ABCB1 and Miyoshi myopathy: This matches well with the striking activity observed when cyclophosphamide was added to a pomalidomide-dexamethasone backbone in patients with heavily pretreated MM, of which 44% were CFZ refractory.9 The low sensitivity of cyclophosphamide to ABCB1-mediated export could have significantly contributed to the therapeutic activity of cyclophosphamide in this setting in heavily pretreated MM patients.