The rejection of Atara Biotherapeutics’ Ebvallo in January was a “complete reversal” of the conesensus FDA reviewers had come to, according to a former agency employee, who said manufacturing problems were the only approvability barrier for the drug.
Atara Biotherapeutics saw a 20% stock jump on Wednesday after STAT News reported that inconsistencies at the FDA may have had something to do with the rejection of its cell therapy Ebvallo last month.
The California-based biotech was proposing Ebvallo’s use for children two years and older diagnosed with post-transplant lymphoproliferative disease (PTLD) who were positive for the Epstein-Barr virus (EBV). The FDA denied the application last month. In its complete response letter to Atara and partner Pierre Fabre, the regulator noted that the package was “insufficient to demonstrate substantial evidence of effectiveness,” according to STAT, which was able to access the communique.
This reasoning, however, is in contrast with what reviewers had landed on a year earlier, a former FDA employee told STAT. Internal reviewers in late 2024 and early 2025 found that Ebvallo’s data were enough and that despite “contentious” internal debates over the application, the only approvability issue in the end was problems at a manufacturing facility.
The rejection, the former staffer continued, represented a “complete reversal that I can’t help but think was due to the FDA’s new leadership.” The CRL for Ebvallo was issued by the Center for Biologics Evaluation and Research, currently under the leadership of Vinay Prasad.
BioSpace has reached out to the Department of Health and Human Services for comment.
Atara closed Wednesday’s trading session at $5.06 apiece, up 20% from its previous closing price of $4.21.
Ebvallo is an allogeneic T cell immunotherapy that has been approved in Europe since 2022 for the treatment of EBV-positive ETLD. The medicine works by selectively targeting B lymphocytes infected with EBV and bringing them close to T cells that could, in turn, destroy these diseased cells. For the U.S. application, Atara backed Ebvallo’s original package with pivotal data covering more than 430 treated patients, showing a 48.8% objective response rate. In January 2025, however, the FDA declined to approve Ebvallo, citing manufacturing issues. Months later, in July last year, Atara offloaded the therapy completely to Pierre Fabre, which assumed responsibility for Ebvallo’s drug application.
The regulator accepted the refiled application, which ultimately ended in its rejection last month.
