Fig. 2: Plasma ctDNA levels are relative to progression.

a Plasma ctDNA levels (copies/mL of plasma) in melanoma samples at the time of progression in patients who had a response to therapy (R) or did not show response to treatment (NR). The geometric mean of ctDNA concentrations is indicated for each group by a line. The P values of a t test comparing the log-transformed ctDNA levels and Fisher’s exact test comparing detection rates are indicated above each comparison. b Changes in ctDNA levels between the time of response and the time of progression. Percentages denote the frequency of patients with detectable ctDNA. Red dots identify patients with intracranial disease only. The geometric mean of ctDNA concentrations is indicated for each group by a line. Paired t test P value of the log-transformed ctDNA levels is indicated above the graph.