- Study design: Primary tumor tissues will be analyzed for the presence of BRAFV600E by pyrosequencing or other quantitative assay. If available, synchronous metastases and post-therapy metachronous metastases will be analyzed as well. The clinical response will be determined according to RECIST, and the association with the percentage of BRAFV600E alleles will be evaluated. Attention will be paid to the possible difference of BRAFwild-type/BRAFV600E ratio between primary tumors and synchronous metastases, primary tumors and post-therapy metachronous metastases, and between responsive and resistant synchronous tumor lesions.