Safety and efficacy of B cell maturation antigen-directed CAR T-cell therapy in patients with relapsed/refractory multiple myeloma and concurrent light chain amyloidosis.

Clinical trials evaluating chimeric antigen receptor (CAR) T-cell therapy in relapsed/refractory multiple myeloma (RRMM) have typically excluded patients with AL amyloidosis. As a result, there are limited data on the safety and efficacy of CAR T-cell therapy in this patient population. We retrospectively reviewed eight consecutive patients with RRMM and AL amyloidosis who were treated with standard of care CAR T-cell therapy. Cytokine release syndrome was seen in 75% of patients (grade ≥3: 0%) and immune effector cell-associated neurotoxicity syndrome (grade 1) in only one patient. Low-grade cytopenias were common (any grade/grade ≥3: neutropenia 62.5%/37.5%, anemia 37.5%/0%, thrombocytopenia 25%/0%). CAR T-cell therapy led to rapid and deep responses with a median time to best response of 43 days and a hematologic very good partial response or better rate of 62.5%. Overall, we found that commercial CAR T-cell therapy was feasible, and effective in patients with RRMM and concurrent AL amyloidosis.