Atara Biotherapeutics Inc. (NASDAQ: ATRA) experienced a steep decrease in its stock price on Monday, as investors reacted to the U.S. Food and Drug Administration's refusal to approve its Biologics License Application (BLA) for EBVALLO (tabelecleucel). The trading session saw a volume of approximately 2.75 million shares, markedly surpassing the stock's usual average daily volume of 92,283 shares, according to Benzinga Pro data.
The FDA’s decision was formalized through a Complete Response Letter (CRL), which denied approval for EBVALLO’s use in treating patients aged two and older, both adult and pediatric populations, with Epstein-Barr virus-positive post-transplant lymphoproliferative disease (EBV+ PTLD). This disease arises as a grave complication post-organ or stem cell transplantation, marked by unchecked B-cell proliferation driven by Epstein-Barr virus due to immunosuppressive therapies.
According to the CRL, the FDA is currently unable to approve the BLA in its existing submission. Notably, Atara had previously resubmitted the application in 2025 following discussions with the FDA that targeted resolution of issues flagged in an earlier CRL from January 2025. At that time, the deficiency pertained solely to Good Manufacturing Practice (GMP) compliance, with no concerns raised regarding the drug's safety, efficacy, or study design.
In the most recent CRL, the FDA acknowledged that the previously identified GMP shortcomings had been satisfactorily addressed by Atara. Moreover, no new safety issues were cited. However, the regulatory body reversed its prior position concerning the ALLELE clinical trial—the single-arm study accepted earlier as sufficient to support accelerated approval.
The FDA now states that the ALLELE trial’s design, execution, and analysis obstruct clear interpretation of the results. This position contrasts with earlier agency guidance and prior alignment with Atara on the appropriateness of a single-arm trial for this particular patient group. The reversal undermines the evidentiary basis for EBVALLO’s effectiveness in treating EBV+ PTLD.
Following the updated CRL, Atara transferred the BLA to Pierre Fabre Pharmaceuticals Inc., a U.S. subsidiary of Pierre Fabre Laboratories, in November 2025. Pierre Fabre has expressed its intention to request a Type A meeting with the FDA promptly, anticipating the meeting will be scheduled within 45 days. Both Pierre Fabre and Atara aim to engage with the FDA quickly in an effort to define a clear regulatory pathway that could enable accelerated approval of EBVALLO in a timely manner.
In parallel corporate developments, Atara amended its commercialization agreement with Pierre Fabre Medicament in December 2025. This amendment aims to reduce the financial burden associated with reconstructing commercial inventory in the United States. Specifically, Atara agreed to lower the milestone payment triggered upon BLA approval to $31 million. In exchange, Atara secured the right to receive an additional milestone payment of up to $15 million.
Financially, Atara reported holding roughly $8.5 million in cash, cash equivalents, and short-term investments as of December 31, 2025. The company also made significant operational adjustments during 2025, including an approximately 90% reduction in headcount and the transfer of all tab-cel-related activities and associated costs to Pierre Fabre Laboratories. These moves reflect efforts to streamline operations in response to the regulatory setback.
Market reaction was swift and pronounced. At the time of reporting, Atara’s stock was down 52.74%, trading at $6.46 per share. This decline marks a considerable drop in market valuation following the FDA’s rejection.
| Ticker | Price | Change |
|---|---|---|
| ATRA | $6.46 | -52.74% |
As Atara and Pierre Fabre pursue next steps with the FDA, the company and its investors face significant uncertainty regarding the path to regulatory approval and commercial viability of EBVALLO.