Clinical application of liquid biopsy to identify predictive and resistance biomarkers in stage IV breast cancer patients treated with CDK4/6 inhibitors

Resumo

HR+/HER2- stage IV breast cancer patients are treated with a combination of CDK4/6 inhibitors plus endocrine therapy (ET). Nevertheless, all patients will develop intrinsic or acquired resistance, but there are not predictive biomarkers identified so far. Hence, in this thesis, it was proved that the study of circulating material lets monitor disease evolution and tailor-patient therapy. The transcriptomic characterization of CTCs classified patients according to therapy response and determine resistance mechanisms to CDK4/6i plus ET. The cfDNA levels can be used to longitudinally study therapy response. In addition, it was proposed the characterization of circulating immune cells to identify predictive biomarkers to CDK4/6i plus ET in HR+/HER2- stage IV BC patients.