In this study, Turner NC et al. did enroll advanced breast cancer patients already treated with >  = 2 hormone therapy options to perform a plasma-based NGS analysis to be divided into 4 parallel treatment groups according to mutational status (ESR1 mutations, HER2 mutations; AKT1 mutations and estrogen receptor-positive; AKT1 mutations and estrogen receptor-negative or PTEN mutation) in order to receive a tailored plasma-guided treatment. The gene discussed is ESR1; the disease is breast cancer.