TNFRSF17 and Miyoshi myopathy: (45) showed that in 8/16 investigated patients progressing under BCMA-directed treatment, biallelic deletions or mutations of the TNFRSF17 (BCMA) locus occurred: in two patients, MM relapse post T-cell bispecific antibody or CART-therapy was driven by BCMA-negative clones harboring focal biallelic deletions at the TNFRSF17 locus at relapse or by selective expansion of pre-existing subclones with biallelic TNFRSF17 loss.