1366 - Tabelecleucel for Epstein-Barr Virus-Driven Posttransplant Lymphoproliferative Disease (EBV+ PTLD) After Treatment Failure in the Phase 3 ALLELE Trial

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Author Block: S. Nikiforow¹, K. Mahadeo², S. Chaganti³, A. Beitinjaneh⁴, S. Choquet⁵, D. Dierickx⁶, A. Ghobadi⁷, R. Valenti⁸, A. Friedetzky⁹, S. Roye⁹, R. Reshef¹⁰, S. E. Prockop¹¹, R. Baiocchi¹², ¹Dana-Farber Cancer Institute, Boston, MA, ²Duke University Medical Center, Durham, NC, ³University Hospitals Birmingham, Birmingham, United Kingdom, ⁴University of Miami, Miami, FL, ⁵University Hospital Pitié Salpêtrière, Paris, France, ⁶University Hospitals Leuven, Leuven, Belgium, ⁷Washington University, St Louis, MO, ⁸Pierre Fabre Laboratories, Boulogne-Billancourt, France, ⁹Institut de Recherche Pierre Fabre, Toulouse, France, ¹⁰Columbia University Irving Medical Center, New York, NY, ¹¹Boston Children's Hospital, Boston, MA, ¹²The Ohio State University, Columbus, OH
*Purpose: Tabelecleucel, an allogeneic EBV-specific cytotoxic T-cell therapy, is being investigated for relapsed/refractory EBV+ PTLD after hematopoietic cell transplant (HCT) or solid organ transplant (SOT) in the ALLELE trial (NCT03394365). We report subgroup analyses based on prior treatment.
*Methods: HCT recipients who failed rituximab treatment and SOT recipients who failed rituximab +/- chemotherapy (SOT-RC or SOT-R) received intravenous tabelecleucel (2x10⁶ cells/kg) on days 1, 8, and 15 in 35-day cycles. Key endpoints were objective response rate (ORR), time to response (TTR), and overall survival (OS). Safety and disease assessments were conducted up to 2 years after treatment, and OS was monitored up to 5 years.
*Results: As of Sept 10, 2024, 29 HCT recipients and 57 SOT recipients (36 SOT-RC, 21 SOT-R) were enrolled and received tabelecleucel. Median (range) age was 42.6 (2.7-81.5) years. ORR (95% CI) was 48% for HCT (29%, 68%), 47% for SOT (34%, 61%), 44% for SOT-RC (28%, 62%) and 52% for SOT-R (30%, 74%). Median (range) TTR was 1.0 (0.6-9.0) and 2.1 (0.7-4.7) months for HCT and SOT treatment responders. Median (95% CI) OS was 18.6 (5.6, not estimable [NE]) months for HCT, NE (9.0, NE) months for SOT, 21.6 (5.0, NE) months for SOT-RC, and NE (5.5, NE) months for SOT-R. The 1-year OS rate (95% CI) was 54% (33%, 71%) for HCT and 63% (48%, 74%) for SOT. For treatment responders, the 1-year OS rate (95% CI) was 71% (41%, 88%) for HCT, 88% (68%, 96%) for SOT, 86% (53%, 96%) for SOT-RC, and 91% (51%, 99%) for SOT-R. The 2-year OS rate (95% CI) was 63% (32%, 83%) for HCT and 79% (56%, 91%) for SOT. Serious adverse events (SAEs) were reported in 59% of HCT and 67% of SOT recipients. SAEs were related to study treatment in 3% of HCT and 12% of SOT recipients. Nontreatment-related fatal SAEs occurred in 17% of HCT and 16% of SOT recipients. Special interest SAEs included 2 cases of graft vs host disease (GvHD), 1 chronic case of GvHD, and 1 case of maculopapular rash in HCT recipients; 1 case of pyrexia in an SOT recipient was possibly study treatment related. The safety profile was favorable without any new concerns.
*Conclusions: These results confirm the efficacy of tabelecleucel, with ORRs of 48% in HCT and 47% in SOT recipients with R/R EBV+ PTLD. The ORR was favorable in SOT-R compared with SOT-RC.