An Open Label, Randomized Phase Iii Trial Evaluating The Treatment (Tx) Effects Of Panitumumab (Pmab) Plus Best Supportive Care (Bsc) Versus Bsc In Chemorefractory Wild-Type (Wt) Kras Exon 2 Metastatic Colorectal Cancer (Mcrc) And In Wt Ras Mcrc.

642 Background: An overall survival (OS) benefit in WT KRAS exon 2 mCRC was not seen with pmab monotherapy in study 20020408 possibly due to crossover of patients (pts) in the BSC arm. Retrospective analyses have indicated that other KRAS and NRAS mutations beyond KRAS exon 2 are predictive of anti-EGFR tx effects. Study 20100007 assesses the OS benefit of pmab in chemorefractory WT KRAS exon 2 mCRC and is the first phase 3 trial to prospectively evaluate pmab tx effects in WT RAS (exons 2, 3, and 4 of KRAS and NRAS) mCRC. Methods: Anti-EGFR naive pts were randomized 1:1 to receive pmab (6 mg/kg Q2W) + BSC or BSC. KRAS exon 2 and RAS mutation status of tumors were determined centrally. The primary endpoint was OS in WT KRAS exon 2 mCRC. Secondary endpoints were OS in WT RAS mCRC and progression-free survival (PFS), objective response rate (ORR), and safety in both WT KRAS exon 2 and WT RAS groups. Crossover was not permitted. Results: 377 pts with WT KRAS exon 2 mCRC were enrolled. RAS ascertainment rate ...