MagnetisMM-3 (NCT04649359) is an open-label, multicenter, non-randomized phase 2 study of elranatamab monotherapy in patients (pts) with multiple myeloma refractory to at least 1 proteasome inhibitor, 1 immunomodulatory drug and 1 anti-CD38 antibody....Genome wide copy number analysis showed that TNFRSF17 locus amplification was associated with non-response (p= 0.008).