A better understanding of endocrine therapy (ET) resistance mechanisms has guided the development of targeted combination therapies for HR-positive/HER2-negative (HR+/HER2–) breast cancer, but resistance evolution complicates long-term disease management.
The CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib have become foundational in the first-line treatment of HR+/HER2– breast cancer, significantly improving survival outcomes.
Emerging next-generation targeted therapies, such as capivasertib and elacestrant, target resistance mechanisms like ESR1 mutations and alterations in the PI3K/AKT/mTOR pathway. These biomarker driven approaches are critical but require testing standardization across institutions.
Antibody-drug conjugates (ADCs), such as trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan, represent a paradigm shift in treating ET-refractory metastatic breast cancer, showing efficacy even in heavily pretreated populations.
Despite improved outcomes with targeted therapies and their combinations, challenges remain regarding their optimal sequencing and rechallenge strategies post progression in the HR+/HER2– breast cancer treatment algorithm.
The FDA approved camizestrant plus a CDK4/6 inhibitor for hormone receptor–positive, HER2-negative metastatic breast cancer that acquires an ESR1 mutation.
The sNDA is supported by VIKTORIA-1 Study 2 data showing that gedatolisib-based regimens approximately doubled median PFS vs alpelisib plus fulvestrant.
The European Commission approved sacituzumab govitecan plus pembrolizumab for treatment-naive, PD-L1–positive, metastatic triple-negative breast cancer.
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