Phase 1a/1b and pharmacogenetic study of docetaxel, oxaliplatin and capecitabine in patients with advanced cancer of the stomach or the gastroesophageal junction

Purpose: The prognosis of gastroesophageal cancer is poor, and current regimens are associated with limited efficacy. The purpose of this study was to explore the safety and preliminary efficacy of docetaxel, oxaliplatin plus capecitabine for advanced cancer of the stomach or the gastroesophageal junction (GEJ). Secondary objectives included pharmacokinetic and pharmacogenetic analyses. Methods: Patients were treated in escalating dose levels with docetaxel and oxaliplatin (both on day 1), plus capecitabine b.i.d. on days 1-14 every 3 weeks, to determine the dose-limiting toxicity and maximum tolerated dose (MTD). An expansion cohort was treated at the MTD. A total of ten polymorphisms in pharmacokinetic and pharmacodynamic candidate genes were analyzed and tested for association with treatment outcome. Results: A total of 34 evaluable patients were enrolled. The MTD was docetaxel 50 mg/m², oxaliplatin 100 mg/m² plus capecitabine 850 mg/m² b.i.d. The median number of treatment cycles was 6 (range 2-8). Grade ≤ 3 toxicities included neutropenia (24 %), leukocytopenia (15 %), febrile neutropenia (12 %), fatigue (9 %) and diarrhea (6 %). The overall response rate was 45 %; two patients achieved a complete response. Median progression-free survival and overall survival were 6.5 months (95 % CI 5.4-7.6) and 11.0 months (95 % CI 7.9-14.1), respectively. The polymorphisms ERCC1 354C>T, TYMS 1053C>T and rs2612091 in ENOSF1 were associated with severe toxicity; ERCC1 354C>T and ERCC2 2251A>C were associated with poor progression-free survival. Conclusion: Docetaxel, oxaliplatin plus capecitabine are a well-tolerable, safe and effective treatment regimen for patients with advanced cancer of the stomach or GEJ. Pharmacogenetic markers in pharmacokinetic and pharmacodynamic candidate genes may be predictive for treatment outcome.