NEW YORK (GenomeWeb News) – The US Food and Drug Administration has revised the prescribing information for a class of epidermal growth factor receptor inhibitors for colorectal cancer to include information on variations in the KRAS gene that may affect patient response to the drugs.
The FDA has updated the "indication and usage" section of the labels of Amgen’s Vectibix and ImClone/Bristol-Myers Squibb’s Erbitux to note that "retrospective analyses of metastatic colorectal cancer trials have not shown a treatment benefit for the EGFR inhibitors in patients whose tumors had KRAS mutations in codon 12 or 13," and that the use of the drugs is not recommended for the treatment of colorectal cancer patients with these mutations.
The agency has also updated the "clinical studies" section of the labels to include results from retrospective analyses across seven randomized clinical trials with agents in this class.
"With this label update, physicians can now eliminate anti-EGFR antibodies as a treatment option for patients with mutated KRAS tumors and redirect those patients to alternative therapies, avoiding unnecessary treatments in patients who are unlikely to benefit," said Sean Harper, chief medical officer and head of global development at Amgen, in a statement.
Amgen noted that the label update is "specific to the utility of KRAS as a biomarker for Vectibix used as a monotherapy." In the combination chemotherapy setting, the company is conduction two prospective Phase 3 clinical studies that will test the clinical utility of KRAS as a predictive biomarker in metastatic colorectal cancer patients in earlier lines of therapy. Data from these trials are expected in the third quarter of 2009.
The FDA label update follows recent guidelines from the American Society of Clinical Oncology and the National Comprehensive Cancer Network, which recommended that doctors test all metastatic colorectal cancer patients for KRAS variants prior to treatment with an anti-EGFR antibody therapy.
ImClone and Bristol-Myers Squibb estimate that around 40 percent of patients with mCRC have KRAS mutations while the remaining 60 percent have the wild-type KRAS gene.
The revision "is the result of a collaborative dialogue between the FDA, the industry and the public about the role of the KRAS biomarker in metastatic colorectal cancer patients being considered for therapy," said Eric K. Rowinsky, executive vice president and chief medical officer of ImClone, in a statement.