the Commission on May 12, 2016, the Company has filed all reports, schedules, exhibits, forms, statements and other documents required to be filed by it under the Exchange Act pursuant to Section 13(a) or 15(d) thereof (the foregoing materials, including the exhibits thereto documents incorporated by reference therein, being collectively referred to herein as the “SEC Reports”), on a timely basis or has received a valid extension of such time of filing and has filed any such SEC Reports prior to the expiration of any such extension. As of their respective filing dates, all of the SEC Reports complied in all material respects with the requirements of the Act and the Exchange Act and the rules and regulations of the Commission promulgated thereunder. None of the SEC Reports, when filed, contained any untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading. (i) The Disclosure Package and the price to the public, the number of Underwritten Securities and the number of Option Securities to be included on the cover page of the Final Prospectus, when taken together as a whole, (ii) each electronic road show, when taken together as a whole with the Disclosure Package and the price to the public, the number of Underwritten Securities and the number of Option Securities to be included on the cover page of the Final Prospectus. The preceding sentence does not apply to statements in or omissions from the Disclosure Package based upon and in conformity with written information furnished to the Company by or on behalf of any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by or on behalf of any Underwriter consists of the information described as such in Section 8 hereof.

(d) (i) At the time of filing of the Registration Statement and (ii) as of the Execution Time (with such date being used as the determination date for purposes of this clause (ii)), the Company was not and is not an Ineligible Issuer (as defined in Rule 405), without taking account of any determination by the Commission pursuant to Rule 405 that it is not necessary that the Company be considered an Ineligible Issuer.

(e) From the time of initial filing of the Registration Statement with the Commission (or, if earlier, the first date on which the Company engaged directly or

through any Person authorized to act on its behalf in any Testing-the-Waters Communication) through the Execution Time, the Company has been and is an “emerging growth company,” as defined in Section 2(a) of the Act (an “Emerging Growth Company”). “Testing-the-Waters Communication” means any oral or written communication with potential investors related to an offering of the Securities undertaken in reliance on Section 5(d) of the Act.

(f) The Company (i) has not alone engaged in any Testing-the-Waters Communication other than Testing-the-Waters Communications with the consent of the Representatives with entities that are qualified institutional buyers within the meaning of Rule 144A under the Act or institutions that are accredited investors within the meaning of Rule 501 under the Act and (ii) has not authorized anyone, including the Representatives, to engage in Testing-the-Waters Communications. The Company has not distributed any Written Testing-the-Waters Communications other than those listed on Schedule IV hereto. “Written Testing-the-Waters Communication” means any Testing-the-Waters Communication that is a written communication within the meaning of Rule 405 under the Act.

(g) Each Issuer Free Writing Prospectus does not include any information that conflicts with the information contained in the Registration Statement, including any document incorporated by reference therein and any prospectus supplement deemed to be a part thereof, that has not been superseded or modified. The foregoing sentence does not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by or on behalf of any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by or on behalf of any Underwriter consists of the information described as such in Section 8 hereof.

(h) The copies of the Registration Statement and any amendments thereto and the copies of each preliminary prospectus, each Issuer Free Writing Prospectus that is required to be filed with the Commission pursuant to Rule 433 and the Preliminary Prospectus, Final Prospectus and any amendments or supplements to any of the foregoing, that have been or subsequently are delivered to the Underwriters in connection with the offering of the Securities (whether to meet the request of purchasers pursuant to Rule 173(d) or otherwise) were and will be identical to the electronically transmitted copies thereof filed with the Commission pursuant to ▇▇▇▇▇, except to the extent permitted by Regulation S-T. For purposes of this Agreement, references to the “delivery” or “furnishing” of any of the foregoing documents to the Underwriters, and any similar terms, include, without limitation, electronic delivery.

(i) The Company and each of its subsidiaries has been duly incorporated and is validly existing as a corporation in good standing under the laws of the jurisdiction in which it is chartered or organized with full corporate power and authority to own or lease, as the case may be, and to operate its properties and conduct its business as described in the Disclosure Package and the Final Prospectus, and is duly qualified to do business as a foreign corporation and is in good standing under the laws of each jurisdiction which requires such qualification, except where the failure to be so qualified or in good standing

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

(j) The Company’s authorized equity capitalization is as set forth in the Disclosure Package and the Final Prospectus; the capital stock of the Company conforms to the description thereof contained in the Disclosure Package and the Final Prospectus; the outstanding shares of Common Stock have been duly and validly authorized and issued and are fully paid and nonassessable; the Securities have been duly and validly authorized and, when issued and delivered to and paid for by the Underwriters pursuant to this Agreement, will be fully paid and nonassessable; the certificates for the Securities are in valid form; the holders of outstanding shares of capital stock of the Company are not entitled to preemptive or other rights to subscribe for the Securities, except for any such rights as have been effectively waived or complied with; and, except as set forth in the Disclosure Package and the Final Prospectus, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, shares of capital stock of or ownership interests in the Company are outstanding.

(k) The Common Stock is registered pursuant to Section 12(b) or 12(g) of the Exchange Act and listed on The NASDAQ Global Market (the “NASDAQ”), and the Company has taken no action designed to, or likely to have the effect of, terminating the registration of its Common Stock under the Exchange Act or delisting 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 NASDAQ.

(l) There is no franchise, contract or other document of a character required to be described in the Registration Statement or Final Prospectus, or to be filed as an exhibit thereto, which is not described or filed as required (and the Preliminary Prospectus contains in all material respects the same description of the foregoing matters contained in the Final Prospectus); and the statements included in the Preliminary Prospectus and the Final Prospectus (or statements incorporated by reference into the Preliminary Prospectus and the Final Prospectus) under the heading “Description of Capital Stock,” as well as Item 14 and Item 15 of the Registration Statement, to the extent they constitute descriptions of agreements, documents, statutes, laws, rules, regulations, judgments, orders or decrees applicable to the Company, fairly summarize the matters therein described.

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

(n) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Disclosure Package and the Final Prospectus, will not be an “investment company” as defined in the Investment Company Act of 1940, as amended.

(o) No consent, approval, authorization, filing with or order of any court or governmental agency or body is required in connection with the Company’s consummation of the transactions contemplated herein, except such as have been obtained under the Act and the Exchange Act and such as may be required under the blue sky laws of any jurisdiction or the by-laws and rules of FINRA in connection with the purchase and distribution of the Securities by the Underwriters in the manner contemplated herein and in the Disclosure Package and the Final Prospectus.

(p) Neither the issue and sale of the Securities nor the consummation of any other of the transactions by the Company herein contemplated nor the Company’s performance of its obligations hereunder will conflict with, result in a breach or violation of, or imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to, (i) the charter or by-laws of the Company or any of its subsidiaries, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which the Company or any of its subsidiaries is a party or bound or to which its or their property is subject, or (iii) any statute, law, rule, regulation, judgment, order or decree applicable to the Company or any of its subsidiaries of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Company or any of its subsidiaries or any of its or their properties, except in the case of clauses (ii) and (iii) as would not have a Material Adverse Effect or a material effect on the Company’s ability to consummate the transactions contemplated hereby.

(q) No holders of securities of the Company have rights to the registration of such securities under the Registration Statement, except for any such rights as have been effectively waived.

(r) The consolidated historical financial statements and schedules of the Company and its consolidated subsidiaries included or incorporated by reference in any Preliminary Prospectus, the Final Prospectus and the Registration Statement present fairly in all material respects the financial condition, results of operations and cash flows of the Company as of the dates and for the periods indicated, comply as to form in all material respects with the applicable accounting requirements of the Act and have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods involved (except as otherwise noted therein). The interactive data in eXtensible Business Reporting Language included or incorporated by reference in the Registration Statement fairly present the information called for in all material respects and have been prepared in accordance with the Commission’s rules and guidelines applicable thereto. No financial statements or supporting schedules are required to be included or incorporated by reference in the Preliminary Prospectus, the Final Prospectus or the Registration Statement other than those that have been so included or incorporated by reference. The financial data set forth or incorporated by reference in each of the Preliminary Prospectus, the Final Prospectus and the Registration Statement under the caption “Selected Financial Data” fairly present the information set forth therein.

(s) The pro forma financial information included or incorporated by reference in the Preliminary Prospectus, the Final Prospectus and the Registration Statement include assumptions that provide a reasonable basis for presenting in all material respects the significant effects directly attributable to the transactions and events described therein, the related pro forma adjustments give in all material respects appropriate effect to those assumptions, and the pro forma adjustments reflect in all material respects the proper application of those adjustments to the historical financial statement amounts included or incorporated by reference in the Preliminary Prospectus, the Final Prospectus and the Registration Statement.

(t) 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 or its or their property is pending or, to the best knowledge of the Company, threatened that could reasonably be expected to have (i) a material adverse effect on the Company’s ability to consummate the transactions contemplated hereby, or (ii) a Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(u) The Company and each of its subsidiaries owns or leases all such properties as are necessary to the conduct of its operations as presently conducted in all material respects.

(v) Neither the Company nor any of its subsidiaries is in violation or default of (i) any provision of its charter or bylaws, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which it is a party or bound or to which its property is subject, or (iii) any statute, law, rule, regulation, judgment, order or decree of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Company or such subsidiary or any of its properties, as applicable, except in the case of clauses (ii) and (iii), for such breach or violation as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(w) PricewaterhouseCoopers LLP, who have certified certain financial statements of the Company and its consolidated subsidiaries and delivered their report with respect to the audited consolidated financial statements and schedules included or incorporated by reference in the Disclosure Package and the Final Prospectus, are independent registered public accountants with respect to the Company within the meaning of the Act and the applicable published rules and regulations thereunder.

(x) There are no transfer taxes or other similar fees or charges under Federal law or the laws of any state, or any political subdivision thereof, required to be paid in connection with the Company’s execution and delivery of this Agreement or the issuance by the Company or sale by the Company of the Securities.

(y) The Company has filed all tax returns that are required to be filed or has requested extensions thereof (except in any case in which the failure so to file would not have a Material Adverse Effect, or except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto)) and has paid all taxes required to be paid by it and any other assessment, fine or penalty levied against it, to the extent that any of the foregoing is due and payable, except for any such assessment, fine or penalty that is currently being contested in good faith or as would not have a Material Adverse Effect, or except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(z) No labor problem or dispute with the employees of the Company or any of its subsidiaries exists or, to the Company’s knowledge, is threatened or imminent, and the Company is not aware of any existing or imminent labor disturbance by the employees of any of its or its subsidiaries’ principal suppliers, contractors or customers, that would reasonably be expected to have a Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(aa) The Company and each of its subsidiaries are insured by insurers of recognized financial responsibility against such losses and risks and in such amounts as the Company reasonably believes are prudent and customary in the businesses in which they are engaged; all policies of insurance and fidelity or surety bonds insuring the Company or any of its subsidiaries or their respective businesses, assets, employees, officers and directors are in full force and effect; the Company and its subsidiaries are in compliance with the terms of such policies and instruments in all material respects; and there are no claims by the Company or any of its subsidiaries under any such policy or instrument as to which any insurance company is denying liability or defending under a reservation of rights clause; neither the Company nor any such subsidiary has been refused any insurance coverage sought or applied for; and neither the Company nor any such subsidiary 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 similar coverage from similar insurers as may be necessary to continue its business at a cost that would not have a Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(bb) No subsidiary of the Company is currently prohibited, directly or indirectly, from paying any dividends to the Company, from making any other distribution on such subsidiary’s capital stock (or equity interests), from repaying to the Company any loans or advances to such subsidiary from the Company or from transferring any of such subsidiary’s property or assets to the Company or any other subsidiary of the Company, except as described in or contemplated by the Disclosure Package and the Final Prospectus.

(cc) The Company and its subsidiaries possess all licenses, certificates, permits and other authorizations issued by all applicable authorities necessary to conduct their respective businesses, except in each case, the lack of which would not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect, and neither

the Company nor any such subsidiary has received any notice of proceedings relating to the revocation or modification of any such certificate, authorization or permit which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would have a Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(dd) The Company and each of its subsidiaries 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 generally accepted accounting principles 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. The Company and its subsidiaries’ internal controls over financial reporting are effective at the reasonable assurance level and the Company and its subsidiaries are not aware of any material weakness in their internal controls over financial reporting except as described in the Disclosure Package and the Final Prospectus.

(ee) The Company and its subsidiaries maintain “disclosure controls and procedures” (as such term is defined in Rule 13a-15(e) under the Exchange Act); such disclosure controls and procedures are effective at the reasonable assurance level.

(ff) The Company has not taken, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in, under the Exchange Act or otherwise, stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities.

(gg) Except as set forth in the Preliminary Prospectus and the Final Prospectus, the Company and its subsidiaries own, possess, license or have other rights to use all patents, patent applications, trade and service marks, trade and service ▇▇▇▇ registrations, trade names, copyrights, licenses, inventions, trade secrets, technology, know-how and other intellectual property necessary for the conduct of the Company’s business as now conducted or as proposed in the Disclosure Package and Final Prospectus to be conducted (collectively, the “Company Intellectual Property”), and, to the Company’s knowledge, the patents, trademarks, and copyrights included within the Company Intellectual Property are valid, enforceable, and subsisting. Except as set forth in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto): (a) there are no rights of third parties to any such Company Intellectual Property; (b) to the Company’s knowledge, there is no material infringement by third parties of any such Company 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 Company Intellectual Property, and the Company is unaware of any facts which would form a reasonable basis for any such claim; (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 Company Intellectual Property, and the Company is

unaware of any facts which would form a reasonable basis for any such claim; (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, and the Company is unaware of any other fact which would form a reasonable basis for any such claim, in each case except as would not reasonably be expected to have a Material Adverse Effect; (f) to the Company’s knowledge, neither the sale nor use of any of the products, proposed products or processes of the Company referred to in the Registration Statement, Disclosure Package, or the Final Prospectus would infringe any currently issued and valid patent of a third party; (g) to the Company’s knowledge, there is no U.S. patent or published U.S. patent application which contains claims that dominate or may dominate any Company Intellectual Property described in the Disclosure Package and the Final Prospectus as being owned by, or licensed to, the Company or that interferes with the issued or pending claims of any such Company 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 or any U.S. patent application held by the Company unpatentable which has not been disclosed to the U.S. Patent and Trademark Office (the “PTO”); and (h) 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 Company Intellectual Property.

(hh) All patent applications owned by the Company or its subsidiaries and filed with the PTO or any foreign or international patent authority (the “Company Patent Applications”) and, to the Company’s knowledge, all patent applications in-licensed by the Company or its subsidiaries and filed with the PTO or any foreign or international patent authority (the “In-licensed Patent Applications”) have been duly and properly filed; the Company and its subsidiaries have complied with their duty of candor and disclosure to the PTO for the Company Patent Applications and, to the Company’s knowledge, the licensors of the In-licensed Patent Applications have complied with their duty of candor and disclosure to the PTO for the In-licensed Patent Applications; the Company is not aware of any facts required to be disclosed to the PTO that were not disclosed to the PTO and which would preclude the grant of a patent in the Company Patent Applications; the Company has no knowledge of any facts which would preclude it from having clear title to the Company Patent Applications that have been identified by the Company as being exclusively owned by the Company.

(ii) The Company possesses such valid and current licenses, certificates, authorizations or permits issued by the appropriate state, local, federal or foreign regulatory agencies or bodies necessary for the conduct of the Company’s business as now conducted, including, without limitation, all such certificates, authorizations and permits required by the United States Food and Drug Administration (the “FDA”) or any other state, local, federal or comparable foreign agencies or bodies engaged in the regulation of pharmaceuticals or biohazardous materials.

(jj) Neither the Company nor any of its subsidiaries has received any written notice or other communication from the FDA or any other foreign, federal, state or local governmental or regulatory authority performing functions similar to those performed by

the FDA regarding material non-compliance with the Federal Food, Drug, and Cosmetic Act, 21 U.S.C. §301 et seq, (the FDCA) and applicable FDA regulations or similar laws, statutes, ordinances, rules or regulations of any other foreign, federal, state or local governmental or regulatory authority, including, but not limited to, any deficiency, any other compliance or enforcement action. To the Company’s knowledge, there has not been any material non-compliance with or violation of any Applicable Laws by the Company or any of its subsidiaries that could reasonably be expected to require the issuance of any such communication, or an investigation, corrective action or enforcement action by the FDA or similar governmental or regulatory authorities. As of the date hereof, to the Company’s knowledge, no review or investigation by a governmental or regulatory authority is pending and no such review or investigation has been threatened.

(kk) Except as described in the Registration Statement, the Disclosure Package and the Final Prospectus, or as would not individually or in the aggregate have a Material Adverse Effect, the Company has not had any product or manufacturing site (whether Company-owned or, to the Company’s knowledge, that of a contract manufacturer for Company products) subject to a governmental authority (including, without limitation, the FDA) shutdown or import or export prohibition, nor received any FDA Form 483 or other governmental authority notice of inspectional observations, “warning letters,” “untitled letters,” requests to make changes to the Company products, processes or operations, or similar correspondence or notice from the FDA or other governmental authority alleging or asserting material noncompliance with any applicable laws. To the Company’s knowledge, neither the FDA nor any other governmental authority has threatened such action.

(ll) All nonclinical tests and all clinical trials (“Studies, Trials and Tests”) conducted by or on behalf of, or sponsored by, the Company, or in which the Company has participated, that are described in the Disclosure Package and the Final Prospectus, or the results of which are referred to in the Disclosure Package and the Final Prospectus, were and, if still pending, are being conducted in all material respects in accordance with: (1) experimental protocols, procedures and controls pursuant to, where applicable, accepted professional and scientific standards for products or product candidates comparable to those being developed by the Company, and (2) all applicable federal statutes, rules and regulations of the FDA, the European Medicines Agency (“EMA”) and other comparable drug regulatory agencies outside of the United States to which they are subject. The descriptions in the Final Prospectus of the results of such Studies, Tests and Trials are accurate and complete in all material respects and fairly present the published data derived from such Studies, Tests and Trials. The descriptions of the results of such Studies, Tests and Trials contained in the Disclosure Package and the Final Prospectus do not contain any misstatement of a material fact or omit to state a material fact necessary to make such statements not misleading; the Company has no knowledge of any Studies, Tests or Trials not described in the Disclosure Package and the Final Prospectus the results of which reasonably call into question in any material respect the results of the Studies, Tests and Trials described in the Disclosure Package or Final Prospectus; and the Company has not received any notices or correspondence from the FDA, EMA or any other comparable foreign, state or local governmental body exercising comparable

authority or any Institutional Review Board or comparable ethical and scientific review authority requiring or threatening the termination, suspension or material modification of any Studies, Tests and Trials conducted by or on behalf of, or sponsored by, the Company or in which the Company has participated, and, to the Company’s knowledge, there are no reasonable grounds for the same.

(mm) Except as disclosed in the Disclosure Package and the Final Prospectus, the Company has not made any knowingly false statements on, or material omissions from, any applications, approvals, reports or other submissions to any applicable regulatory authority, or in or from any other records and documentation prepared or maintained to comply with the requirements of FDA or any comparable regulatory authority relating to the Company’s product candidates.

(nn) Neither the Company, any of its subsidiaries nor, to the Company’s knowledge, any of their respective directors, officers, employees or agents, have with respect to each of the following statutes, or regulations promulgated thereto: (i) engaged in activities under 42 U.S.C. §§ 1320a-7 or 1395nn; (ii) knowingly engaged in any activities under 42 U.S.C. § 1320a-7a or the Federal False Claims Act, 31 U.S.C. § 3729; or (iii) knowingly and willfully engaged in any activities under 42 U.S.C. § 1320a-7b, which are, as applicable, prohibited, cause for civil penalties, or mandatory or permissive exclusion from Medicare, Medicaid, or any other State Health Care Program or Federal Health Care Program.

(oo) Except in each case as would not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect, the Company and its subsidiaries are (i) 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 and are in compliance with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) have not received notice of any actual or potential liability under any Environmental Law, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto). Except as set forth in the Disclosure Package and the Final Prospectus, neither the Company nor any of its subsidiaries has been named as a “potentially responsible party” under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended.

(pp) Nothing has come to the attention of the Company that has caused the Company to believe that the statistical and market-related data included in the Registration Statement, the Disclosure Package and the Final Prospectus is not based on or derived from sources that are reliable and accurate in all material respects, and, to the extent required by such sources, the Company has obtained the written consent to the use of such data from such sources.

(qq) Each Plan (as defined herein) has been maintained in all material respects in compliance with its terms and the requirements of any applicable statutes, orders, rules

and regulations, including but not limited to, the United States Employee Retirement Income Security Act of 1974, as amended (“ERISA”) and the Internal Revenue Code of 1986, as amended, and the regulations and published interpretations thereunder (the “Code”). Each Plan established or maintained by the Company, its subsidiaries or any of their ERISA Affiliates (as defined herein) 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. None of the following events has occurred or exists: (i) a failure to fulfill the obligations, if any, under the minimum funding standards of Section 302 of ERISA, and the regulations and published interpretations thereunder with respect to a Plan, determined without regard to any waiver of such obligations or extension of any amortization period; (ii) an audit or investigation by the Internal Revenue Service, the U.S. Department of Labor, the Pension Benefit Guaranty Corporation or any other federal or state governmental agency or any foreign regulatory agency with respect to any Plan or the employment or compensation of employees by any of the Company or any of its subsidiaries that could have a Material Adverse Effect; (iii) any breach of any contractual obligation, or any violation of law or applicable qualification standards, with respect to any Plan or the employment or compensation of employees by the Company or any of its subsidiaries that would reasonably be expected to have a Material Adverse Effect; or (iv) a non-exempt prohibited transaction , within the meaning of Section 406 of ERISA or Section 4975 of the Code with respect to any Plan that could have a material adverse effect. None of the following events has occurred or is reasonably likely to occur: (i) a material increase in the aggregate amount of contributions required to be made to all Plans in the current fiscal year of the Company and its subsidiaries compared to the amount of such contributions made in the most recently completed fiscal year of the Company and its subsidiaries; (ii) a material increase in the “accumulated post-retirement benefit obligations” (within the meaning of Statement of Financial Accounting Standards 106) of the Company and its subsidiaries compared to the amount of such obligations in the most recently completed fiscal year of the Company and its subsidiaries; (iii) any event or condition giving rise to a liability under Title IV of ERISA that would reasonably be expected to have a Material Adverse Effect; or (iv) the filing of a claim by one or more employees or former employees of the Company or any of its subsidiaries related to their employment that would reasonably be expected to have a Material Adverse Effect. For purposes of this paragraph, (x) the term “ERISA Affiliates” 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 Code, and (y) the term “Plan” means a plan (within the meaning of Section 3(3) of ERISA) with respect to which the Company or any of its ERISA Affiliates may have any liability under ERISA.

(rr) There is and has been no failure on the part of the Company and any of the Company’s directors or officers, in their capacities as such, to comply with any provision of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002 and the rules and regulations promulgated in connection therewith (the “▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act”), including Section 402 relating to loans and Sections 302 and 906 relating to certifications.

(ss) Neither the Company nor any of its subsidiaries, nor any officer of the Company or its subsidiaries, nor, to the knowledge of the Company, any director, agent,

employee or affiliate of the Company or any of its subsidiaries is aware of or has taken any action, directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder (the “FCPA”), including, without limitation, making use of the mails or any means or instrumentality of interstate commerce corruptly in furtherance of an offer, payment, promise to pay or authorization of the payment of any money, or other property, gift, promise to give, or authorization of the giving of anything of value to any “foreign official” (as such term is defined in the FCPA) or any foreign political party or official thereof or any candidate for foreign political office, in contravention of the FCPA, or the U.K. ▇▇▇▇▇▇▇ ▇▇▇ ▇▇▇▇, or any applicable law or regulation implementing the OECD Convention on Combating Bribery of Foreign Public Officials in International Business Transactions, or committed an offense under any other applicable anti-bribery or anti-corruption laws; and the Company, its subsidiaries and, to the knowledge of the Company, its affiliates have conducted their businesses in compliance with all applicable anti-bribery and anti-corruption laws and have instituted and maintain policies and procedures designed to ensure, and which are reasonably expected to continue to ensure, continued compliance therewith.

(tt) The operations of the Company and its subsidiaries are and have been conducted at all times in compliance with applicable financial recordkeeping and reporting requirements and the money laundering statutes and the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “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 Money Laundering Laws is pending or, to the best knowledge of the Company, threatened.

(uu) Neither the Company nor any of its subsidiaries, nor any officer of the Company or its subsidiaries, nor, to the knowledge of the Company, any director, agent, employee or affiliate of the Company or any of its subsidiaries is currently subject to any sanctions administered or enforced by the U.S. government (including, without limitation, the Office of Foreign Assets Control of the U.S. Treasury Department (“OFAC”) or the U.S. Department of State and including, without limitation, the designation as a “specially designated national” or “blocked person”), the United Nations Security Council, the European Union or Her Majesty’s Treasury (collectively, “Sanctions”), nor is the Company or any of its subsidiaries located, organized or resident in a country or territory that is the subject or target of Sanctions, including, without limitation, Cuba, Iran, North Korea, Sudan and Syria (each, a “Sanctioned Country”); and the Company will not directly or indirectly use the proceeds of the offering, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other person or entity (i) to fund or facilitate any activities of or business with any person that, at the time of such funding or facilitation, is the subject or the target of Sanctions or (ii) in any other manner that will result in a violation by any person (including any person participating in the offering, whether as underwriter, advisor, investor or otherwise) of Sanctions. For the past five years, the Company and its subsidiaries have not knowingly engaged in, are not now knowingly engaged in, and will not engage in, any dealings or transactions with any person that at the time of the dealing or transaction is or was the subject or the target of Sanctions or with any Sanctioned Country.

(vv) Other than Flexion Therapeutics Securities Corporation, the Company does not have any subsidiaries that constitute a “significant subsidiary” under Rule 1-02 of Regulation S-X. All the outstanding shares of capital stock of Flexion Therapeutics Securities Corporation have been duly and validly authorized and issued and are fully paid and nonassessable, and, except as otherwise set forth in the Disclosure Package and the Final Prospectus, all outstanding shares of capital stock of Flexion Therapeutics Securities Corporation (except for any directors’ qualifying shares) are owned by the Company either directly or through wholly owned subsidiaries free and clear of any perfected security interest or any other security interests, claims or liens.

(ww) Except as disclosed in the Registration Statement, the Disclosure Package and the Final Prospectus, the Company (i) does not have any material lending or other relationship with any bank or lending affiliate of the Representatives and (ii) does not intend to use any of the proceeds from the sale of the Securities hereunder to repay any outstanding debt owed to any affiliate of the Representatives.

(xx) There are no business relationships or related party transactions involving the Company or any other person required to be described in the Registration Statement, the Disclosure Package or the Final Prospectus in accordance with Item 404 of Regulation S-K that have not been described. No relationship, direct or indirect, exists between or among the Company or any of its subsidiaries on the one hand, and the directors, officers, stockholders, customers or suppliers of the Company on the other hand, that is required to be described in the Registration Statement, the Disclosure Package or the Final Prospectus in accordance with Item 404 of Regulation S-K and that is not so described. The Company has provided to the Representatives true, correct and complete copies of all documentation pertaining to any extension of credit in the form of a personal loan made, directly or indirectly, by the Company to any director or executive officer of the Company, or to any family member or affiliate of any director or executive officer of the Company. The Company has not, directly or indirectly, including through any subsidiary: (i) extended or maintained credit, arranged to extend credit, or renewed any extension of credit, in the form of a personal loan, to or for any director or executive officer of the Company, or to or for any family member or affiliate of any director or executive officer of the Company or (ii) made any material modification, including any renewal thereof, to any term of any personal loan to any director or executive officer of the Company, or any family member or affiliate of any director or executive officer.

Any certificate signed by any officer of the Company and delivered to the Representatives or counsel for the Underwriters in connection with the offering of the Securities shall be deemed a representation and warranty by the Company, as to matters covered thereby, to each Underwriter.

2. Purchase and Sale.

(a) Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company agrees to sell to each Underwriter, and each Underwriter agrees, severally and not jointly, to purchase from the Company, at the purchase price per share set forth in Schedule I hereto opposite the heading “Price per Share to the Underwriters”, the amount of the Underwritten Securities set forth opposite such Underwriter’s name in Schedule II hereto.

(b) Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company hereby grants an option to the several Underwriters to purchase, severally and not jointly, up to the number of Option Securities set forth in Schedule I hereto at the same purchase price per share as the Underwriters shall pay for the Underwritten Securities, less an amount per share equal to any dividends or distributions declared by the Company and payable on the Underwritten Securities but not payable on the Option Securities. Said option may be exercised only to cover over-allotments in the sale of the Underwritten Securities by the Underwriters. Said option may be exercised in whole or in part at any time on or before the 30th day after the date of the Final Prospectus upon written or telegraphic notice by the Representatives to the Company setting forth the number of shares of the Option Securities as to which the several Underwriters are exercising the option and the settlement date. The number of Option Securities to be purchased by each Underwriter shall be the same percentage of the total number of shares of the Option Securities to be purchased by the several Underwriters as such Underwriter is purchasing of the Underwritten Securities, subject to such adjustments as the Representatives in their absolute discretion shall make to eliminate any fractional shares.

3. Delivery and Payment. Delivery of and payment for the Underwritten Securities and the Option Securities (if the option provided for in Section 2(b) hereof shall have been exercised on or before the Business Day immediately preceding the Closing Date (as defined herein)) shall be made on the date and at the time specified in Schedule I hereto, or at such time on such later date not more than three Business Days after the foregoing date as the Representatives shall designate, which date and time may be postponed by agreement between the Representatives and the Company or as provided in Section 9 hereof (such date and time of delivery and payment for the Securities being herein called the “Closing Date”). Delivery of the Securities sold at the Closing Date shall be made to the Representatives for the respective accounts of the several Underwriters against payment by the several Underwriters through the Representatives of the purchase price thereof to or upon the order of the Company by wire transfer payable in same-day funds to an account specified by the Company. Delivery of the Underwritten Securities and the Option Securities shall be made through the facilities of The Depository Trust Company unless the Representatives shall otherwise instruct.

If the option provided for in Section 2(b) hereof is exercised after the Business Day immediately preceding the Closing Date, the Company will deliver the Option Securities (at the expense of the Company) to the Representatives through the facilities of The Depository Trust Company (unless the Representatives shall otherwise instruct) on the date specified by the Representatives (which shall be three Business Days after the delivery of the notice of exercise of said option unless the Representatives and the Company agree to a later date) for the respective accounts of the several Underwriters, against payment by the several Underwriters

through the Representatives of the purchase price thereof to or upon the order of the Company by wire transfer payable in same-day funds to an account specified by the Company. If settlement for the Option Securities occurs after the Closing Date, the Company will deliver to the Representatives on the settlement date for the Option Securities, and the obligation of the Underwriters to purchase the Option Securities shall be conditioned upon receipt of, supplemental opinions, certificates and letters confirming as of such date the opinions, certificates and letters delivered on the Closing Date pursuant to Section 6 hereof.

4. Offering by Underwriters. It is understood that the several Underwriters propose to offer the Securities for sale to the public as set forth in the Final Prospectus.

5. Agreements. The Company agrees with the several Underwriters that:

(a) Prior to the termination of the offering of the Securities, the Company will not file any amendment of the Registration Statement or supplement (including the Final Prospectus or any Preliminary Prospectus) to the Base Prospectus unless the Company has furnished a copy to the Representatives for review prior to filing and will not file any such proposed amendment or supplement to which the Representatives reasonably object. The Company will cause the Final Prospectus, properly completed, and any supplement thereto to be filed in a form approved by the Representatives with the Commission pursuant to the applicable paragraph of Rule 424(b) within the time period prescribed. During the time when a prospectus relating to the Securities is required to be delivered under the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), the Company will promptly advise the Representatives (i) when the Final Prospectus, and any supplement thereto, shall have been filed (if required) with the Commission pursuant to Rule 424(b), (ii) when, prior to termination of the offering of the Securities, any amendment to the Registration Statement shall have been filed or become effective, (iii) of any request by the Commission or its staff for any amendment of the Registration Statement, or any Rule 462(b) Registration Statement, or for any supplement to the Final Prospectus or for any additional information, (iv) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement or of any notice objecting to its use or the institution or threatening of any proceeding for that purpose and (v) of the receipt by the Company of any notification with respect to the suspension of the qualification of the Securities for sale in any jurisdiction or the institution or threatening of any proceeding for such purpose. The Company will use its reasonable best efforts to prevent the issuance of any such stop order or the occurrence of any such suspension or objection to the use of the Registration Statement and, upon such issuance, occurrence or notice of objection, to obtain as soon as possible the withdrawal of such stop order or relief from such occurrence or objection, including, if necessary, by filing an amendment to the Registration Statement or a new registration statement and using its reasonable best efforts to have such amendment or new registration statement declared effective as soon as practicable.

(b) If, at any time prior to the filing of the Final Prospectus pursuant to Rule 424(b), any event occurs as a result of which the Disclosure Package would include any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein in the light of the circumstances under which they were made at such

time not misleading, the Company will (i) notify promptly the Representatives so that any use of the Disclosure Package may cease until it is amended or supplemented; (ii) amend or supplement the Disclosure Package to correct such statement or omission; and (iii) supply any amendment or supplement to the Representatives in such quantities as they may reasonably request.

(c) If, at any time when a prospectus relating to the Securities is required to be delivered under the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), any event occurs as a result of which the Final Prospectus as then supplemented would include any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein in the light of the circumstances under which they were made or the circumstances then prevailing not misleading, or if it shall be necessary to amend the Registration Statement or supplement the Final Prospectus to comply with the Act or the Exchange Act or the respective the rules thereunder, including in connection with use or delivery of the Final Prospectus, the Company promptly will (i) notify the Representatives of any such event; (ii) prepare and file with the Commission, subject to the second sentence of paragraph (a) of this Section 5, an amendment or supplement which will correct such statement or omission or effect such compliance; (iii) use its best efforts to have any amendment to the Registration Statement declared effective as soon as practicable in order to avoid any disruption in use of the Final Prospectus; and (iv) supply any supplemented Final Prospectus to the Representatives in such quantities as they may reasonably request.

(d) As soon as practicable during the time when a prospectus relating to the Securities is required to be delivered under the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), the Company will make generally available to its security holders and to the Representatives an earnings statement or statements of the Company and its subsidiaries which will satisfy the provisions of Section 11(a) of the Act and Rule 158.

(e) The Company will furnish to the Representatives and counsel for the Underwriters, without charge, signed copies of the Registration Statement (including exhibits thereto) and to each other Underwriter a conformed copy of the Registration Statement (without exhibits thereto) and, so long as delivery of a prospectus by an Underwriter or dealer may be required by the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), as many copies of each Preliminary Prospectus, the Final Prospectus and each Issuer Free Writing Prospectus and any supplement thereto as the Representatives may reasonably request.

(f) The Company will arrange, if necessary, for the qualification of the Securities for sale under the laws of such jurisdictions as the Representatives may reasonably designate and will use its reasonable best efforts to maintain such qualifications in effect so long as required for the distribution of the Securities; provided that in no event shall the Company be obligated to qualify to do business in any jurisdiction where it is not now so qualified or to take any action that would subject it to service of process in suits, other than those arising out of the offering or sale of the Securities, in any jurisdiction where it is not now so subject.

(g) The Company will not, without the prior written consent of ▇▇▇▇▇ Fargo Securities, LLC and RBC Capital Markets, LLC, offer, sell, contract to sell, pledge, or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the Company or any affiliate of the Company) directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Commission (except for a registration statement on Form S-8 relating to the Company’s equity incentive plans) in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act, any other shares of Common Stock or any securities convertible into, or exercisable, or exchangeable for, shares of Common Stock; or publicly announce an intention to effect any such transaction, for a period of 90 days after the date of this Agreement, provided, however, that the Company may (i) issue and sell Common Stock, or any securities convertible into, or exercisable, or exchangeable for, shares of Common Stock, pursuant to any employee stock option plan, stock ownership plan or dividend reinvestment plan of the Company in effect at the Execution Time, or disclosed in the Final Prospectus, (ii) issue Common Stock issuable upon the conversion of securities or the exercise of warrants outstanding at the Execution Time, and (iii) offer, issue and sell shares of Common Stock or any securities convertible into, or exercisable, or exchangeable for, shares of Common Stock in connection with any acquisition or strategic investment (including any joint venture, strategic alliance or partnership) as long as (x) the aggregate number of shares of Common Stock issued or issuable does not exceed 5% of the number of shares of Common Stock outstanding immediately after the issuance and sale of the Securities, and (y) each recipient of any such shares or other securities agrees to restrictions on the resale of securities that are consistent with the lock-up letters described in Section 6(i) hereof for the remainder of the 90-day restricted period.

(h) [Reserved].

(i) The Company will not take, directly or indirectly, without giving effect to the activities by the Underwriters, any action designed to or that would constitute or that would reasonably be expected to cause or result in, under the Exchange Act or otherwise, stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities.

(j) The Company agrees to pay the costs and expenses relating to the following matters: (i) the preparation, printing or reproduction and filing with the Commission of the Registration Statement (including financial statements and exhibits thereto), each Preliminary Prospectus, the Final Prospectus, including one or more versions of each Preliminary Prospectus and the Final Prospectus for distribution in Canada, often in the form of a “Canadian wrapper” (including reasonable fees and expenses of Canadian counsel to the Underwriters for the purpose of preparing such “Canadian wrapper”), and each Issuer Free Writing Prospectus, and each amendment or supplement to any of them; (ii) the printing (or reproduction) and delivery (including postage, air freight charges and charges for counting and packaging) of such copies of the Registration Statement, each Preliminary Prospectus, the Final Prospectus, including one

or more versions of each Preliminary Prospectus and the Final Prospectus for distribution in Canada, often in the form of a “Canadian wrapper,” and each Issuer Free Writing Prospectus, and all amendments or supplements to any of them, as may, in each case, be reasonably requested for use in connection with the offering and sale of the Securities; (iii) the preparation, printing, authentication, issuance and delivery of certificates for the Securities, including any stamp or transfer taxes in connection with the original issuance and sale of the Securities; (iv) the printing (or reproduction) and delivery of this Agreement, any blue sky memorandum and all other agreements or documents printed (or reproduced) and delivered in connection with the offering of the Securities; (v) the registration of the Securities under the Exchange Act and the listing of the Securities on the NASDAQ; (vi) any registration or qualification of the Securities for offer and sale under the securities or blue sky laws of the several states or under foreign securities laws (including filing fees and the reasonable fees and expenses of counsel for the Underwriters relating to such registration and qualification); (vii) any filings required to be made with the Financial Industry Regulatory Authority, Inc. (including filing fees and the reasonable fees and expenses of counsel for the Underwriters relating to such filings); provided, however, that the reasonable fees and expenses of counsel for the Underwriters relating to subclauses (vi) and (vii) of this Section 5(j) shall not exceed $10,000; (viii) the transportation and other expenses incurred by or on behalf of Company representatives in connection with presentations to prospective purchasers of the Securities; provided, however, that the Company shall be responsible for half of the cost and expenses of any aircraft chartered in connection with the “road show” for the Securities and the Underwriters shall be responsible for the balance; (ix) the fees and expenses of the Company’s accountants and the fees and expenses of counsel (including local and special counsel) for the Company; and (x) all other costs and expenses incident to the performance by the Company of its obligations hereunder.

(k) The Company agrees that, unless it has or shall have obtained the prior written consent of the Representatives, and each Underwriter, severally and not jointly, agrees with the Company that, unless it has or shall have obtained, as the case may be, the prior written consent of the Company, it has not made and will not make any offer relating to the Securities that would constitute a Written Testing-the-Waters Communication or an Issuer Free Writing Prospectus or that would otherwise constitute a Free Writing Prospectus required to be filed by the Company with the Commission or retained by the Company under Rule 433; provided that the prior written consent of the parties hereto shall be deemed to have been given in respect of the Free Writing Prospectuses included in Schedule III hereto and any electronic road show. Any such Free Writing Prospectus consented to by the Representatives or the Company is hereinafter referred to as a “Permitted Free Writing Prospectus.” The Company agrees that (x) it has treated and will treat, as the case may be, each Permitted Free Writing Prospectus as an Issuer Free Writing Prospectus and (y) it has complied and will comply, as the case may be, with the requirements of Rules 164 and 433 applicable to any Permitted Free Writing Prospectus, including in respect of timely filing with the Commission, legending and record keeping.

(l) The Company will promptly notify the Representatives if the Company ceases to be an Emerging Growth Company at any time prior to the later of (a) completion of the distribution of the Securities within the meaning of the Act and (b) completion of the 90-day restricted period referred to in Section 5(g) hereof.

(m) If at any time following the distribution of any Written Testing-the-Waters Communication, any event occurs as a result of which such Written Testing-the-Waters Communication would include any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein in the light of the circumstances under which they were made at such time not misleading, the Company will (i) notify promptly the Representatives so that use of the Written Testing-the-Waters Communication may cease until it is amended or supplemented; (ii) amend or supplement the Written Testing-the-Waters Communication to correct such statement or omission; and (iii) supply any amendment or supplement to the Representatives in such quantities as may be reasonably requested.

6. Conditions to the Obligations of the Underwriters. The obligations of the Underwriters to purchase the Underwritten Securities and the Option Securities, as the case may be, shall be subject to the accuracy of the representations and warranties on the part of the Company contained herein as of the Execution Time, the Closing Date and any settlement date pursuant to Section 3 hereof, to the accuracy of the statements of the Company made in any certificates pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions:

(a) The Final Prospectus, and any supplement thereto, have been filed in the manner and within the time period required by Rule 424(b); any material required to be filed by the Company pursuant to Rule 433(d) under the Act shall have been filed with the Commission within the applicable time periods prescribed for such filings by Rule 433; and no stop order suspending the effectiveness of the Registration Statement or any notice objecting to its use shall have been issued and no proceedings for that purpose shall have been instituted or threatened.

(b) The Company shall have requested and caused ▇▇▇▇▇▇ LLP, counsel for the Company, to have furnished to the Representatives their opinions, each dated the Closing Date and addressed to the Representatives, as attached as Exhibit B-1 and Exhibit B-2.

(c) (i) The Representatives shall have received from ▇▇▇▇▇▇▇ Procter LLP, counsel for the Underwriters, such opinion or opinions, dated the Closing Date and addressed to the Representatives, with respect to the issuance and sale of the Securities, the Registration Statement, the Disclosure Package, the Final Prospectus (together with any supplement thereto) and other related matters as the Representatives may reasonably require, and (ii) the Company shall have furnished to such counsel such documents as they may reasonably request for the purpose of enabling them to pass upon such matters.

(d) The Company shall have furnished to the Representatives a certificate of the Company, signed by the Chairman of the Board or the President and the principal financial or accounting officer of the Company, dated the Closing Date, to the effect that the signers of such certificate have carefully examined the Registration Statement, the

Disclosure Package, the Final Prospectus and any amendment or supplement thereto, as well as each electronic road show used in connection with the offering of the Securities, and this Agreement and that:

(i) the representations and warranties of the Company in this Agreement are true and correct on and as of the Closing Date with the same effect as if made on the Closing Date and the Company has complied with all the agreements and satisfied all the conditions on its part to be performed or satisfied at or prior to the Closing Date;

(ii) no stop order suspending the effectiveness of the Registration Statement or any notice objecting to its use has been issued and no proceedings for that purpose have been instituted or, to the Company’s knowledge, threatened; and

(iii) since the date of the most recent financial statements included in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto), there has been no Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto).

(e) The Company shall have furnished to the Representatives a certificate of the Company, signed by the Chief Financial Officer of the Company, dated the Closing Date, in form and substance satisfactory to the Underwriters.

(f) The Company shall have requested and caused PricewaterhouseCoopers LLP to have furnished to the Representatives, at the Execution Time and at the Closing Date, letters, dated respectively as of the Execution Time and as of the Closing Date, in form and substance reasonably satisfactory to the Representatives.

(g) Subsequent to the Execution Time or, if earlier, the dates as of which information is given in the Registration Statement (exclusive of any amendment thereof) and the Final Prospectus (exclusive of any amendment or supplement thereto), there shall not have been any change, or any development involving a prospective change, in or affecting the condition (financial or otherwise), earnings, business or properties of the Company and its subsidiaries taken as a whole, whether or not arising from transactions in the ordinary course of business, except as set forth in or contemplated in the Disclosure Package and the Final Prospectus (exclusive of any supplement thereto) the effect of which is, in the sole judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the offering or delivery of the Securities as contemplated by the Registration Statement (exclusive of any amendment thereof), the Disclosure Package and the Final Prospectus (exclusive of any amendment or supplement thereto).

(h) Prior to the Closing Date, the Company shall have furnished to the Representatives such further customary information, certificates and documents as the Representatives may reasonably request.

(i) The Securities shall have been listed and admitted and authorized for trading on the NASDAQ, and satisfactory evidence of such actions shall have been provided to the Representatives.

(j) At the Execution Time, the Company shall have furnished to the Representatives a letter substantially in the form of Exhibit A hereto from each executive officer and director of the Company and specified holders of the Company’s equity securities addressed to the Representatives.

(k) If a filing has been made with FINRA, FINRA shall have raised no objection to the fairness and reasonableness of the underwriting terms and arrangements.

If any of the conditions specified in this Section 6 shall not have been fulfilled when and as provided in this Agreement, or if any of the opinions and certificates mentioned above or elsewhere in this Agreement shall not be reasonably satisfactory in form and substance to the Representatives and counsel for the Underwriters, this Agreement and all obligations of the Underwriters hereunder may be canceled at, or at any time prior to, the Closing Date by the Representatives. Notice of such cancellation shall be given to the Company in writing or by telephone or facsimile confirmed in writing.

The documents required to be delivered by this Section 6 shall be delivered, on the Closing Date, at the office of ▇▇▇▇▇▇▇ Procter LLP, counsel for the Underwriters, at ▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇ or, if after June 24, 2016, at ▇▇▇▇▇▇▇ Procter LLP, ▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇.

7. Reimbursement of Underwriters’ Expenses. If the sale of the Securities provided for herein is not consummated because any condition to the obligations of the Underwriters set forth in Section 6 hereof (other than clause (i) of Section 6(c)) is not satisfied, because of any termination pursuant to Section 10 hereof or because of any refusal, inability or failure on the part of the Company to perform any agreement herein or comply with any provision hereof other than by reason of a default by any of the Underwriters, the Company will reimburse the Underwriters severally through the Representatives on demand for all out of pocket expenses (including reasonable and documented fees and disbursements of counsel) that shall have been reasonably incurred by them in connection with the proposed purchase and sale of the Securities; provided, however, that in the event any such termination is effected after the closing of the purchase and sale of the Underwritten Securities and the reimbursement of any fees and expenses of the Underwriters as otherwise provided in this Agreement but prior to any closing with respect to the purchase and sale of any Option Securities, the Company shall only be obligated to reimburse the Underwriters for their out of pocket expenses (including reasonable and documented fees and disbursements of counsel), incurred after the closing of the purchase and sale of the Underwritten Securities and in connection with the proposed purchase and sale of any such Option Securities.

8. Indemnification and Contribution.

(a) The Company agrees to indemnify and hold harmless each Underwriter, its affiliates, and its and their directors, officers, employees and agents and each person who

controls any Underwriter within the meaning of either the Act or the Exchange Act against any and all losses, claims, damages or liabilities, joint or several, to which they or any of them may become subject under the Act, the Exchange Act or other Federal or state statutory law or regulation, at common law or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of a material fact contained in the registration statement for the registration of the Securities as originally filed or in any amendment thereof, or in the Base Prospectus, any Preliminary Prospectus, the Final Prospectus, any Issuer Free Writing Prospectus, or any Written Testing-the-Waters Communication or in any amendment thereof or supplement thereto or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and agrees to reimburse each such indemnified party, as incurred, for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however, that the Company will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon any such untrue statement or alleged untrue statement or omission or alleged omission made therein in reliance upon and in conformity with written information furnished to the Company by or on behalf of any Underwriter through the Representatives specifically for inclusion therein. This indemnity agreement will be in addition to any liability which the Company may otherwise have.

(b) Each Underwriter severally and not jointly agrees to indemnify and hold harmless the Company, each of its directors, each of its officers who signs the Registration Statement, and each person who controls the Company within the meaning of either the Act or the Exchange Act, to the same extent as the foregoing indemnity from the Company to each Underwriter, but only with reference to written information relating to such Underwriter furnished to the Company by or on behalf of such Underwriter through the Representatives specifically for inclusion in the documents referred to in the foregoing indemnity. This indemnity agreement will be in addition to any liability which any Underwriter may otherwise have. The Company acknowledges that the statements set forth (i) in the last paragraph of the cover page regarding delivery of the Securities, and (ii) under the heading “Underwriting”, (A) the list of Underwriters and their respective participation in the sale of the Securities, (B) the sentences related to concessions and reallowances and (C) the paragraph related to stabilization, syndicate covering transactions and penalty bids in any Preliminary Prospectus and the Final Prospectus constitute the only information furnished in writing by or on behalf of the several Underwriters for inclusion in any Preliminary Prospectus, the Final Prospectus or any Issuer Free Writing Prospectus.

(c) Promptly after receipt by an indemnified party under this Section 8 of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against the indemnifying party under this Section 8, notify the indemnifying party in writing of the commencement thereof; but the failure so to notify the indemnifying party (i) will not relieve it from liability under paragraph (a) or (b) above unless and to the extent it did not otherwise learn of such action and such failure results in the forfeiture by the indemnifying party of substantial rights and

defenses and (ii) will not, in any event, relieve the indemnifying party from any obligations to any indemnified party other than the indemnification obligation provided in paragraph (a) or (b) above. The indemnifying party shall be entitled to appoint counsel of the indemnifying party’s choice at the indemnifying party’s expense to represent the indemnified party in any action for which indemnification is sought (in which case the indemnifying party shall not thereafter be responsible for the fees and expenses of any separate counsel retained by the indemnified party or parties except as set forth below); provided, however, that such counsel shall be reasonably satisfactory to the indemnified party. Notwithstanding the indemnifying party’s election to appoint counsel to represent the indemnified party in an action, the indemnified party shall have the right to employ separate counsel (including local counsel), and the indemnifying party shall bear the reasonable fees, costs and expenses of such separate counsel (which, if the Company is the indemnifying party, shall be limited to one such separate counsel (in addition to any local counsel) for any Underwriter together with all persons who control such Underwriter within the meaning of the Exchange Act or the Act, and no more than three such separate counsel (in addition to any local counsel) for all the Underwriters) if (i) the use of counsel chosen by the indemnifying party to represent the indemnified party would present such counsel with a conflict of interest, (ii) the actual or potential defendants in, or targets of, any such action include both the indemnified party and the indemnifying party and the indemnified party shall have reasonably concluded that there may be legal defenses available to it and/or other indemnified parties which are different from or additional to those available to the indemnifying party, (iii) the indemnifying party shall not have employed counsel satisfactory to the indemnified party to represent the indemnified party within a reasonable time after notice of the institution of such action or (iv) the indemnifying party shall authorize the indemnified party to employ separate counsel at the expense of the indemnifying party. An indemnifying party will not, without the prior written consent of the indemnified parties, settle or compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless such settlement, compromise or consent includes an unconditional release of each indemnified party from all liability arising out of such claim, action, suit or proceeding.

(d) In the event that the indemnity provided in paragraph (a), (b) or (c) of this Section 8 is unavailable to or insufficient to hold harmless an indemnified party for any reason, the Company and the Underwriters severally agree to contribute to the aggregate losses, claims, damages and liabilities (including legal or other expenses reasonably incurred in connection with investigating or defending the same) (collectively “Losses”) to which the Company and one or more of the Underwriters may be subject in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and by the Underwriters on the other from the offering of the Securities; provided, however, that in no case shall any Underwriter (except as may be provided in any agreement among underwriters relating to the offering of the Securities) be responsible for any amount in excess of the underwriting discount or commission applicable to the Securities purchased by such Underwriter hereunder. If the allocation provided by the immediately preceding sentence is unavailable for any reason, the

Company and the Underwriters severally shall contribute in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and of the Underwriters on the other in connection with the statements or omissions which resulted in such Losses as well as any other relevant equitable considerations. Benefits received by the Company shall be deemed to be equal to the total net proceeds from the offering (before deducting expenses) received by it, and benefits received by the Underwriters shall be deemed to be equal to the total underwriting discounts and commissions, in each case as set forth on the cover page of the Final Prospectus. Relative fault shall be determined by reference to, among other things, whether any untrue or any alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information provided by the Company on the one hand or the Underwriters on the other, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The Company and the Underwriters agree that it would not be just and equitable if contribution were determined by pro rata allocation or any other method of allocation which does not take account of the equitable considerations referred to above. Notwithstanding the provisions of this paragraph (d), no person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 8, each person who controls an Underwriter within the meaning of either the Act or the Exchange Act and each director, officer, employee and agent of an Underwriter shall have the same rights to contribution as such Underwriter, and each person who controls the Company within the meaning of either the Act or the Exchange Act, each officer of the Company who shall have signed the Registration Statement and each director of the Company shall have the same rights to contribution as the Company, subject in each case to the applicable terms and conditions of this paragraph (d).

9. Default by an Underwriter. If any one or more Underwriters shall fail to purchase and pay for any of the Securities agreed to be purchased by such Underwriter or Underwriters hereunder and such failure to purchase shall constitute a default in the performance of its or their obligations under this Agreement, the remaining Underwriters shall be obligated severally to take up and pay for (in the respective proportions which the amount of Securities set forth opposite their names in Schedule II hereto bears to the aggregate amount of Securities set forth opposite the names of all the remaining Underwriters) the Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase; provided, however, that in the event that the aggregate amount of Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase shall exceed 10% of the aggregate amount of Securities set forth in Schedule II hereto, the remaining Underwriters shall have the right to purchase all, but shall not be under any obligation to purchase any, of the Securities, and if such nondefaulting Underwriters do not purchase all the Securities, this Agreement will terminate without liability to any nondefaulting Underwriter or the Company. In the event of a default by any Underwriter as set forth in this Section 9, the Closing Date shall be postponed for such period, not exceeding five Business Days, as the Representatives shall determine in order that the required changes in the Registration Statement and the Final Prospectus or in any other documents or arrangements may be effected. Nothing contained in this Agreement shall relieve any defaulting Underwriter of its liability, if any, to the Company and any nondefaulting Underwriter for damages occasioned by its default hereunder.

10. Termination. This Agreement shall be subject to termination in the absolute discretion of the Representatives, by notice given to the Company prior to delivery of and payment for the Securities, if at any time prior to such delivery and payment (i) trading in the Company’s Common Stock shall have been suspended by the Commission or NASDAQ or trading in securities generally on the New York Stock Exchange or NASDAQ shall have been suspended or limited or minimum prices shall have been established on either of such exchanges, (ii) a banking moratorium shall have been declared either by Federal or New York State authorities or (iii) there shall have occurred any outbreak or escalation of hostilities, declaration by the United States of a national emergency or war, or other calamity or crisis the effect of which on financial markets is such as to make it, in the sole judgment of the Representatives, impractical or inadvisable to proceed with the offering or delivery of the Securities as contemplated by any Preliminary Prospectus or the Final Prospectus (exclusive of any amendment or supplement thereto).

11. Representations and Indemnities to Survive. The respective agreements, representations, warranties, indemnities and other statements of the Company or its officers and of the Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation made by or on behalf of any Underwriter or the Company or any of the officers, directors, employees, agents or controlling persons referred to in Section 8 hereof, and will survive delivery of and payment for the Securities. The provisions of Sections 7 and 8 hereof shall survive the termination or cancellation of this Agreement.

12. Notices. All communications hereunder will be in writing and effective only on receipt, and, if sent to the Representatives, will be mailed, delivered or faxed to (i) ▇▇▇▇▇ Fargo Securities, LLC, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention: Equity Syndicate Department (fax no: (▇▇▇) ▇▇▇-▇▇▇▇) and (ii) RBC Capital Markets, LLC, Attention: Equity Syndicate, ▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, or by telephone at (▇▇▇) ▇▇▇-▇▇▇▇, with copies mailed, delivered or faxed to ▇▇▇▇▇▇▇ Procter LLP, Exchange Place, ▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention ▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇, Esq. and ▇▇▇▇ ▇. ▇▇▇▇▇▇, Esq. (fax no.: (▇▇▇) ▇▇▇-▇▇▇▇), or if after June 24, 2016, to ▇▇▇▇▇▇▇ Procter LLP, ▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention ▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇, Esq. and ▇▇▇▇ ▇. ▇▇▇▇▇▇, Esq. (fax no.: (▇▇▇) ▇▇▇-▇▇▇▇); or, if sent to the Company, will be mailed, delivered or faxed to ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇, Chief Financial Officer (fax no.: (▇▇▇) ▇▇▇-▇▇▇▇) and confirmed to such recipient at Flexion Therapeutics, Inc., ▇▇ ▇▇▇▇ ▇▇▇▇, ▇▇▇▇▇ ▇▇▇, ▇▇▇▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇, with copies mailed, delivered or faxed to ▇▇▇ ▇▇▇▇ and ▇▇▇▇ ▇▇▇▇▇▇▇ (fax no.: (▇▇▇) ▇▇▇-▇▇▇▇) and confirmed to such recipient at ▇▇▇▇▇▇ LLP, ▇▇▇▇ ▇▇▇▇▇▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇▇, ▇▇ ▇▇▇▇▇-▇▇▇▇.

13. Successors. This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective successors and the officers, directors, employees, agents and controlling persons referred to in Section 8 hereof, and no other person will have any right or obligation hereunder.

14. No Fiduciary Duty. The Company hereby acknowledges that (a) the purchase and sale of the Securities pursuant to this Agreement is an arm’s-length commercial

transaction between the Company, on the one hand, and the Underwriters and any affiliate through which it may be acting, on the other, (b) the Underwriters are acting as principal and not as an agent or fiduciary of the Company and (c) the Company’s engagement of the Underwriters in connection with the offering and the process leading up to the offering is as independent contractors and not in any other capacity. Furthermore, the Company agrees that it is solely responsible for making its own judgments in connection with the offering (irrespective of whether any of the Underwriters has advised or is currently advising the Company on related or other matters). The Company agrees that it will not claim that the Underwriters have rendered advisory services of any nature or respect, or owe an agency, fiduciary or similar duty to the Company, in connection with such transaction or the process leading thereto.

15. Integration. This Agreement supersedes all prior agreements and understandings (whether written or oral) between the Company and the Underwriters, or any of them, with respect to the subject matter hereof.

16. Applicable Law. This Agreement will be governed by and construed in accordance with the laws of the State of New York applicable to contracts made and to be performed within the State of New York.

17. Waiver of Jury Trial. The Company and the Underwriters hereby irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to this Agreement or the transactions contemplated hereby.

18. Counterparts. This Agreement may be signed in one or more counterparts, each of which shall constitute an original and all of which together shall constitute one and the same agreement.

19. Headings. The section headings used herein are for convenience only and shall not affect the construction hereof.

20. Definitions. The terms that follow, when used in this Agreement, shall have the meanings indicated.

“Act” shall mean the Securities Act of 1933, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Base Prospectus” shall mean the base prospectus referred to in paragraph 1(a) above contained in the Registration Statement at the Execution Time.

“Business Day” shall mean any day other than a Saturday, a Sunday or a legal holiday or a day on which banking institutions or trust companies are authorized or obligated by law to close in New York City.

“Commission” shall mean the Securities and Exchange Commission.

“Disclosure Package” shall mean (i) the Base Prospectus, (ii) the Preliminary Prospectus used most recently prior to the Execution Time, (iii) the Issuer Free Writing Prospectuses, if any, identified in Schedule III hereto, and (iv) any other Free Writing Prospectus that the parties hereto shall hereafter expressly agree in writing to treat as part of the Disclosure Package.

“Effective Date” shall mean each date and time that the Registration Statement, any post-effective amendment or amendments thereto and any Rule 462(b) Registration Statement became or becomes effective.

“Exchange Act” shall mean the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Execution Time” shall mean the date and time that this Agreement is executed and delivered by the parties hereto.

“Free Writing Prospectus” shall mean a free writing prospectus, as defined in Rule 405.

“Final Prospectus” shall mean the prospectus supplement relating to the Securities that was first filed pursuant to Rule 424(b) after the Execution Time, together with the Base Prospectus.

“Issuer Free Writing Prospectus” shall mean an issuer free writing prospectus, as defined in Rule 433.

“Preliminary Prospectus” shall mean any preliminary prospectus supplement to the Base Prospectus referred to in paragraph 1(a) above which is relating to the Securities and used prior to the filing of the Final Prospectus, together with the Base Prospectus.

“Registration Statement” shall mean the registration statement referred to in paragraph 1(a) above, including exhibits and financial statements and any prospectus supplement relating to the Securities that is filed with the Commission pursuant to Rule 424(b) and deemed part of such registration statement pursuant to Rule 430B, as amended on each Effective Date and, in the event any post-effective amendment thereto becomes effective prior to the Closing Date, shall also mean such registration statement as so amended, in each case including any SEC Reports incorporated therein.

“Rule 158”, “Rule 163”, “Rule 164”, “Rule 172”, “Rule 405”, “Rule 415”, “Rule 424”, “Rule 430B” and “Rule 433” refer to such rules under the Act.

“Rule 462(b) Registration Statement” shall mean a registration statement and any amendments thereto filed pursuant to Rule 462(b) relating to the offering covered by the registration statement referred to in Section 1(a) hereof.

If the foregoing is in accordance with your understanding of our agreement, please sign and return to us the enclosed duplicate hereof, whereupon this letter and your acceptance shall represent a binding agreement among the Company and the several Underwriters.


Very truly yours,

Flexion Therapeutics, Inc.

By:		/s/ ▇▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇
Name:		▇▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇
Title:		Chief Financial Officer

[Signature Page to Underwriting Agreement]


The foregoing Agreement is hereby
confirmed and accepted as of the date first above written.

▇▇▇▇▇ Fargo Securities, LLC
RBC Capital Markets, LLC

By:		▇▇▇▇▇ Fargo Securities, LLC

By:		/s/ ▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
Name:		▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
Title:		Managing Director

By:		RBC Capital Markets, LLC

By:		/s/ ▇▇▇▇ ▇▇▇▇▇
Name:		▇▇▇▇ ▇▇▇▇▇
Title:		Managing Director

For themselves and the other several Underwriters named in
Schedule II to the foregoing
Agreement.

[Signature Page to Underwriting Agreement]

SCHEDULE I

Underwriting Agreement dated June 8, 2016

Registration Statement No. 333-203706

Representative(s): ▇▇▇▇▇ Fargo Securities, LLC and RBC Capital Markets, LLC

Title, Purchase Price and Description of Securities:

Title: Flexion Therapeutics, Inc. Common Stock, par value $0.001 per share

Number of Underwritten Securities to be sold by the Company: 5,500,000

Number of Option Securities to be sold by the Company: 825,000

Price per Share to Public (include accrued dividends, if any): $14.00

Price per Share to the Underwriters: $13.16

Closing Date and Time: 10:00 AM, New York City time, on June 13, 2016

Type of Offering: Non-Delayed

SCHEDULE II


Underwriters	Number of Underwritten Securities to be Purchased
▇▇▇▇▇ Fargo Securities, LLC		2,062,500
RBC Capital Markets, LLC		1,787,500
BMO Capital Markets Corp.		1,100,000
▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇ LLC		275,000
▇▇▇▇▇▇▇ & Company (UK) Ltd.		275,000
Total		5,500,000

SCHEDULE III

Schedule of Free Writing Prospectuses included in the Disclosure Package

None.

SCHEDULE IV

Schedule of Written Testing-the-Waters Communications

None.

EXHIBIT A

Flexion Therapeutics, Inc.

Public Offering of Common Stock

, 2016

▇▇▇▇▇ Fargo Securities, LLC

As Representative of the several Underwriters,

c/o Wells Fargo Securities, LLC

▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇

▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇

Ladies and Gentlemen:

This letter is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”), between Flexion Therapeutics, Inc., a Delaware corporation (the “Company”), and you as representative of a group of Underwriters named therein, relating to an underwritten public offering of Common Stock, $0.001 par value (the “Common Stock”), of the Company (the “Offering”).

In order to induce you and the other Underwriters to enter into the Underwriting Agreement, the undersigned will not, without the prior written consent of ▇▇▇▇▇ Fargo Securities, LLC and RBC Capital Markets, LLC, as representatives of the several Underwriters, offer, sell, contract to sell, pledge or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the undersigned or any affiliate of the undersigned or any person in privity with the undersigned or any affiliate of the undersigned), directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Securities and Exchange Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the Securities and Exchange Commission promulgated thereunder with respect to, any shares of capital stock of the Company or any securities convertible into, or exercisable or exchangeable for such capital stock, or publicly announce an intention to effect any such transaction, for a period from the date hereof until 90 days after the date of the Underwriting Agreement (the “Lock-Up Period”). The foregoing sentence shall not apply to: transfers of shares of Common Stock or any security convertible into Common Stock (i) as a bona fide gift or gifts, or by will or intestate succession upon the death of the undersigned, (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, or (iii) as a distribution or transfer to: (x) general or limited partners, members, stockholders or affiliates of the undersigned; or (y) any corporation, partnership, limited liability company or other entity which controls or is controlled by the undersigned or to entities under common control with the undersigned; provided that that in the case of any transfer under each of clauses (i), (ii) and (iii) it shall be a condition to such transfer that (A) each transferee shall sign and deliver a lock up letter substantially in the form of this lock up letter;

(B) any such transfer shall not involve a disposition for value; and (C) no filing under the Exchange Act or other public announcement shall be required or shall be voluntarily made during the Lock-up Period. The foregoing restrictions shall also not apply to any shares of Common Stock purchased by the undersigned in the Offering or acquired by the undersigned in the open market after the date of the Underwriting Agreement; provided, however, that no filing under Section 16 of the Exchange Act (other than required filings under Schedule 13D and 13F) shall be required or shall be voluntarily made during the Lock-Up Period with respect to a sale or other disposition of such shares of Common Stock. For the purposes of this lock-up letter, “immediate family” shall mean the spouse, domestic partner, lineal descendant (including adopted children), father, mother, brother or sister of the undersigned.

Notwithstanding anything herein to the contrary, nothing herein shall prevent (i) the undersigned from establishing a written plan meeting the requirements of Rule 10b5-1 (a “10b5-1 Plan”) under the Exchange Act, relating to the sale of securities of the Company, provided that (x) the securities subject to such plan may not be sold until after the expiration of the Lock-up Period and (y) that the establishment of such 10b5-1 Plan will not result in any public filing or other public announcement of such 10b5-1 Plan by the undersigned or the Company during the Lock-up Period, or (ii) the exercise of any options or warrants to purchase, or settlement of restricted stock units covering, capital stock of the Company (including net exercises, through the surrender of shares of Common Stock directly to the Company, and withholding of shares of Common Stock by the Company to pay tax withholding obligations required to be paid or satisfied upon the settlement of restricted stock units, in each case to the extent permitted by the instruments representing such options, warrants or restricted stock units); provided, however, that in any such case the shares of capital stock issued upon exercise or settlement shall remain subject to the provisions of this lock-up letter and no filing under the Exchange Act or other public announcement shall be required or shall be voluntarily made during the Lock-Up Period with respect to a sale or other disposition of such shares of Common Stock.

The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent and registrar against the transfer of the undersigned’s shares of Common Stock except in compliance with the foregoing restrictions.

It is understood that, (i) if either the Company notifies ▇▇▇▇▇ Fargo Securities, LLC in writing on the one hand, or ▇▇▇▇▇ Fargo Securities, LLC notifies the Company in writing on the other hand, that it does not intend to proceed with the Offering, (ii) if the Underwriting Agreement is not executed by June 30, 2016; provided, however, that the Company may, by written notice to you prior to June 30, 2016, extend such date for a period of up to an additional 30 days, or (iii) if the Underwriting Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated for any reason prior to payment for and delivery of the shares of Common Stock to be sold in the Offering, this lock-up letter shall immediately be terminated and the undersigned shall automatically be released from all of his, her or its obligations under this lock-up letter.

The undersigned represents and warrants that the undersigned has full power and authority to enter into this lock-up letter. All authority herein conferred or agreed to be conferred and any obligations of the undersigned shall be binding upon the successors, assigns, heirs and personal representatives of the undersigned. The undersigned understands that the Underwriters are entering into the Underwriting Agreement and proceeding with the Offering in reliance upon this lock-up letter.

This lock-up letter and any claim, controversy or dispute arising under or related to this lock-up letter shall be governed by and construed in accordance with the laws of the State of New York.


Yours very truly,

[If by an individual:]


Name:

[If by an entity:]

[Name of entity]


By:

Its:

Address:

[Signature Page to Lock-Up Letter]

Flexion Therapeutics, Inc. 5,500,000 Shares Common Stock ($0.001 par value) Underwriting Agreement

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