526P - Phase Ii Study of Combined Chemotherapy with 5-Week Cycles of S-1 and Cpt-11 (Iris) Plus Bevacizumab in Patients with Metastatic Colon Cancer

Abstract

ABSTRACT Aim: Combined chemotherapy with S-1 and irinotecan (IRIS) for metastatic colorectal cancer has been reported to be effective and safe. However, there are only a few studies on the effects of adding bevacizumab to the IRIS. We conducted a clinical study to evaluate the efficacy and safety of the IRIS plus bevacizumab as first-line therapy for metastatic colorectal cancer. Methods: Forty metastatic colorectal cancer patients were enrolled in this phase II study. All patients received irinotecan (80 mg/m2) and bevacizumab (7 mg/kg) on days 1 and 15 and S-1 (40-60 mg twice daily) on days 1-21 of a 5-week repeated cycle. All toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Patients underwent laboratory tests and computed tomography (CT) of the chest and abdomen at enrollment. CT tumor assessments were performed every 4–5 weeks from baseline to tumor response, which was evaluated in accordance with the RECIST version 1.1 guidelines. Complete and partial responses were confirmed after an interval of at least four weeks. Results: The median age of the eligible patients was 62 years (range: 34-73 years). There were 24 men and 14 women. PS was 0 in 36 and 1 in 2 patients. The primary malignancies were colon cancer in 22 patients and rectal cancer in 16. The primary lesions were resected in 33 patients and not resected in 5. The sites of metastasis or recurrence were the liver in 19 patients, lung in 10, lymph nodes in 10, peritoneum in 5, a local site in 3, and bone in 2, as well as the uterus, ovary, and pleura in 1 patient each. The response rate was 47.4% (95% confidence interval [CI]: 31.5-63.2%), progression-free survival was 11.9 months (95% CI: 9.4-16.8 months), and overall survival was 23.4 months (95% CI: 19.0 months-). The only grade 3 hematological toxicity was neutropenia (16%) and the incidences of grade 3 non-hematological toxicity were low at less than 10% other than diarrhea (10.9%). Conclusions: In this clinical study, we revealed IRIS plus bevacizumab to be a promising first-line regimen for metastatic colorectal cancer with a low incidence of serious toxicities, in which favorable response rates and extension of survival time can be expected. Disclosure: All authors have declared no conflicts of interest.