An Open-Label, Bayesian Adaptive Phase II Clinical Study in HR+/HER2- Advanced Breast Cancer After Progression on Standard Therapy

Women aged ≥ 18 years old.

Patients with histologically confirmed HR+/HER2- invasive breast cancer (specific definition: ER \> 10% tumor cell positivity by immunohistochemistry is defined as ER positive, PR positive, PR \> 10% tumor cell positivity is defined as PR positive; HER2 0 - 1+ or HER2 ++ but negative by FISH without amplification is defined as HER2 negative).

Patients with HR+/HER2- advanced breast cancer who have experienced disease progression after receiving systemic therapy including CDK4/6 inhibitors and endocrine therapy.

Patients whom the investigator judges to be suitable for continued endocrine therapy

Patients with at least one measurable lesion per RECIST version 1.1 criteria (≥ 20 mm on conventional CT scan, ≥ 10 mm on spiral CT scan, and without prior radiotherapy for measurable lesion).

Patients whose main organs function normally by meeting the following requirements:

Hematology criteria: HB ≥ 90 g/L (no blood transfusion within 14 days); ANC ≥ 1.5 × 109/L; PLT ≥ 75 × 109/L;

Blood chemistry criteria: TBIL ≤ 1.5 × ULN (upper limit of normal); ALT and AST ≤ 3 × ULN; if liver metastasis is present, then ALT and AST ≤ 5 × ULN; serum Cr ≤ 1× ULN, endogenous creatinine clearance \> 50 mL/min (Cockcroft-Gault formula);

Patients who have not received radiotherapy, molecular targeted therapy, or surgery within 3 weeks prior to the start of the study and have recovered from acute toxicities of prior therapies (if a surgery has been undergone, the wound has completely healed); patients who have no peripheral neuropathy or Grade I peripheral neurotoxicity;

Patients with ECOG score ≤ 2, and life expectancy ≥ 3 months;

Female subjects of childbearing potential are required to use a medically acceptable method of contraception during study treatment and for at least 3 months after the last dose of study drug;

Subjects will be enrolled in this study voluntarily, sign the informed consent form (ICF), have good compliance, and cooperate with follow-up.

What this study is about