A better test for evaluating and tracking progression of metastatic melanoma

By John Murphy, MDLinx
Published January 12, 2016

Key Takeaways

An alternate blood test for metastatic melanoma outperformed the current test in evaluating and tracking disease progression, according to an article published January 12, 2016 in Molecular Oncology.

The test, which measures circulating tumor DNA (ctDNA), detected measurable disease in 80% of subjects who were about to undergo treatment for metastatic melanoma. By comparison, the current standard test, which measures the enzyme lactate dehydrogenase (LDH), was much less sensitive, detecting measurable levels in 30% of subjects.

Also, as a biomarker of disease progression, ctDNA detected cancer recurrence (as confirmed by X-ray or CT scan) in 85% of patients tested and undergoing therapy, while LDH was elevated in 54% of patients.

“Our study results show that circulating tumor DNA is a superior blood test for evaluating and tracking progression of metastatic melanoma,” said senior study investigator and dermatologist David Polsky, MD, PhD, Professor of Dermatologic Oncology at New York University’s Langone Medical Center, in New York, NY.

Serum ctDNA testing has already shown promise as a disease biomarker in breast and colon cancers. Currently, Dr. Polsky noted, no clinically useful blood-based biomarker exists to guide management of patients with metastatic melanoma. However, ctDNA analysis is particularly attractive for patients with metastatic cutaneous melanoma, which is commonly characterized by the genetic mutations BRAF and NRAS.

In this small study of 31 patients with inoperable metastatic melanoma, investigators obtained serum levels of LDH and ctDNA (looking for BRAF and NRAS mutations), and compared these with patients’ radiographic scans.

They found that ctDNA was substantially better as an indicator of tumor burden and a biomarker of disease progression than LDH. “The 80% sensitivity to detect disease progression is highly encouraging for a blood-based melanoma biomarker, and further follow-up studies are warranted,” the researchers wrote.

Another important finding was that the ctDNA test was helpful in patients with small tumors whose melanoma had spread, Dr. Polsky said. Specifically, ctDNA blood levels were elevated in 5 of 7 such patients (71%) while LDH levels were elevated in only 1 of 13 (8%). This finding showed that ctDNA is more sensitive than LDH for detecting lower levels of measurable disease.

“With further study, ctDNA monitoring in melanoma may inform clinical decision-making regarding radiographic disease monitoring and treatment decisions among stage IV patients undergoing systemic treatment who have clinically stable disease,” the researchers wrote.

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