Immunophenotypic analyses of T cells at baseline and at cycle 3 day 1 after teclistamab monotherapy in BM correlate with disease burden status. (A-C) Frequency of PD-1, PD-1/TIM-3, and PD-1/CD38 expression in the CD8 T-cell subset relative to percentage of BMPCs at baseline from the RP2D cohort assessed by flow cytometry. (D-E) Frequency of CD4 T cells expressing CD25 or CD38 at baseline relative to disease burden assessed by the percentage of BMPCs. (F-G) Frequency of PD-1/TIM-3 and PD-1/CD38 expression in CD8 T cells relative to composite tumor burden. (H-I) Frequency of CD4 T cells coexpressing PD-1/TIM-3 or PD-1/CD38 assessed by flow cytometry relative to tumor burden at baseline. (J) Maximum fold change from baseline to cycle 3 day 1 of CD8 T cells coexpressing PD-1 and CD38 relative to low (BMPCs <60%) or high (BMPCs ≥60%) tumor burden. Representative staining is shown on the right of panels B-E,H,I. Statistical analyses were performed using the Wilcoxon rank-sum test for panels A-E,J or Kruskal-Wallis test for panels F-I.