As partners Atara Biotherapeutics and Pierre Fabre Laboratories work to grow the reach of their novel T-cell immunotherapy Ebvallo, a manufacturing-related hitch has tripped up their ambition to launch the off-the-shelf cell therapy in the U.S.

Thursday, Atara said the FDA has issued a complete response letter for its biologics license application "solely related to inspection findings" at a third-party manufacturer. The company didn't name the manufacturer involved, and it said the FDA's letter didn't flag issues related to the drug's actual manufacturing process.

Instead, the agency made "observations as part of a standard pre-license inspection" of the facility, according to a press release. In rejecting the drug application, the FDA didn't raise concerns with efficacy or safety data nor did it request new trials, Atara stressed.

“Once the third-party manufacturer GMP compliance issues have been adequately addressed, we will file for a resubmission, which we would expect to be potentially approved within six months of resubmission," Atara CEO Cokey Nguyen, Ph.D., explained in a statement.

In the meantime, Atara says it has hired a financial advisor to weigh potential strategic options such as a merger or sale of assets. It's also secured $15 million in credit from Redmile Group to fund the activities needed to secure FDA approval. 

The company's cash, cash equivalents and short-term investments totaled about $43 million at the end of 2024, according to a preliminary estimate.

Atara and Pierre Fabre are seeking approval for Ebvallo to treat patients two years and older with Epstein-Barr virus positive post-transplant lymphoproliferative disease (EBV+PTLD) who've received at least one prior therapy. The EBV-specific T-cell immunotherapy scored approval in Europe in late 2022, becoming the first “off-the-shelf” T-cell therapy approved anywhere.

While autologous cell therapies leverage patients' own cells—which are harvested, reengineered and then reinfused—to treat disease, allogenic cell therapies utilize cells from healthy donors. This approach aims to avoid some of the common pitfalls seen in earlier cell therapy launches related to logistics and manufacturing constraints.

As for its Pierre Fabre collaboration, Atara first linked up with the French biopharma in 2021 in a commercialization agreement covering Europe, the Middle East, Africa and certain other markets. Then in 2023, Pierre Fabre took on the drug's U.S. rights in a deal worth up to $640 million.

Atara remains eligible to receive a $60 million milestone payment from Pierre Fabre upon Ebvallo's potential U.S. approval, the company said Thursday.