FDA Declines Approval of Atara’s Cell Therapy for Rare Blood Cancer

January 13, 2026

The U.S. Food and Drug Administration (FDA) has declined to approve Atara Biotherapeutics’ cell therapy tabelecleucel for the treatment of Epstein-Barr virus positive post-transplant lymphoproliferative disease (EBV+ PTLD), a rare and often fatal blood cancer following organ or stem cell transplants.

In a Complete Response Letter (CRL) issued in January 2026, the FDA stated it is unable to approve the Biologics License Application (BLA) in its current form because the pivotal Phase 3 ALLELE trial is no longer considered adequate to demonstrate the therapy’s effectiveness for accelerated approval. The agency cited concerns over the trial’s design, conduct, and interpretability.

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Atara and its partner, Pierre Fabre Pharmaceuticals, expressed disappointment, stating that the decision contradicts extensive dialogue they have had with the FDA over the past five years and could have “far-reaching consequences for the development of rare disease treatments.”

The therapy tabelecleucel — marketed in Europe as Ebvallo — is designed as a T-cell immunotherapy to eliminate EBV-infected cells. It received approval in parts of Europe in 2022 but lacked U.S. approval, leaving patients currently treated with chemotherapy, rituximab, or surgery under standard care.

Following the news, Atara’s shares plummeted by more than 55% in early trading, reflecting investor concern about the regulatory setback and its impact on the company’s prospects in the rare disease space.

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This decision marks the latest regulatory challenge for Atara. The company’s development and review process for tabelecleucel has been complex, with initial CRLs and clinical holds previously tied to manufacturing compliance issues at a third-party facility.

With the current rejection, Atara is expected to engage further with the FDA to address the agency’s concerns, potentially through additional analysis or trial adjustments. The setback highlights ongoing challenges in gaining approval for complex cell therapies, especially for rare indications where clinical trial design and limited patient populations add layers of regulatory complexity.

Source: Reuters — US FDA declines to approve Atara’s therapy for rare blood cancer (January 12, 2026)