New Blood-Based BRAF Test for Melanoma

A new quantitative, blood-based test to identify BRAF-mutated melanoma tumors is now available according to the test’s manufacturer, Biocept, Inc.¹

Approximately one-half of metastatic melanoma patients have tumors that harbor either a V600E or V600K activating BRAF mutation, and are therefore eligible for BRAF-targeted oral therapies including Novartis’s dabrafenib (Tafinlar) and Roche’s vemurafenib (Zelboraf). These patients are also eligible for combination oral therapies of a BRAF and MEK inhibitor which, in phase III clinical trials, have shown to be more effective compared to a BRAF inhibitor alone.²

Other currently available tests to detect the presence of a BRAF mutation in patients with metastatic melanoma rely on a tumor tissue sample. The new test, in contrast, works by detecting circulating tumor DNA shed from a patient’s tumor into the blood stream. The DNA in the blood stream comes from dying tumor cells, also shed into a patient’s circulation. This type of test is noninvasive and is referred to as a "liquid biopsy." The majority of mutations in tumor cells are somatic, meaning that they are not common to all of the cells in the patient’s body, but only to those of the tumor.

The amount of circulating tumor DNA shed into the blood stream, studies have found, correlates with the stage of the cancer, providing a potentially quantitative measure of tumor burden.

According to the company, the high sensitivity of the test allows it to be used to monitor a patient’s response to BRAF-targeted therapy as well as to monitor for disease relapse. "Our test is highly specific and sensitive, and can therefore detect even low levels of mutant BRAF. This test holds promise as a therapeutic monitoring tool for patients with advanced melanoma,” said Veena Singh, MD, FCAP, FCAMG, Biocept’s Senior Medical Director.

According to Dr. Singh, the test could improve treatment for patients with its ability to detect those with BRAF-mutated tumors that were previously found negative with a tissue biopsy-based test. Because tumors are heterogeneous and may have some portions of the tumor with or without a particular mutation, the result of a tumor biopsy assay can give different results depending on where the biopsy was taken.

"Due to their high sensitivity, our mutation tests offer a great advantage in assessing patients with advanced disease and provide a new tool for following patients who are likely to be at high risk for disease recurrence," added Lyle Arnold, Ph.D., Biocept's Chief Scientific Officer, also in a statement.

References:

• Biocept, Inc. (2015). Biocept Launches Diagnostic Assay for BRAF Mutations in Patients with Melanoma.
• Robert C, Karaszewska B, Schachter J, et al. (2015). Improved Overall Survival in Melanoma with Combined Dabrafenib and Trametinib. The New England Journal of Medicine, 372:30-39.