CD38 and Miyoshi myopathy: These mAbs bind to different epitopes of CD38,2 a receptor that is uniformly overexpressed on MM, but the degree of overexpression of CD38 varies in MM patients.3–5 Both mAbs can cause cell death by complement-dependent cytotoxicity (CDC),6,7 among other mechanisms.8 Daratumumab is usually administered in combination with bortezomib/lenalidomide and dexamethasone9,10 in transplant-ineligible patients with progressive disease and, more recently, also in frontline settings.