CD38 and Miyoshi myopathy: Patients that previously achieved at least a partial response or minimal response/stable disease with prior daratumumab monotherapy had a significantly longer PFS compared with patients who immediately progressed on daratumumab as single agent (median PFS 3.4 and 2.8 vs. 1.3 months). Addition of ATRA and re-intensification of daratumumab had limited activity in patients with daratumumab-refractory MM, which may be explained by transient upregulation of CD38 [176].