Kidney Transplantation Post-Chimeric Antigen Receptor (CAR) T-Cell Therapy in Multiple Myeloma.

Kidney disease affects approximately half of patients with multiple myeloma (MM), and kidney failure is associated with poor prognosis. Kidney transplantation is rarely pursued in MM owing to concerns of relapse, infection, and allograft rejection. However, advances in therapy, including B-cell maturation antigen-directed chimeric antigen receptor (CAR) T-cell therapy, have led to deep and durable hematologic responses, creating new opportunities for transplantation in select patients. We report a 71-year-old man with stage III MM and high-risk cytogenetics [del(17p)] who developed end-stage kidney disease requiring hemodialysis during his treatment course. Despite multiple lines of therapy, he had never achieved a deep remission until he received ciltacabtagene autoleucel (cilta-cel) CAR T-cell therapy, which led to minimal residual disease (MRD)-negative disease status. One year following CAR T-cell therapy, he underwent living donor kidney transplantation with basiliximab induction, and tacrolimus/mycophenolate maintenance immunosuppression. His course was complicated by hypogammaglobulinemia, cytopenia, BK viremia, and acute rejection, all managed with immunosuppression adjustment and supportive therapies. At 17 months post-transplant, allograft function remains stable (creatinine 1.8 mg/dL), and he has achieved an MRD-negative, complete hematologic remission. This case highlights both the feasibility and the challenges of kidney transplantation after CAR T-cell therapy in MM.