Genetic variants of genes in CCL5/CCR5 pathway to predict regorafenib-induced hand-foot skin reaction in patients with refractory metastatic colorectal cancer: A report of ethnic difference.

Abstract

615 Background: CCL5/CCR5 pathway is involved in VEGF-A production and a recent study reported that serum CCL5 levels predict onset of hand-foot skin reaction (HFSR) due to regorafenib. We therefore tested whether genetic polymorphisms in the CCL5/CCR5 pathway predict onset of HFSR in patients with refractory metastatic colorectal cancer (mCRC) receiving regorafenib. Methods: Two independent cohorts treated with regorafenib were included in this study: a training cohort from Japan with 79 patients (median age 62 years, male 47%); and a testing cohort from Italy with 150 patients (median age 62 years, male 54%). Single nucleotide polymorphisms (SNPs) of genes in CCL5/CCR5 pathway ( CCL5, CCR5, PRCKD, CCL3, CCL4, KLF13, HIF1A) were selected for analyses using PCR-based direct sequencing. Adverse events were graded according to the CTCAE version 4.0. Comparisons of variants’ and adverse events’ distributions across two cohorts, and association between SNPs and adverse events were analyzed using contingency tables and Fisher’s exact test. Results: Grade 3 ≤ HFSR was more frequent in Japanese patients compared with Italian patients (32.9% vs. 16.0%, P= 0.004). The frequency of homozygous variant in CCL5 SNPs varied between Japanese and Italian patients (G/G variant in rs2280789, 21.5% vs. 1.3%, P< 0.001; T/T variant in rs3817655, 22.8% vs. 2.7%, P< 0.001). In the training cohort, patients with the G/G variant in rs2280789 had a higher incidence of grade 3 ≤ HFSR compared to those with any A allele (53% vs. 27%, P= 0.078); and the T/T variant in rs3817655 was significantly associated with onset of grade 3 ≤ HFSR compare to any A allele (56% vs. 26%, P= 0.026). These findings were not confirmed in the testing cohort, and no significant differences for toxicities were observed in the other candidate SNPs. Conclusions: Germline CCL5 polymorphisms in the CCL5/CCR5 pathway may serve as predictor of onset of severe HFSR in refractory mCRC patients receiving regorafenib. The different percentage of homozygote of CCL5 SNPs confers the ethnic difference in developing severe HFSR between Italian and Japanese patients.