Sacituzumab Govitecan (SG; Trodelvy) is a targeted therapy designed for adults with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) who have received hormone therapy and at least two additional treatments for metastatic disease. It is an antibody-drug conjugate that binds to the Trop-2 antigen, delivering a potent chemotherapy directly to cancer cells6. Clinical trials have demonstrated that SG significantly improves progression-free survival and overall survival compared to traditional chemotherapy in this patient population. This therapy offers a new treatment option for patients with HR+/HER2- MBC, who historically have had limited treatment choices and poor survival outcomes. SG's mechanism of action and clinical efficacy make it a valuable addition to the treatment landscape for this challenging form of breast cancer.

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2025乳房醫學線上研討會，今年度共3場會議，將於6/27, 7/25, 08/29，在乳e學院線上進行，歡迎有意報考乳房專科醫師的學員及各位會員踴躍上網觀看影片!

In this session, to define the risk of recurrence there are multi-factors like tumor size, lymph node status, age, and genetic testing in assessing the risk for hormone receptor-positive early breast cancer patients.

In Part I, focuses on the impact of tumor size and lymph node status on high and low risk. A cross-generational study involving 151 clinical trials and over 150,000 patients shows that recurrence risk persists over time despite advancements in medication.

Although the more lymph node metastasis, the higher the recurrence risk, a 2024 ASCO retrospective study from MSKCC indicates a 3-year recurrence risk of 8.5% and a 5-year risk of 17.4% and 7 year risk of 25.7 in re-define high risk N0 population.

In part 2, focuses on discussing the impact of age and genetic testing on the risk for hormone receptor-positive early breast cancer patients.

Age is a significant prognostic factor, with younger patients having relatively poorer prognosis.

Genetic tests (e.g., Oncotype DX, MammaPrint, Prosigna, EndoPredict, Breast Cancer Index) are used to predict patient risk and guide treatment decisions.

Personalized treatment plans are developed based on age and genetic test results with more consideration treatment schedule needed.

2025乳房醫學線上研討會，今年度共3場會議，將於6/27, 7/25, 08/29，在乳e學院線上進行，歡迎有意報考乳房專科醫師的學員及各位會員踴躍上網觀看影片!

CDK4/6 inhibitors and endocrine therapies offer a dual benefit: they block estrogen signaling while also reshaping the TIM. CDK4/6 inhibitors, in particular, have shown promise in triggering anti-tumor immunity and reducing recurrence risk. The presentation primarily discusses clinical management strategies for hormone receptor-positive, HER2-negative metastatic breast cancer (HR+/HER2- mBC) after treatment with CDK4/6 inhibitors. 

Although CDK4/6 inhibitors show significant progression-free survival (PFS) benefits in initial treatment, resistance eventually emerges. Post-CDK4/6 inhibitor treatment options for HR+/HER2- mBC include continuing CDK4/6 inhibitor-based regimens, switching to other treatments (such as targeted therapy, PARP inhibitors, chemotherapy, antibody-drug conjugates, etc.), and endocrine therapy. The presentation also discusses the optimal treatment choices after CDK4/6 inhibitor treatment and summarizes the results of several studies.

Besides, the importance of the PI3K-AKT-mTOR pathway in HR+ breast cancer, noting that approximately 40% of HR+/HER2- mBC patients harbor PIK3CA mutations in their tumors, which are associated with a poorer prognosis. PIK3CA mutations are considered truncal mutations in HR+HER2- breast cancer, often occurring early in tumor development and being selected for during tumor progression.

The results of several clinical trials, such as the SOLAR-1 trial, which showed that PI3K inhibitors (like alpelisib) have clinical efficacy in HR+HER2- mBC patients with PIK3CA mutations. Additionally, the BYLieve study evaluated the combination of alpelisib and endocrine therapy in HR+HER2- PIK3CA-mutant mBC patients, demonstrating long-term and very-long-term disease control.

In summary, this presentation provides detailed information on treatment options and strategies for HR+/HER2- mBC patients after CDK4/6 inhibitor treatment, highlighting the significance of PIK3CA mutations and their treatment options.