PI3K/AKT/mTOR inhibitors for hormone receptor-positive advanced breast cancer

Dysregulation of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway plays a pivotal role in the development and progression of various cancers. In hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer, aberrations in this pathway are increasingly recognized as key drivers of resistance to endocrine therapy and cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, the first-line treatments for this disease subtype. Recognizing the urgent need for alternative therapeutic strategies, significant advancements have been made in developing PI3K/AKT/mTOR inhibitors for HR+ advanced/metastatic breast cancer. Among these inhibitors, capivasertib and alpelisib have received approval as targeted therapies for this indication. This review provides a comprehensive summary of the latest developments in PI3K/AKT/mTOR inhibitors for HR+ breast cancer. It also delves into different aspects, including sampling, testing method and timing, of PI3K/AKT/mTOR diagnostic testing. Additionally, the review discusses key considerations for integrating these inhibitors into clinical practice, such as timing and choice of PI3K/AKT/mTOR inhibitors, and management of treatment toxicities. By examining these different aspects, this review aims to provide valuable insights into optimizing the clinical utility of PI3K/AKT/mTOR inhibitors in HR+ advanced breast cancer.