CAR-BCMA T cells became more differentiated after infusion. For A-L, cells from patient 10 are shown. All plots are gated on live lymphocytes, and the numbers on the plots are the percentages of cells in the indicated regions of the plots. Staining for CAR-BCMA was performed with PE-BCMA-Fc. All postinfusion samples were PBMCs that were collected 16 days after CAR-BCMA T-cell infusion. (A) Cells from the time of infusion (infusion cells) were stained for CD3 and CAR-BCMA. (B) This plot is gated on the CD3⁺CAR⁺ infusion cells. (C) Postinfusion cells were stained for CD3 and CAR-BCMA. (D) This plot is gated on postinfusion CD3⁺CAR⁺ cells. CAR T cells after infusion were predominantly CD8⁺. (E) CCR7 and CD45RA expression of CD3⁺CD4⁺CAR⁺ infusion cells is shown. (F) CCR7 and CD45RA expression of CD3⁺CD8⁺CAR⁺ infusion cells is shown. (G) CCR7 and CD45RA expression of postinfusion blood CD3⁺CD4⁺CAR⁺ T cells. (H) CCR7 and CD45RA expression of postinfusion blood CD3⁺CD8⁺CAR⁺ T cells. (I) CD3⁺CD8⁺CAR⁺ infusion cell PD-1 and CD28 expression are shown. (J) PD-1 and CD28 expression is shown on postinfusion blood CD3⁺CD8⁺CAR⁺ T cells. (K) CD57 and CD28 expression on CD3⁺CD8⁺CAR⁺ infusion cells is shown. (L) CD57 and CD28 expression of postinfusion blood CD3⁺CD8⁺CAR⁺ T cells is shown. For M-P, results are shown for all 4 patients with sufficient blood CAR-BCMA⁺ T cells from 7 to 16 days after infusion for analysis. Gating and analysis were performed as described above in A-L. The results are all for live CD3⁺CAR⁺ cells. The symbols shown in M correspond to the same patients for M-P. (M) The CD8⁺ to CD4⁺ ratio of CAR-BCMA T cells increased for all 4 assessable patients between infusion and the time the postinfusion samples were collected. The percentage of CD8⁺ CAR-BCMA T cells with (N) EM or EMRA phenotypes, (O) PD-1 expression, and (P) CD57 expression increased in all 4 assessable patients between infusion and the time a postinfusion sample was collected.