Association of genetic polymorphisms of CYP3A4 and CYP2D6 with gefitinib-induced toxicities.

Dermatological, gastrointestinal and hepatic toxicities are the most common adverse events associated with gefitinib use. Gefitinib is metabolized by cytochrome P450. Inconsistent associations of single nucleotide genetic polymorphisms of CYP450 and gefitinib-induced adverse effects were reported. We aim to investigate the association between CYP450 genetic polymorphism and the development of gefitinib-associated adverse events. A retrospective cohort study of Chinese patients with metastatic nonsmall cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations who received first-line gefitinib treatment was conducted. Single nucleotide polymorphisms (SNPs) of CYP2D6, CYP3A4 and CYP3A5 were assayed using a multiplex SNP microarray. Risks of development of gefitinib-induced toxicities associated with different SNPs were determined. Among the 152 patients treated with gefitinib, 52 (34.2%) had gefitinib-induced hepatotoxicity, 113 (74.3%) had cutaneous reactions and 53 (34.9%) had gastrointestinal adverse effects. CYP2D641 CT, CYP2D610 AA and CYP3A41/1G TT genotypes were significantly associated with hepatic, cutaneous and gastrointestinal adverse effects [odds ratio (OR) 3.773; (95% confidence interval {CI},1.046-13.610; P  = 0.043), 3.368 (95% CI, 1.000-11.345; P  = 0.050) and 20.000 (95% CI, 2.381-167.965; P  = 0.006), respectively]. CYP2D641 CT, CYP2D610 AA and CYP3A4*1/*1G TT genotypes may be associated with increased risks of gefitinib-induced toxicities in the liver, skin and gastrointestinal tract.