Impact of ABCB1 Gene Polymorphisms and Smoking on the Susceptibility Risk of Chronic Myeloid Leukemia and Cytogenetic Response.

Background: Imatinib mesylate (IM), a strong and selective tyrosine kinase inhibitor, has been approved as the front line of treatment in chronic myeloid leukemia (CML) patients. In spite of satisfactory results of imatinib in the treatment of patients with CML, patients with treatment failure or suboptimal response developed resistance that might be because of pharmacogenetic variants. This study attempted to evaluate the influence of ABCB1 gene polymorphisms and smoking on CML risk and resistance to imatinib.

Methods: ABCB1 (c.1236C>T, c.3435C>T) polymorphisms were genotyped in 98 CML patients and 100 sex- and age-matched healthy subjects by PCR-RFLP method, followed by sequencing. The patients were evaluated for cytogenetic response by the standard chromosome banding analysis in regular intervals.

Results: Our results showed that c.1236CC genotype was significantly associated with imatinib resistance (OR = 3.94; p = 0.038). Analysis of the joint of single nucleotide polymorphism -smoking combination showed that smokers with c.1236TT/CT and c.1236CC genotypes had the increased risk of CML (OR = 6.04; p = 0.00 and OR = 4.95, p = 0.005) and treatment failure (OR = 5.36, p = 0.001 and OR = 15.7, p = 0.002), respectively. Smokers with c.3435TT/CT and c.3435CC genotypes also displayed the elevated risk of CML development (OR = 6.01, p = 0 and OR = 4.36, p = 0.011) and IM resistance (OR = 5.61, p = 0.001 and OR = 13.58, p = 0.002), respectively.

Conclusion: Our findings suggest that c.1236CC genotype has clinical importance in the prediction of treatment outcome with IM, and smoking could have a synergistic role in CML risk and IM resistance.