Lastly, we examined the activity of ES in CD138-selected MM cells isolated from 34 patient bone marrow samples (newly diagnosed MM, early RRMM, and late RRMM) using an ex vivo organoid model system designed to assess drug sensitivity in patient-derived MM samples that incorporates essential elements of the bone marrow tumor microenvironment as previously described (36–38). Here, SDC1 is linked to Miyoshi myopathy.