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The Food and Drug Administration has, for the second time, rejected Atara Biotherapeutics’ application for tabelecleucel, a potential treatment for adults and children battling Epstein-Barr virus-positive post-transplant lymphoproliferative disease. This setback, delivered January 12, 2026, throws a wrench into hopes for a novel therapy for a challenging condition, leaving doctors and patients wondering what comes next.
second Rejection Raises Questions About Trial Design
The FDA’s latest complete response letter centers not on safety or manufacturing, but on the design of the clinical trial supporting the application.
the FDA has issued a second complete response letter for Atara Biotherapeutics’ tabelecleucel.
Tabelecleucel is an allogeneic T-cell immunotherapy designed to target EBV-infected cells. The initial application was for adult and pediatric patients aged 2 years and older who had already tried at least one prior therapy, including a regimen containing anti-CD20. The application was resubmitted in 2025 after addressing initial concerns regarding Good Manufacturing Practice compliance, as identified in the first complete response letter. According to Atara, the FDA had not raised any concerns about the safety, efficacy, or design of the trial itself at that time.
However, the FDA now states that the single-arm ALLELE trial, a study published December 18, 2024, no longer provides sufficient evidence of efficacy. The agency expressed concerns that the trial’s design,execution,and data analysis could potentially obscure the true benefits of the treatment.
What is Post-Transplant Lymphoproliferative Disease (PTLD)? PTLD is a type of cancer that can occur after an organ transplant. It’s often caused by the Epstein-Barr virus (EBV) and can be difficult to treat.
Atara strongly disagrees with the FDA’s new position, stating it contradicts previous guidance, alignment on the clinical trial data, and the initial acceptance of the single-arm study design as appropriate for this patient population.
“We are surprised and disappointed by this FDA decision for EBV+ PTLD patients who have a meaningful unmet need, highlighted by tabelecleucel’s orphan drug designation and by the granting of breakthrough status at the time we submitted the ALLELE primary data,” said Cokey Nguyen, PhD, Atara’s president and CEO, in a company release. “The issues highlighted in the [complete response letter] were issues Atara and the FDA aligned on in previous reviews or communications.”
Nguyen added, “We strongly believe that tabelecleucel can bring significant benefit to post-transplant lymphoproliferative disease patients and look
