FOCUS 3: A study to determine the feasibility of molecular selection of therapy using K-RAS, B-RAF, and topo-1 in patients with advanced colorectal cancer (ACRC).

563 Background: Molecular characteristics of cancer vary between individuals. In future increasing numbers of trials will require assessment of biomarkers in order to allocate patients into enriched populations in which targeted therapies are more likely to be effective. The FOCUS 3 trial is a feasibility study to assess whether tumour samples could be collected from referring hospitals’ pathology departments, sent to designated reference laboratories for biomarker evaluation, and results provided to oncologists within 10 working days. Methods: Patients with ACRC, fit for chemotherapy, were registered from 24 centres between 02.10 and 04.11. Following consent, paraffin embedded tumour samples were sent to Cardiff or Leeds for analysis of topoisomerase 1 (topo-1) by immunohistochemistry and of KRAS and BRAF mutation status, and results were forwarded to the MRC CTU. Patients were classified into 1 of 4 molecular strata, which determined the set of 2 hypothesis driven experimental therapies they could be ra...