Early deep response to cilta-cel as 2nd CAR T-Cell therapy after CELMoD-based bridging for advanced multiple myeloma

Abstract Chimeric antigen receptor (CAR) T-cell therapy has emerged as an innovative and highly effective treatment option for patients with relapsed/refractory multiple myeloma (RRMM). This effect is based on redirecting modified T-cells towards plasma cells expressing target antigens, specifically B cell maturation antigen (BCMA). Despite high initial response rates, disease relapse remains a major clinical challenge. Therapeutic options after progression following prior BCMA-directed CAR T-cell therapy are limited, and prognosis is often poor. We report on a 58-year-old male with high-risk IgA kappa multiple myeloma who was heavily pretreated and received idecabtagene vicleucel as sixth-line therapy, achieving a deep response lasting for approximately one year. Following disease progression, the patient received bridging therapy with mezigdomide,carfilzomib, and dexamethasone, followed by a second BCMA-directed CAR T-cell infusion using ciltacabtagene autoleucel. Previous whole genome sequencing had confirmed preserved BCMA expression. Early post-infusion assessment showed a rapid and profound response, with marked declines in serum IgA and free kappa light chains, accompanied by robust CAR T-cell expansion. Treatment-related toxicities were manageable, including grade II cytokine release syndrome and prolonged cytopenias, without evidence of neurotoxicity. This case provides additional knowledge that retreatment with BCMA-directed CAR T-cell therapy may be feasible and clinically effective in heavily pretreated multiple myeloma, particularly after a durable response to initial CAR T-cell therapy. Bridging therapy and the use of an alternative CAR T-cell construct may further improve outcomes. Prospective studies are needed to define optimal patient selection and treatment sequencing in this setting.