13D Filings
Atara Biotherapeutics, Inc.
ATRA
Amendment
Ownership

20.00%

Total Shares

1,712,900

Issuer CIK

1604464

CUSIP

046513107

Event Date

Aug 14, 2025

Accepted

Aug 19, 2025, 08:15 PM

Reporting Persons (6)
Joint Filing

This is a joint filing. The reported shares may overlap between reporting persons and should not be summed.

NameType% of ClassAggregateSole VotingShared Voting
Panacea Innovation Limited
CO
20.00%1,712,90001,712,900
Panacea Venture Healthcare Fund II, L.P.
Partnership
20.00%1,405,00001,405,000
Panacea Venture Healthcare Fund II GP Company, Ltd.
CO
20.00%1,405,00001,405,000
James Huang
Individual
20.00%1,712,90001,712,900
Panacea Opportunity Fund I, L.P.
Partnership
4.20%307,9000307,900
Panacea Opportunity Fund I GP Company, Ltd.
CO
4.20%307,9000307,900
Disclosure Items (3)

Security Title

Common Stock

Issuer Name

Atara Biotherapeutics, Inc.

Issuer Address

1280 Rancho Conejo Blvd, Thousand Oaks, CA, 91320

From July 17, 2025 through August 19, 2025, Panacea Venture Healthcare Fund II, L.P. purchased 74,335 shares of Common Stock in a series of open market transactions for aggregate cash consideration of approximately $857,000. Panacea Venture Healthcare Fund II, L.P. obtained the funds used to purchase the Common Stock through capital contributions from their partners.

Percentage of Class

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 1,405,000 shares of Common Stock, and Panacea Opportunity Fund I, L.P. is the record holder of warrants to purchase 307,900 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.

Number of Shares

The information contained on the cover pages is incorporated by reference into this Item 5.

Transactions

On July 17, 2025, Panacea Venture Healthcare Fund II, L.P. purchased 19,335 shares of Common Stock at a weighted average price of $9.6391 per share in a series of open market transactions. On August 15, 2025, Panacea Venture Healthcare Fund II, L.P. purchased 55,000 shares of Common Stock at a weighted average price of $12.1895 per share in a series of open market transactions. Except for the transactions disclosed in this Item 5(c), none of the Reporting Persons has effected any transactions in the Common Stock during the past sixty days.

Shareholders

None.

Date of 5% Ownership

Not applicable

Atara Biotherapeutics, Inc. — Schedule 13D | 13D Filings