TNFRSF17 and Miyoshi myopathy: Dose‐dependent PC lysis was triggered in all cases by TNB‐383B at doses as low as 0.001 μg (P = .0102). Primary MM cells varied in BCMA expression. High BCMA+ PC count correlated with increased PC lysis (P = .005) and significant CTL degranulation specific to TNB‐383B treatment (P = .0153 at 1 μg).