- administration of IFN-α before CP caused a 63% decrease in its clearance (p = 0.004) compared to an administration of IFN-α 24 h after CP, - there is a 45% decrease in exposure of CP active metabolite’s (4-OHCP) when IFN-α was administered before CP, expressed as AUC (p = 0.002), compared with that observed when IFN-α was administered 24H after CP, - this resulting in a greater decrease in leukocyte count (45%, p = 0.02) when IFN-α was given after CP in the 10 patients with multiple myeloma. This evidence concerns the gene IFNA2 and plasma cell myeloma.