Multiple myeloma (MM) patients who develop disease refractory to immunomodulatory drugs (IMiDs), proteasome inhibitors, and anti-CD38 antibodies have a very poor overall survival of less than 1 year.1 2 Adoptive cell therapy with chimeric antigen receptor (CAR) T-cells has emerged as a potent treatment strategy with recent approval of two CAR T-cell therapies (ide-cel and cilta-cel) for the treatment of patients with heavily pretreated MM.3, 5 These BCMA-targeting CAR T-cell products use genetically modified autologous T-cells from each individual patient.6 Here, CD38 is linked to Miyoshi myopathy.