Tumour Shrinkage and Response Outcomes During Second-Line Panitumumab (Pmab) + Folfiri Vs Folfiri Treatment

ABSTRACT Aim: Tumour shrinkage/response are important outcomes for patients (pts) with metastatic colorectal cancer (mCRC) as they may delay progression and ultimately improve survival. Here we report tumour response data for pts with RAS WT mCRC treated with FOLFIRI ± pmab. Methods: 181 was a phase 3 randomised study of second-line pmab + FOLFIRI vs FOLFIRI alone in pts with previously treated mCRC. KRAS exon 2 wild-type (WT) samples from this study were tested for mutations in KRAS exons 3/4 and NRAS exons 2/3/4 via bidirectional Sanger sequencing and WAVE-based SURVEYOR® to identify pts with RAS WT tumours (no mutations in KRAS/NRAS exons 2, 3 or 4). Objective response rates (ORRs) and m…