[T-cell lymphoma arising during epcoritamab therapy for relapsed diffuse large B-cell lymphoma].

A 78-year-old woman was diagnosed with diffuse large B-cell lymphoma (DLBCL) in 2021. She experienced early relapse after six cycles of R-THP-COP chemotherapy, but subsequently achieved complete response after four cycles of R-ESHAP. Regular follow-up care was continued. In May 2024, an elevated soluble interleukin-2 receptor (sIL2R) level was noted, and PET-CT revealed signs suggestive of relapse. Treatment with epcoritamab, a bispecific antibody targeting CD20 and CD3, was initiated. While the therapy showed initial efficacy, the patient developed a fever at the beginning of the third treatment cycle, necessitating hospitalization. Upon admission, she exhibited altered mental status, and subsequent investigations, including bone marrow biopsy and cerebrospinal fluid analysis, confirmed the presence of peripheral T-cell lymphoma (PTCL, not otherwise specified: PTCL-NOS). The clinical course was aggressive, and the patient died of the disease on the 13th day of hospitalization. This case highlights the potential for aggressive T-cell lymphoma to emerge during bispecific antibody therapy, a phenomenon that has also been noted in the context of CAR-T cell therapy.