KRAS and BRAF mutational status as selective criteria for targeted therapy in cholangiocarcinoma.

Background: Mutations of KRAS and BRAF genes have been associated with resistance to treatments targeted at EGFR pathway in advanced colorectal cancer and other solid tumors. Cetuximab is currently being tested in advanced biliary tract cancer, with encouraging preliminary results although definitive evidence of activity is still lacking. It is reasonable that cetuximab efficacy be restricted to tumors bearing wild-type KRAS and BRAF. Our study is aimed at determining KRAS and BRAF mutational status to evaluate the proportion of patients affected by biliary tract cancer who could benefit from EGFR-cascade targeted therapies. Methods: This is a retrospective analysis on 24 consecutive cases of cholangiocarcinoma undergone potentially curative resection in our institution. The mutational analyses have been conducted on the surgical specimen. After microdissection of the neoplastic area, DNA was extracted from enriched pathologic material with QIAmp DNA FFPE Tissue Kit (Qiagen S. p. A., Milan, Italy). Extracted DNA have been quantified after real-time PCR (Quantifiler Human DNA Quantification Kit, Applied Biosystems, Foster City, CA, USA) with ABI PRISM 7000 Sequence Detection System (Applied Biosystems). KRAS and BRAF mutations were detected in real-time PCR using specific commercially available kits (DxS Diagnostic, Manchester, UK) and confirmed with direct genomic sequencing of the same DNA specimen (Applied Biosystems 3730xl DNA Analyzer, Applied Biosystems). Results: Among patients included, 16 were extrahepatic cholangiocarcinomas and 8 intrahepatic; 14 pts showed lymph nodes involvement at surgery. 7 mutations of KRAS (all in exon 2, codon 12) and 2 of BRAF (1 in exon 11, 1 in exon 15) were identified, occurring respectively in 29% and 8% of patients. There were no double-mutated patients. 63% of study population (15 patients) was wild-type for both KRAS and BRAF. No relationship between mutational status and time to relapse has been found in this population (p 0.7). Conclusions: These preliminary data show that the majority of biliary tract cancer patients could benefit from anti-EGFR targeted therapies. Expansion of the number of patients and correlation with clinical data are ongoing.