481 Background: Survival advantage of second line FOLFIRI plus cetuximab in patients with KRAS wild-type metastatic colorectal cancer has not been well reported. Since mutations in codons 12 and 13 of the KRAS gene predict lack of response to Cetuximab, mutations of V600E BRAF and PI3CA have been controversial. Methods: The aim of this study was to assess the efficacy of second-line FOLFIRI plus cetuximab in KRAS wt mCRC. Primary endpoint was response rate, other secondary endpoints were PFS, OS and safety. KRAS, BRAF, PI3CA tests by direct sequence were performed in Yamaguchi University. The starting dose of irinotecan was 150mg/ m2 (approved dose in Japan), but decreased to 100mg/m2 with UGT1A1 *28,*6 homozygous or both heterozygous. Results: From December 2008 to November 2009, 112 pts were preregistered. 67 (59.8%) pts were KRAS codon 12, 13 wt, and 60 pts were enrolled: 39 males (65%), 21 females (35%); median age was 62 years (range 37-82). The incidence of UGT1A1*28, *6 homozygous was 2.8%, 4.7% respectively. Grade 3/4 adverse events were leucopenia 26.7%, neutropenia 43.3%, paronychia 10.0%, skin toxity (fissure) 10.0% and acne 5.0%. The confirmed response rate (RECIST) was 31.7% (19/60). The median progression free survival and overall survival were 7.5 (C.I. 5.2-10.1) and 19.5 (C.I. 11.7-22.2) months respectively. Three pts had BRAF mutations and tumor shirinkage were +50.9%, +12%, +85.6% respectively. Two pts had PI3CA mutations and tumor shirinkage were +4%, +44%, respectively. Conclusions: FLIER was the first multicenter phase II trial with prospective analysis of KRAS as a predictive biomarker for cetuximab in second-line mCRC in Japan. Second-line FOLFIRI+cetuximab is well-tolerated and active. Mutations in BRAF and PI3CA gene seemed to be lack of response to cetuximab.
172PD Final analysis: Phase II trial of irinotecan/S-1/cetuximab (IRIS/Cet) as second line treatment in patients with KRAS exon2 wild type metastatic colorectal cancer: HGCSG0902. Comparison of administration interval in cetuximab treatment
