Change in tumor burden was classified as complete response (CR), partial response (PR), stable disease
(SD) or progressive disease (PD). Patients with CR or PR were included in overall response rate (ORR). Patients had imaging studies every 4 cycles of chemotherapy. Best response after the start of chemotherapy was considered for ORR. Statistical analysis Response to treatment according to the mutational status was evaluated using the Fisher’s exact test. Progression free survival (PFS) was defined as the time from initiation of FOLFOX (with or without bevacizumab) until first evidence of radiographic progression or death, whichever occurred earlier. Overall survival (OS) was calculated as the period from the beginning of treatment to death or the Inhibitors,research,lifescience,medical last follow-up at which point data were censored. OS and PFS were estimated with the Kaplan-Meier algorithm. A P-value P≤0.05 was considered to indicate statistical significance. Test for differences in survival distributions was done using the log-rank test. Statistical analysis and Inhibitors,research,lifescience,medical plots were done using SAS, version 9.1, statistical software (SAS Institute Inc., Cary, NC). KRAS mutation detection Tumor
DNA was isolated from formaldehyde-fixed paraffin-embedded tissues and screened for the presence of KRAS codon 12 and 13 mutations using a DxS K-RAS mutation test kit (DxS Ltd). This assay detects 7 KRAS mutations in Inhibitors,research,lifescience,medical codons 12 and 13 using qualitative Inhibitors,research,lifescience,medical real-time PCR assay combining Scorpions® and ARMS® (allele-specific PCR) technologies. Detectable mutations are; 1. Gly12Asp
(GGT>GAT) 2. Gly12Ala (GGT>GCT) 3. Gly12Val (GGT>GTT) 4. Gly12Ser (GGT>AGT) 5. Gly12Arg (GGT>CGT) 6. Gly12Cys (GGT>TGT) 7. Gly13Asp (GGC>GAC). The method used in this kit is highly sensitive and depending on the total amount of DNA present, can detect approximately 1% of mutant in a background of wild-type genomic DNA. Results Patient demographics We identified 191 patients with CRC who underwent KRAS gene mutation testing using Inhibitors,research,lifescience,medical DxS assay at Roswell Park Cancer Institute (RPCI). KRAS DsX assays were performed between June 2008 and May 2009. 181/191 patients had confirmed metastatic disease and were included to assess the impact of KRAS status on the pattern of metastatic disease. The sites of metastastic disease at Selleckchem Cisplatin presentation through were classified into 3 main categories: liver, lung, and peritoneum. Only 83 of the 181 patients received first-line FOLFOX or FOLFOX plus bevacizumab chemotherapy at RPCI and were subject to efficacy analysis. Baseline patient characteristics are summarized in Table 2. Table 2 Baseline characteristics of the study patients (n=181) KRAS mutation status and pattern of metastasis Mutations in the KRAS were detected in 77 (40.31%) tumors with the following distributions: codon 13 mutations (Aspartate) 9.09%, codon 12 mutations (Aspartate) 46.75%, (Valine) 19.48%, and (Alanine) 7.79%. The most common site of metastasis was the liver, followed by lung, and peritoneum.