Abstract
BACKGROUND: Epcoritamab, a bispecific CD3×CD20 antibody, offers a promising treatment for relapsed diffuse large B-cell lymphoma (DLBCL). Its efficacy and safety after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain unclear. CASE REPORT: In a 64-year-old man with relapsed DLBCL, epcoritamab showed limited efficacy, achieving stable disease prior to allo-HSCT; nevertheless, re-administration after donor T-cell engraftment resulted in a complete response without severe graft-versus-host disease or cytokine release syndrome. CONCLUSIONS: This observation suggests that donor-derived T-cell redirection with epcoritamab may enhance antitumor efficacy while maintaining safety in the post-transplant setting, supporting its potential as a salvage therapy for relapsed DLBCL post-allo-HSCT.