Tabelecleucel Shows Activity and Favorable Safety for Pediatric Patients With R/R EBV-Positive Post-Transplant Lymphoproliferative Disease: ALLELE Trial
Key Clinical Summary
- Population and Design: Phase 3 ALLELE trial subgroup of 12 pediatric patients (< 17 y) with R/R EBV+ PTLD following hematopoietic cell (n = 3) or solid organ transplantation (n = 9); patients received tabelecleucel 2 × 10⁶ cells/kg IV on days 1, 8, and 15 of each 35-day cycle.
- Efficacy: ORR 50% (CR 4; PR 2), consistent with the overall study ORR (47.7%); median TTR 1.6 mo, and 2 patients achieved durable responses > 6 mo; at 5.2-month median follow-up, 5 of 6 responders remained alive and progression-free.
- Safety: Serious AEs in 6 patients (2 treatment-related); no cytokine release syndrome, neurotoxicity, GVHD, or transplant rejection observed. Findings support tabelecleucel as an effective and well-tolerated off-the-shelf cellular therapy for pediatric R/R EBV+ PTLD with historically poor outcomes.
Tabelecleucel demonstrated clinically meaningful activity with a favorable safety profile among pediatric patients with relapsed/refractory (R/R) Epstein–Barr virus (EBV)-positive post-transplant lymphoproliferative disease (PTLD), according to a subgroup analysis from the phase 3 ALLELE trial.
These results were presented by Sonali Chaudhury, MD, Lurie Children's Hospital, Chicago, Illinois, at the 2025 ASH Annual Meeting & Exposition.
Researchers conducted a multicenter, open-label phase 3 trial evaluating tabelecleucel among pediatric patients R/R EBV+ PTLD following hematopoietic cell transplantation (HCT) or solid organ transplantation (SOT).
Tabelecleucel is an off-the-shelf allogeneic EBV-specific cytotoxic T-cell therapy. Patients received tabelecleucel intravenously at a dose of 2 × 10⁶ cells/kg on days 1, 8, and 15 of each 35-day cycle.
The primary end point was objective response rate (ORR), with secondary endpoints including complete response (CR), partial response (PR), time to response (TTR), duration of response (DOR), and overall survival (OS).
Overall, 12 pediatric patients younger than 17 years of age were included in this analysis, of which 3 had undergone HCT and 9 SOT. The median age was 8.8 years (range, 2.7 to 16.8). Most pediatric patients had advanced disease at diagnosis, with 9 presenting with stage III or IV disease, and all had extranodal involvement.
Among patients, the ORR was 50.0%. After a median follow-up of 5.2 months, 50% of pediatric patients were alive, including 5 responders and 1 non-responder. The pediatric ORR was consistent with that observed in the overall study population (47.7%).
A CR was met by 4 patients, 1 with prior HCT and 3 with prior SOT and a PR in 2 patients, 1 with prior HCT and 1 with SOT. The median time to response among responders was 1.6 months (range, 0.9 to 4.7). A durable response lasting longer than 6 months was achieved by 2 responders, and at the time of data cutoff, 5 of 6 responders remained alive without disease progression.
In terms of safety, serious adverse events occurred among 6 patients, with only 2 considered treatment related. There were no cases of cytokine release syndrome, immune effector cell–associated neurotoxicity, graft-versus-host disease, tumor flare reactions, or transplant rejection.
The researchers concluded, “These findings support the use of tabelecleucel in pediatric patients with R/R EBV+ PTLD who have historically poor survival and very limited treatment options. The safety profile of tabelecleucel was favorable and no new concerns were identified for the pediatric population.”
Source:
Chaudhury S, Reshef R, Nikiforow S, et al. Subgroup analysis in pediatric patients from the phase 3 study of tabelecleucel for allogeneic or solid organ transplant recipients with Epstein–Barr virus-driven post-transplant lymphoproliferative disease after failure of rituximab or rituximab and chemotherapy (ALLELE). Dec 6-9, 2025; Orlando, FL. Abstract: 5488
