UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Amendment No. 3)

Poseida Therapeutics, Inc.

(Name of Subject Company (Issuer))

Blue Giant Acquisition Corp.

(Name of Filing Person (Offeror))

A wholly owned subsidiary of

Roche Holdings, Inc.

(Name of Filing Person (Parent of Offeror))

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

73730P108

(CUSIP Number of Class of Securities)

Roger Brown

Roche Holdings, Inc.

1 DNA Way

South San Francisco, California 94080

Telephone: (650) 225-1000

(Name, Address and Telephone Numbers of Person Authorized to Receive Notices and Communications on Behalf of Filing Persons)

Copies to:

Sharon R. Flanagan

John H. Butler

Sally Wagner Partin

Sidley Austin LLP

555 California Street, Suite 2000

San Francisco, California 94104

Telephone: (415) 772-1200

Check the appropriate boxes below to designate any transactions to which the statement relates:

Check the following box if the filing is a final amendment reporting the results of the tender offer: ☐

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

This Amendment No. 3 (“Amendment No. 3”) to the Tender Offer Statement on Schedule TO (together with the exhibits thereto, the “Schedule TO”) amends and supplements the statement originally filed on December 9, 2024 by Roche Holdings, Inc., a Delaware corporation (“Parent”), and Blue Giant Acquisition Corp., a Delaware corporation and wholly owned subsidiary of Parent (“Offeror”). This Amendment No. 3 and the Schedule TO relate to the offer by Offeror to acquire all outstanding shares of common stock, par value $0.0001 per share (the “Shares”), of Poseida Therapeutics, Inc., a Delaware corporation (“Poseida”), for (i) $9.00 per Share, in cash, without interest (the “Cash Amount”) less any applicable withholding taxes, plus (ii) one non-transferable contingent value right (each, a “CVR”) per Share, representing the right to receive certain contingent payments of up to an aggregate amount of $4.00 per Share, in cash, without interest less any applicable withholding taxes, upon the achievement of certain specified milestones on or prior to the applicable milestone outside dates in accordance with the terms and conditions set forth in the contingent value rights agreement to be entered into with Computershare Inc., a Delaware corporation (“Computershare”) and Computershare Trust Company, N.A., a federally chartered trust company (together with Computershare, the “Rights Agent”), upon the terms and subject to the conditions set forth in the Offer to Purchase, dated December 9, 2024 (together with any amendments or supplements thereto, the “Offer to Purchase”), and in the related Letter of Transmittal (together with any amendments or supplements thereto, the “Letter of Transmittal”), copies of which are filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively (the Offer to Purchase and the Letter of Transmittal, collectively, the “Offer”).

Capitalized terms used, but not otherwise defined, in this Amendment No. 3 shall have the meanings ascribed to them in the Offer to Purchase. Except as set forth below, the information set forth in the Schedule TO remains unchanged and is incorporated herein by reference as relevant to the items in this Amendment No. 3.

Items 1 through 9, and Item 11.

The Offer to Purchase and Items 1 through 9 and 11 of the Schedule TO, to the extent such Items incorporate by reference the information contained in the Offer to Purchase, are hereby amended and supplemented as follows:

“Each of Parent and Poseida filed a Premerger Notification and Report Form under the HSR Act with respect to the Offer and the Merger with the Antitrust Division and the FTC on December 6, 2024. As of 11:59 p.m., New York City time, on January 6, 2025, the waiting period under the HSR Act applicable to the Offer expired. Accordingly, the condition to the Offer relating to the expiration or termination of the waiting period under the HSR Act has been satisfied.”

Item 12.

SIGNATURES

After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: January 7, 2025