ATLANTA, GA – – (Globe Newswire – March 24, 2026) – – A shareholder class action lawsuit has been filed against Atara Biotherapeutics, Inc. (“Atara”) (NASDAQ: ATRA). The lawsuit alleges that Defendants issued false and misleading statements and/or failed to disclose material adverse facts regarding Atara’s business, operations, and prospects, including allegations that: (i) certain manufacturing issues, as well as deficiencies inherent in the ALLELE study, made it unlikely that the FDA would approve the tabelecleucel Biologics License Application; (ii) accordingly, tabelecleucel’s regulatory prospects were overstated; (iii) the aforementioned manufacturing issues also subjected Atara to a heightened risk of regulatory scrutiny, as well as jeopardized its ongoing clinical trials; and (iv) all the foregoing was likely to have a significant negative impact on Atara’s business and financial condition.

If you purchased Atara shares between May 20, 2024 and January 9, 2026, and experienced a significant loss on that investment, you are encouraged to discuss your legal rights by contacting Corey D. Holzer, Esq. at cholzer@holzerlaw.com, by toll-free telephone at (888) 508-6832, or by visiting the firm’s website at www.holzerlaw.com/case/atara-biotherapeutics/ for more information.

The deadline to ask the court to be appointed lead plaintiff in the case is May 22, 2026.