• Women ≥18 years old

• Histologically or cytologically confirmed locally advanced or metastatic breast cancer.

• Pathologically documented breast cancer that is HER2-negative for both primary tumor and metastases (if puncture results are available)

• ECOG PS of 0-1.

• For locally advanced or metastatic breast cancer, the tumor tissue HRD score\> 42 is needed (for HRD testing, the recipient must provide a test report from an institution with a qualified testing unit prior to enrollment; if no report is available, the relevant test sample must be provided for confirmation in the central laboratory prior to enrollment).

• Presence of at least 1 measurable lesion based on computed tomography (CT) or magnetic resonance imaging (MRI) per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1).

• If treated with PARP inhibitors or immune checkpoint inhibitors in the (neo) adjuvant phase, a relapse-free interval of more than 1 year after the end of treatment is required.

• Prior treatment with paclitaxel-based chemotherapeutic agents is allowed.

• ≤ 2 lines of prior chemotherapy in the advanced stage.

⁃ For HR+ patients, progression within two years of (neo) adjuvant endocrine therapy is required; patients who have progressed after more than two years of endocrine therapy are required to have received at least first-line endocrine therapy for metastatic disease (including CDK4/6 inhibitors, cidarabine and PI3K inhibitors, etc.).

⁃ ≤ grade 1 (CTCAE v5.0) for all toxicities occurring in relation to prior antitumor therapy. However, patients with any grade of alopecia are allowed to enter the study.

⁃ CNS metastases without symptoms may be enrolled.

∙ If there is no extracranial assessable lesion, intracranial lesions are required to be assessable and suitable for systemic therapy only

‣ If there is an extracranial evaluable lesion, patients with an intracranial lesion that has been stabilized with local therapy may be accepted for enrollment

⁃ Routine blood tests within 1 week prior to enrollment are essentially normal.

∙ White blood cell count (WBC) ≥ 2.5 × 109/L.

‣ Neutrophil count (ANC) ≥ 1.5 × 109/L.

‣ Platelet count (PLT) ≥ 75 × 109/L.

‣ Patients may receive blood transfusions or erythropoietin therapy to meet this criterion.

⁃ Basic normal liver and renal function tests within 1 week prior to enrollment.

∙ Total bilirubin (T BIL) ≤ 1.5 x the upper limit of normal (ULN).

‣ Glutathione transaminase (SGPT/ALT) ≤ 2.5 x ULN (≤ 5 x ULN in patients with liver metastases).

‣ Glutathione aminotransferase (SGOT/AST) ≤ 2.5× ULN (≤ 5× ULN in patients with liver metastases).

‣ creatinine clearance (Ccr) ≥ 60 ml/min.

⁃ Patients subjects of reproductive/childbearing potential must agree to use a highly effective form of contraception or avoid intercourse during and upon completion of the study and after the last dose of treatment medicine for at least 90 days.

⁃ A life expectancy of at least 12 weeks.

⁃ Patients must be able to participate and comply with treatment and follow-up.