Belantamab Mafodotin, a first-in-class anti-BCMA antibody–drug conjugate, demonstrated good efficacy and safety profile in triple-refractory patients in the phase 2 DREAMM-2 trial, and it was approved for the treatment of MM triple-exposed patients with >4 prior lines of therapy. The gene discussed is TNFRSF17; the disease is Miyoshi myopathy.