Breast cancer is a genetically and clinically diverse disease with various subtypes. The most widely recognized classification method is based on immunohistochemistry, which assesses the expression of hormone receptors (HR) such as estrogen (ER), progesterone (PR), and the human epidermal growth factor receptor 2 (HER2).
Triple-negative breast cancer (TNBC) accounts for about 15% of all breast cancer cases and is more frequently diagnosed in young and premenopausal women.
Triple-negative breast cancer (TNBC) is considered particularly aggressive, with approximately 40% of patients developing metastases (metastatic TNBC, mTNBC) after initial treatment. The long-term survival rate for TNBC patients is low, the 5-year relative survival rates are 92% for localized disease, 67% for regional disease, and only 14% for patients diagnosed with metastatic disease4. This poor prognosis is partly due to the ineffectiveness of targeted therapies that work for other types of breast cancer. Although TNBC and mTNBC initially respond to chemotherapy, they tend to become resistant or refractory to it. TNBC/mTNBC recurs approximately twice as quickly as other breast cancer types5. However, recent advancements in the use of novel antibody-drug conjugates (ADCs) for mTNBC treatment have shown promising results, providing more treatment options and hope for mTNBC patients6.
Learn more about TNBC (French version)
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HR+/HER2- breast cancer (BC) is the most prevalent subtype, representing 70% of all breast cancer cases. This subtype typically has a more favorable prognosis than others.
The 5-year relative survival rates are 100% for localized disease, 90.5% for regional disease, and 35.4% for patients diagnosed with metastatic disease4. In HR+/HER2- BC, the overexpression of hormone receptors allows estrogen and progesterone to stimulate tumor growth and proliferation; and hence endocrine therapy (ET) is generally used as the standard treatment, often combined with CDK4/6 inhibitors or targeted therapies when suitable. However, once the cancer progresses on ET, treating HR+/HER2- mBC becomes more challenging and treatment options are often limited to different single-agent chemotherapy regimens. The median overall survival with chemotherapy after ET resistance is only about one year and decreases further with each subsequent chemotherapy regimen7. Therefore, patients with endocrine-resistant HR+/HER2- mBC are in need for alternative treatment options that prolong their survival and maintain quality of life.
In recent years, studies with novel antibody-drug conjugates (ADCs) for HR+/HER2- mBC have shown promising results, offering more treatment options and giving hope to patients with this subtype of breast cancer.
HER2+ breast cancer (BC) comprises approximately 15% of all breast cancer cases and is marked by the overexpression of the HER2 gene8. This subtype is considered more aggressive and previously had a very poor prognosis. However, HER2-targeted treatments have significantly improved outcomes for patients with this type of breast cancer. Consequently, the 5-year survival rate for early-stage HER2+ BC is now nearly 90%, and up to 46% for metastatic BC4. Treatment options range from chemotherapy to ADCs and various other targeted agents.
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