Illustrative case of an acquired CD38 deletion. (A) M-protein quantification is shown over time. The yellow area denotes the treatment period with CD38-targeted agents. After treatment with isatuximab and daratumumab, (B) single-cell RNA-sequencing data and (C) respective violin plots demonstrate reduced CD38 expression. BCMA, B-cell maturation antigen; BRd, bendamustine, bortezomib, and dexamethasone; CAR-T, chimeric antigen receptor T cells; Dd, daratumumab and dexamethasone; DRd, daratumumab, lenalidomide, and dexamethasone; DVd, daratumumab, bortezomib, and dexamethasone; KPd, carfilzomib, pomalidomide, and dexamethasone.