Can we predict treatment response using circulating tumor DNA in patients with melanoma?

This study investigated the use of circulating tumor DNA (ctDNA) to predict treatment response in advanced melanoma. 

They found that ctDNA levels can predict survival in these patients.

Melanoma is categorized, like many cancers, in stages. At stage 3 and above, survival rates can vary depending on treatment.

Identifying a biomarker may predict the chance of survival in advanced melanoma. A biomarker is a gene, protein or chemical that can be identified in a blood or tissue sample. If the level of a biomarker changes relative to other indicators, e.g. survival, then it can be used to predict the success of treatment. This is particularly important for new drugs. Immune-checkpoint inhibitors (ICIs) are a new type of cancer drug. They are expensive and have some side effects. Predicting the response to treatment is important in advanced cancer. 

This study included 174 patients with stage 3 skin melanoma. Blood samples were taken before surgery and processed for biomarkers. The investigators analyzed tumor DNA circulating in the blood (ctDNA). Patients were followed up for an average of 26 months.

ctDNA was found in 33-34% of patients. ctDNA levels were higher in patients with worse disease and larger tumors. Survival with melanoma was 17.6- 23.9 months in patients with average ctDNA levels. This was compared to 49.4- 92.1 months in patients with undetectable ctDNA. The risk of death was 2.11-2.29-times higher in patients with the average detected ctDNA.

The authors concluded that ctDNA levels can predict survival in patients with melanoma undergoing surgery. They suggested that this biomarker may help identify patients that would benefit from treatment after surgery.

Measuring ctDNA before surgery to remove the tumor appears to predict survival. ctDNA levels were not measured after surgery. This may be important in predicting outcomes also. More investigation is needed.