RAS Panel for Detecting Genetic CRC Mutations Approved by FDA

The FDA has approved the Praxis Extended RAS Panel for genetic testing in patients with metastatic colorectal cancer (CRC). Detecting certain tumor mutations using the test could have important implications for treatment decisions.

According to the FDA’s announcement, the test, sold by Illumina Inc, is used to analyze patients’ tumor samples for the presence of any of 56 mutations in the RAS genes. This makes it the first FDA-approved genetic sequencing test capable of spotting multiple CRC gene mutations with just 1 test. The National Cancer Institute states that about a third of all cancers in humans, and 45% of colorectal cancers, are caused by mutations of the RAS genes.

The test results will be used to determine which patients may receive panitumumab, a monoclonal antibody which has previously shown a lack of efficacy in patients with certain RAS mutations. If the test detects a mutation in the CRC tumor tissue, oncologists are advised to administer a therapy other than panitumumab. If no mutations are found, “then panitumumab may be an appropriate treatment,” the FDA’s announcement stated.

Panitumumab has been shown to be safe and effective, as evidenced by both progression-free and overall survival measures, in treating CRC tumors without a RAS mutation. The ability of the Praxis Extended RAS Panel to accurately identify the mutations was confirmed through retrospective testing on tumor specimens from patients with metastatic CRC. All patients were already participating in a clinical trial of panitumumab in conjunction with the drug combination FOLFOX.

Following the testing panel’s approval, the product labeling of panitumumab “has been modified to align the indication for panitumumab and intended use for the Praxis Extended RAS Panel, stating that panitumumab is indicated in first-line therapy in combination with FOLFOX for patients with wild-type RAS (defined as wild-type in both KRAS and NRAS as determined by an FDA-approved test for this use) metastatic colorectal cancer,” according to the FDA announcement.

Additional information on the panel’s safety and effectiveness noted that some risks include the potential for false results. Patients could be prevented from receiving the possibly helpful panitumumab if the genetic testing inaccurately indicated they had a tumor mutation, or they could needlessly receive panitumumab because the test wrongly indicated they did not have a mutation. However, the FDA determined that these “probable risks associated with false results are mitigated by the analytical performance of the device.”