CD38 and Miyoshi myopathy: MAMMOTH is the first study investigating clinical outcomes of MM patients refractory to an anti-CD38 mAb, and a significant decrease in OS is reported for “penta-refractory” subjects with a median survival of 5.6 months, an overall response rate (ORR) after at least one subsequent line of therapy of 31%, and a median progression-free survival (PFS) of 3.4 months (4, 5).