Association of ABCB1, ABCG2 drug transporter polymorphisms and smoking with disease risk and cytogenetic response to imatinib in chronic myeloid leukemia patients

Background: Despite acceptable results of imatinib in the treatment of chronic myeloid leukemia (CML), some patients fail to acquire a complete cytogenetic response (CCyR), which may be caused by polymorphisms in the pharmacogenetic genes. The study aimed to evaluate the association of two polymorphisms in the ABCB1 and ABCG2 genes with cytogenetic response to imatinib and the risk of CML development. Methods: We genotyped ABCB1 (c .2677G/T/A) and ABCG2 (c .421C/A) polymorphisms by PCR-RFLP, T-ARMSPCR methods in 111 patients with CML and 102 sex- and age-matched healthy subjects. CCyR was determined by standard chromosome banding analysis (CBA). Results: Analysis of polymorphisms showed significant association of ABCG2 c.421CA genotype (p < 0.0001; OR = 0. 17), and ABCG2c.421A allele (p < 0.0001; OR = 0.31) with decreased risk of CML. Moreover, ABCB1c.2677GT- ABCG2c.421CC combined genotype (p = 0.017; OR = 4.20) was associated with increased risk of CML. Analysis of the joint effect of SNP-smoking combination showed that smoker subjects with the ABCB1c.2677GG/GT (p = 0.001; OR = 15.96, p = 0.001; OR = 8.13, respectively) or ABCG2c.421CC genotypes (p = 0.001; OR = 5.82) had the increased risk of CML, while the risk of the CML in non-smokers carrying the ABCG2c.421CA (p < 0.0001; OR = 0. 18) genotype was strongly decreased compared with reference group. Regarding drug response, ABCG2c.421 CC/CA genotypes in the smoker patients were associated with an increased risk of resistance to imatinib (p < 0.0001; OR = 7.02, p = 0.018; OR = 4.67, respectively). Conclusion: Our results suggest the impact of ABCG2c .421C/A polymorphism on CML development, and smoking may have a synergistic role in the risk of CML and resistance to imatinib.