BALTIMORE and HAMBURG, Germany, April 9, 2013 /PRNewswire/ -- A study presented at the AACR Annual Meeting 2013 indicates that a DNA blood test using Inostics' BEAMing Digital PCR can detect more mutations associated with secondary drug resistance in GIST patients than testing conventional biopsies. Therapies targeted to specific cancer-causing mutations may be the most promising strategy in cancer treatment. However, inter- and intra-tumor heterogeneity pose a significant challenge to maximizing therapeutic efficacy. Within a single patient, different cancer cells may have different sets of mutations making it very difficult to detect all of the relevant mutations in a single tissue biopsy. "To develop the right drug for the right patient, and to use those drugs most effectively, we need to understand the tumor burden in patients as fully as possible. Inostics' BEAMing technology may offer physicians a real-time composite picture of all the mutations across all tumors in any given patient using just a simple blood sample", George D. Demetri, M.D., Director of the Ludwig Center at Dana-Farber Cancer Institute and Harvard Medical School in Boston, Mass., said. Demetri refers to data from a sub-analysis of the phase III GIST-Regorafenib in Progressive Desease (GRID) trial, designed to assess the efficacy of regorafenib in patients with GIST. Comparing conventional sequencing on tumor tissue with data generated using the BEAMing technology on blood samples they found resistance mutations 4 times more often in blood samples (48%) than in tumor tissue samples (12%). Furthermore, nearly half of the blood samples that had secondary KIT mutations harbored multiple secondary mutations. "By using this technology we hope to develop the most rational drug combinations and better tests to match patients with the most effective therapies going forward", Demetri said.