Atara Biotherapeutics Hit With Investor Class Action as Firms Press May 22 Lead-Plaintiff Deadline

Overview

• Multiple plaintiff firms this week highlighted a federal class action for Atara investors and reminded shareholders they have until May 22, 2026 to seek appointment as lead plaintiff.
• The putative class covers purchases from May 20, 2024 to January 9, 2026 and alleges the company overstated the approval prospects of its EBVALLO tabelecleucel therapy.
• The complaint points to FDA findings that the single‑arm ALLELE study was not adequate for accelerated approval because its design, conduct, and analysis undermined how the results could be interpreted.
• Atara also disclosed a clinical hold on January 21, 2025 after inspectors flagged unresolved good manufacturing practice problems at a third‑party plant, which the notices say increased regulatory risk.
• Shares fell sharply after these disclosures, including a 56.99% drop on January 12, 2026 following the FDA’s Complete Response Letter, and investors are told no class has been certified and representation is on contingency.