TY - JOUR T1 - A combined oncogenic pathway signature of <em>BRAF</em>, <em>KRAS</em> and <em>PI3KCA</em> mutation improves colorectal cancer classification and cetuximab treatment prediction JF - Gut JO - Gut SP - 540 LP - 549 DO - 10.1136/gutjnl-2012-302423 VL - 62 IS - 4 AU - Sun Tian AU - Iris Simon AU - Victor Moreno AU - Paul Roepman AU - Josep Tabernero AU - Mireille Snel AU - Laura van't Veer AU - Ramon Salazar AU - Rene Bernards AU - Gabriel Capella Y1 - 2013/04/01 UR - http://gut.bmj.com/content/62/4/540.abstract N2 - Objective To develop gene expression profiles that characterise KRAS-, BRAF- or PIK3CA-activated- tumours, and to explore whether these profiles might be helpful in predicting the response to the epidermal growth factor receptor (EGFR) pathway inhibitors better than mutation status alone. Design Fresh frozen tumour samples from 381 colorectal cancer (CRC) patients were collected and mutations in KRAS, BRAF and PIK3CA were assessed. Using microarray data, three individual oncogenic and a combined model were developed and validated in an independent set of 80 CRC patients, and in a dataset from metastatic CRC patients treated with cetuximab. Results 175 tumours (45.9%) harboured oncogenic mutations in KRAS (30.2%), BRAF (11.0%) and PIK3CA (11.5%). Activating mutation signatures for KRAS (75 genes), for BRAF (58 genes,) and for PIK3CA (49 genes) were developed. The development of a combined oncogenic pathway signature-classified tumours as ‘activated oncogenic’, or as ‘wildtype-like’ with a sensitivity of 90.3% and a specificity of 61.7%. The identified signature revealed other mechanisms that can activate ERK/MAPK pathway in KRAS, BRAF and PIK3CA wildtype patients. The combined signature is associated with response to cetuximab treatment in patients with metastatic CRC (HR 2.51, p&lt;0.0009). Conclusion A combined oncogenic pathway signature allows the identification of patients with an active EGFR-signalling pathway that could benefit from downstream pathway inhibition. ER -