Bispecific CD3xBCMA antibodies targeting the B-cell maturation antigen (BCMA; CD269/TNFRS17) on MM cells, such as EM801, REGN5458 (NCT03761108) and AMG 420 (NCT03836053) showed single agent activity in relapsed/refractory MM patients (41–46) (Figure 2). Here, TNFRSF17 is linked to Miyoshi myopathy.