Exhibit 32.1


18 U.S.C. SECTION 1350,




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 Annual Report of Atara Biotherapeutics, Inc. (the “Company”) on Form 10-K for the year ended December 31, 2021, as filed with the Securities and Exchange Commission (the “Report”), Pascal Touchon, Chief Executive Officer of the Company, and Utpal Koppikar, 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:


The Report fully complies with the requirements of Section 13(a) or 15(d) of the Exchange Act; and


The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.


Date: February 28, 2022


/s/ Pascal Touchon 

Pascal Touchon

President and Chief Executive Officer

(Principal Executive Officer)


/s/ Utpal Koppikar 

Utpal Koppikar

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.

This certification accompanies the Annual Report on Form 10-K to which it relates, is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended, or the Exchange Act (whether made before or after the date of the Form 10-K), irrespective of any general incorporation language contained in such filing.