Can tumor DNA in the blood predict how well patients with melanoma will respond to immune therapy?

This study looked at the role of circulating tumor DNA (ctDNA) in predicting treatment response in advanced melanoma. They found that in patients treated for the first time with immune treatment, patients with low ctDNA levels had a longer survival without cancer worsening.

Advanced melanoma describes melanoma which has spread to other organs. Immune treatments have improved outcomes for patients with this cancer. However not all patients have a lasting response to this treatment and it is hard to identify which patients will respond best.

Circulating tumour DNA (ctDNA) is DNA from cancer cells that is found in a patient’s blood. Research into the uses of ctDNA in different types of cancer is underway. There is some evidence that ctDNA may be used to predict how well patients will respond to different therapies but more research is needed to confirm this.

This study looked at 125 patients with advanced melanoma. CtDNA levels were measured in these patients before starting treatment. Patients were then followed for an average of 95 weeks to monitor for progression of the melanoma.

In patients who had not been treated with immune therapy before, those with low ctDNA levels (20 copies/mL or less) had a more lasting response to immune therapy than those with high levels. Patients with low ctDNA levels survived on average 57 weeks without any signs of cancer progression compared to 29 weeks for those with high ctDNA levels. Patients receiving immune therapy as a second treatment had similar survival without cancer progression, without relation to ctDNA levels.

This study showed that for patients treated for the first time with immune therapy, low ctDNA levels were associated with a longer survival without cancer progression than those with high ctDNA levels.

The results of this study are limited by the small number of patients involved. More studies are needed to confirm these findings.