How Physicians Can Detect ctDNA in Melanoma

Source: Targeted Oncology, March 2020

David Polsky, MD, PhD, a professor of dermatology in the Ronald L. Perlman Department of Dermatology at NYU Langone Health’s Perlmutter Cancer Center, discusses methods to identify circulating tumor DNA (ctDNA) in patients with melanoma.

In the laboratory at Polsky’s institution, they use the Droplet Digital™ PCR (polymerase chain reaction), which is a highly sensitive and specific method to detect ctDNA in patients with melanoma. He and his colleagues presented data at the American Society of Clinical Oncology (ASCO) 2019 Annual Meeting showing a 93% detection rate in the COMBI-d trial of patients with unresectable or metastatic melanoma. They were able to detect the BRAF mutation in the tumor prior to treatment in 93% of patients, which has been the highest number reported so far in this setting, according to Polsky.

Sequencing-based assays have advantages over the ctDNA identification method Polsky used and are able to detect multiple mutations at the same time. He says the sensitivity of ctDNA is thought to be the highest when looking at a single molecule target at a time.
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