Study of SHR-A1811 Combined With Pyrotinib and Bevacizumab in Advanced Breast Cancer With Brain Metastasis

Inclusion Criteria: * More than 18 years old; * ECOG PS Score: 0\~2; * Patients must have a life expectancy ≥ 3 months; * Brian metastasis confirmed by MRI, at least one measurable brain lesion based on RANO-BM with no prior radiotherapy; * Mannitol or hormone therapy is allowed to use for brain metastasis before enrolment, but treatment dosage should be stable for one week and not need to be increased; * Adequate organ function and marrow function; * Has recovered from any AEs (≤ grade 1) related to prior anti-tumour treatments before first dose of study therapy, except: a. alopecia; b. hyperpigmentation; * Willing to join in this study, able to provide written informed consent, good compliance and willing to cooperate with follow-up. Exclusion Criteria: * Has leptomeningeal metastasis or cystic metastatic lesions confirmed by MRI or lumbar puncture; * Existence of third space fluid (e.g. massive ascites, pleural effusion, pericardial effusion) that is not well controlled by effective methods, e.g. drainage; * Has CNS complications with the need for emergency intervention, or brain metastasis with poorly controlled symptoms by hormone or dehydration therapy, such as uncontrollable intracranial hypertension, mental disorder or epilepsy; * Prior bevacizumab or EGFR-TKI is allowed, but should meet the following requirements at the same time: 1. No disease progression during prior bevacizumab or EGFR-TKI; 2. More than 3 months from the interruption of bevacizumab or EGFR-TKI to disease progression; * Has received whole brain radiotherapy, chemotherapy, surgery within 2 weeks before first dose of study therapy; has received trastuzumab-based therapy or endocrine therapy within one week before first dose of study therapy; has received palliative radiotherapy for bone metastasis within 2 weeks before first dose of study therapy; * Has known clinically significant lung disease, that is, moderate-to-severe lung disease which severely affects respiratory function, including but not limited to: idiopathic pulmonary fibrosis, pneumonitis. Prior ≥ grade 3 interstitial lung disease is not allowed to enrolment; * Has received full-dose anticoagulants or thrombolytics within 10 days before enrolment, or non-steroid anti-inflammatory drugs with platelet inhibition (except low-dose aspirin (≤325mg qd) for preventive use); * Existence of unhealed wound, active gastric ulcer, and other diseases which may cause haemorrhage risk (e.g., prior major operation within 4 weeks before enrolment, prior arterial or venous thrombotic event within one year before enrolment, prior cerebralvascular accident); * Has known hereditary haemorrhagic tendency or coagulation disorder; * Has joined in other clinical drug trials within 2 weeks before enrolment; * Use of other antitumor systemic treatment during the study at the same time, except bisphosphonates for the treatment of bone metastasis or osteoporosis prevention; * Other malignancy within prior 5 years unless curatively treated with no evidence of disease for at least recent 3 years, except: curatively treated in situ cancer of the cervix, skin basal cell carcinoma or skin squamous cell carcinoma; * Cardiac insufficiency, including but not limited to: congestive heart failure, transmural myocardial infarction, angina which needs drug treatments, clinically significant valvulopathy and high-risk arrhythmia, or QTc abnormity with clinical significance in ECG examination during the screening period (corrected QTc \>450 msec \[male\] or QTc \>470 msec \[female\] under the resting state); * Uncontrolled hypertension (under the resting state: systolic pressure \>160mmHg or diastolic pressure \>100mmHg); * Other diseases which may affect study results, including but not limited to: 1) known history of immunodeficiency, including HIV-positive, other acquired or innate immunodeficient disease, or known history of organ transplantation; 2) HBsAg-positive and HBV DNA≥1000 IU/mL, or HCV antibody-positive, or treponema pallidum antibody-positive; 3) hypersensitivity to study therapy or any of its excipients; 4) severe infection requiring antibiotics, antiviral or antifungal treatment; * Female patients during the gestation or suckling period, of childbearing potential and pregnancy test-positive, or unwilling to use an effective method of contraception during the whole study; * Inability to swallow, intestinal obstruction or existence of other factors affecting medication and absorption; * Any other conditions not appropriate for study enrolment in the opinion of the investigator.