On June 5, 2023 Atara Biotherapeutics, Inc. (Nasdaq: ATRA), a leader in T-cell immunotherapy, leveraging its novel allogeneic Epstein-Barr virus (EBV) T-cell platform to develop transformative therapies for patients with cancer and autoimmune diseases, reported updated effectiveness and safety data for tabelecleucel (tab-cel or EBVALLO) from the multicenter Expanded Access Program (EAP) study in Europe (Press release, Atara Biotherapeutics, JUN 5, 2023, View Source [SID1234632460]). The results will be featured in a poster presentation at the 2023 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting taking place June 2-6 in Chicago.

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Atara supported 27 EAP requests in Europe for patients 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). 24 EBV+ PTLD patients, 16 SOT recipients and eight HCT recipients, consented to use of data and received at least one dose of tab-cel, including four patients with EBV+ primary central nervous system (PCNS) PTLD.

An objective response rate (ORR) of 66.7% (16/24) was observed for both SOT and HCT groups (95% CI: 44.7, 84.4), 56.3% (9/16) for patients following SOT (95% CI: 29.9, 80.2) and 87.5% (7/8) for HCT patients (95% CI: 47.3, 99.7) with a best overall response of Complete Response (CR; 33.3%; n=4, SOT, n=4, HCT) or Partial Response (PR; 33.3%; n=5, SOT, n=3, HCT).

"These real-world results affirm the favorable risk-benefit profile seen in the pivotal Phase 3 ALLELE study which supported tab-cel as the first-ever allogeneic T-cell immunotherapy approved," said AJ Joshi, MD, Chief Medical Officer at Atara. "Tab-cel was well tolerated and delivered a one-year survival rate of nearly 91% in responders, reinforcing its potential to address an urgent unmet medical need for EBV+ PTLD patients."

The median time to response (TTR) in all patients was 1.0 month (range: 0.8–2.2). Of the subgroup of patients with EBV+ PCNS PTLD, three out of four (75%; 95% CI: 19.4, 99.4) treated patients achieved a response with one CR and two PRs.

One-year survival rates were 73.7% (95% CI: 47.3, 88.3) across both groups, 66.5% for SOT patients (95% CI: 32.7, 86.2) and 87.5% for HCT patients (95% CI: 38.7, 98.1). EBV+ PTLD patients responding to tab-cel had longer one-year survival compared to the non-responders, with a one-year survival rate of 90.9% (95% CI: 50.8, 98.7) versus 34.3% (95% CI: 4.8, 68.5) for non-responders.

"These data provide important insights on the effectiveness of EBVALLO in the real-world treatment setting," said Dr. Sylvain Choquet, Head of the Clinical Hematology Department at Pitié-Salpêtrière, Paris, France. "Findings further reinforce the clinical profile already established for EBVALLO, underscoring its potential as new treatment option for an ultra-rare and highly aggressive form of lymphoma that occurs in some transplant patients."

Safety findings in this real-world program were consistent with previously published data from clinical studies. All treatment-emergent adverse events (TEAEs) were assessed as unrelated to tab-cel by the treating physician and were consistent with patients’ underlying diseases. Detailed results on baseline demographics and disease characteristics, and additional safety data including tab-cel exposure details, will be shared at the conference.

Pierre Fabre leads all commercialization, distribution, medical and regulatory activities for EbvalloTM in Europe, Middle East, Africa and other selected markets.

Poster Presentation Details:

Title: Effectiveness and safety outcomes in patients with EBV+ PTLD treated with allogeneic EBV-specific T-cell immunotherapy (tabelecleucel) under an expanded access program (EAP) in Europe
Presenting Author: Ralf Trappe, M.D., DIAKO Evangelisches Diakonie-Krankenhaus Bremen, Bremen, Germany
Date & Time: June 5, 2023, at 8-11 a.m. CDT / 6-9 a.m. PDT
Abstract Number: 7521
Poster Number: 72
Session: Hematologic Malignancies—Lymphoma and Chronic Lymphocytic Leukemia
Location: McCormick Place Convention Center Chicago, Hall A