Genetic Polymorphisms Correlated with Outcome in Multiple Myeloma Patients Receiving High Dose Melphalan.

High dose melphalan is an essential component in the treatment of patients with advanced multiple myeloma. However few data are available regarding genetic polymorphisms possibly correlated with patient outcome or toxicity in this setting. To identify polymorphisms predictive of survival and/or toxicity we performed a retrospective single nucleotide polymorphism (SNP) analysis using APEX technology in 169 patients having received high dose melphalan for multiple myeloma. All patients had received one or two courses of high dose melphalan with stem cell reinfusion. DNA was obtained from peripheral blood mononuclear cells and analyzed for 230 SNPs in genes selected for their role in drug metabolism, DNA repair, cell cycling or apoptosis. There were 108 males and 61 females and the median age was 55 years. The average number of VAD courses received before high dose melphalan was 4 (3–6). 58 patients (34%) received two high dose melphalan courses. A complete/very good response was observed in 43 of 103 evaluable patients (42%). Forty patients among 107 evaluable (37%) experienced high grade (III–IV) mucositis after high dose melphalan. The median freedom from progression was 45 months and the overall survival was 91 months. SNPs in SULT1A1, MDR, ERCC5, GSTP1, NQO1, CYP1A2, CCND1, PARP, RAD51, DRD4, P53 or associated proteins were found to be correlated with response to VAD therapy. SNPs in GRPR, ERCC5, GSTM3, GSTP1, XRCC1, ERCC4, CYP1B1, BARD1, MDR1, P53BP1, TERT, DRD4 were found to be correlated with response to high dose melphalan. Polymorphisms in CYP2E1, CYP2C9, CYP1A1, CYP1B1, TMPT, OGG1, PCNA, DRD2, XPC were correlated with disease progression while polymorphisms in ERCC1, DRD4, CYP2D6, CYP2C9, CYP1A1, CYP1A2, CYP1B1, ALDH, BARD1, BRCA1, MYH, TP53BP1 were correlated with death. Polymorphisms in XRCC1, SNP103, CYP2C9, CYP2C19, BRCA1, BRCA2, NBS1, CDKN1A were correlated with severe mucositis. These results suggest that SNPs of genes involved in drug metabolism or repair could be used to distinguish patients subgroups with different toxicity/efficacy profiles after high dose melphalan.