Predictive Biomarkers and Personalized Medicine MutationPro fi ling andMicrosatellite Instability in Stage II and III Colon Cancer : An Assessment of Their Prognostic and Oxaliplatin Predictive Value

Purpose: The purpose of this study was to examine the prognostic and oxaliplatin predictive value of mismatch repair (MMR) status and common hot spot mutations, which we previously identified in stage II and III colon cancer. ExperimentalDesign:Mutations inBRAF,KRAS,NRAS,MET, andPIK3CAwere profiled in 2,299 stage II and III colon tumors fromNational Surgical Adjuvant Breast and Bowel Project (NSABP) clinical trials C-07 (n1⁄4 1,836) and C-08 (n1⁄4 463) with Type Plex chemistry and mass spectrometry. C-07 tested the worth of adding oxaliplatin to 5-fluorouracil plus leucovorin, and C-08 tested the worth of adding bevacizumab to FOLFOX. Cox proportional hazard models were used to assess prognostic or oxaliplatin predictive value of mutations for tumor recurrence, overall survival (OS), and survival after recurrence (SAR). Results: BRAFmutations were associated with MMR-deficient tumors (P < 0.0001), poor OS [HR, 1.46; 95% confidence interval (CI), 1.20–1.79; P 0.0002], and poor SAR (HR, 2.31; 95% CI, 1.83–2.95; P < 0.0001). Mutations in KRAS, NRAS, MET, and PIK3CA were not associated with recurrence, OS, or SAR. MMR-deficient tumorswere associatedwith an improved prognosis based on recurrence (HR, 0.48; 95%CI, 0.33–0.70; P < 0.0001). Mutations and MMR status were not predictive for oxaliplatin benefit. Conclusions: This study shows that BRAFmutations profiled from stage II and III colon cancer tumors were associated with poor SAR and validates and explains, at least in part, previous observations associating it with poor OS. Profiling of all of these mutations is warranted for future clinical trials testing new targeted therapies that block relevant signaling pathways. Such clinical trials are under development at NSABP. Clin Cancer Res; 18(23); 6531–41. 2012 AACR.