Patients relapsed after CAR-T can display sensitivity to CD38 antibody re-treatment. (A) Waterfall plot showing the Dara sensitivity ex vivo measured in BM samples from patients refractory to Dara who had also relapsed after anti-BCMA CAR-T. (B) CD38 overexpression ratio compared with ex vivo Dara sensitivity in the same 3 patients with Dara-refractory MM relapsed after anti-BCMA CAR-T. (C) Ex vivo drug sensitivity as determined by normalized viability with My-DST vs depth of clinical response in 2 patients who received Dara-based re-treatment after CAR-T. Clinically predictive drug sensitivity was defined as <50% normalized viability and PR as a 50% change in paraprotein from baseline after initiating treatment.