3560 Background: Downsizing with chemotherapy (CT) unresectable liver-limited disease (LLD) can permit resection and prolonged survival in patients (pts) with colorectal cancer (CRC). We assessed the value of adding panitumumab (P) to standard CT in this setting. Methods: This was a phase II, open-label, randomized, multicenter study which included pts≥18 years with wild-type (WT) KRAS exon 2 metastatic CRC and LLD fulfilling one of the following criteria: ≥4 metastases; at least 1 metastasis>10 cm in diameter; or technically not resectable. Pts were randomized 1:1 to receive P-FOLFOX4 or P-FOLFIRI every two weeks. The primary endpoint was the objective response rate. Results: There were77 pts analyzed (38 received P-FOLFOX4 and 39 P-FOLFIRI). Not confirmed response was noted in 70.1% pts (73.7% with P-FOLFOX4 and 66.7% with P-FOLFIRI). After a median of 8 P infusions in both groups, 51.9% underwent surgical resection of liver metastases (44.7% and 59.0%, respectively). The resection rate (R0+R1) was 77.5...