Atara Biotherapeutics, Inc. SEC Filings

Atara Biotherapeutics reported that its partner Pierre Fabre Pharmaceuticals has requested a Type A meeting with the U.S. Food and Drug Administration to discuss tabelecleucel (tab-cel). The meeting request follows the Complete Response Letter for the EBVALLO™ Biologics License Application dated January 9, 2026.

Atara states that a briefing book was submitted to the FDA addressing points in the letter, including arguments that the ALLELE study was adequate, well-controlled, and sufficient to support the application. The briefing materials also summarize updated longer-term efficacy data from ALLELE, additional supportive data from the development program, and post-marketing data in Europe that may be used in a potential resubmission.

ATRA reported a Rule 144 notice to sell 7,788 shares of Common Stock. The filing shows these shares relate to the settlement of vested RSUs issued under an S-8 registration plan and are dated 03/01/2026.

The filing lists the transaction as equity compensation for services rendered and identifies Morgan Stanley Smith Barney LLC Executive Services as the broker.

Issuer files a Form 144 notice to sell 4,759 shares of common stock. The filing states these shares result from the settlement of vested RSUs issued under an S-8 registration plan on 03/01/2026. The submission appears as a routine insider resale notice under applicable resale rules.

Atara Biotherapeutics has amended its royalty purchase agreement with HealthCare Royalty (HCRx), pushing back a one-time $9.0 million milestone payment from June 30, 2026 to January 1, 2028. This later due date eases near-term cash obligations tied to its commercialization agreement with Pierre Fabre Medicament.

In return, Atara issued HCRx a warrant to purchase up to 400,000 shares of common stock at an exercise price of $0.0001 per share. The warrant is immediately exercisable, has no expiration date, and includes a 4.99% beneficial ownership cap, with the option for cashless exercise. Atara plans to register the resale of the underlying shares in a future registration statement.

Panacea-affiliated investors filed Amendment No. 2 to a Schedule 13D reporting their stake in Atara Biotherapeutics’ common stock. Panacea Innovation Limited and related entities report beneficial ownership of 1,632,345 shares, or 19.99% of Atara’s common stock, including 259,163 warrants that are immediately exercisable and do not expire. Based on 7,258,971 shares outstanding as of November 28, 2025, they may exercise warrants to purchase 97,345 shares without exceeding the 19.99% ownership cap.

Panacea Venture Healthcare Fund II, L.P. holds 1,324,446 shares, representing 18.2% of the class, while Panacea Opportunity Fund I, L.P. holds 307,899 shares, or 4.1%. On November 28, 2025, Panacea Opportunity Fund I, L.P. exercised warrants for 48,736 shares after tax withholding, and on January 12, 2026, Panacea Venture Healthcare Fund II, L.P. sold 80,554 shares in open market transactions at a weighted average price of $6.0707 per share.

Panacea-affiliated investment funds reported an insider sale of Atara Biotherapeutics, Inc. common stock. On January 12, 2026, Panacea Venture Healthcare Fund II, L.P. sold 80,554 shares of Atara common stock in an open-market transaction at a weighted average price of $6.0707 per share, with individual trades ranging from $5.9888 to $6.2838.

After this sale, Panacea Venture Healthcare Fund II, L.P. held 1,324,446 shares of Atara common stock indirectly for the reporting persons, and Panacea Opportunity Fund I, L.P. held an additional 48,736 shares. Panacea Innovation Ltd and James Huang are reporting persons because of their control of the general partners of these funds and may be deemed to share beneficial ownership of these holdings, although each disclaims such beneficial ownership.

Atara Biotherapeutics, Inc. (ATRA) has a shareholder filing a notice of proposed sales of common stock under Rule 144. The notice lists planned sales of 40,000 shares through Cantor Fitzgerald, 20,000 shares through Jefferies, and 20,554 shares through JP Morgan, all as common stock traded on NASDAQ, with an approximate sale date of 01/12/2026. The corresponding aggregate market values are stated as 235,200, 117,600.00, and 120,858.00, respectively. The filing notes that 7,210,235 shares of common stock are outstanding. The seller reports having acquired 1,405,000 shares of common stock on 08/15/2025, through multiple open market purchases from January 2025 through August 2025 and a registered direct financing in May 2025, paid in cash.

Atara Biotherapeutics, Inc. filed a current report describing two developments. The company provided a preliminary estimate of its cash, cash equivalents and short-term investments as of December 31, 2025, explaining that this early figure does not include all information needed to fully understand its year-end financial condition or fourth-quarter results.

Atara also reported that the U.S. Food and Drug Administration issued a Complete Response Letter for the Biologics License Application for EBVALLO™ (tabelecleucel). This means the application was not approved in its current form and further action would be required before EBVALLO could be considered again for U.S. approval. The company disclosed this regulatory and business update via a press release attached as an exhibit.

Atara Biotherapeutics (ATRA) President and CEO AnhCo Nguyen, who also serves as a director, reported an automatic sale of company common stock related to tax withholding on vested restricted stock units. On 11/17/2025, Nguyen sold 2,859 shares of common stock at a weighted average price of $13.186 per share and an additional 56 shares at a weighted average price of $13.188 per share. These transactions were carried out by a broker as part of a group sale for multiple employees to satisfy withholding tax liabilities tied to equity awards. Following the transactions, Nguyen directly beneficially owned 64,974 shares of Atara Biotherapeutics common stock.