Fig. 2.

Serial measurement of BRAF V600mut ctDNA in plasma of 2 patients (a, b = patient 1; c, d = patient 2) with advanced melanoma during targeted therapy. The y-axis represents the BRAF V600mut ctDNA copy number per millilitre. Results obtained with the Idylla™ system (Biocartis) and digital PCR (Bio-rad) are shown. a Treatment with dabrafenib and trametinib (dabra 2 × 150 mg + trame 2 mg) was initiated after obtaining the baseline plasma sample. Within 1 week the BRAF V600mut ctDNA copy number dropped significantly. After switching targeted therapy to pembrolizumab (Pem 2 mg/kg) due to side effects on the moment of best response (PR PET–CT), an increase of the BRAF v600mut ctDNA copy number was detected within 9 days. After reintroducing dabrafenib and trametinib, due to rapid clinical disease progression (Clinical PD), the BRAF V600mut ctDNA copy number dropped again. b The evolution of the BRA F V600mut ctDNA copy number in patient 1 during the first 2 days of treatment. c Treatment with dabrafenib and trametinib (dabra 2 × 150 mg + trame 2 mg) was initiated after obtaining the baseline plasma sample. Within 1 week the BRAF V600mut ctDNA copy number dropped significantly. d The evolution of the BRAF V600mut ctDNA copy number in patient 2 during the first day of treatment