Breast Cancer Clinical Trials

• Aged ≥ 18 years old at the time of signing the informed consent form, regardless of gender;

• Patient must meet one of the following pathological diagnoses and classifications:

⁃ 1) For TNBC Cohort: -Histological/cytological confirmed of triple-negative breast cancer (TNBC) from the most recent pre-SKB264 biopsy/pathological report, with: HER2 negative: immunohistochemistry (IHC) of 0 or 1+; if is 2+ by IHC, negative HER2 expression must be confirmed by fluorescence in situ hybridization (FISH); Estrogen and progesterone receptor negative means that less than 1% of the cells express hormone receptors as indicated by IHC; -Locally advanced, recurrent, or metastatic disease (locally advanced disease should be confirmed by investigators as ineligible for curative resection); 2.2) For HR+/HER2- BC Cohort: -Histological/cytological confirmed of HR+/HER2- breast cancer from the most recent pre-SKB264 biopsy/pathological report, with: HER2 negative: IHC of 0 or 1+; if is 2+ by IHC, negative HER2 expression must be confirmed by FISH; HR positive: Hormone receptor-positive (HR, ER, or PR status) was defined as ≥1% expression by IHC.-Locally advanced, recurrent, or metastatic disease (locally advanced disease should be confirmed by investigators as ineligible for curative resection);

• Plan to receive SKB264 monotherapy or combination therapy;

• Prior treatment lines: -For TNBC Cohort: ≤2 lines of systemic antitumor therapy for unresectable locally advanced, recurrent, or metastatic disease; -For HR+/HER2- BC Cohort: ≤2 lines of systemic antitumor therapy (excluding endocrine therapy) for unresectable locally advanced, recurrent, or metastatic disease;

• Voluntarily participate in the study, sign the informed consent form and demonstrate good compliance.