Are BRAF mutated metastatic colorectal cancer (mCRC) tumors more responsive to VEGFR-2 blockage? Analysis of patient outcomes by RAS/RAF mutation status in the RAISE study—A global, randomized, double-blind, phase III study.

Abstract

622 Background: The RAISE trial (NCT01183780) demonstrated that ramucirumab (RAM) plus leucovorin, fluorouracil, and irinotecan (FOLFIRI) significantly improved overall survival (OS) and progression-free survival (PFS) compared with placebo (PBO) plus FOLFIRI as second-line mCRC treatment. RAS/RAF mutations are associated with resistance to anti-EGFR therapies and poor prognosis, particularly BRAF mutations. The extensive RAISE biomarker program assessed the association of multiple candidate markers with efficacy outcomes. Here we present the results for RAS/ RAF mutations. Methods: Plasma and tumor tissue collection were mandatory. KRAS mutation status was determined locally before randomization. Further RAS and RAF mutations were assessed centrally by multiplex qPCR using the Modaplex system (Qiagen) only in samples that were initially reported as KRAS wild type. Thus, patients were classified into one of the 3 categories in the table. OS and PFS by RAS and RAF subgroups were evaluated by Kaplan-Meier and Cox proportional hazards analyses. Results: As with previously reported KRAS analyses, the favorable RAM treatment effect was similar between patients with expanded RAS mutations compared with patients with RAS/ RAF wild-type tumors. However, in the 41 patients with BRAF mutated tumors, the RAM benefit was even more notable for both OS (hazard ratio [HR] 0.54; 95% CI 0.25–1.13) and PFS (HR 0.55; 95% CI 0.28–1.08). Conclusions: RAISE demonstrated that the addition of RAM to FOLFIRI improved patient outcomes regardless of RAS mutation status. The noteworthy signal for patients with BRAF mutant tumors is encouraging due to their poor prognosis but requires further validation in other clinical trials. Clinical trial information: NCT01183780. [Table: see text]