The FDA has given the green light to the cobas EGFR Mutation Test v2 (Roche Molecular Systems), a blood-based companion diagnostic for the cancer drug erlotinib (Tarceva, Astellas Pharma Technologies/Genentech). This is the first FDA-approved, blood-based genetic test that can detect epidermal growth factor receptor (EGFR) gene mutations in patients with non–small-cell lung cancer (NSCLC). Such mutations are present in approximately 10% to 20% of NSCLC.
Lung cancer is the leading cause of cancer-related death among men and women in the United States. According to the National Cancer Institute, an estimated 221,200 Americans will be diagnosed with lung cancer and 158,040 will die from the disease in 2016. NSCLC is the most common type of lung cancer.
NSCLC tumors may shed tumor DNA into a patient’s blood, making it possible to detect specific mutations in blood samples. Testing for tumor DNA using a blood sample is also called a “liquid biopsy.”
With the cobas EGFR Mutation Test v2, the presence of specific NSCLC mutations––exon 19 deletion or exon 21 (L858R) substitution mutations––detected in patients’ blood samples aids in selecting those who may benefit from treatment with erlotinib. However, if such mutations are not detected in the blood, then a tumor biopsy should be performed to determine whether the NSCLC mutations are present. Insofar as the test provides positive results, it may benefit patients who may be too ill or are otherwise unable to provide a tumor specimen for EGFR testing, according to the FDA.
The efficacy of the cobas EGFR Mutation Test v2 using blood samples was determined by using the test to identify the EGFR mutation status in patients enrolled into a clinical trial whose tumor biopsies were previously confirmed positive for the EGFR exon 19 deletion or L858R mutations, as determined by the cobas EGFR Mutation Test v1.
The FDA approved erlotinib in 2004 to treat patients with locally advanced or metastatic NSCLC after the failure of at least one prior chemotherapy regimen. In 2013, the FDA approved the drug for the first-line treatment of patients with metastatic NSCLC whose tumors have EGFR exon 19 deletions or L858R substitution mutations, as detected by an FDA-approved test.
The most common adverse events associated with erlotinib include rash, diarrhea, anorexia, fatigue, dyspnea, cough, nausea, and vomiting. Erlotinib is not recommended for use in combination with platinum-based chemotherapy, and the drug has not been evaluated as first-line treatment in patients with metastatic NSCLC whose tumors have EGFR mutations other than exon 19 deletions or L858R substitution mutations.
Source: FDA; June 1, 2016.