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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13D/A 0002010692 XXXXXXXX LIVE 2 Common Stock 01/12/2026 true 0001604464 046513107 Atara Biotherapeutics, Inc. 1280 Rancho Conejo Blvd Thousand Oaks CA 91320 James Huang (86-21) 6176-1101 Panacea Venture No. 5, Lane 1350, Fuxing Middle Road Xuhui District, Shanghai F4 200031 0002010692 N Panacea Innovation Limited OO N E9 0 1632345 0 1632345 1632345 N 19.99 CO Includes 259,163 warrants to purchase Common Stock. The warrants are immediately exercisable and do not expire. No portion of the warrants beneficially owned by the Reporting Persons may be exercised to the extent that, after giving effect to the attempted exercise, the Reporting Persons would beneficially own in excess of 19.99% of the outstanding Common Stock. Based on 7,258,971 shares of Common Stock outstanding as of November 28, 2025, the Reporting Persons may exercise warrants to purchase 97,345 shares of Common Stock. 0001869939 N Panacea Venture Healthcare Fund II, L.P. OO N E9 0 1324446 0 1324446 1324446 N 18.2 PN Y Panacea Venture Healthcare Fund II GP Company, Ltd. OO N E9 0 1324446 0 1324446 1324446 N 18.2 CO 0001869966 N Panacea Opportunity Fund I, L.P. OO N E9 0 307899 0 307899 307899 N 4.1 PN Includes 259,163 warrants to purchase Common Stock. The warrants are immediately exercisable and do not expire. No portion of the warrants beneficially owned by the Reporting Persons may be exercised to the extent that, after giving effect to the attempted exercise, the Reporting Persons would beneficially own in excess of 19.99% of the outstanding Common Stock. Based on 7,258,971 shares of Common Stock outstanding as of November 28, 2025, the Reporting Persons may exercise warrants to purchase 97,345 shares of Common Stock. Y Panacea Opportunity Fund I GP Company, Ltd. OO N E9 0 307899 0 307899 307899 N 4.1 CO Includes 259,163 warrants to purchase Common Stock. The warrants are immediately exercisable and do not expire. No portion of the warrants beneficially owned by the Reporting Persons may be exercised to the extent that, after giving effect to the attempted exercise, the Reporting Persons would beneficially own in excess of 19.99% of the outstanding Common Stock. Based on 7,258,971 shares of Common Stock outstanding as of November 28, 2025, the Reporting Persons may exercise warrants to purchase 97,345 shares of Common Stock. 0001573160 N James Huang OO N F4 0 1632345 0 1632345 1632345 N 19.99 IN Includes 259,163 warrants to purchase Common Stock. The warrants are immediately exercisable and do not expire. No portion of the warrants beneficially owned by the Reporting Persons may be exercised to the extent that, after giving effect to the attempted exercise, the Reporting Persons would beneficially own in excess of 19.99% of the outstanding Common Stock. Based on 7,258,971 shares of Common Stock outstanding as of November 28, 2025, the Reporting Persons may exercise warrants to purchase 97,345 shares of Common Stock. Common Stock Atara Biotherapeutics, Inc. 1280 Rancho Conejo Blvd Thousand Oaks CA 91320 This Amendment No. 2 to Schedule 13D amends and supplements the statement on Schedule 13D originally filed with the United States Securities and Exchange Commission on May 21, 2025 (as amended, the "Schedule 13D"), relating to the Common Stock. Capitalized terms used herein without definition shall have the meaning set forth in the Schedule 13D. The information contained on the cover pages is incorporated by reference into this Item 5. Panacea Venture Healthcare Fund II, L.P. is the record holder of 1,324,446 shares of Common Stock, and Panacea Opportunity Fund I, L.P. is the record holder of 48,736 shares of Common Stock and warrants to purchase 259,163 shares of Common Stock. The warrants are immediately exercisable and do not expire. No portion of the warrants beneficially owned by the Reporting Persons may be exercised to the extent that, after giving effect to the attempted exercise, the Reporting Persons would beneficially own in excess of 19.99% of the outstanding Common Stock. James Huang is the sole owner of Panacea Innovation Limited, which is the sole owner of Panacea Venture Healthcare Fund II GP Company, Ltd. and Panacea Opportunity Fund I GP Company, Ltd., which are the general partners of Panacea Venture Healthcare Fund II, L.P. and Panacea Opportunity Fund I, L.P., respectively. As a result, Panacea Venture Healthcare Fund II GP Company, Ltd. and Panacea Opportunity Fund I GP Company, Ltd. may be deemed to share beneficial ownership of the securities held of record by Panacea Venture Healthcare Fund II, L.P. and Panacea Opportunity Fund I, L.P., respectively. Panacea Innovation Limited and Mr. Huang may be deemed to share beneficial ownership of the securities beneficially owned by the foregoing entities, but each disclaims such beneficial ownership. The information contained on the cover pages is incorporated by reference into this Item 5. On November 28, 2025, Panacea Opportunity Fund I, L.P. exercised warrants to purchase an aggregate of 48,736 shares of Common Stock, after tax witholding. On January 12, 2026, Panacea Venture Healthcare Fund II, L.P. sold 80,554 shares of Common Stock in open market transactions at a weighted average price of $6.0707 per share. The Reporting Persons undertake to provide, upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price for this transaction. None. Not applicable Panacea Innovation Limited /s/ James Huang James Huang, Founding Managing Partner 01/14/2026 Panacea Venture Healthcare Fund II, L.P. By: Panacea Venture Healthcare Fund II GP Company, Ltd., its general partner By: Panacea Innovation Limited, its sole owner By: /s/ James Huang James Huang, Founding Managing Partner 01/14/2026 Panacea Venture Healthcare Fund II GP Company, Ltd. By: Panacea Innovation Limited, its sole owner By: /s/ James Huang James Huang, Founding Managing Partner 01/14/2026 Panacea Opportunity Fund I, L.P. By: Panacea Opportunity Fund I GP Company, Ltd., its general partner By: Panacea Innovation Limited, its sole owner By: /s/ James Huang James Huang, Founding Managing Partner 01/14/2026 Panacea Opportunity Fund I GP Company, Ltd. By: Panacea Innovation Limited, its sole owner By: /s/ James Huang James Huang, Founding Managing Partner 01/14/2026 James Huang /s/ James Huang James Huang 01/14/2026