Treatment course of patients receiving serial BCMA-targeted therapies. CAR T-cell expression and serum free light chain (SFLC) expression (A) and sBCMA and anti-CAR antibodies (B) in patient #1 receiving 2 infusions of BCMA-targeted CAR T cells and belantamab. CAR T-cell expression and circulating plasma cells (C) and sBCMA and anti-CAR antibodies (D) in patient #2 receiving 1 infusion of BCMA-targeted CAR T cells followed by belantamab.