Overall survival (OS) analysis from PRIME: Randomized phase III study of panitumumab (pmab) with FOLFOX4 for first-line metastatic colorectal cancer (mCRC).

3620 Background: The primary and final analyses of PRIME demonstrated that pmab + FOLFOX4 significantly improved progression-free survival (PFS) vs FOLFOX4 alone for first-line treatment of patients (pts) with wild-type (WT) KRAS exon 2 mCRC. Methods: Pts were randomized 1:1 to pmab 6.0 mg/kg every 2 weeks + FOLFOX4 or FOLFOX4 alone and had no prior chemotherapy for mCRC, ECOG performance status ≤ 2, and tumor tissue for biomarker testing. The primary endpoint was PFS by central assessment. Secondary endpoints included OS, objective response rate, and safety. KRAS exon 2 tumor status was determined by a blinded central lab prior to the primary analysis. This exploratory analysis of updated survival (>80% OS events) estimated the treatment effect of pmab + FOLFOX4 compared with FOLFOX4 alone on OS by KRAS exon 2 status. Previous analyses in pts with WT KRAS exon 2 tumor status reported OS with an event rate of 54% of pts in the primary analysis and 68% of pts in the final analysis. Results: 1183 pts were r...