Exhibit 1.1

[·] Shares

NEON THERAPEUTICS, INC.

COMMON STOCK, PAR VALUE $0.001 PER SHARE

UNDERWRITING AGREEMENT

[·], 2018

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[·], 2018

Morgan Stanley & Co. LLC
Merrill Lynch, Pierce, Fenner & Smith

Incorporated

c/o       Morgan Stanley & Co. LLC
1585 Broadway
New York, New York 10036

c/o       Merrill Lynch, Pierce, Fenner & Smith

Incorporated

One Bryant Park

New York, NY 10036

Ladies and Gentlemen:

Neon Therapeutics, Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the several Underwriters named in Schedule I hereto (the “Underwriters”), for whom Morgan Stanley & Co. LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated are acting as representatives (the “Representatives”), [·] shares of its common stock, par value $0.001 per share (the “Firm Shares”).  The Company also proposes to issue and sell to the several Underwriters not more than an additional [·] shares of its common stock, par value $0.001 per share (the “Additional Shares”), if and to the extent that the Representatives shall have determined to exercise, on behalf of the Underwriters, the right to purchase such shares of common stock granted to the Underwriters in Section 2 hereof.  The Firm Shares and the Additional Shares are hereinafter collectively referred to as the “Shares.” The shares of common stock, par value $0.001 per share, of the Company to be outstanding after giving effect to the sales contemplated hereby are hereinafter referred to as the “Common Stock.”

The Company has filed with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-1 (File No. [·]), including a prospectus, relating to the Shares.  The registration statement as amended at the time it becomes effective, including the information (if any) deemed to be part of the registration statement at the time of effectiveness pursuant to Rule 430A under the Securities Act of 1933, as amended (the “Securities Act”), is hereinafter referred to as the “Registration Statement”; the prospectus in the form first used to confirm sales of the Shares (or in the form first made available to the Underwriters by the Company to meet requests of purchasers pursuant to Rule 173 under the Securities Act) is hereinafter referred to as the “Prospectus.”  If the Company has filed an abbreviated registration statement to register additional shares of Common Stock pursuant to Rule 462(b) under the Securities Act (the

“Rule 462 Registration Statement”), then any reference herein to the term “Registration Statement” shall be deemed to include such Rule 462 Registration Statement.

For purposes of this Agreement, “free writing prospectus” has the meaning set forth in Rule 405 under the Securities Act, “Time of Sale Prospectus” means the preliminary prospectus together with the documents and pricing information set forth in Schedule II hereto, and “broadly available road show” means a “bona fide electronic road show” as defined in Rule 433(h)(5) under the Securities Act that has been made available without restriction to any person.  As used herein, the terms “Registration Statement,” “preliminary prospectus,” “Time of Sale Prospectus” and “Prospectus” shall include the documents, if any, incorporated by reference therein as of the date hereof.

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

(a)                       The Registration Statement has become effective; no stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose are pending before or to the knowledge of the Company threatened by the Commission.

(b)                       (i) The Registration Statement, when it became effective, did not contain and, as amended or supplemented, if applicable, will not as of the date of such amendment or supplement contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (ii) the Registration Statement and the Prospectus comply and, as amended or supplemented, if applicable, will comply in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder, (iii) the Time of Sale Prospectus does not, and at the time of each sale of the Shares in connection with the offering when the Prospectus is not yet available to prospective purchasers and at the Closing Date (as defined in Section 4), the Time of Sale Prospectus, as then amended or supplemented by the Company, if applicable, will not, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, (iv) each broadly available road show, if any, does not contain any information that conflicts with the information contained in the Registration Statement, the Time of Sale Prospectus or the Prospectus, and when considered together with the Time of Sale Prospectus, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading and (v) the Prospectus, as of its date, does not contain and, as amended or supplemented, if applicable, will not contain as of the date of such amendment or supplement or as of the Closing Date and each Option Closing Date (as defined in Section 2) any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, except that the

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representations and warranties set forth in this paragraph do not apply to statements or omissions in the Registration Statement, the Time of Sale Prospectus or the Prospectus based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use therein.

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

(d)                       The Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the State of Delaware, has the corporate power and authority to own or lease its property and to conduct its business as described in the Time of Sale Prospectus and the Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not reasonably be expected to have a material adverse effect on the Company and its subsidiaries, taken as a whole.

(e)                        Each subsidiary of the Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own its property and to conduct its business as described in the Time of Sale Prospectus and the Prospectus and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not have a material adverse effect on the Company and its subsidiaries, taken as a whole; all of the issued shares of capital stock of each subsidiary of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and are owned directly by the Company, free and clear of all liens, encumbrances, equities or claims.

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

(g)                        The authorized capital stock of the Company conforms as to legal matters to the description thereof contained under the headings “Description of Capital Stock” and “Capitalization” in each of the Time of Sale Prospectus and the Prospectus.

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

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

(j)                          With respect to the stock options granted pursuant to the stock-based compensation plans of the Company and its subsidiaries (the “Company Stock Plans”), (i) each grant of a stock option was duly authorized no later than the date on which the grant of such stock option was by its terms to be effective by all necessary corporate action, including, as applicable, approval by the board of directors of the Company (or a duly constituted and authorized committee thereof) and any required stockholder approval by the necessary number of votes or written consents, and the award agreement governing such grant (if any) was duly executed and delivered by each party thereto, and (ii) each such grant was made in accordance with the terms of the Company Stock Plans, and all applicable laws and regulatory rules or requirements, including all applicable federal securities laws.

(k)                       The execution and delivery by the Company of, and the performance by the Company of its obligations under, this Agreement will not contravene any provision of (i) applicable law, (ii) the certificate of incorporation or by-laws of the Company, (iii) any agreement or other instrument binding upon the Company or any of its subsidiaries that is material to the Company and its subsidiaries, taken as a whole, or (iv) any judgment, order or decree of any governmental body, agency or court having jurisdiction over the Company or any subsidiary, except that, in the case of clauses (i) and (iii) as would not, individually or in the aggregate, reasonably be expected to have a material adverse effect on the Company or on the power and ability of the Company to perform its obligations under this Agreement; and no consent, approval, authorization or order of, or qualification with, any governmental body or agency is required for the performance by the Company of its obligations under this Agreement, except such as may be required by the securities or Blue Sky laws of the various states in connection with the offer and sale of the Shares.

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(l)                           There has not occurred any material adverse change, or any development involving a prospective material adverse change, in the condition, financial or otherwise, or in the earnings, business or operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus.

(m)                   Neither the Company nor any of its subsidiaries is (i) in violation of its respective certificate of incorporation or bylaws; (ii) in default, and no event has occurred that, with notice or lapse of time or both, would constitute such a default, in the due performance or observance of any term, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject; or (iii) in violation of any law or statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory authority applicable to the Company, any of its subsidiaries or their respective businesses and properties, except, in the case of clauses (ii) and (iii) above, for any such default or violation that would not, individually or in the aggregate, have a material adverse effect on the Company and its subsidiaries, taken as a whole.

(n)                       There are no legal or governmental proceedings pending or, to the knowledge of the Company, threatened to which the Company or any of its subsidiaries is a party or to which any of the properties of the Company or any of its subsidiaries is subject (i) other than proceedings accurately described in all material respects in the Time of Sale Prospectus and the Prospectus and proceedings that would not reasonably be expected to have a material adverse effect on the Company and its subsidiaries, taken as a whole, or on the power or ability of the Company to perform its obligations under this Agreement or to consummate the transactions contemplated by the Time of Sale Prospectus and the Prospectus or (ii) that are required to be described in the Registration Statement or the Prospectus and are not so described in all material respects; and there are no statutes, regulations, contracts or other documents that are required to be described in the Registration Statement or the Prospectus or to be filed as exhibits to the Registration Statement that are not described in all material respects or filed as required.

(o)                       Each preliminary prospectus filed as part of the Registration Statement as originally filed or as part of any amendment thereto, or filed pursuant to Rule 424 under the Securities Act, complied when so filed in all material respects with the Securities Act and the applicable rules and regulations of the Commission thereunder.

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

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

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

(s)                         There are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Securities Act with respect to any securities of the Company or to require the Company to include such securities with the Shares registered pursuant to the Registration Statement except as have been validly waived or complied with in connection with the issuance and sale of the Shares contemplated hereby and as have been described in the Time of Sale Prospectus and the Prospectus.

(t)                          (i) None of the Company or its subsidiaries or affiliates, or any director or officer of the Company nor, to the Company’s knowledge, any agent, representative or employee of the Company or of any of its subsidiaries or affiliates, has taken or will take any action in furtherance of an offer, payment, promise to pay, or authorization or approval of the payment, giving or receipt of money, property, gifts, benefits, or anything else of value, directly or indirectly, to any government official (including any officer or employee of a government or government-owned or controlled entity or of a public international organization, or any person acting in an official capacity for or on behalf of any of the foregoing, or any political party or party official or candidate for political office) (“Government Official”) in order to influence official action, or to any person in violation of any applicable anti-corruption laws; (ii) the Company and its subsidiaries and affiliates have conducted their businesses in compliance with applicable anti-corruption laws and have instituted and maintained and will continue to maintain policies and procedures reasonably designed to promote and achieve compliance with such laws and with the representations and warranties contained herein; and (iii) neither the Company nor its subsidiaries will use,

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directly or indirectly, the proceeds of  the offering in furtherance of an offer, payment, promise to pay, or authorization of the payment or giving of money, or anything else of value, to any person in violation of any applicable anti-corruption laws.

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

(v)                       (i) None of the Company, any of its subsidiaries, or any director, officer, or employee thereof, or, to the Company’s knowledge, any agent, affiliate or representative of the Company or any of its subsidiaries, is an individual or entity (“Person”) that is, or is owned or controlled by one or more Persons that are:

(A)                               the subject of any sanctions administered or enforced by the U.S. Department of Treasury’s Office of Foreign Assets Control, the United Nations Security Council, the European Union, Her Majesty’s Treasury, or other relevant sanctions authority (collectively, “Sanctions”), or

(B)                               located, organized or resident in a country or territory that is the subject of Sanctions (including, without limitation, Crimea, Cuba, Iran, North Korea and Syria).

(ii)                                  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:

(A)                               to fund or facilitate any activities or business of or with any Person or in any country or territory that, at the time of such funding or facilitation, is the subject of Sanctions; or

(B)                               in any other manner that will result in a violation of Sanctions by any Person (including any Person

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participating in the offering, whether as underwriter, advisor, investor or otherwise).

(iii)                               For the past five years, the Company and its subsidiaries have not engaged in, are not now engaged in, and will not engage in, any dealings or transactions with any Person, or in any country or territory, that at the time of the dealing or transaction is or was the subject of Sanctions.

(w)                     Subsequent to the respective dates as of which information is given in each of the Registration Statement, the Time of Sale Prospectus and the Prospectus, (i) the Company and its subsidiaries have not incurred any material liability or obligation, direct or contingent, nor entered into any material transaction; (ii) the Company has not purchased any of its outstanding capital stock, nor declared, paid or otherwise made any dividend or distribution of any kind on its capital stock other than ordinary and customary dividends; and (iii) there has not been any material change in the capital stock, short-term debt or long-term debt of the Company and its subsidiaries, except in each case as described in each of the Registration Statement, the Time of Sale Prospectus and the Prospectus, respectively.

(x)                       The Company and its subsidiaries have good and marketable title in fee simple to all real property and good and marketable title to all personal property owned by them which is material to the business of the Company and its subsidiaries, in each case free and clear of all liens, encumbrances and defects except such as are described in the Time of Sale Prospectus and the Prospectus or such as do not materially affect the value of such property and do not interfere  in any material respect with the use made and proposed to be made of such property by the Company and its subsidiaries; and any real property and buildings held under lease by the Company and its subsidiaries are held by them under valid, subsisting and enforceable leases with such exceptions as are not material and do not interfere in any material respect with the use made and proposed to be made of such property and buildings by the Company and its subsidiaries, in each case except as described in the Time of Sale Prospectus and the Prospectus.

(y)                       Except as disclosed in the Registration Statement, the Time of Sale Prospectus or the Prospectus, the Company and its subsidiaries own, have obtained licenses or can acquire on reasonable terms sufficient patent rights, inventions, trademarks, trade names, service marks, logos, trade dress, designs, data, database rights, Internet domain names, copyrights, works of authorship, trade secrets, know-how and proprietary information (including unpatented and unpatentable proprietary or confidential information, systems or procedures) and other intellectual property rights (collectively, “Intellectual Property Rights”) necessary or material to the conduct of the business as described in the Registration Statement, the Time of Sale Prospectus, and the Prospectus, except where any failure to own, possess or acquire such Intellectual Property Rights would not, individually or in the aggregate, reasonably be expected to have a

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material adverse effect. Such Intellectual Property Rights owned by or licensed to the Company have not been adjudged by a court of competent jurisdiction to be invalid or unenforceable, in whole or in part. Except as disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, to the Company’s knowledge:  (i) there are no third parties who have rights to any Intellectual Property Rights of the Company or its subsidiaries except for (a) customary retained and reversionary rights of third-party licensors with respect to Intellectual Property Rights licensed to the Company or its subsidiaries, (b) non-exclusively licensed Intellectual Property Rights, where the licensor may provide licenses to a third party and (c) third parties who have been explicitly granted licenses by the Company and (ii) there is no infringement by third parties of any Intellectual Property Rights of the Company or its subsidiaries. Except as disclosed in the Registration Statement, the Time of Sale Prospectus and the Prospectus, there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by any third party: (A) challenging the Company’s or any of its subsidiaries’ rights in or to any of their Intellectual Property Rights; (B) challenging the validity, enforceability or scope of any Intellectual Property Rights of the Company; or (C) asserting that the Company infringes, misappropriates, or otherwise violates, or would, upon the commercialization of any product or service described in the Registration Statement, the Time of Sale Prospectus or the Prospectus as under development, infringe, misappropriate, or violate, any patent, trademark, trade name, service name, copyright, trade secret or other proprietary rights of others.  The Company and its subsidiaries have complied in all material respects with the terms of each agreement pursuant to which Intellectual Property Rights have been licensed to the Company, and all such agreements are in full force and effect.  The Company and its subsidiaries have taken all reasonable steps necessary to secure their interests in the Company owned Intellectual Property Rights from their employees and contractors and to protect the confidentiality of all of their confidential information and trade secrets, including the execution of appropriate nondisclosure, confidentiality agreements, invention assignment agreements and invention assignments with their employees, and to the Company’s knowledge, no employee of the Company is in or has been in violation of any term of any employment contract, patent disclosure agreement, invention assignment agreement, non-competition agreement, non-solicitation agreement, nondisclosure agreement, or any restrictive covenant to or with a former employer where the basis of such violation relates to such employee’s employment with the Company.  The product candidates described in the Registration Statement, the Time of Sale Prospectus and the Prospectus as under development by the Company fall within the scope of one or more claim of one or more patents or patent applications owned by, or exclusively licensed to, the Company. To the Company’s knowledge, the duties of candor and good faith required by the United States Patent and Trademark Office (the “USPTO”), including citation of material prior art that the Company is aware of, during the prosecution of Company owned United States patents and patent applications included in the Intellectual Property Rights have been complied with.

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(z)                        To the Company’s knowledge, none of the Company owned Intellectual Property Rights or technology (including information technology and outsourced arrangements) employed by the Company or its subsidiaries has been obtained or is being used by the Company or its subsidiary in violation of any contractual obligation binding on the Company or its subsidiaries or any of their respective officers, directors or employees or otherwise in violation of the rights of any persons.

(aa)                Except as would not, individually or in the aggregate, reasonably be expected to result in a material adverse effect on the Company and its subsidiaries, taken as a whole, (A) each Plan (as defined below) has been maintained in compliance with its terms and the requirements of any applicable statutes, orders, rules and regulations, including but not limited to the Employee Retirement Income Security Act of 1974, as amended (“ERISA”) and the Internal Revenue Code of 1986, as amended (the “Code”); (B) no non-exempt prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code, has occurred with respect to any Plan; (C) for each Plan, no failure to satisfy the minimum funding standards (within the meaning of Section 412 of the Code or Section 302 of ERISA), whether or not waived, has occurred or is reasonably expected to occur; (D) no “reportable event” (within the meaning of Section 4043(c) of ERISA, other than those events as to which notice is waived) has occurred or is reasonably expected to occur; and (E) neither the Company nor any member of its “Controlled Group” (defined as any organization which is a member of a controlled group of corporations within the meaning of Section 414 of the Code) has incurred, nor is reasonably expected to incur, any liability under Title IV of ERISA (other than contributions to any Plan or any Multiemployer Plan or premiums to the PBGC, in the ordinary course and without default) in respect of a Plan or a Multiemployer Plan. For purposes of this paragraph, (x) the term “Plan” means an employee benefit plan, within the meaning of Section 3(3) of ERISA, subject to Title IV of ERISA, but excluding any Multiemployer Plan, for which the Company or any member of its “Controlled Group” has any liability and (y) the term “Multiemployer Plan” means a multiemployer plan within the meaning of Section 4001(a)(3) of ERISA.

(bb)                No material labor dispute with the employees of the Company or any of its subsidiaries exists, except as described in the Time of Sale Prospectus and the Prospectus, or, to the knowledge of the Company, is imminent; and the Company is not aware of any existing, threatened or imminent labor disturbance by the employees of any of its principal suppliers, manufacturers or contractors that could have a material adverse effect on the Company and its subsidiaries, taken as a whole.

(cc)                  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 are prudent and customary in the businesses in which they are engaged; neither the Company nor any of its subsidiaries has been refused any insurance coverage sought or applied for; and neither the Company nor any of its

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subsidiaries has any reason to believe that it will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain similar coverage from similar insurers as may be necessary to continue its business at a cost that would not reasonably be expected to have a material adverse effect on the Company and its subsidiaries, taken as a whole, except as described in the Time of Sale Prospectus and the Prospectus.

(dd)                The Company and its subsidiaries possess all certificates, authorizations and permits issued by the appropriate federal, state or foreign regulatory authorities necessary to conduct their respective businesses, and neither the Company nor any of its subsidiaries 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 on the Company and its subsidiaries, taken as a whole, except as described in the Time of Sale Prospectus and the Prospectus.

(ee)                  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 U.S. generally accepted accounting principles (“U.S. GAAP”) and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. Except as described in the Time of Sale Prospectus and the Prospectus, since the end of the Company’s most recent audited fiscal year, there has been (i) no material weakness in the Company’s internal control over financial reporting (whether or not remediated) and (ii) no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting.

(ff)                    The financial statements of the Company filed with the Commission as a part of the Registration Statement and included in the Time of Sale Prospectus and the Prospectus comply as to form in all material respects with the applicable accounting requirements of the Securities Act and present fairly the financial position of the Company as of the dates indicated and the results of its operations and cash flows for the periods specified. Such financial statements have been prepared in conformity with U.S. GAAP applied on a consistent basis throughout the periods involved, except in the case of unaudited, interim financial statements, which are subject to normal year end adjustments and do not contain certain footnotes as permitted by the applicable rules of the Commission. The other financial information included in the Registration Statement, the Time of Sale Prospectus and the Prospectus has been derived from the accounting records

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of the Company and its subsidiaries and presents fairly in all material respects the information shown thereby.

(gg)                  PricewaterhouseCoopers LLP, which has expressed its opinion with respect to certain of the financial statements of the Company and its subsidiaries filed with the Commission as part of the Registration Statement and included in each of the Time of Sale Prospectus and the Prospectus, is an independent registered public accounting firm with respect to the Company and its subsidiaries within the applicable rules and regulations adopted by the Commission and the Public Company Accounting Oversight Board (United States) and as required by the Securities Act.

(hh)                The statistical, industry and market related data included in the Registration Statement, the Time of Sale Prospectus and the Prospectus are based on or derived from sources that the Company believes, after reasonable inquiry, to be reliable and accurate. To the Company’s knowledge, after reasonable investigation, it does not require the consent of any third party for the use of any such data except as already obtained.

(ii)                        To the extent required under applicable rules, the Company maintains disclosure controls and procedures that comply with the requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”); such disclosure controls and procedures have been designed to ensure that material information relating to the Company and its subsidiaries is made known to the Company’s principal executive officer and principal financial officer by others within those entities; and such disclosure controls and procedures are effective.

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

(kk)                The Company and each of its subsidiaries have filed all federal, state, local and foreign tax returns required to be filed through the date of this Agreement or have requested extensions thereof (except where the failure to file would not, individually or in the aggregate, reasonably be expected to have a material adverse effect) and have paid all taxes required to be paid thereon (except for cases in which the failure to file or pay would not reasonably be expected to have a material adverse effect, or, except as are currently being contested in good faith and for which reserves required by U.S. GAAP have been created in the financial statements of the Company), and no tax deficiency has been determined adversely to the Company or any of its subsidiaries which has had (nor does the Company nor any of its subsidiaries have any notice or knowledge of any tax deficiency which would reasonably be expected to be

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determined adversely to the Company or its subsidiaries and which would reasonably be expected to have) a material adverse effect.

(ll)                        The Company has taken all necessary actions to ensure that, upon the effectiveness of the Registration Statement, it will be in compliance, to the extent required, with all provisions of the Sarbanes-Oxley Act of 2002, as amended (the “Sarbanes-Oxley Act”), and all rules and regulations promulgated thereunder applicable to the Company at such time, and is taking steps designed to ensure that it will be in compliance, at all times, with the other provisions of the Sarbanes-Oxley Act when they become applicable to the Company after the effectiveness of the Registration Statement.

(mm)        The Company has not taken, directly or indirectly, any action designed to or that would reasonably be expected to cause or result in any stabilization or manipulation of the price of the Shares.

(nn)                From the time of initial confidential submission of the Registration Statement to 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 date hereof, the Company has been and is an “emerging growth company,” as defined in Section 2(a) of the Securities Act (an “Emerging Growth Company”).  “Testing-the-Waters Communication” means any oral or written communication with potential investors undertaken in reliance on Section 5(d) of the Securities Act.

(oo)                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 Securities Act or institutions that are accredited investors within the meaning of Rule 501 under the Securities Act and (ii) has not authorized anyone other than the Representatives to engage in Testing-the-Waters Communications.  The Company reconfirms that the Representatives have been authorized to act on its behalf in undertaking Testing-the-Waters Communications.  The Company has not distributed any Written Testing-the-Waters Communications other than those listed on Schedule III 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 Securities Act.

(pp)                As of the time of each sale of the Shares in connection with the offering when the Prospectus is not yet available to prospective purchasers, none of (A) the Time of Sale Prospectus, (B) any free writing prospectus, when considered together with the Time of Sale Prospectus, and (C) any individual Written Testing-the-Waters Communication, when considered together with the Time of Sale Prospectus, included, includes or will include an untrue statement of a material fact or omitted, omits or will omit to state a material fact necessary in

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order to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(qq)                The Company and each of its subsidiaries have complied, and are presently in compliance, with their privacy and security policies, and with all obligations, laws and regulations regarding the collection, use, transfer, storage, protection, disposal or disclosure of personally identifiable information or any other information collected from or provided by third parties. The Company and its subsidiaries have taken commercially reasonable steps to protect the information technology systems and data used in connection with the operation of the Company or its subsidiaries.  The Company and its subsidiaries have used reasonable efforts to establish, and have established, commercially reasonable disaster recovery and security plans, procedures and facilities for the business, including, without limitation, for the information technology systems and data held or used by or for the Company or any of its subsidiaries.  There has been no material security breach or attack or other compromise of or relating to any such information technology system or data.

(rr)                      The preclinical tests and clinical trials, and other studies (collectively, “studies”) that are described in, or the results of which are referred to in, the Registration Statement, the Time of Sale Prospectus or the Prospectus were and, if still pending, are being conducted in all material respects in accordance with the protocols, procedures and controls designed and approved for such studies and with standard medical and scientific research procedures; each description of the results of such studies is accurate and complete in all material respects and fairly presents the data derived from such studies, and the Company has no knowledge of any other studies the results of which are inconsistent with, or otherwise call into question, the results described or referred to in the Registration Statement, the Time of Sale Prospectus or the Prospectus; the Company has made all such filings and obtained all such approvals or authorizations as may be required by the Food and Drug Administration of the U.S. Department of Health and Human Services or from any other U.S. or foreign government or drug regulatory agency, or health care facility Institutional Review Board (collectively, the “Regulatory Agencies”), except where the failure to make such filing or obtain such approval would not reasonably be expected to, individually or in the aggregate, result in a material adverse effect on the Company and its subsidiaries, taken as a whole; except as described in the Registration Statement, the Time of Sale Prospectus and the Prospectus, the Company has not received any notice of, or correspondence from, any Regulatory Agency requiring the termination, suspension or material modification of any clinical trials that are described or referred to in the Registration Statement, the Time of Sale Prospectus; and the Company has operated and currently is in compliance in all material respects with all applicable rules and regulations of the Regulatory Agencies.

(ss)                    The Company and its subsidiaries are, and at all times have been, in compliance with all applicable Health Care Laws except where failure to be in

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compliance would not be expected reasonably to have a material adverse effect on the Company and its subsidiaries, taken as a whole.  For purposes of this Agreement, “Health Care Laws” means:  (i) the Federal Food, Drug, and Cosmetic Act, the Public Health Service Act and the regulations promulgated thereunder; (ii) all applicable federal, state, local and all applicable foreign health care related fraud and abuse laws, including, without limitation, the U.S. Anti-Kickback Statute (42 U.S.C. Section 1320a-7b(b)), the U.S. False Statements Law (42 U.S.C. § 1320a-7b(a)), the Civil Monetary Penalties Law (42 U.S.C. §1320a-7a), the U.S. Civil False Claims Act (31 U.S.C. Section 3729 et seq.), all criminal laws relating to health care fraud and abuse, including but not limited to 18 U.S.C. Sections 286 and 287, and the health care fraud criminal provisions under the U.S. Health Insurance Portability and Accountability Act of 1996 (“HIPAA”) (42 U.S.C. Section 1320d et seq.), the Physician Payments Sunshine Act (42 U.S.C. § 1320a-7h), the exclusion law (42 U.S.C. §1320a-7), the statutes, regulations and directives of applicable federal healthcare programs (as defined in 42 U.S.C. Section 1320a-7b(f)), and the regulations promulgated pursuant to such statutes, including but not limited to Medicare (Title XVIII of the Social Security Act) and Medicaid (Title XIX of the Social Security Act); (iii) the Standards for Privacy of Individually Identifiable Health Information (the “Privacy Rule”), the Security Standards, and the Standards for Electronic Transactions and Code Sets promulgated under HIPAA, the Health Information Technology for Economic and Clinical Health Act (42 U.S.C. Section 17921 et seq.), and the regulations promulgated thereunder and any state or non-U.S. counterpart thereof or other law or regulation the purpose of which is to protect the privacy of individuals or prescribers; (iv) the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, the regulations promulgated thereunder; (v) the U.S. Controlled Substances Act (21 U.S.C. Section 801 et seq.); and (vi) any and all other applicable health care laws and regulation applicable to the ownership, testing, development, manufacture, packaging, processing, use, distribution, marketing, advertising, labeling, promotion, sale, offer for sale, storage, import, export or disposal of any product manufactured or distributed by the Company.  Neither the Company nor its subsidiaries has received written notice of any claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action from any court or arbitrator or governmental or regulatory authority or third party alleging that it is in material violation of any Health Care Laws, and, to the Company’s knowledge, no such claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action is threatened.  Neither the Company nor its subsidiaries is a party to any corporate integrity agreements, monitoring agreements, consent decrees, settlement orders, or similar agreements with or imposed by any governmental or regulatory authority.  Additionally, neither the Company nor any of its employees, officers or directors, nor its subsidiaries or any of the subsidiary’s employees, officers or directors has been excluded, suspended or debarred from participation in any federal health care program (as defined in 42 U.S.C. Section 1320a-7b(f)) or human clinical research or, to the knowledge of the Company, is subject to a governmental inquiry, investigation, proceeding, or

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other similar action that could reasonably be expected to result in such debarment, suspension, or exclusion.  The Company and its subsidiaries have filed, obtained, maintained or submitted all material reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments as required by the Health Care Laws, and all such reports, documents, forms, notices, applications, records, claims, submissions and supplements or amendments were timely, complete, accurate and not misleading on the date filed in all material respects (or were corrected or supplemented by a subsequent submission).

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

On the basis of the representations and warranties contained in this Agreement, and subject to its terms and conditions, the Company agrees to sell to the Underwriters the Additional Shares, and the Underwriters shall have the right to purchase, severally and not jointly, up to [·] Additional Shares at the Purchase Price, provided, however, that the amount paid by the Underwriters for any Additional Shares shall be reduced by an amount per share equal to any dividends declared by the Company and payable on the Firm Shares but not payable on such Additional Shares.  The Representatives may exercise this right on behalf of the Underwriters in whole or from time to time in part by giving written notice not later than 30 days after the date of this Agreement.  Any exercise notice shall specify the number of Additional Shares to be purchased by the Underwriters and the date on which such shares are to be purchased.  Each purchase date must be at least one business day after the written notice is given and may not be earlier than the closing date for the Firm Shares nor later than ten business days after the date of such notice.  Additional Shares may be purchased as provided in Section 4 hereof solely for the purpose of covering over-allotments made in connection with the offering of the Firm Shares.  On each day, if any, that Additional Shares are to be purchased (an “Option Closing Date”), each Underwriter agrees, severally and not jointly, to purchase the number of Additional Shares (subject to such adjustments to eliminate fractional shares as the Representatives may determine) that bears the same proportion to the total number of Additional Shares to be purchased on such Option Closing Date as the number of Firm Shares set forth in Schedule I hereto opposite the name of such Underwriter bears to the total number of Firm Shares.

3.                             Terms of Public Offering.  The Company is advised by the Representatives that the Underwriters propose to make a public offering of their respective portions of the Shares as soon after the Registration Statement and this Agreement have become effective as in the judgment of the Representatives is advisable.  The Company is further advised by the Representatives that the Shares are to be offered to the public initially at $[·] a share (the “Public Offering Price”) and to certain dealers selected by the

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Representatives at a price that represents a concession not in excess of $[·] a share under the Public Offering Price.

4.                             Payment and Delivery.  Payment for the Firm Shares shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Firm Shares for the respective accounts of the several Underwriters at 10:00 a.m., New York City time, on [·], 2018, or at such other time on the same or such other date, not later than [·], 2018, as shall be designated in writing by the Representatives.  The time and date of such payment are hereinafter referred to as the “Closing Date.”

Payment for any Additional Shares shall be made to the Company in Federal or other funds immediately available in New York City against delivery of such Additional Shares for the respective accounts of the several Underwriters at 10:00 a.m., New York City time, on the date specified in the corresponding notice described in Section 2 or at such other time on the same or on such other date, in any event not later than [·], 2018, as shall be designated in writing by the Representatives.

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

5.                             Conditions to the Underwriters’ Obligations.  The obligations of the Company to sell the Shares to the Underwriters and the several obligations of the Underwriters to purchase and pay for the Shares on the Closing Date are subject to the condition that the Registration Statement shall have become effective not later than [5:00 p.m.] (New York City time) on the date hereof.

The several obligations of the Underwriters are subject to the following further conditions:

(a)                       Subsequent to the execution and delivery of this Agreement and prior to the Closing Date:

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

(ii)                                  there shall not have occurred any change, or any development involving a prospective change, in the condition, financial or otherwise, or in the earnings, business or operations of the Company and its subsidiaries, taken as a whole, from that set forth in the Time of Sale Prospectus and the Prospectus that, in the judgment of the Representatives, is material and adverse and that makes it, in the judgment of the Representatives, impracticable to market the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus and the Prospectus.

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

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

(c)                        The Underwriters shall have received on the Closing Date an opinion of Goodwin Procter LLP, outside counsel for the Company, dated the Closing Date, in form and substance reasonably satisfactory to the Representatives.

(d)                       The Underwriters shall have received on the Closing Date an opinion of Cooley LLP, counsel for the Underwriters, dated the Closing Date, in form and substance satisfactory to the Underwriters.

With respect to Sections 5(c) and (d) above, Goodwin Procter LLP and Cooley LLP may state that their opinions and beliefs are based upon their participation in the preparation of the Registration Statement, the Time of Sale Prospectus and the Prospectus and any amendments or supplements thereto and review and discussion of the contents thereof, but are without independent check or verification, except as specified.

The opinion of Goodwin Procter LLP described in Section 5(c) above shall be rendered to the Underwriters at the request of the Company and shall so state therein.

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(e)                        The Underwriters shall have received on the Closing Date an opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation, intellectual property counsel for the Company, dated the Closing Date, in form and substance satisfactory to the Underwriters.

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

(g)                        The “lock-up” agreements, each substantially in the form of Exhibit A hereto, executed by substantially all securityholders, officers and directors of the Company relating to sales and certain other dispositions of shares of Common Stock or certain other securities, delivered to the Representatives on or before the date hereof, shall be in full force and effect on the Closing Date.

(h)                       [The chief financial officer of the Company shall have delivered to the Underwriters, on each of the date hereof and on the Closing Date, a certificate in a form reasonably acceptable to the Representatives.]

(i)                           The several obligations of the Underwriters to purchase Additional Shares hereunder are subject to the delivery to the Representatives on the applicable Option Closing Date of the following:

(i)                                     a certificate, dated the Option Closing Date and signed by an executive officer of the Company, confirming that the certificate delivered on the Closing Date pursuant to Section 5(b) hereof remains true and correct as of such Option Closing Date;

(ii)                                  an opinion of Goodwin Procter LLP, outside counsel for the Company, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(c) hereof;

(iii)                               an opinion of Cooley LLP, counsel for the Underwriters, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(d) hereof;

(iv)                              a letter dated the Option Closing Date, in form and substance satisfactory to the Underwriters, from PricewaterhouseCoopers LLP, independent public accountants, substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section

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5(g) hereof; provided that the letter delivered on the Option Closing Date shall use a “cut-off date” not earlier than three business days prior to such Option Closing Date;

(v)                                 an opinion of [·], regulatory counsel for the Underwriters, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(e) hereof;

(vi)                              an opinion of [·], intellectual property counsel for the Underwriters, dated the Option Closing Date, relating to the Additional Shares to be purchased on such Option Closing Date and otherwise to the same effect as the opinion required by Section 5(f) hereof;

(vii)                           [a certificate, dated the Option Closing Date and signed by the chief financial officer of the Company substantially in the same form and substance as the letter furnished to the Underwriters pursuant to Section 5(i) hereof;] and

(viii)                        such other documents as the Representatives may reasonably request with respect to the good standing of the Company, the due authorization and issuance of the Additional Shares to be sold on such Option Closing Date and other matters related to the issuance of such Additional Shares.

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

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

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

(c)                        To furnish to the Representatives a copy of each proposed free writing prospectus to be prepared by or on behalf of, used by, or referred to by the

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Company and not to use or refer to any proposed free writing prospectus to which the Representatives reasonably object.

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

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

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

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(g)                        To endeavor to qualify the Shares for offer and sale under the securities or Blue Sky laws of such jurisdictions as the Representatives shall reasonably request.

(h)                       To make generally available to the Company’s security holders and to the Representatives as soon as practicable an earning statement covering a period of at least twelve months beginning with the first fiscal quarter of the Company occurring after the date of this Agreement which shall satisfy the provisions of Section 11(a) of the Securities Act and the rules and regulations of the Commission thereunder.

(i)                           Whether or not the transactions contemplated in this Agreement are consummated or this Agreement is terminated, to pay or cause to be paid all expenses incident to the performance of its obligations under this Agreement, including:(i) the fees, disbursements and expenses of the Company’s counsel and the Company’s accountants in connection with the registration and delivery of the Shares under the Securities Act and all other fees or expenses in connection with the preparation and filing of the Registration Statement, any preliminary prospectus, the Time of Sale Prospectus, the Prospectus, any free writing prospectus prepared by or on behalf of, used by, or referred to by the Company and amendments and supplements to any of the foregoing, including all printing costs associated therewith, and the mailing and delivering of copies thereof to the Underwriters and dealers, in the quantities hereinabove specified, (ii) all costs and expenses related to the transfer and delivery of the Shares to the Underwriters, including any transfer or other taxes payable thereon, (iii) the cost of printing or producing any Blue Sky or Legal Investment memorandum in connection with the offer and sale of the Shares under state securities laws and all expenses in connection with the qualification of the Shares for offer and sale under state securities laws as provided in Section 6(g) hereof, including filing fees and the reasonable fees and disbursements of counsel for the Underwriters in connection with such qualification and in connection with the Blue Sky or Legal Investment memorandum; provided, that the amount of such fees and disbursements of counsel to be paid by the Company shall not exceed $2,500 in the aggregate, (iv) all filing fees and the reasonable fees and disbursements of counsel to the Underwriters incurred in connection with the review and qualification of the offering of the Shares by the Financial Industry Regulatory Authority, provided, that the amount of such fees and disbursements of counsel to be paid by the Company shall not exceed $40,000 in the aggregate, (v) all fees and expenses in connection with the preparation and filing of the registration statement on Form 8-A relating to the Common Stock and all costs and expenses incident to listing the Shares on the NASDAQ Global Market, (vi) the cost of printing certificates representing the Shares, (vii) the costs and charges of any transfer agent, registrar or depositary, (viii) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the offering of the Shares, including, without limitation, expenses associated with the preparation or dissemination of any electronic road show, expenses associated with the production of road show slides and graphics,

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fees and expenses of any consultants engaged in connection with the road show presentations with the prior approval of the Company, travel and lodging expenses of the representatives and officers of the Company and any such consultants, and 50% of the cost of any aircraft or other transportation chartered in connection with the road show, (with the remaining 50% of such costs to be paid by the Underwriters), (ix) the document production charges and expenses associated with printing this Agreement and (x) all other costs and expenses incident to the performance of the obligations of the Company hereunder for which provision is not otherwise made in this Section.  It is understood, however, that except as provided in this Section, Section 8 entitled “Indemnity and Contribution” and the last paragraph of Section 10 below, the Underwriters will pay all of their costs and expenses, including fees and disbursements of their counsel, stock transfer taxes payable on resale of any of the Shares by them and any advertising expenses connected with any offers they may make.

(j)                          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 Shares within the meaning of the Securities Act and (b) completion of the Restricted Period (as defined in this Section 6).

(k)                       If at any time following the distribution of any Written Testing-the-Waters Communication there occurred or occurs an event or development as a result of which such Written Testing-the-Waters Communication included or would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances existing at that subsequent time, not misleading, the Company will promptly notify the Representatives and will promptly amend or supplement, at its own expense, such Written Testing-the-Waters Communication to eliminate or correct such untrue statement or omission.

(l)                           The Company will deliver to the Representatives, on the date of execution of this Agreement, a properly completed and executed Certification Regarding Beneficial Owners of Legal Entity Customers, together with copies of identifying documentation, and the Company undertakes to provide such additional supporting documentation as the Representatives may reasonably request in connection with the verification of the foregoing certification.

The Company also covenants with each Underwriter that, without the prior written consent of the Representatives on behalf of the Underwriters, it will not, during the period ending 180 days after the date of the Prospectus (the “Restricted Period”), and will not publicly disclose an intention to, (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership

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of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (3) confidentially submit any draft registration statement or file any registration statement other than on Form S-8 or any successor form thereto with respect to securities issued or issuable under the Company’s equity incentive plans described in the Time of Sale Prospectus) with the Commission relating to the offering of any shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock.

The restrictions contained in the preceding paragraph shall not apply to (a) the Shares to be sold hereunder, (b) the issuance by the Company of shares of Common Stock or securities convertible into or exercisable for shares of Common Stock upon the exercise of an option or warrant or the conversion of a security outstanding on the date hereof of which the Underwriters have been advised in writing, (c) the issuance by the Company of shares of Common Stock or options to purchase shares of, Common Stock to employees, officers, directors, advisors or consultants of the Company pursuant to employee benefit plans described in the Time of Sale Prospectus and Prospectus, provided that, prior to the issuance of any such shares or the grant of any such options, the Company shall cause each recipient of such grant or issuance to execute and deliver a “lock-up” agreement, substantially in the form of Exhibit A hereto, (d) the filing by the Company of registration statements on Form S-8 with respect to the employee benefit plans described in the Time of Sale Prospectus and Prospectus; (e) the sale or issuance of or entry into an agreement to sell or issue shares of Common Stock in connection with the Company’s acquisition of one or more businesses, products, assets or technologies (whether by means of merger, stock purchase, asset purchase or otherwise) or in connection with joint ventures, collaboration or licensing agreements, marketing or distribution arrangements, commercial relationships or other strategic transactions; provided, that, the aggregate number of shares of Common Stock that the Company may sell or issue or agree to sell or issue pursuant to this clause (e) shall not exceed 5% of the total number of shares of Common Stock issued and outstanding immediately following the completion of the transactions contemplated by this Agreement and provided further that the Company shall cause each recipient of such shares to execute and deliver to you, on or prior to such issuance, a “lock up” agreement, substantially in the form of Exhibit A hereto or (f) the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act for the transfer of shares of Common Stock, provided that (i) such plan does not provide for the transfer of Common Stock during the Restricted Period and (ii) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made by the Company regarding the establishment of such plan, such announcement or filing shall include a statement to the effect that no transfer of Common Stock may be made under such plan during the Restricted Period.

If the Representatives, in their sole discretion, agree to release or waive the restrictions set forth in a lock-up letter described in Section 5(h) hereof for an officer or director of the Company and provides the Company with notice of the impending release or waiver at least three business days before the effective date of the release or waiver, the Company agrees to announce the impending release or waiver by a press release

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substantially in the form of Exhibit B hereto through a major news service at least two business days before the effective date of the release or waiver.

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

8.                             Indemnity and Contribution.  (a) The Company agrees to indemnify and hold harmless each Underwriter, each person, if any, who controls any Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act and each affiliate of any Underwriter within the meaning of Rule 405 under the Securities Act from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) caused by any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof, any preliminary prospectus, the Time of Sale Prospectus or any amendment or supplement thereto, any issuer free writing prospectus as defined in Rule 433(h) under the Securities Act, any Company information that the Company has filed, or is required to file, pursuant to Rule 433(d) under the Securities Act, any road show as defined in Rule 433(h) under the Securities Act (a “road show”), or the Prospectus or any amendment or supplement thereto, or any Written Testing-the-Waters Communication, or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as such losses, claims, damages or liabilities are caused by any such untrue statement or omission or alleged untrue statement or omission based upon information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use therein. [The Company agrees and confirms that references to “affiliates” of Morgan Stanley that appear in this Agreement shall be understood to include Mitsubishi UFJ Morgan Stanley Securities Co., Ltd.]

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

(c)                        In case any proceeding (including any governmental investigation) shall be instituted involving any person in respect of which indemnity may be sought pursuant to Section 8(a) or 8(b), such person (the “indemnified party”)

25

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

(d)                       To the extent the indemnification provided for in Section 8(a) or 8(b) is unavailable to an indemnified party or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each indemnifying party under such paragraph, in lieu of indemnifying such indemnified party thereunder, shall contribute to the amount paid or payable by such indemnified party as a

26

result of such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other hand from the offering of the Shares or (ii) if the allocation provided by clause 8(d)(i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause 8(d)(i) above but also the relative fault of the Company on the one hand and of the Underwriters on the other hand in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations.  The relative benefits received by the Company on the one hand and the Underwriters on the other hand in connection with the offering of the Shares shall be deemed to be in the same respective proportions as the net proceeds from the offering of the Shares (before deducting expenses) received by the Company and the total underwriting discounts and commissions received by the Underwriters, in each case as set forth in the table on the cover of the Prospectus, bear to the aggregate Public Offering Price of the Shares.  The relative fault of the Company on the one hand and the Underwriters on the other hand shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.  The Underwriters’ respective obligations to contribute pursuant to this Section 8 are several in proportion to the respective number of Shares they have purchased hereunder, and not joint.

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

27

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

9.                             Termination.  The Underwriters may terminate this Agreement by notice given by the Representatives to the Company, if after the execution and delivery of this Agreement and prior to the Closing Date (i) trading generally shall have been suspended or materially limited on, or by, as the case may be, any of the New York Stock Exchange, the NYSE MKT, the NASDAQ Global Market, the Chicago Board of Options Exchange, the Chicago Mercantile Exchange or the Chicago Board of Trade or other relevant exchanges, (ii) trading of any securities of the Company shall have been suspended on any exchange or in any over-the-counter market, (iii) a material disruption in securities settlement, payment or clearance services in the United States or other relevant jurisdiction shall have occurred, (iv) any moratorium on commercial banking activities shall have been declared by Federal or New York State authorities or (v) there shall have occurred any outbreak or escalation of hostilities, or any change in financial markets or any calamity or crisis that, in the judgment of the Representatives, is material and adverse and which, singly or together with any other event specified in this clause (v), makes it, in the judgment of the Representatives, impracticable or inadvisable to proceed with the offer, sale or delivery of the Shares on the terms and in the manner contemplated in the Time of Sale Prospectus or the Prospectus.

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

If, on the Closing Date or an Option Closing Date, as the case may be, any one or more of the Underwriters shall fail or refuse to purchase Shares that it has or they have agreed to purchase hereunder on such date, and the aggregate number of Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase is not more than one-tenth of the aggregate number of the Shares to be purchased on such date, the other Underwriters shall be obligated severally in the proportions that the number of Firm Shares set forth opposite their respective names in Schedule I bears to the aggregate number of Firm Shares set forth opposite the names of all such non-defaulting Underwriters, or in such other proportions as the Representatives may specify, to purchase the Shares which such defaulting Underwriter or Underwriters agreed but failed or refused to purchase on such date; provided that in no event shall the number of Shares that any Underwriter has agreed to purchase pursuant to this Agreement be increased pursuant to this Section 10 by an amount in excess of one-ninth of such number of Shares without the written consent of such Underwriter.  If, on the Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Firm Shares and the aggregate number of Firm Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Firm Shares to be purchased on

28

such date, and arrangements satisfactory to the Representatives and the Company for the purchase of such Firm Shares are not made within 36 hours after such default, this Agreement shall terminate without liability on the part of any non-defaulting Underwriter or the Company.  In any such case either the Representatives or the Company shall have the right to postpone the Closing Date, but in no event for longer than seven days, in order that the required changes, if any, in the Registration Statement, in the Time of Sale Prospectus, in the Prospectus or in any other documents or arrangements may be effected.  If, on an Option Closing Date, any Underwriter or Underwriters shall fail or refuse to purchase Additional Shares and the aggregate number of Additional Shares with respect to which such default occurs is more than one-tenth of the aggregate number of Additional Shares to be purchased on such Option Closing Date, the non-defaulting Underwriters shall have the option to (i) terminate their obligation hereunder to purchase the Additional Shares to be sold on such Option Closing Date or (ii) purchase not less than the number of Additional Shares that such non-defaulting Underwriters would have been obligated to purchase in the absence of such default.  Any action taken under this paragraph shall not relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

If this Agreement shall be terminated by the Underwriters, or any of them, because of any failure or refusal on the part of the Company to comply with the terms or to fulfill any of the conditions of this Agreement, or if for any reason the Company shall be unable to perform its obligations under this Agreement, the Company will reimburse the Underwriters or such Underwriters as have so terminated this Agreement with respect to themselves, severally, for all out-of-pocket expenses (including the fees and disbursements of their counsel) reasonably incurred by such Underwriters in connection with this Agreement or the offering contemplated hereunder.

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

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

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

29

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

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

15.       Notices.  All communications hereunder shall be in writing and effective only upon receipt and if to the Underwriters shall be delivered, mailed or sent to the Representatives in care of Morgan Stanley & Co. LLC, 1585 Broadway, New York, New York 10036, Attention: Equity Syndicate Desk, with a copy to the Legal Department; and Merrill Lynch, Pierce, Fenner & Smith Incorporated, One Bryant Park, New York, New York 10036, Attention: Syndicate Department (facsimile: (646) 855-3073), with a copy to ECM Legal (facsimile: (212) 230-8730); and if to the Company shall be delivered, mailed or sent to Neon Therapeutics, Inc., 40 Erie Street, Suite 110, Cambridge, MA 02139, Attention: Chief Executive Officer.

[Signature page follows]

30

Accepted as of the date hereof

Morgan Stanley & Co. LLC

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

Acting severally on behalf of themselves and

the several Underwriters named in

Schedule I hereto.

Morgan Stanley & Co. LLC

31

SCHEDULE I

I-1

SCHEDULE II

Time of Sale Prospectus

1.                                      Preliminary Prospectus issued [·], 2018

2.                                      [identify all free writing prospectuses filed by the Company under Rule 433(d) of the Securities Act]

3.                                      [free writing prospectus containing a description of terms that does not reflect final terms, if the Time of Sale Prospectus does not include a final term sheet]

4.                                      [orally communicated pricing information such as price per share and size of offering if a Rule 134 pricing term sheet is used at the time of sale instead of a pricing term sheet filed by the Company under Rule 433(d) as a free writing prospectus]

II-1

SCHEDULE III

Written Testing-the-Waters Communications

[To come.]

III-1

EXHIBIT A

FORM OF LOCK-UP LETTER

                      , 20[   ]

Morgan Stanley & Co. LLC

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

c/o                               Morgan Stanley & Co. LLC
1585 Broadway
New York, NY 10036

c/o          Merrill Lynch, Pierce, Fenner & Smith

Incorporated

One Bryant Park

New York, NY 10036

Ladies and Gentlemen:

The undersigned understands that Morgan Stanley & Co. LLC (“Morgan Stanley”) and Merrill Lynch, Pierce, Fenner & Smith Incorporated (“Merrill Lynch”) propose to enter into an Underwriting Agreement (the “Underwriting Agreement”) with Neon Therapeutics, Inc., a Delaware corporation (the “Company”), providing for the public offering (the “Public Offering”) by the several Underwriters, including Morgan Stanley and Merrill Lynch (the “Underwriters”), of shares of common stock (the “Shares”), par value $0.001 per share, of the Company (the “Common Stock”).

To induce the Underwriters that may participate in the Public Offering to continue their efforts in connection with the Public Offering, the undersigned hereby agrees that, without the prior written consent of Morgan Stanley and Merrill Lynch on behalf of the Underwriters, it will not, and will not publicly disclose an intention to, during the period commencing on the date hereof and ending 180 days after the date of the final prospectus (the “Restricted Period”) relating to the Public Offering (the “Prospectus”), (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of Common Stock beneficially owned (as such term is used in Rule 13d-3 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), by the undersigned or any other securities so owned convertible into or exercisable or exchangeable for Common Stock or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Common Stock, whether any such transaction described in clause (1) or (2) above is to be settled by delivery of Common

1

Stock or such other securities, in cash or otherwise.  The foregoing sentence shall not apply to:

(a)           transactions relating to shares of Common Stock or other securities sold or acquired in the Public Offering (other than Issuer-Directed Shares, as defined below) or acquired in open market transactions after the completion of the Public Offering, provided that no filing under Section 16(a) of the Exchange Act or other public announcement shall be required or shall be voluntarily made in connection with subsequent sales of Common Stock or other securities acquired in such open market transactions or in the Public Offering;

(b)           transfers of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock (i) by will or intestacy, (ii) by bona fide gift, (iii) to an immediate family member of the undersigned or to a trust formed for the benefit of one or more immediate family members, (iv) if the undersigned is a corporation, partnership or other business entity, (x) to another corporation, partnership or other business entity that controls, is controlled by or is under common control with the undersigned or (y) as part of a disposition, transfer or distribution without consideration by the undersigned to its equity holders, limited partners or members or (v)  if the undersigned is a trust, to a trustee or beneficiary of the trust, provided that in the case of any transfer or distribution pursuant to this clause (b), such transfer shall not involve the payment of consideration in exchange for such transfer and each transferee, donee or distributee shall sign and deliver to the Underwriters a lock-up letter substantially in the form of this letter, and provided, further, in the cases of clauses (ii) through (v), that no filing under the Exchange Act or other public announcement, reporting a reduction in beneficial ownership of shares of Common Stock, shall be required or shall be voluntarily made during the Restricted Period (provided, however, that the undersigned shall be permitted to make required filings on a Schedule 13D, Form 13F, or Schedule 13G under the Exchange Act, provided that any such filings shall not be made in connection with a transfer, disposition or distribution of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock);

(c)                                  the transfer of shares of Common Stock or any securities convertible into Common Stock to the Company upon a vesting event of the Company’s securities or upon the exercise of options or warrants to purchase the Company’s securities, in each case on a “cashless” or “net exercise” basis or to cover tax withholding obligations of the undersigned in connection with such vesting or exercise, provided that such securities were granted pursuant to the Company’s stock incentive plan or stock purchase plan described in the Registration Statement on Form S-1 to be filed with the U.S. Securities and Exchange Commission with respect to the Public Offering (as amended, the “Registration Statement”) prior to the date of the Underwriting Agreement, provided, further, that the underlying shares of Common Stock continue to be subject to the restrictions set forth in this letter and, provided, further, that no filing under the Exchange Act reporting a disposition of shares of Common Stock or other public announcement shall be required or shall be made voluntarily in connection with such vesting or exercise during the Restricted Period, other than a filing on a Form 4 that reports such disposition under the transaction code “F” and includes a footnote noting the circumstances described in this clause;

2

(d)                                 the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act for the transfer of shares of Common Stock, provided that (i) such plan does not provide for the transfer of Common Stock during the Restricted Period and (ii) to the extent a public announcement or filing under the Exchange Act, if any, is required of or voluntarily made by or on behalf of the undersigned or the Company regarding the establishment of such plan, such announcement or filing shall include a statement to the effect that no transfer of Common Stock may be made under such plan during the Restricted Period;

(e)                                  the conversion of the outstanding preferred stock of the Company into shares of Common Stock as described in the Registration Statement, provided that such shares of Common Stock remain subject to the terms of this letter;

(f)                                   the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock to the Company in connection with the termination of the undersigned’s employment or other service relationship with the Company, pursuant to agreements under which the Company has the option to repurchase such shares or a right of first refusal with respect to transfers of such shares, provided that no filing under the Exchange Act reporting a disposition of shares of Common Stock or other public announcement shall be required or shall be made voluntarily during the Restricted Period, other than a filing on a Form 4 that includes a footnote noting the circumstances described in this clause;

(g)                                  the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock that occurs pursuant to a qualified domestic order or in connection with a divorce settlement, provided that each transferee shall sign and deliver to the Underwriters a lock-up letter substantially in the form of this letter and provided, further, that no filing under the Exchange Act reporting a disposition of shares of Common Stock or other public announcement shall be made voluntarily during the Restricted Period and that any required filing or other public announcement shall include a footnote or other disclosure noting the circumstances described in this clause; or

(h)                                 the transfer of shares of Common Stock or any security convertible into or exercisable or exchangeable for Common Stock pursuant to a bona fide third party tender offer, merger, consolidation or other similar transaction made to all holders of the Common Stock involving a change of control of the Company (including, without limitation, entering into any lock-up, voting or similar agreement pursuant to which the undersigned may agree to transfer, sell, tender or otherwise dispose of Common Stock or such other securities in connection with any such transaction, or vote any securities in favor of any such transaction) following the completion of the Public Offering that has been approved by a majority of the independent members of the board of directors of the Company, provided that if the tender offer, merger, consolidation or other such transaction is not completed, the Common Stock owned by the undersigned shall remain subject to the restrictions contained in this letter.

For the purposes of clause (h), a “change of control” means the transfer (whether by tender offer, merger, consolidation or other similar transaction), in one transaction or a series of related transactions, to a person or group of affiliated persons (other than the

3

Underwriters pursuant to the Public Offering), of shares of Common Stock or any securities convertible into or exercisable or exchangeable for Common Stock if, after such transfer, the stockholders of the Company immediately prior to such transfer do not own a majority of the outstanding voting securities of the Company (or the surviving entity).

If the undersigned is an officer or director of the Company, the undersigned further agrees that the foregoing provisions shall be equally applicable to any issuer-directed Shares the undersigned may purchase in the Public Offering (“Issuer-Directed Shares”).

If the undersigned is an officer or director of the Company, (i) Morgan Stanley and Merrill Lynch agrees that, at least three business days before the effective date of any release or waiver of the foregoing restrictions in connection with a transfer of shares of Common Stock, Morgan Stanley and Merrill Lynch will notify the Company of the impending release or waiver, and (ii) the Company will agree or has agreed in the Underwriting Agreement to announce the impending release or waiver by press release through a major news service at least two business days before the effective date of the release or waiver.  Any release or waiver granted by Morgan Stanley and Merrill Lynch hereunder to any such officer or director shall only be effective two business days after the publication date of such press release.  The provisions of this paragraph will not apply if (a) the release or waiver is effected solely to permit a transfer not for consideration and (b) the transferee has agreed in writing to be bound by the same terms described in this letter to the extent and for the duration that such terms remain in effect at the time of the transfer.

By accepting the obligations of the undersigned contained herein, each of Morgan Stanley and Merrill Lynch, on behalf of the underwriters, agree that if Morgan Stanley and Merrill Lynch waive or terminate any of the foregoing restrictions in connection with a transfer of capital stock of the Company, with respect to any of the securities of any executive officer or director of the Company or person that held at least 5% of the Common Stock prior to the Public Offering (calculated on an as-converted, fully-diluted basis and as of the close of business on the date set forth on the final prospectus used to sell the Shares) (a “Triggering Release”), the provisions of this letter shall be waived or terminated, as applicable, to the same extent, on the same terms and with respect to the same percentage of securities of the undersigned as the percentage of Common Stock being released in the Triggering Release represent with respect to the securities held by the applicable executive officer, director or greater-than-5% stockholder; provided however, that the provisions of this paragraph shall not apply, (a) unless and until Morgan Stanley and Merrill Lynch have first waived such prohibitions with respect to more than 3%, in the aggregate, of the Company’s total outstanding equity securities from this letter (calculated on an as-converted, fully-diluted basis and as of the close of business on the date set forth on the final prospectus used to sell the Shares), (b) with respect to any release granted by Morgan Stanley and Merrill Lynch to a director or officer of the Company due to financial hardship, as determined by Morgan Stanley and Merrill Lynch in their sole discretion or (c) with respect to any release granted by Morgan Stanley and

4

Merrill Lynch to enable participation in any underwritten public offering of the Company’s securities during the Restricted Period.

With respect to the Public Offering only, the undersigned waives any registration rights relating to registration under the Securities Act of 1933, as amended, of the offer and sale of any Shares owned either of record or beneficially by the undersigned, including any rights to receive notice of the Public Offering.

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

Whether or not the Public Offering actually occurs depends on a number of factors, including market conditions.  Any Public Offering will only be made pursuant to an Underwriting Agreement, the terms of which are subject to negotiation between the Company and the Underwriters.

The undersigned understands that, (i) if either the Underwriters, on the one hand, or the Company, on the other hand, informs the other, prior to the execution of the Underwriting Agreement, that it has determined not to proceed with the Public Offering, (ii) if the Underwriting Agreement (other than the provisions thereof which survive termination) shall terminate or be terminated prior to payment for and delivery of the Securities to be sold thereunder, (iii) if the registration statement related to the Public Offering has been withdrawn prior to the execution of the Underwriting Agreement, or (iv) the Underwriting Agreement is not executed on or before June 30, 2018, the undersigned shall be automatically released from all obligations under this letter.

This letter and any claim, controversy or dispute arising under or related to this letter shall be governed by and construed in accordance with the laws of the State of New York, without regard to the conflict of laws principles thereof.

[Signature page follows]

5

A-1

EXHIBIT B

FORM OF WAIVER OF LOCK-UP

                      , 20   

[Name and Address of
Officer or Director
Requesting Waiver]

Dear Mr./Ms. [Name]:

This letter is being delivered to you in connection with the offering by Neon Therapeutics, Inc. (the “Company”) of [·] shares of common stock, $[·] par value per share (the “Common Stock”), of the Company and the lock-up letter dated     , 2017 (the “Lock-up Letter”), executed by you in connection with such offering, and your request for a [waiver] [release] dated     , 20  , with respect to      shares of Common Stock (the “Shares”).

Morgan Stanley & Co. LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated hereby agree to [waive] [release] the transfer restrictions set forth in the Lock-up Letter, but only with respect to the Shares, effective      , 20  ; provided, however, that such [waiver] [release] is conditioned on the Company announcing the impending [waiver] [release] by press release through a major news service at least two business days before effectiveness of such [waiver] [release].  This letter will serve as notice to the Company of the impending [waiver] [release].

Except as expressly [waived] [released] hereby, the Lock-up Letter shall remain in full force and effect.

B-1

cc:  Neon Therapeutics, Inc

B-2

FORM OF PRESS RELEASE

Neon Therapeutics, Inc.

[Date]

Neon Therapeutics, Inc. (the “Company”) announced today that Morgan Stanley & Co. LLC and Merrill Lynch, Pierce, Fenner & Smith Incorporated, the lead book-running managers in the Company’s recent public sale of [·] shares of common stock are [waiving][releasing] a lock-up restriction with respect to      shares of the Company’s common stock held by [certain officers or directors] [an officer or director] of the Company.  The [waiver][release] will take effect on     , 20   , and the shares may be sold on or after such date.

This press release is not an offer for sale of the securities in the United States or in any other jurisdiction where such offer is prohibited, and such securities may not be offered or sold in the United States absent registration or an exemption from registration under the United States Securities Act of 1933, as amended.

B-3