Efficacy of Pyrotinib Plus Capecitabine in HER2-positive MBC With Active Brain Metastases That Have Failed ADCs

Inclusion Criteria

• •1. Patients must be ≥18 years old;
• •2. Eastern Cooperative Oncology Group (ECOG) performance status ≤2;
• •3. Pathologically confirmed HER2-positive invasive breast cancer with metastatic disease; patients with no pathological or cytologically confirmed metastatic disease should obtain clear evidence of metastasis through physical examination or radiological examination; Note: Positive HER2 -positive refers in the pathological examination/rechecking of primary lesions or metastatic lesions performed by the Research site's Pathology Laboratory, at least once the tumour cells defined as 3+ staining by immunohistochemistry, or fluorescence in situ hybridization (FISH) confirmed positive;
• •4. Fam-trastuzumab deruxtecan-nxki or A1811 had failed treatment for active brain metastasis and had received no local radiotherapy previously. Patients with new lesions in the brain after craniotomy are allowed to be included, provided that radiotherapy is not performed after surgery;
• •5. Enhanced MRI confirmed brain metastasis. According to RANO criteria, there is at least one measurable brain lesion, and the measurability of extracranial lesions is not required;
• •6. Previous treatment:Capecitabine is not allowed, except for patients without progression or intolerance during use and no relapse at least 6 months (as neoadjuvant /adjuvant therapy) after discontinuation of a capecitabine-containing treatment. Pyrotinib is not allowed, except for patients without progression or intolerance during use and no relapse at least 6 months (as neoadjuvant /adjuvant therapy) after discontinuation of a pyrotinib-containing treatment ; Patients who have not previously used pyrotinib , but have used pyrotinib in the neoadjuvant / adjuvant phase, have not proven disease progression or intolerance during use, and have relapsed 6 months after the last dose are allowed to be enrolled; Concurrent use of bisphosphonates, mannitol and glucocorticoids is allowed, provided that the dosage (\<2 mg dexamethasone \[or equivalent\])
• •7. Expected survival period of 3 months;
• •8. Patients must have adequate organ function, criteria as follows: Blood routine test (no blood transfusion within 14 days, no correction of Granulocyte colony-stimulating factor(G-CSF) and other hematopoietic stimulating factors): Absolute Neutrophil Count (ANC) 1.5X10\^9 / L; PLT 75X10\^9 / L; Hemoglobin（Hb） 90g / L; Blood chemistry test:total bilirubin (TBIL) ≤1.5 times the upper limit of normal (ULN); Alanine transaminase(ALT) and Aspartate transaminase(AST) ≤3 times ULN; For patients with liver metastases, ALT and AST ≤5 times ULN(Upper Limit of Normal); Blood urea nitrogen(BUN) and creatinine(Cr) ≤1 times ULN and creatinine clearance ≥ 50 mL/min (CockcroftGault formula);Ultrasonic cardiogram: left ventricular ejection fraction (LVEF) ≥50%; Electrocardiograph (ECG): The QT interval corrected by Fridericia's formula (QTcF)is less than 450 ms for males and less than 470 ms for females.
• •9. Patients need to voluntarily join this study after they fully understand and sign the informed consent form. Patients need to have good compliance and be willing to cooperate with follow-up.