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The Food and Drug Administration has approved the use of the first genetic test that can help with the decision about whether cetuximab (Erbitux) would be an effective treatment for certain colorectal patients.


The therascreen KRAS RGQ PCR Kit can provide information about the KRAS gene mutation in patients whose colorectal cancer has metastasized. Studies have found that Eribitux is not effective in patients who have the mutation.


Erbitux targets the epidermal growth factor receptor on the surface of colorectal cancer cells, interrupting a signal to reproduce that can stop the growth of colorectal cancer cells. However, when the cells have a mutation in the KRAS gene, they continue to reproduce even when Erbitux blocks EGFR.


The FDA first approved Erbitux in 2004 to treat EGFR-expressing late-stage colorectal cancer after patients stopped responding to chemotherapy. In 2009, the FDA approved updated recommendations for Erbitux, based on studies that found that the drug was not effective in patients whose tumors have a mutated KRAS gene.


"This test helps clinicians determine whether this specific treatment is an effective option," Alberto Gutierrez, PhD, Director of the Office of In Vitro Diagnostic Device Evaluation and Safety in the FDA's Center for Devices and Radiological Health, said in an FDA news release.

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The agency also approved a new indication for Erbitux for use in combination with FOLFIRI chemotherapy (irinotecan, fluorouracil, and leucovorin), as a first-line treatment in patients with metastatic colorectal cancer who have EGFR-expressing, and KRAS wild-type (no mutations) tumors.


Among patients with tumors that did not have one of the seven KRAS mutations, median survival was 23.5 months for those who received Erbitux plus FOLFIRI compared with 19.5 months for those who received just FOLFIRI. Among patients whose tumors had a KRAS mutation, median survival was similar between those who received Erbitux and those who did not.


"The approval of this new Erbitux indication with the concurrent approval of a genetic test provides clear guidance on selecting patients who will optimally benefit," said Richard Pazdur, MD, Director of the Office of Oncology Drug Products in the FDA's Center for Drug Evaluation and Research.


"Clinical trial data leading to the approval of this new indication supports the recommendation to treat those patients whose colorectal tumors do not have KRAS mutations and to avoid treating those with KRAS mutations."


The therascreen KRAS RGQ PCR Kit was developed by QIAGEN Manchester Ltd., of Manchester, England.


Erbitux is co-marketed by Bristol-Myers Squibb and Eli Lilly and Company.