OBJECTIVETo explore the relationship between KRAS gene status and efficacy of Cetuximab (C225) combined with chemotherapy on advanced colorectal cancer in Chinese patients, and to evaluate the safety of C225.

METHODSFrom May 2006 to March 2009, 81 patients with advanced colorectal cancer received Cetuximab combined with chemotherapy were enrolled in this study. The rate of KRAS mutation and the relationship of KRAS with response rate (RR), progression-free survivor (PFS), overall survival (OS) and adverse reaction of C225 were analyzed retrospectively.

RESULTSAll the 81 patients received C225 therapy, and the overall RR was 33.3%. The RR of initiate therapy was 57.1%; of the second line and over the third line therapy was 38.5% and 22.0% respectively. KRAS gene phenotype examination was performed in 44 patients whose tumor samples were available. KRAS mutation was found in 20 cases (45%). Out of 44 patients, 43 were evaluable for response. RR was 5% and 43.48% in KRAS mutation and wild KRAS patients respectively (P =0.002). The median PFS was 7.0 weeks and 18.6 weeks in mutational KRAS patients and wild KRAS patients, reaching statistical significance (P =0.003). The median OS was 15.2 months and 17.3 months in mutational KRAS patients and wild KRAS patients respectively without statistical significance (P =0.463). The common adverse reactions were leucopenia, nausea, vomiting and rash. All the adverse reactions were tolerated. The incidence of skin rash in patients with mutational KRAS and patients without KRAS mutation was 40% and 42% respectively, without statistical significance (P =0.91).

CONCLUSIONC225 combined with chemotherapy is well-tolerated in Chinese patients with advanced colorectal cancer, and it can significantly prolong PFS of patients with wild KRAS as compared to patients with KRAS mutation.