Outcome according to metastatic site in patients with KRAS wild-type tumors: Analysis from the CRYSTAL and OPUS studies.

Abstract

472 Background: The randomized CRYSTAL and OPUS studies showed that adding cetuximab (cet) to first-line chemotherapy (CT) significantly improved clinical benefit in patients (pts) with KRAS wild-type (wt) metastatic colorectal cancer (mCRC). R0 resection of colorectal liver metastases is a potentially curative option in this setting. In this descriptive analysis of these trials the benefit of adding cet to CT according to metastatic site was investigated. Methods: KRAS wt pts were grouped according to liver-limited disease (LLD) and those with other metastatic sites (non-LLD). Treatment arms were compared for response rates (RR), R0 resection rates (R0R), progression-free (PFS) and overall survival (OS). Results: The proportion of patients with LLD was comparable in each study and treatment arm (21%-30%). For most efficacy endpoints, pts with LLD derived greater benefit from CT alone or cet + CT compared with pts with non-LLD (Table). The highest R0R were seen in pts with LLD receiving cet + CT; increasing 2.3 and 3.7 fold from CT alone in the CRYSTAL and OPUS studies respectively. In pts with non-LLD adding cet to CT increased median OS by 5.1 and 3.4 months in the CRYSTAL and OPUS studies respectively (Table). Conclusions: The addition of cet to standard CT increases the R0R, RR, PFS and prolongs OS in first-line mCRC in KRAS wt pts, regardless of LLD. In pts with non- LLD treated with cet and FOLFIRI median OS was prolonged by more than 5 months. [Table: see text] [Table: see text]