Our EGFR Pathway test will provide physicians with the most comprehensive data available from a single test offering for identifying RAS and BRAF gene mutations in patients with mCRC who may be considered for anti-EGFR therapy. Given that research suggests these gene mutations may inhibit therapeutic response in many patients, our goal is to give physicians a personalized diagnostic tool that can help them determine more reliably whether or not to provide therapy with EGFR antagonists to the individual patient, said Dr. Maher Albitar, M.D., medical director and chief of Research and Development, Hematology and Oncology, Quest Diagnostics.
Anti-EGFR therapies are designed to impede cellular proliferation caused by activation of EGFR, but can trigger several side effects, including fatigue, skin rash, and nausea and vomiting. Up to 40 percent of patients with mCRC in the US have mutations in the KRAS gene that render anti-EGFR therapy ineffective. In January 2009, the American Society of Clinical Oncology (ASCO) produced a provisional clinical opinion (PCO) recommending that all patients with mCRC who are candidates for anti-EFGR therapy be tested for KRAS gene mutations (specifically in codons 12 and 13), and that anti-EFGR antibody therapy should not be administered if mutations are found.
However, fewer than 50 percent of patients with wild-type (normal) KRAS genes respond to anti-EGFR therapy, suggesting that additional mechanisms may affect response. Studies demonstrate that in patients with mCRC, about five percent may have mutations in the NRAS gene and eight percent may have mutations in the BRAF gene, and that mutations in these genes are associated with poor anti-EGFR treatment response.
The Quest Diagnostics EGFR Pathway Test sequentially detects mutations along the EGFR Pathway, beginning with KRAS followed by NRAS and BRAF. If a mutation is identified before the entire series is analyzed, the reflex testing process stops, and the test result is provided to the physician. Since any individual patient is only likely to experience one mutation in either KRAS, NRAS and BRAF, combined testing for mutations from these three genes in the EGFR pathway would theoretically accurately classify more patients as non-responders than KRAS and/or BRAF testing alone.
While KRAS mutation analysis of codons 12 and 13 is well established as an aid in predicting anti-EGFR therapy response, a growing body of research has revealed that other mutations in the EGFR signaling pathway, including those at codon 61 of KRAS and NRAS, also impede treatment response in patients with mCRC, said Jay G. Wohlgemuth, M.D., vice president, Science and Innovation, Quest Diagnostics. Our new test will enable physicians to gain a deeper understanding of a patient’s EGFR pathway status, based on the latest scientific research, than is available using competing tests. We believe this test is an important diagnostic advance that will help physicians potentially identify more non-responder EGFR patients who might be missed using standard KRAS assessments, potentially sparing a substantial number of patients lost time, not to mention side effects and high costs of anti-EGFR therapies.
In addition to the EGFR Pathway Test, the company launched individual laboratory tests for identifying mutations in the NRAS and BRAF genes for physicians who prefer to order individual tests. The company launched its first laboratory test for detecting mutations in the KRAS gene in August 2008.
