ERBB2 and breast cancer: Consistent with this preclinical observation, the median PFS in our BM population was 11.0 months, and CNS-ORR of patients with measurable intracranial diseases was 66.7% (6/9), which was similar to pyrotinib plus capecitabine in HER2-positive metastatic BC with radiotherapy-naïve BM (median PFS = 11.3 months, CNS-ORR = 74.6%)24, and superior to other anti-HER2 regimens in active BMs (intracranial response rate = 11–57.1%25–28, median time to progression = 5.5 months27).