Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

Pursuant to the requirement set forth in Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and in connection with the Quarterly Report of Atara Biotherapeutics, Inc. (the “Company”) on Form 10-Q for the quarter ended March 31, 2023, as filed with the Securities and Exchange Commission (the “Report”), Pascal Touchon, Chief Executive Officer of the Company, and Eric Hyllengren, Chief Financial Officer of the Company, respectively, do each hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

(1)
The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and
(2)
The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 8, 2023

 

/s/ Pascal Touchon

Pascal Touchon

Chief Executive Officer

(Principal Executive Officer)

 

/s/ Eric Hyllengren

Eric Hyllengren

Chief Financial Officer

(Principal Financial and Accounting Officer)

 

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.