A dose-escalation study of oxaliplatin/capecitabine/irinotecan (XELOXIRI) and bevacizumab (bev) as a first-line therapy for patients with metastatic colorectal cancer.

Abstract

612 Background: In a recent study by Loupakis, F. et al. (ASCO-GI 2013), a FOLFOXIRI and bevacizumab regimen showed promising activity and conversion rate in patients (pts) with metastatic colorectal cancer (mCRC). In order to evaluate a treatment regimen that was easier to administer, we conducted a dose-escalation study to determine the recommended dose (RD) of irinotecan (IRI) in combination with oxaliplatin and capecitabine and bevacizumab (XELOXIRI/bev) in pts with mCRC. Methods: Pts were eligible if they had mCRC (liver and/or other metastases), ECOG PS 0-1, were either negative or heterozygous for UGT1A1*6 or UGT1A1*28 and were not pretreated for metastatic disease. Treatment consisted of oxaliplatin (100 mg/m2 day 1), capecitabine (1700 mg/m2/day from day 2 to 15), IRI (100,120,150 mg/m2 for dose levels 1, 2, or 3, day 1) and bev (7.5 mg/kg, day 1), repeated every 3 weeks. The dose of IRI was escalated if dose limiting toxicities (DLT) were absent in the first three pts per cohort, or if <2 DLTs were observed in six pts. If the MTD was not reached at the planned dose levels, the RD of IRI was defined as 150mg/m2, which is the maximum dosage approved for use in Japan. Results: 12 pts (F/M: 4/8, median age: 58 years, PS 0/1: 11/1) received a median of 6 cycles of therapy (range 2-12). The DLT was grade 4 neutropenia, which was observed in 1 of 6 pts at dose level 2. MTD was not reached at dose level 3. Therefore, the RD of IRI was defined as 150 mg/m2. Most common grade ≥ 3 toxicities were neutropenia (58.3%), anemia (16.6 %), diarrhea (8.3%), and febrile neutropenia (8.3 %). The response rate was 83.3%(95% CI 60-89), including 1 CR, 9 PRs. The disease control rate was 100%(95% CI 80-100). At a median follow-up of 8 months, median PFS was 15 months and median OS was not yet reached. Conclusions: XELOXIRI/bev is a feasible regimen; neutropenia was the DLT; recommended dose of IRI is 150 mg/m². The observed response rate of 83.3% is very promising and warrants further investigation. Clinical trial information: UMIN000005440.