Fig. 1: Patients disposition.

A total of 119 patients were enrolled, including 101 patients with metastatic TNBC and 18 patients with HER2-negative BCBM. At the cutoff date of June 5, 2023, all 119 patients discontinued the treatment due to disease progression, withdrawn from the study, intolerable toxicity, and others. BCBM breast cancer brain metastasis, EAS efficacy analysis set, FAS full analysis set, HER2 human epidermal growth factor receptor, PKCS pharmacokinetics concentration set, PKPS pharmacokinetics parameter set, TNBC triple negative breast cancer.