Oral Metronomic Capecitabine Combined With Pyrotinib in ADC-treated HER2-positive Metastatic Breast Cancer

Inclusion criteria

• Aged ≥18 and ≤75 years.
• Histologically or cytologically confirmed HER2-positive metastatic breast cancer.
• Patients must have either experienced disease progression following anti-HER2 antibody-drug conjugate (ADC) therapy in the advanced/metastatic setting (including regimens containing SHR-A1811, T-DXd, T-DM1, or other approved ADCs) or discontinued prior anti-HER2 ADC treatment due to intolerable toxicity, financial constraints, or patient preference without evidence of disease progression.
• ECOG performance status of 0 to 2.
• The functions of the main organs are basically normal
• Signed informed consent

Exclusion criteria

• Prior treatment with a TKI or capecitabine (or other fluoropyrimidine-based chemotherapy) in the advanced or metastatic setting.
• Known dihydropyrimidine dehydrogenase (DPD) deficiency.
• Pregnant or lactating patients;
• Malignancy (except basal cell carcinoma of the skin, which has been cured, and carcinoma in situ of the cervix) in the past 5 years;
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to the study agent or accompanying supportive medications;
• Serious physical or mental illnesses or laboratory abnormalities that may increase the risk of participating in the study or interfere with the study results
• Deemed by the investigator to be ineligible for participation in the study.