CAR T-Cell Therapy for Richter’s Syndrome and Central Nervous System PTLD After Solid Organ Transplantation: Two Case Reports

Richter’s transformation to diffuse large B-cell lymphoma (DLBCL) represents a rare and aggressive malignancy, typically associated with poor prognosis and limited therapeutic options. We report the case of a 72-year-old patient with rapidly progressing, high-tumor burden disease after several intensive chemotherapy regimens. The patient subsequently received chimeric antigen receptor (CAR) T-cell therapy, achieving a complete response just one month after infusion, which was sustained at the 18-month follow-up. This positive outcome highlights the potential of CAR T cells in refractory, high-risk rare cases that are often excluded from clinical trials. In addition, we describe a second case involving a 48-year-old patient with post-transplant lymphoproliferative disorder (PTLD) after solid organ transplantation complicated by central nervous system (CNS) involvement, who similarly attained complete remission (CR) following CAR T-cell therapy. Together, these cases underscore the efficacy and versatility of CAR T-cell therapy in rare and challenging DLBCL presentations, providing further clinical evidence to support its use in high-risk patient populations. PEER REVIEWED ARTICLE **Peer reviewers:** Prof. Dr Dr Dominik Schneidawind, University Hospital Zurich, Zurich, Switzerland One anonymous peer reviewer Received on November 10, 2025; accepted after peer review on December 05, 2025; published on December 08, 2025.