VEGF, VEGFR2 and GSTM1 polymorphisms in Outcome of Multiple Myeloma Patients in the Thalidomide Era

Introduction: Angiogenesis (AG) abnormalities are crucial in pathogenesis of multiple myeloma (MM), and give support to treat patients with antiangiogenic agents. However, patients with similar clinicopathological aspects may present distinct outcome under AG inhibitors treatment. Single nucleotide polymorphisms (SNPs) in genes involved in blood vessels formation may constitute a plausible explanation for this finding. The wild-type alleles of VEGF c.-2595C>A (rs699947), c.-1154G>A (rs1570360), c.-634G>C (rs2010963), c.*237C>T (rs3025039), VEGFR2 c.-906T>C (rs2071559) and c.889G>A SNPs (rs2305948) SNPs, and GSTM1 and GSTT1 genes determine higher production, transcriptional activity, binding efficiency or best-characterized regulator of VEGF. This study aimed to investigate the roles of VEGF c.-2595C>A, c.-1154G>A, c.-634G>C, c.*237C>T, VEGFR2 c.-906T>C, c.889G>A SNPs, and GSTM1 and GSTT1 genes in outcome of MM patients treated with thalidomide-based regimens. Patients and methods: The study comprised 102 MM patients diagnosed at the Haematology and Haemotherapy Centre of University of Campinas between June 2005 and June 2013. The tumor was diagnosed by standard criteriaand staged by International Staging System. Therapeutic regimens consisted in thalidomide combined with steroids and chemotherapy, followed or not by autologous steam cell transplantation (ASCT). Response was evaluated at the end of treatment using the International Myeloma Working Group guidelines. The follow-up of patients was performed with hematological, biochemical, and immunological exams. The end of the study was February 2016. Genotypes of VEGF, VEGFR2 SNPs, and GSTM1 and GSTT1 genes were analyzed in genomic DNA by polymerase chain reaction based methods. The pairwise linkage disequilibrium (LD) was performed to ensure that markers were appropriate for inclusion in the VEGF and VEGFR2 haplotype estimates. The chi-square test and logistic regression model were used to identify variables influencing response to treatment. The Kaplan-Meier method, log-rank test and Cox hazards models served to assess the associations between event-free survival (EFS) and overall survival (OS). Results: Near half of patients enrolled in this study were male, and most of them were caucasians and with tumor at stages II or III. ASCT was performed after chemotherapy in near 40% of patients. LDs between VEGF and VEGFR2 SNPs were seen in study, and common haplotypes (frequency >1%) of the genes were included in further analyses. Patients with the wild-type allele of VEGF c.-2595C>A alone or plus the wild-type allele of VEGFR2 c.-906T>C SNPs, and the CGGC haplotype of all respective VEGF SNPs had 3.55, 9.91, and 3.86 more chances of achieving better response to therapy than others. The median follow-up time of 102 MM patients enrolled in the study was 43 months (range: 1-88). The estimated probabilities of 60-months EFS and OS were 24.5% and 48.1%, respectively. At 60 months of follow-up, patients with VEGFR2 c.889GG, VEGF c.-634GG plus VEGFR2 c.889GG, and VEGFR2 c.889GGplus GSTM1 present genotypes had 2.62, 2.64, and 2.80 more chances of presenting disease relapse or progression, and 2.21, 4.88, and 4.23 more chances of evolving to death in multivariate analysis, respectively. Conclusion: Our data present, for the first time, a preliminary evidence that VEGF c.-2595C>A, c.-1154G>A, c.-634G>C, c.*237C>T, VEGFR2 c.-906T>C, c.889G>A SNPs, and GSTM1 gene alter outcome of MM patients treated with thalidomide-based regimens. If these findings could be confirmed in multi-center studies with larger sample size, this might constitute a promise in assisting optimal patient choice for treatment with angiogenic agents. Financial support: São Paulo Research Foundation (FAPESP).