Atara Biotherapeutics, Inc. and Pierre Fabre Laboratories announced that data from the pivotal Phase 3 ALLELE study of tab-cel, approved in the European Union in adults and children two years of age and older with relapsed or refractory (r/r) Epstein-Barr virus positive post-transplant lymphoproliferative disease (EBV+ PTLD) following solid organ transplant (SOT) or hematopoietic cell transplant (HCT), were published for the first time online in TheLancet Oncology. As reported in The Lancet Oncology publication, the ALLELE study met its primary endpoint. 22 of 43 EBV+ PTLD patients achieved an objective response (51.2% objective response rate, or ORR).

Those that responded to tab-cel had longer survival, with an estimated one-year overall survival of 84.4% (95% CI: 58.9, 94.7) for responders versus 34.8% (95% CI: 14.6, 56.1) for non-responders. The median duration of response was 23.0 months and the median overall survival was 18.4 months. Tab-cel was well tolerated with no reports of tumor flare reaction, cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome, and no events of graft-versus-host disease or SOT rejection as related to tab-cel.

These interim data were previously presented [3] at the 2022 American Society of Hematology (ASH) Annual Meeting. These pivotal trial data are supported by a recent updated analysis from the October 2023 data cut of the ongoing ALLELE study that continued to demonstrate a statistically significant 49% ORR (p<0.0001), consistent durability of response, estimated OS, and favorable safety profile in the intended population for the proposed U.S. label. ln addition, real-world results from the multicenter Expanded Access Program study in Europe demonstrated an ORR of 66.7% in 24 EBV+ PTLD patients and were presented [4] at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.