Famitinib Combined With SHR-A1811, Versus SHR-A1811 for CDK4/6 Inhibitors-resistent Advanced HR+/HER2- Breast Cancer With SNF4 Subtype

Inclusion criteria

• ✓. Women aged 18-70 years old;
• ✓. Histologically confirmed HR+/HER2- invasive breast cancer (specific definition: ER \>10% of tumor cells positive by immunohistochemistry is defined as ER positive, PR \>10% of tumor cells positive by immunohistochemistry is defined as PR positive, ER and/or PR positive is defined as HR positive; HER2 low expression or ultra-low expression \[FISH/CISH- and IHC+/++ or IHC 0 but with ≤10% of tumor cells showing incomplete and weak cell membrane staining\]);
• ✓. SNF4 subtype definition: SNF4 subtype confirmed by digital pathology of H\&E sections and artificial intelligence;
• ✓. Locally advanced breast cancer (unresectable locally) or recurrent and metastatic breast cancer;
• ✓. Have used CDK4/6 inhibitors in the recurrent and metastatic stage, or have relapsed and metastasized within 1 year of adjuvant CDK4/6 inhibitor use;
• ✓. At least one measurable lesion according to RECIST 1.1 criteria (≥20 mm by conventional CT scan, ≥10 mm by spiral CT scan, and the measurable lesion has not received radiotherapy), or in the absence of measurable lesions, have non-measurable osteolytic or mixed (osteolytic + osteoblastic) bone lesions;
• ✓. Basic normal major organ function, meeting the following conditions: (a) Blood routine examination standards need to meet: HB ≥90 g/L (no blood transfusion within 14 days); ANC ≥1.5×109/L; PLT ≥75×109/L;(b) Biochemical examination needs to meet the following standards: TBIL ≤1.5×ULN (upper limit of normal value); ALT and AST ≤3×ULN; if there is liver metastasis, ALT and AST ≤5×ULN; serum Cr ≤1.5×ULN, endogenous creatinine clearance rate \>50 ml/min (Cockcroft-Gault formula);(c) Electrocardiogram: Fridericia's corrected QT interval (QTcF) \< 450 ms for men and \< 470 ms for women;
• ✓. ECOG score ≤2, and expected survival ≥3 months;

Exclusion criteria