Atara And Pierre Fabre Resubmit Ebvallo After FDA Reopened A Single-Arm Path

Atara Biotherapeutics and Pierre Fabre Pharmaceuticals have resubmitted Ebvallo to the FDA, reopening a review process that has already produced two complete response letters for the cell therapy. The candidate, also called tabelecleucel, is being pursued for patients 2 years and older with Epstein-Barr virus-positive posttransplant lymphoproliferative disease, a rare and potentially life-threatening complication that can occur after solid organ transplant.

The filing matters because the FDA previously reversed itself on what evidence would be acceptable. In January this year, the agency said the single-arm Phase 3 ALLELE study was insufficient to support the biologics license application, despite what Atara said had been years of documented alignment. Then in May, the FDA agreed that a single-arm study "using an appropriate historical control applicable to the trial population" may serve as an adequate and well controlled study for the application.

The road here

Ebvallo’s first rejection was tied solely to inspection findings at a third-party manufacturer, according to Atara’s January 2025 announcement. In the second complete response letter, issued in January this year, the FDA said the trial’s interpretability was confounded by study design, conduct and analysis, according to Atara. The regulator also confirmed that the GMP compliance issues had been satisfactorily resolved and raised no safety issues.

That sequence has made Ebvallo part of a broader pattern cited by biotechs, particularly in rare disease, that said FDA expectations shifted during Marty Makary’s tenure as commissioner. BioSpace reported that uniQure, REGENXBIO, Biohaven and Capricor Therapeutics also voiced similar frustrations, and that some companies were later told after leadership changes this spring that their current data were sufficient after all.

What is in the new filing

Atara and Pierre Fabre are not relying only on the FDA’s apparent return to a single-arm path. The resubmission includes an updated data package with additional patients and longer follow up from ALLELE, plus supplemental data from expanded access programs, a separate clinical study, and commercial experience in Europe.

Mizhuo analysts said the filing is a positive step in terms of alignment with the FDA on a path forward. The firm added that, given the additional data included, the application will most likely be treated as a Class 2 BLA resubmission, which could imply a target FDA action date of March 29, 2027.

For Atara, the commercial stakes are also defined. Under the companies’ November 2023 commercialization agreement, Atara is eligible for a $31 million milestone payment upon Ebvallo’s FDA approval. The larger signal for the sector is that regulatory reversals can force companies to rebuild submissions even after being told their dataset was acceptable, raising execution risk well beyond the underlying clinical results.