Primary tumor location and expression of mir-664 as a combined biomarker for bevacizumab effectiveness in metastatic colorectal cancer.

3572 Background: We aimed to identify tissue microRNAs (miRs) that could predict outcome for patients with metastatic colorectal cancer (mCRC) treated with first line bevacizumab (BEV) and chemotherapy (CT) but not for patients treated with CT alone. Methods: Patients with mCRC treated with first line capecitabine and oxaliplatin (CT) with or without BEV at ten hospitals were identified and data was extracted retrospectively. Formalin-fixed paraffin-embedded tissue samples from primary tumors were collected and RNA was purified from 3 x 10 µm sections, without micro-dissection. miR expression was measured using Applied Biosystems TaqMan Custom LDA cards profiling 22 selected miRs in duplicate. The 22 miRs were selected from a previous discovery study profiling 754 miRs. miR expression was related to time to disease progression (TTP) and overall survival (OS) in multivariate analyses using Cox proportional hazards models with adjustment for age, prior adjuvant treatment, and no. of metastatic sites. We hav...