Monitoring the blood levels of DNA fragments released by dying tumor cells may be an early indicator of successful treatment in an advanced form of skin cancer - melanoma, as per a study at NYU Grossman School of Medicine and Perlmutter Cancer Center, published in the journal The Lancet Oncology.
This gene-based blood test serves as an accurate indicator of treatment progress in melanoma. Melanoma is one of the most aggressive forms of skin cancer, generally affecting the cells (melanocytes) that are responsible for skin pigmentation. It kills nearly 7,000 Americans a year and is notoriously difficult to treat once it spreads to other body parts.
"Our findings suggest that levels of ctDNA may serve as a fast and reliable tool to gauge whether an anticancer medication is working. The blood test results could help support continuing the current treatment strategy or else encourage patients and physicians to consider other options," says study senior author David Polsky, the Alfred W. Kopf, M.D. Professor of Dermatologic Oncology at NYU Langone Health and its Perlmutter Cancer Center.
The long search for better ways to monitor the aggressive types of skin cancers via specific biomarkers allowed the team to explore this largest analysis to date, over two years. Blood samples from two pivotal clinical trials involving 383 American, European, and Australian men and women were analyzed.
The enrolled participants had unresectable metastatic melanoma tumors with mutations in the BRAF gene, and were receiving targeted treatment with drugs dabrafenib and trametinib.
Undetectable levels of freely circulating tumor DNA (ctDNA) four weeks after the drug treatment were detected in patients who had twice as long a longer survival rate without cancer growth as compared to those who continued to have detectable levels of freely circulating tumor DNA (ctDNA).
It was also found that patients with 64 or fewer copies of ctDNA per milliliter of blood before treatment were likely to respond well to therapy, with a survival rate of nearly three years on average. By contrast, levels above that threshold were linked to a significantly poorer chance of survival, with patients living just over a year.
Role of ctDNA in Skin Cancer
The mutated DNA code found in melanoma cells spills into surrounding blood as the cancer cells break down which helps track the progression of cancer. Standard diagnostic tools like X-ray, CT scan, require almost three months to measure the tumor response to treatment but gene-based blood test fulfills the requirement in reliably a quick time as seen in 93% of patients.
"Although this gene-based test focuses on tumors with BRAFV600 mutations, we believe it will be similarly useful for melanomas that have other mutations, such as defects in the NRAS and TERT genes, which are also commonly mutated in this disease. Ultimately, we'd like to see this test used routinely in the clinic to help guide treatment decisions," says study lead author Mahrukh Syeda, MS, a research scientist in the Department of Dermatology at NYU Langone Health.
With the promising results of this gene-based blood test, the team anticipates its FDA-approval for testing its further accuracy in earlier stages of melanoma, other future applications, and clinical use.