SLCO1B1 Polymorphism Is a Drug Response Predictive Marker for Advanced Pancreatic Cancer Patients Treated With Gemcitabine, S-1, or Gemcitabine Plus S-1.

Objectives: The aim of this study was to evaluate the effects of single-nucleotide polymorphisms (SNPs) on advanced pancreatic cancer risk and overall survival (OS) in a candidate-gene approach.
Methods: Overall, 5438 SNPs in 219 candidate genes encoding several drug-metabolizing enzymes or transporters were analyzed. In the screening study, 3 SNPs were found associated with OS (P ≤ 0.0005). We validated these SNPs as part of the randomized phase 3 study (GEST study). The associations between OS and SNPs were investigated using log-rank test and Cox proportional hazards model.
Results: From the GEST study, the SNP rs4149086 in the 3' UTR of the solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene showed significant interaction with treatment (P = 0.02). In the gemcitabine group, the SNP was associated with short OS (hazard ratio [HR], 3.75; 95% confidence interval [CI], 1.30-10.8; P = 0.008) even after multiple-comparisons adjustment. In contrast, the SNP was not associated with OS in S-1 (HR, 0.77; 95% CI, 0.33-1.81; P = 0.55) or gemcitabine plus S-1 groups (HR, 1.18; 95% CI, 0.46-3.00; P = 0.72).
Conclusions: Patients with advanced pancreatic cancer with the rs4149086 AG or GG genotype may obtain good clinical results when treated with S-1-containing regimens.