MM was eliminated from the bone marrow of patient 11 after CAR-BCMA infusion. (A) Before treatment, BCMA expression was uniform and strong on the MM cells of patient 11 (500×). (B) Flow cytometry showed strong uniform BCMA expression on CD19-negative malignant plasma cells (red), whereas BCMA expression was absent on CD19⁺ B lymphocytes (black). The plot shows a combination of the plasma cell gate (CD38^bright, CD138⁺, CD45^dim-negative) and the mature B-cell gate (CD45⁺, CD19⁺ lymphocytes). (C) Four hours after CAR-BCMA infusion, patient 11 became febrile. He was febrile until 5 days after the CAR T-cell infusion. The plot shows the maximum temperature for each day. The CRP was also elevated. (D) Before protocol treatment, patient 11 had a hypercellular bone marrow (hematoxylin and eosin ). Bone marrow cells were 80% plasma cells as shown by CD138 staining. (E) Four weeks after CAR T-cell infusion, the bone marrow was hypocellular, and bone marrow plasma cells were completely absent as shown by negative CD138 and BCMA staining. (F) Eight weeks after CAR T-cell infusion, the marrow was recovering with an overall cellularity of 20%; plasma cells remained absent. Magnification for D-F was 40×. (G) Before protocol treatment, the patient’s serum λ free light chains level was 95.9 mg/dL. The λ free light chains decreased to an undetectable level after CAR-BCMA T-cell infusion. Before treatment, the patient had an IgG λ M-protein level of 3.7 g/dL. The M-protein decreased after treatment. (H) Patient 11’s bone marrow contained an infiltrate of CD3⁺ T cells 4 weeks after CAR T-cell infusion. (I) Flow cytometry with PE-BCMA-Fc showed that 19% of bone marrow T cells were CAR-BCMA T cells 4 weeks after CAR T-cell infusion. The plot is gated on CD45⁺, CD3⁺ lymphocytes.