The efficacy and safety outcomes of bevacizumab and systemic therapy in metastatic colorectal cancer patients with peritoneal disease in the AGITG MAX clinical trial and in nontrial patients in two cancer centers.

Abstract

595 Background: Metastatic colorectal cancer with peritoneal disease (PmCRC) represents a phenotype that may derive a greater clinical benefit from bevacizumab (BEV) due to the effect of VEGF on peritoneal spread and ascites production. However, there is concern of greater adverse events, in particular GI perforations. We investigated the clinical benefit and safety of adding BEV to chemotherapy in PmCRC in clinical trial and nontrial populations. Methods: We compared PFS and OS in PmCRC patients receiving first-line chemotherapy with and without BEV in: (1) the AGITG MAX trial (capecitabine [CAP] vs CAP/BEV +/- mitomycin C) and (2) two cancer centers in New South Wales between Jan 2005 and Dec 2012 (any regimen +/- BEV). Secondary endpoints included chemotherapy duration and GI adverse events. Time to event outcomes were estimated using the method of Kaplan-Meier and comparisons made using the logrank test. Proportional hazards models were used to obtain hazard ratios for regression analysis. Results: See Table. 84 MAX and 69 nontrial pts had PmCRC and there was a 37% reduction in the risk of progression in those receiving BEV, which is similar when compared to the nonperitoneal disease pts (HR= 0.63 95% CI 0.52-0.79 p value < 0.001). OS in the PmCRC group was significantly worse than the nonperitoneal group (14.3 months vs 18.8 months p value = 0.02). Chemotherapy duration was similar across the groups. The rate of notable GI adverse events, including GI perforation was not increased in the PmCRC group receiving BEV in either cohort. One pt had a GI perforation after receiving CAP+BEV. Conclusions: Pts with mCRC and peritoneal disease receiving first-line therapy in trial and nontrial populations appear to derive a similar proportional benefit when BEV is added to systemic therapy without an increase in GI adverse events. However, this subgroup of patients continues to have a worse prognosis. [Table: see text]