Outcomes of patients with TCR MM treated with a second subsequent SoC regimen (including compassionate belantamab mafodotin (n = 1) and selinexor (n = 5)) after anti-CD38 mAb progression were even poorer (n = 50 TCR patients, ORR 30% [15/50 patients], CR 2% [1/50 patients]; median PFS and OS from start of second subsequent SoC treatment were 2.8 (95% CI1.8–4.6) months versus 6.4 (95% CI 3.7–18) months, respectively). Here, CD38 is linked to Miyoshi myopathy.