A multicentre, open-label phase II study of Irinotecan, capecitabine (Xeloda®), and Oxaliplatin (IXO) as first-line treatment in patients with metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma

Purpose Chemotherapy remains the primary treatment for metastatic gastric/GEJ cancer but optimal agents and schedule remain controversial. This study examined the safety and efficacy of first-line Irinotecan, capecitabine (Xeloda®), and Oxaliplatin (IXO). Patients and Methods Eligible patients with HER2-unamplified/unknown, metastatic gastric/GEJ adenocarcinoma were treated with 21-day cycle IXO at dose level 1 (DL1: Day 1 O-100 mg/m² & I-160 mg/m² IV, Day 2–15 X-1900 mg/m²/day PO divided doses) or modified IXO (mIXO): Day 1 O-85 mg/m² & I-120 mg/m² IV, Day 2–15 X-1425 mg/m²/day PO divided doses). This Bryant and Day two-stage designed study had dual primary endpoints of objective response rate (ORR) and toxicity. Secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results Fifty patients were enrolled and received a median of 7 cycles. After accrual of 9 patients at DL1, evaluable RR was 88% however dose limiting toxicity (DLT) rate was 56% thus doses were adjusted to mIXO. Fifteen patients accrued at mIXO had a RR of 60% and DLT rate of 13% allowing continuation to stage 2. Overall, 48 and 49 patients were evaluable for efficacy and safety, respectively, with ORR of 54% and DLTs in 24% of patients (DL1 = 56%; mIXO = 18%). Disease control rate was 85%. The most frequent grade 3/4 adverse events were diarrhea, neutropenia, fatigue, hypokalemia, and nausea. Median PFS and OS were 7.5 and 13.0 months, respectively, with a median follow-up of 9.7 months. Conclusion mIXO demonstrates promising ORR, PFS, OS, and acceptable toxicity compared to standard triplet regimens. IXO should be evaluated in phase III trials.