Inclusion Criteria:
1. Voluntarily join this study and sign the informed consent form;
2. Female patients aged ≥18 years and ≤70 years old who had been dignosed with breast cancer;
3. According to the definition of the latest ASCO/CAP guidelines, histologically confirmed estrogen receptor negative (ER-) and progesterone receptor negative (PR-), human epidermal growth factor receptor 2 negative
4. For patients with locally advanced, recurrent or metastatic breast cancer who have not used any systematic treatment (it is allowed to accept adjuvant/neoadjuvant treatment, and the time from the last administration to recurrence and metastasis should be ≥ 6 months);
5. According to RECIST 1.1, there is at least one measurable lesion;
6. ECOG score: 0\~1;
7. Tumor tissue specimens that can be used for biomarker detection;
8. Adequate organ function (no blood components or cell growth factor drugs are allowed within 14 days before the first medication): (1) Absolute neutrophil count ≥1.5×109/L; (2) Platelets ≥100×109/L; (3) Hemoglobin ≥90 g/L; (4) Serum albumin ≥30 g/L; (5) Thyroid-stimulating hormone (TSH) ≤1×ULN (if abnormal, the FT3 and FT4 levels should be examined at the same time. If the FT3 and FT4 levels are normal, you can be included in the group); (6) Serum total bilirubin ≤1.5×ULN，if liver metastasis is present, ≤3ULN; (7) ALT and AST ≤2.5×ULN, if liver metastasis is present, ALT and AST ≤5ULN; (8) AKP≤2.5×ULN; Serum creatinine ≤1.5×ULN; (9) International normalized ratio (INR) ≤1.5 (not receiving anticoagulant therapy).
Exclusion Criteria:
* 1.The presence of any active autoimmune disease or a history of autoimmune disease (such as the following, but not limited to autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hypophysitis, vasculitis, nephritis, hyperthyroidism;Those who suffer from vitiligo or whose asthma has been completely relieved in childhood and do not need any intervention in adulthood can be included; asthma that requires medical intervention with bronchodilators cannot be included); 2.Are currently using immunosuppressants or systemic steroid therapy to achieve immunosuppression ((in dosing exceeding 10 mg daily of prednisone equivalent), and are still using it within 2 weeks before enrollment; 3.Severe allergic reactions to other monoclonal antibodies; 4. Known history or evidence of interstitial lung disease or active non-infectious pneumonia; 5.Known central nervous system metastasis; 6.Known additional malignant tumors within the past 5 years (except cured basal cell carcinoma of the skin and cervical cancer in situ); 7. The presence of uncontrolled hypertension (systolic blood pressure \>140mmHg or diastolic blood pressure \>90mmHg) or dignosis with hypertensive crisis or hypertensive encephalopathy. Known history of hypertension are admitted to the study if their blood pressure is controlled below this standard and maintained with antihypertensive therapy.
8.Patients with a history of severe cardiovascular and cerebrovascular disease, including but not limited to: (1) NYHA grade 2 or above heart failure (2) Unstable angina (3) Myocardial infarction within 1 year (4) Clinically significant supraventricular infarction or ventricular arrhythmia requiring treatment or intervention (5) QTc\>450ms (male); QTc\>470ms (female); 9.Those who are receiving thrombolysis or anticoagulation therapy; prophylactically use of low-dose aspirin and low-molecular-weight heparin are allowed; 10.Have clinically significant bleeding symptoms or a clear bleeding tendency within 3 months before enrollment; if fecal occult blood is positive in the screening, it should be re-examined. If it is still positive after the reexamination, a gastroscopy is required; 11.The tumor invades vital blood vessels, or a high possibility that the cancer will invade important blood vessels in the future study period, which may lead to fatal bleeding; 12.Patients with pleural effusion, ascites or pericardial effusion that require drainage can be enrolled if the researcher assesses that the symptoms are stable after drainage; 13.Arterial/venous thrombosis events that occurred within 6 months before enrollment, such as cerebrovascular accidents (including transient ischemic attack, cerebral hemorrhage, cerebral infarction), deep vein thrombosis and pulmonary embolism; 14.Major vascular disease (for example, aortic aneurysm requiring surgical repair or recent peripheral arterial thrombosis) within 6 months before the start of study treatment; 15.Urine routine shows urine protein ≥ ++ and confirmed 24-hour urine protein amount \>1.0 g; 16.Suffering from active infection, unexplained fever ≥38.5℃ within 7 days before taking the drug, or baseline white blood cell count \>15×109/L; 17.Those with congenital or acquired immune deficiency (such as HIV infection); those who are hepatitis B surface antigen (HBsAg) positive and hepatitis B virus deoxyribonucleic acid (HBV DNA) ≥ 2000 IU/ml, or hepatitis C virus antibody positive; Have received live vaccines less than 4 weeks before study medication or may be vaccinated during the study period; 18.In the judgment of the researcher, the patient has other factors that may affect the study results or cause the study to be terminated midway, such as alcoholism, drug abuse, other serious diseases (including mental illness) that require combined treatment, and serious laboratory tests. Abnormalities, accompanied by family or social factors, may affect the patient\'s safety.
