Isatuximab is often administered after unsuccessful daratumumab treatment.11 Most patients develop progressive disease after anti-CD38 mAb therapy, and their prognosis is poor.12 For example, in a multicenter study that examined 107 patients with relapsed/refractory MM on daratumumab monotherapy, the overall response rate was 42.1%, and the median first and second progression-free survival were 3.6 and 8.1 months, respectively, with an overall survival of 11.9 months in this group.13 The overall response rate was 46.2% in the patients who received isatuximab after daratumumab treatment. This evidence concerns the gene CD38 and Miyoshi myopathy.