Exhibit 3.1

FIFTH AMENDED AND RESTATED
CERTIFICATE OF INCORPORATION
OF
CHECKMATE PHARMACEUTICALS, INC.

ARTICLE I

The name of the corporation is Checkmate Pharmaceuticals, Inc. (the “Corporation”).

ARTICLE II

The address, including street, number, city, and county, of the registered office of the Corporation in the State of Delaware is the Corporation Trust Company, 1209 Orange Street, City of Wilmington, County of New Castle, State of Delaware 19801. The name of the registered agent of the Corporation in the State of Delaware at such address is The Corporation Trust Company.

ARTICLE III

The purpose of the Corporation shall be to engage in any lawful act or activity for which corporations may be organized and incorporated under the General Corporation Law of the State of Delaware.

ARTICLE IV

Section 1     The Corporation shall be authorized to issue 1,000 shares of capital stock, all of which 1,000 shares shall be shares of common stock, par value $0.01 per share (the “Common Stock”).

Section 2     Except as otherwise provided by law, the Common Stock shall have the exclusive right to vote for the election of directors and for all other purposes. Each share of the Common Stock shall have one vote and the Common Stock shall vote together as a single class.

ARTICLE V

Any one or more directors may be removed, with or without cause, by the vote or written consent of the holders of a majority of the issued and outstanding shares of capital stock of the Corporation entitled to be voted in the election of directors.

ARTICLE VI

In furtherance and not in limitation of those powers conferred by the DGCL, the board of directors of the Corporation is expressly authorized and empowered to make, alter and repeal the by-laws of the Corporation (the “By-Laws”) to the fullest extent permitted by the provisions of the DGCL.

ARTICLE VII

Meetings of the stockholders shall be held at such place, within or without the State of Delaware as may be designated by, or in the manner provided in, the By-Laws or, if not so designated, at the registered office of the Corporation in the State of Delaware. Elections of directors need not be by written ballot unless and to the extent that the By-Laws so provide.

ARTICLE VIII

The Corporation reserves the right at any time from time to time to amend, alter, change or repeal any provision contained in this Certificate of Incorporation, and any other provisions authorized by the laws of the State of Delaware at the time in force may be added or inserted, in the manner now or hereinafter prescribed by law, and all rights, preferences and privileges of whatsoever nature conferred upon stockholders, directors or any other persons whomsoever by and pursuant to this Certificate of Incorporation in its present form or as hereafter amended are granted subject to the right reserved in this Article.

ARTICLE IX

Section 1     The personal liability of the directors of the Corporation is hereby eliminated to the fullest extent permitted by the provisions of paragraph (7) of subsection (b) of § 102 of the DGCL, as the same may be amended and supplemented.

Section 2     The Corporation shall, to the fullest extent permitted by the provisions of § 145 of the General Corporation Law of the State of Delaware, as the same may be amended and supplemented, indemnify any and all persons whom it shall have power to indemnify under said section from and against any and all of the expenses, liabilities, or other matters referred to in or covered by said section, and the indemnification provided for herein shall not be deemed exclusive of any other rights to which those indemnified may be entitled under any By-Law, agreement, vote of stockholders or disinterested directors or otherwise, both as to action in his official capacity and as to action in another capacity while holding such office, and shall continue as to a person who has ceased to be a director, officer, employee, or agent and shall inure to the benefit of the heirs, executors, and administrators of such a person.

Section 3     Any repeal or modification of the clauses in this Article IX shall be prospective only and shall not adversely affect any right or protection of a director, officer, agent or other person existing at the time of, or increase the liability of any director or officer of the Corporation with respect to any acts or omissions of such director occurring prior to, such repeal or modification.

IN WITNESS WHEREOF, the Corporation has caused this Amended and Restated Certificate of Incorporation to be executed on its behalf this 31st day of May, 2022.

CHECKMATE PHARMACEUTICALS, INC.
By:	/s/ Alan Bash
	Name: Alan Bash
	Title: Chief Executive Officer

[Signature Page to Fifth Amended and Restated Certificate of Incorporation of Checkmate Pharmaceuticals, Inc.]