Mismatched donor transplantation with post-transplantation cyclophosphamide for advanced cutaneous T-cell lymphoma: A single-center experience.

Abstract

e19045 Background: Mismatched blood or marrow transplantation (BMT) using post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GvHD) prophylaxis has not been well-studied in CTCL. Methods: We analyzed all patients above 18 years old with relapsed/refractory CTCL undergoing mismatched alloBMT. Primary endpoints included disease-free survival (DFS) and overall survival (OS). Secondary endpoints included time to neutrophil and platelet recovery, GvHD outcomes, and day +30 and day +60 donor chimerism. Results: From 2003-2020, 8 patients with relapsed CTCL underwent mismatched related (n=7) or mismatched unrelated (n=1) BMT. Mean age was 50 years (range 30-62); median time from diagnosis was 2 years (range 1.3-11.4). All had received prior treatment for their disease; two (25%) had received immune checkpoint inhibitors. Four (50%) were in partial response and 4 (50%) were in complete remission prior to BMT. Six received bone marrow grafts. Two received mobilized peripheral blood. Five (62.5%) achieved full donor chimerism by day 30 after BMT; 6 (75%) had achieved full donor chimerism by day 60 after BMT. One patient failed to engraft. Mean time to neutrophil recovery was 17.3 days (range 17-45); mean time to platelet recovery was 28.4 days (range 11-69). Median DFS was 11.3 months (95% confidence interval 2.6 months-not reached). Median OS was not reached. One patient developed grade 1 acute GvHD, and 2 patients developed mild chronic GvHD. There were no instances of transplantation-related mortality (TRM). At 1 year post-BMT, 4 patients had relapsed (50%), and no patients had died. At 3 years post-BMT, 7 patients had relapsed (87.5%), and 1 patient had died (12.5%). Conclusions: In our preliminary retrospective study, partially mismatched BMT with PTCy-based GVHD prophylaxis for advanced-stage CTCL was associated with minimal GvHD, no TRM, and good long-term survival. Investigation into relapse reduction is warranted.[Table: see text]