Atara Biotherapeutics Faces Securities Class Action as Investors Race Toward May 22 Lead Plaintiff Deadline

Overview

• Plaintiffs filed a securities class action in the Central District of California, docketed as 26-cv-03083, on behalf of buyers of Atara shares from May 20, 2024 to January 9, 2026, with a lead plaintiff deadline of May 22, 2026.
• The complaint alleges executives made false or misleading statements by downplaying manufacturing problems and weaknesses in the single-arm ALLELE study, which allegedly overstated tabelecleucel’s chances at the FDA and put trials and finances at risk.
• Regulatory setbacks began on January 16, 2025, when the FDA issued a Complete Response Letter tied to observations from a pre-license inspection of a third-party manufacturing site for EBVALLO.
• After a January 21, 2025 FDA clinical hold over unresolved good manufacturing practice issues, the agency issued another CRL on January 12, 2026 saying the ALLELE data were no longer adequate for accelerated approval and were confounded by trial design, conduct, and analysis, which drove a 56.99% stock drop to $5.88.
• Law firms including Pomerantz, Faruqi & Faruqi, and the Law Offices of Howard G. Smith are urging investors to seek lead-plaintiff status as the suit pursues damages under Sections 10(b) and 20(a) and Rule 10b-5.