Patients were recruited into four parallel treatment cohorts matched to identified ctDNA mutations: cohort A included patients with ESR1 mutations (treated with fulvestrant); cohort B included patients with HER2 mutations (treated with neratinib and, if estrogen receptor positive, with fulvestrant); cohort C included patients with AKT1 mutations and estrogen receptor positive cancer (treated with capivasertib plus fulvestrant); and cohort D included patients with AKT1 mutations and estrogen receptor-negative cancer or PTEN mutation (treated with capivasertib). This evidence concerns the gene ESR1 and cancer.