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.

7521 Background: Pts with relapsed or refractory (r/r) EBV + post-transplant lymphoproliferative disease (PTLD) in Europe have had historically poor overall response rates and median overall survival (OS) with no approved treatment options. Tabelecleucel, an off-the-shelf, allogeneic EBV-specific T-cell immunotherapy has shown clinical benefit and favorable safety profile in the treatment of EBV + PTLD failing rituximab ± chemotherapy (Prockop EBMT 2021, ATC 2021, ASH 2022). Its recent European marketing authorization (EMA) represents the first approval of an allogenic T-cell immunotherapy globally. Methods: Atara Bio supported expanded access requests for tabelecleucel in Europe. Here we report updated effectiveness and safety data for r/r EBV + PTLD pts who provided consent for research between Sep 2020 and Dec 2022. Results: 74 EAP requests were received from 10 countries for pts with r/r EBV + diseases. 27 EBV + PTLD pts consented to secondary use of data and 24 pts had received ≥1 dose of tabelecleucel, including 4 pts with primary central nervous system (PCNS) PTLD. 16 of 24 (66.7%) PTLD pts achieved a partial (PR) (33.3%) or complete (CR) (33.3%) response, with median time to response (TTR) of 1.0 mo (0.8–2.2). Response rate for PCNS PTLD pts was 75% (1 CR, 2 PR). 1-yr OS Kaplan–Meier (KM) estimate rates were 73.7% (95% CI: 47.3, 88.3) overall, 87.5% in allogeneic hematopoietic stem cell transplant (HCT) and 66.5% in solid organ transplant (SOT), with a median follow-up time of 9.9 (2.4–13.9) and 6.0 (0.7–18.0) mo, respectively. Serious treatment-emergent adverse events (TESAEs) were reported in 7 (29.2%) pts, including 1 fatal event of disease progression. Predefined risks for tabelecleucel were reported in 3 pts; 1 (4.2%) SOT pt had a TESAE of liver transplant rejection (grade 2) and 2 (8.3%) HCT pts had non-serious TEAEs of chronic graft-versus-host disease (grade 1 and 2). No cases of cytokine release syndrome or tumor flare reaction were reported. No AEs were reported as related to tabelecleucel by the treating physician. Conclusions: These updated real-world results for pts with r/r EBV+ PTLD post-HCT or post-SOT treated in the European EAP continue to reinforce the favorable risk:benefit profile of tabelecleucel and are in line with clinical study data supporting its recent EMA approval. [Table: see text]