Repeat tumor biopsies to study genomic changes during therapy are difficult, invasive and data are confounded by tumoral heterogeneity.,The analysis of circulating tumor DNA (ctDNA) can provide a non-invasive approach to assess prognosis and the genetic evolution of tumors in response to therapy.,Mutation-specific droplet digital PCR was used to measure plasma concentrations of oncogenic BRAF and NRAS variants in 48 patients with advanced metastatic melanoma prior to treatment with targeted therapies (vemurafenib, dabrafenib or dabrafenib/trametinib combination) or immunotherapies (ipilimumab, nivolumab or pembrolizumab).,Baseline ctDNA levels were evaluated relative to treatment response and progression-free survival (PFS).,Tumor-associated ctDNA was detected in the plasma of 35/48 (73%) patients prior to treatment and lower ctDNA levels at this time point were significantly associated with response to treatment and prolonged PFS, irrespective of therapy type.,Levels of ctDNA decreased significantly in patients treated with MAPK inhibitors (p < 0.001) in accordance with response to therapy, but this was not apparent in patients receiving immunotherapies.,We show that circulating NRAS mutations, known to confer resistance to BRAF inhibitors, were detected in 3 of 7 (43%) patients progressing on kinase inhibitor therapy.,Significantly, ctDNA rebound and circulating mutant NRAS preceded radiological detection of progressive disease.,Our data demonstrate that ctDNA is a useful biomarker of response to kinase inhibitor therapy and can be used to monitor tumor evolution and detect the early appearance of resistance effectors.
Because only a small fraction of asbestos-exposed individuals develop malignant mesothelioma1, and because mesothelioma clustering is observed in some families1, we searched for genetic predisposing factors.,We discovered germline mutations in BAP1 (BRCA1-associated protein 1) in two families with a high incidence of mesothelioma.,Somatic alterations affecting BAP1 were observed in familial mesotheliomas, indicating biallelic inactivation.,Besides mesothelioma, some BAP1 mutation carriers developed uveal melanoma.,Germline BAP1 mutations were also found in two of 26 sporadic mesotheliomas: both patients with mutant BAP1 were previously diagnosed with uveal melanoma.,Truncating mutations and aberrant BAP1 expression were common in sporadic mesotheliomas without germline mutations.,These results reveal a BAP1-related cancer syndrome characterized by mesothelioma and uveal melanoma.,We hypothesize that other cancers may also be involved, and that mesothelioma predominates upon asbestos exposure.,These findings will help identify individuals at high risk of mesothelioma who could be targeted for early intervention.