Efficacy of everolimus in patients with hormone receptor positive, HER2 negative, metastatic breast cancer pretreated with CDK4/6 inhibitors

Patients who had prior exposure to CDK4/6 inhibitors experienced a shorter median PFS benefit from everolimus based-treatment compared to those who were CDK4/6 inhibitor-naive. In this study, they also demonstrated shorter OS, likely due to a more pronounced endocrine-resistant profile. Although a reduction in PFS is expected with successive lines of therapy, the use of everolimus after exposure to CDK4/6 inhibitors and aromatase inhibitors remains an option and allows to propose another endocrine-based therapy and to postpone the use of chemotherapy. Managing endocrine resistance remains challenging and further research is needed to identify predictive biomarkers for improved outcomes.