Panitumumab Ineffective for Colorectal Cancers with Rare RAS Mutations

The epidermal growth factor receptor (EGFR)-targeted agents panitumumab and cetuximab have demonstrated single-agent activity in advanced colorectal cancer (CRC) and have improved response and survival when combined with chemotherapy. However, the benefit of these drugs is limited to KRAS–wild-type tumors. Activating KRAS mutations, which are present in at least 40% of colorectal cancers, make tumors resistant to EGFR-targeted therapies, and adding panitumumab or cetuximab to chemotherapy may worsen outcomes in patients with such mutations.

Now, to test whether EGFR-targeted therapy is influenced by rarer mutations in RAS (beyond the more common KRAS exon 2 mutations), investigators analyzed the impact of the full range of RAS mutations on t…