EXHIBIT 3.1

CERTIFICATE OF AMENDMENT OF

AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

OF

TOCAGEN INC.

Martin J. Duvall, hereby certifies that:

ONE: He is the duly elected and acting Chief Executive Officer of Tocagen Inc. (the “Company”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”).

TWO: The date of filing of the Company’s original certificate of incorporation with the Delaware Secretary of State was August 24, 2007.

THREE: The board of directors of the Company, acting in accordance with the provisions of Sections 141 and 242 of the DGCL, adopted resolutions amending its current Amended and Restated Certificate of Incorporation as follows:

Article I of the Company’s Amended and Restated Certificate of Incorporation is hereby amended and restated as follows:

“The name of this corporation is Forte Biosciences, Inc. (the “Company”).”

FOUR: The board of directors of the Company, acting in accordance with the provisions of Sections 141 and 242 of the DGCL, adopted resolutions amending its current Amended and Restated Certificate of Incorporation as follows:

Paragraph A of Article IV of the Company’s Amended and Restated Certificate of Incorporation is hereby amended to add the following at the end of Paragraph A, which shall read in its entirety as follows:

“Effective at 4:01 p.m., Eastern time, on June 15, 2020 (the “Effective Time”), each fifteen (15) shares of the Company’s Common Stock, par value $0.001 per share, issued and outstanding immediately prior to the Effective Time (“Old Common Stock”) shall, automatically and without any action on the part of the Company or the respective holders thereof, be combined and reclassified into one (1) share of Common Stock, par value $0.001 per share, of the Company (“New Common Stock”). Notwithstanding the immediately preceding sentence, no fractional shares of New Common Stock shall be issued in the reclassification and, in lieu thereof, upon receipt after the Effective Time by the exchange agent selected by the Company of a properly completed and duly executed transmittal letter and, where shares are held in certificated form, the surrender of the stock certificate(s) formerly representing shares of Old Common Stock, any stockholder who would otherwise be entitled to a fractional share of New Common Stock as a result of the foregoing combination and reclassification of the Old Common Stock (such combination and reclassification, the “Reverse Stock Split”), following the Effective Time (after taking into account all fractional shares of New Common Stock otherwise issuable to such stockholder), shall be entitled to receive a cash payment (without interest) equal to the fractional share of New Common Stock to which such stockholder would otherwise be entitled multiplied by the closing sales price of a share of the Company’s Common Stock (as adjusted to give effect to the Reverse Stock Split) as reported on The Nasdaq Stock Market, LLC on the date this Certificate of Amendment to the Amended and Restated Certificate of Incorporation is filed with the Secretary of State of the State of Delaware. Each stock certificate that, immediately prior to the Effective Time, represented shares of Old Common Stock shall, from and after the Effective Time, automatically and without any action on the part of the Company or the respective holders

thereof, represent that number of whole shares of New Common Stock into which the shares of Old Common Stock represented by such certificate shall have been combined and reclassified (as well as the right to receive cash in lieu of any fractional shares of New Common Stock as set forth above); provided, however, that each holder of record of a certificate that represented shares of Old Common Stock shall receive, upon surrender of such certificate, a new certificate representing the number of whole shares of New Common Stock into which the shares of Old Common Stock represented by such certificate shall have been combined and reclassified, as well as any cash in lieu of fractional shares of New Common Stock to which such holder may be entitled as set forth above.”

FIVE: Thereafter, pursuant to a resolution by the Company’s board of directors, Article FOUR of this Certificate of Amendment was submitted to the stockholders of the Company for their approval in accordance with the provisions of Section 211 and 242 of the DGCL and was approved. Accordingly, this Certificate of Amendment has been adopted in accordance with Section 242 of the DGCL.

SIX: This Certificate of Amendment of Amended and Restated Certificate of Incorporation shall become effective as of June 15, 2020 at 4:01 pm Eastern Time, following the filing with the Secretary of State of the State of Delaware.

[signature page follows]

IN WITNESS WHEREOF, this Certificate of Amendment of Amended and Restated Certificate of Incorporation has been duly executed by an authorized officer of the Company on June 15, 2020.