Atara Biotherapeutics experienced a 20% increase in its stock price on Wednesday following a report by STAT News that suggested inconsistencies within the U.S. Food and Drug Administration (FDA) may have contributed to the recent rejection of its cell therapy, Ebvallo.
The company, based in California, had sought approval for Ebvallo as a treatment for children aged two years and older with post-transplant lymphoproliferative disease (PTLD) who test positive for the Epstein-Barr virus (EBV). The FDA denied this application last month. According to STAT News, which reviewed the agency’s complete response letter sent to Atara and its partner Pierre Fabre, the FDA stated that the submission was “insufficient to demonstrate substantial evidence of effectiveness.”
A former FDA employee told STAT that this rationale differed from earlier internal reviews conducted in late 2024 and early 2025. Those reviewers reportedly found Ebvallo’s data adequate and indicated that while there were “contentious” debates over the application, manufacturing facility issues were seen as the main barrier to approval at that time.
The same former staff member described the rejection as a “complete reversal that I can’t help but think was due to the FDA’s new leadership.” The Center for Biologics Evaluation and Research, led by Vinay Prasad, issued the decision regarding Ebvallo.
BioSpace has contacted the Department of Health and Human Services for comment.
Atara's shares closed at $5.06 on Wednesday, up from $4.21 at Tuesday's close.
Ebvallo is an allogeneic T cell immunotherapy already approved in Europe since 2022 for treating EBV-positive ETLD. The therapy targets B lymphocytes infected with EBV and brings them into proximity with T cells capable of destroying these diseased cells. For its U.S. submission, Atara included pivotal data from more than 430 treated patients showing an objective response rate of 48.8%. In January 2025, however, the FDA declined approval due to manufacturing concerns. Later that year in July, Atara transferred full responsibility for Ebvallo to Pierre Fabre.
The FDA accepted a refiled application but ultimately rejected it last month.
