Current observations of Busch et al. reveal that combination of vitamin D3 with immunomodulatory drugs (IMiDs), such as lenalidomide, helps to restore the defective vitamin D3 metabolism in myeloma-associated macrophages and improves cytotoxicity against multiple myeloma cells mediated by specific anti-CD38 antibodies such as MOR202 (137, 138). This evidence concerns the gene CD38 and plasma cell myeloma.