Exhibit 3.1

FIFTH AMENDED AND RESTATED

CERTIFICATE OF INCORPORATION

OF

ARCELLX, INC.

FIRST: The name of the corporation is Arcellx, Inc. (hereinafter, the “Corporation”).

SECOND: The address of the Corporation’s registered office in the State of Delaware is 251 Little Falls Drive, Wilmington, New Castle County, Delaware 19808, and the name of its registered agent at such address is Corporation Service Company.

THIRD: The purpose of the Corporation is to engage in any lawful act or activity for which a corporation may be organized under the General Corporation Law of the State of Delaware (the “DGCL”).

FOURTH: The total number of shares of stock which the Corporation shall have authority to issue is 100 shares of common stock, par value $0.001 per share.

FIFTH: The business and affairs of the Corporation shall be managed by or under the direction of the board of directors, and the directors need not be elected by ballot unless required by the bylaws of the Corporation.

SIXTH: In furtherance and not in limitation of the powers conferred by the laws of the State of Delaware, the board of directors is expressly authorized to make, amend or repeal the bylaws or adopt new bylaws without any action on the part of the stockholders of the Corporation; provided that any bylaw adopted or amended by the board of directors, and any powers thereby conferred, may be amended, altered or repealed by the stockholders of the Corporation.

SEVENTH: To the fullest extent permitted by the DGCL as the same exists or as may hereafter be amended from time to time, a director of the Corporation shall not be personally liable to the Corporation or its stockholders for monetary damages for breach of fiduciary duty as a director. If the DGCL is amended to authorize corporate action further eliminating or limiting the personal liability of directors, then the liability of a director of the Corporation shall be eliminated or limited to the fullest extent permitted by the DGCL, as so amended.

Subject to any provisions in the bylaws of the Corporation related to indemnification of directors of the Corporation, the Corporation shall indemnify, to the fullest extent permitted by applicable law, any director of the Corporation who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (a “Proceeding”) by reason of the fact that he or she is or was a director of the Corporation or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, including service with respect to employee benefit plans, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with any such Proceeding. The Corporation shall be required to indemnify a person in connection with a Proceeding (or part thereof) initiated by such person only if the Proceeding (or part thereof) was authorized by the board of directors.

The Corporation shall have the power to indemnify, to the extent permitted by applicable law, any officer, employee or agent of the Corporation who was or is a party or is threatened to be made a party to any Proceeding by reason of the fact that he or she is or was a director, officer, employee or agent of the Corporation or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, including service with respect to employee benefit plans, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with any such Proceeding.

Neither any amendment, repeal nor elimination of any section of this Article Seventh, nor the adoption of any provision of this certificate of incorporation or the bylaws of the Corporation inconsistent with this section, shall eliminate or reduce the effect of this section in respect of any matter occurring, or any Proceeding accruing or arising or that, but for this section, would accrue or arise, prior to such amendment, repeal, elimination or adoption of an inconsistent provision.

EIGHTH: The Corporation reserves the right to amend and repeal any provision contained in this Certificate of Incorporation in the manner from time to time as prescribed by the laws of the State of Delaware. All rights herein conferred are granted subject to this reservation.