Nestle Health Science US Holdings, Inc. Stamford, CT 06902

Exhibit 4.2

Nestle Health Science US Holdings, Inc.

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February 4, 2020

Aimmune Therapeutics, Inc.

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Attention: Chief Executive Officer

Ladies and Gentlemen:

In connection with the acquisition of Common Stock, par value $0.0001 per share (the “Common Stock”), and Series A Preferred Stock, par value $0.0001 per share (the “Series A Preferred Stock”) of Aimmune Therapeutics, Inc., a Delaware corporation (the “Company”), by Nestle Health Science US Holdings, Inc., a Delaware corporation (the “Purchaser”), pursuant to the Securities Purchase Agreement, dated as of February 4, 2020, between the Company and the Purchaser (the “Purchase Agreement”), the Company and the Purchaser desire to amend and restate that certain amended and restated standstill agreement, dated November 11, 2018 (the “Prior Agreement”) to accept the rights and covenants hereof in lieu of their rights and covenants in the Prior Agreement. In connection therewith, the Purchaser hereby delivers this amended and restated standstill agreement (this “Standstill Agreement”) to the Company in accordance with the terms of the Purchase Agreement. Capitalized terms used but not otherwise defined herein shall have the respective meanings ascribed to them in the Purchase Agreement.

In consideration of the mutual covenants contained in the Purchase Agreement and this Standstill Agreement, and for other good and valuable consideration the receipt and adequacy of which are hereby acknowledged, the Company and the Purchaser agree as follows:

1. Standstill. During the period beginning on the date hereof and ending at 11:59 pm Pacific Time on November 11, 2020 (the “Termination Date”), neither the Purchaser nor any of its Affiliates (as defined below) shall, directly or indirectly, without the prior written consent of a majority of the members of the Board of Directors of the Company (the “Board”) who are not affiliated with the Purchaser:

provided that, the foregoing restrictions shall not apply after (A) a public announcement by the Company of the initiation of any merger, consolidation, acquisition, scheme, business combination or other extraordinary transaction in which the Company or any of its subsidiaries is a constituent corporation or party and following consummation of such transaction, either (i) substantially all of the persons or entities who, immediately prior to such transaction, had beneficial ownership of 50% or more of the voting power of the Company would not continue to beneficially own at least 50% of the voting power of the combined entity and would not have the ability to elect a majority of the directors of the combined entity or (ii) all or a substantial part of the assets of the Company and its subsidiaries would be transferred to a third party (a “Business Combination”) or (B) the submission of any bona fide offer by any third party to acquire all or a substantial portion of the securities or assets of the Company or its subsidiaries (which for the avoidance of doubt shall exclude any offer with respect to which the Company elects not to engage in substantive negotiations), prompt notice of which shall be provided to the Purchaser; provided, further, that nothing in this Section 1 is intended to (X) restrict the Purchaser’s right to vote its shares of Common Stock purchased pursuant to the Purchase Agreement (or any prior purchase agreement entered into with the Company) or shares of Common Stock issuable upon conversion of the Series A Preferred Stock purchased pursuant to the Purchase Agreement or otherwise in its discretion on matters brought to a vote of the stockholders of the Company, (Y) restrict the activities of the Purchaser or the discussions among the representatives of the Company and the Purchaser, in each case, as contemplated by that certain Amended and Restated Collaboration Agreement, dated the date hereof, by and among the Company and Société des Produits Nestlé S.A. (the successor to Nestec Ltd.). or (Z) restrict the Purchaser’s or any of its Affiliates’ right to acquire any rights, title or interest in any options or other securities of the Company granted to members of the Board who are affiliated with the Purchaser.

For purposes of this letter agreement, (i) “Affiliates” shall mean (1) any person, corporation, partnership, trust, limited liability company or other entity, whether existing now or in the future, that, directly or indirectly, controls, is controlled by or is under common control with, the Purchaser and (ii) “Beneficially Owns” (including the terms “Beneficial Ownership”, “Beneficially Owned” or “Beneficially Owning”) shall mean beneficial ownership within the meaning of Rule 13d-3 under the Exchange Act.

2. No Effect. Notwithstanding any of the foregoing, the provisions set forth in Section 1 shall in no way limit (i) the ability of any individual who is serving as a director of the Company to take any actions (or to refrain from taking any actions) in his/her capacity as a director of the Company or (ii) the ability of the Purchaser or its Affiliates to initiate and engage in confidential discussions with the Board regarding the transactions referred to in clauses (a)(i)-(iii) of Section 1.

3. Market Standoff. During the period beginning on the date hereof and ending at 11:59 pm Pacific Time on November 11, 2021 (the “Market Standoff Termination Date”), neither the Purchaser nor any of its Affiliates shall, directly or indirectly, without the prior written consent of a majority of the members of the Board who are not affiliated with the Purchaser:

4. Limitation on Sales. Notwithstanding anything herein to the contrary, during the period beginning on the date hereof and ending on the Market Standoff Termination Date, no sales of Common Stock or Series A Preferred Stock (or Common Stock issuable upon conversion of the Series A Preferred Stock) Beneficially Owned by the Purchaser or any of its Affiliates shall be made to DBV Technologies SA pursuant to a private sale or other exemption from the registration requirements of the Securities Act of 1933, as amended, without the prior written consent of the Company.

5. Change of Control Transaction. In connection with any Change of Control Transaction approved by the Board during the period beginning on the date hereof and ending on the Market Standoff Termination Date, the Purchaser on behalf of itself and its Affiliates agrees not to seek an appraisal remedy under Section 262 of the Delaware General Corporation Law with respect to any shares of Common Stock held by it as of the date of the consummation of the Change of Control Transaction. For purposes hereof, “Change of Control Transaction” shall mean any transaction (or series of related transactions) after the date hereof (including the consummation of a scheme of arrangement/amalgamation, merger, de-merger, share purchase, recapitalization, redemption, issuance of capital stock, consolidation, tender offer, combination of shares, reorganization or otherwise) pursuant to which (a) a person (or group of persons) Beneficially Owns immediately upon completion of such transaction (or series of related transactions) securities representing more than fifty percent (50%) of the combined voting power for the election of directors of the outstanding voting securities of the entity surviving or resulting from such transaction (or series of related transactions) or (b) the Company sells or otherwise disposes of all or substantially all of the assets of the Company and its subsidiaries on a consolidated basis to a person (or group of persons).

6. Representations. Each party represents to the other that: (a) this Letter Agreement has been duly authorized by all necessary corporate or partnership action, as the case may be; and (b) this letter agreement is a valid and binding agreement of such party, enforceable against it in accordance with its terms, subject to the Enforceability Limitations. The Company represents that this Letter Agreement was approved by the vote a majority of the members of the Board who are not affiliated with the Purchaser.

7. Specific Enforcement; Legal Effect. The parties hereto agree that any breach of this Letter Agreement would result in irreparable injury to other party and that money damages would not be an adequate remedy for such breach. Accordingly, without prejudice to the rights and remedies otherwise available under applicable law, either party shall be entitled to specific performance and equitable relief by way of injunction or otherwise if the other party breaches or threatens to breach any of the provisions of this letter agreement. It is further understood and agreed that no failure or delay by either party in exercising any right, power or privilege hereunder shall operate as a waiver thereof, nor shall any single or partial exercise thereof preclude any other or further exercise thereof or the exercise of any right, power or privilege hereunder. This Letter Agreement contains the entire agreement between the parties hereto concerning the matters addressed herein. No modification of this Letter Agreement or waiver of the terms and conditions hereof shall be binding upon either party hereto, unless approved in writing by each such party; provided, however, that no waiver or amendment shall be effective as against the Company unless such waiver or amendment is approved in writing by the vote a majority of the members of the Board who are not affiliated with the Purchaser. This Letter Agreement shall be governed by and construed in accordance with the law of the State of New York without regard to principles of conflicts of law that would cause the application of the laws of any jurisdiction other than the State of New York. Any dispute arise under or in connection with this Agreement shall be resolved in accordance with the dispute resolution procedures set out in Section 13.6 of the Purchase Agreement, which procedures are incorporated herein by this reference.

8. Counterparts. This Standstill Agreement may be executed and delivered (including by facsimile or portable document format (“pdf”) in two or more counterparts, each of which shall constitute an original, but all of which, when taken together, shall constitute but one instrument, and shall become effective when one or more counterparts have been signed by each party hereto and delivered to the other parties.

9. Entire Agreement. This Standstill Agreement and the other Transaction Documents contain the entire agreement among the parties with respect to the subject matter hereof and thereof and supersede all prior and contemporaneous arrangements or understandings, whether written or oral, with respect hereto and thereto. Upon the effectiveness of this Standstill Agreement, the Prior Agreement shall be deemed amended and restated and superseded and replaced in its entirety by this Standstill Agreement, and shall be of no further force or effect.

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IN WITNESS WHEREOF, the parties hereto have executed this Standstill Agreement effective as of the Closing.