The Circulating Tumor DNA Guided Switch (CAcTUS; NCT03808441) phase II clinical trial aims to determine whether changes in ctDNA levels can be used to accurately inform when to switch from targeted to immune therapy in patients with BRAF-mutant melanoma, assessing the response to BRAF treatment and evaluating whether this might improve the efficacy of immune therapy [220]. The gene discussed is BRAF; the disease is neoplasm.