Phase I study of the IXO regimen, irinotecan (I), capecitabine (X), oxaliplatin (O), as first-line therapy for metastatic colorectal cancer: Final survival results

Abstract

4082 Background: This study was designed to determine the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and efficacy of the IXO regimen when used as first-line treatment for metastatic colorectal cancer (mCRC). Methods: Patients with ECOG PS 0–2, histologically proven, chemo-naïve, non-resectable mCRC were eligible. Phase I starting doses were as follows: I (180 mg/m2 i.v.) d1, X (850 mg/m2 bid orally) d2–15, O (85 mg/m2 i.v.) d1; q3w. Dose escalation (3+3 design) was based on toxicity observed at previous dose levels (DL) until DLT and the MTD were reached. Results: 39 pts (31 male/8 female, median age 58 years, ECOG PS 0–1 in 37, 95%) received a median of 11 cycles (range 1–34) at 8 DLs. 39 pts were evaluable for toxicity. The most common grade 3/4 hematological adverse events (AEs) were granulocytopenia (60%) and fever/febrile neutropenia (18%). The most common grade 3 non-hematological AEs were diarrhea (15%), vomiting (10%), fatigue (8%). No grade 3/4 neuropathy was reported. DLTs: 1 DLT was observed at each of the first 4 DLs, no DLTs at DL5 & 6, 1 at DL7 and 2 at DL8. MTD was reached at DL8. The recommended phase II dose (DL7) is as follows: I (160 mg/m2), X (950 mg/m2), O (100 mg/m2). Efficacy: 38 pts are evaluable for efficacy. The RR is 74% (95% CI 60–89), including 4 CRs, 25 PRs and 6 SDs. The disease control rate is 90% (95% CI 80–100). 10 (26%) pts had subsequent liver surgery with curative intent; 1 had lung resection. Median progression-free survival was 12.3 months (95% CI, 8–17). Overall median survival was 26.4 months (95% CI, 13–36). Conclusions: Diarrhea is the main DLT. Severe neutropenia was of short duration and manageable. The IXO regimen is well tolerated and highly effective as first-line treatment for mCRC. It appears to be particularly effective in downsizing of initially unresectable colorectal cancer liver metastases. A phase II study to confirm the efficacy/safety of IXO in combination with bevacizumab (Avastin) is ongoing. Supported by: Hoffmann La-Roche, Sanofi-Aventis, Pfizer Canada. [Table: see text]