Herombopag Treated T-DM1 Induced Platelet Reduction

Inclusion： * Age 18-75 years, any gender; * Pathologically diagnosed with breast cancer based on histological or cytological examination, and previously treated with neoadjuvant anti-HER-2 therapy followed by T-DM1 adjuvant therapy; * Experienced grade 2 or higher tumor treatment-related thrombocytopenia during the previous T-DM1 treatment cycle, with platelet count restored to ≥100 × 109/L and ≤200 × 109/L prior to the next treatment; * ECOG performance status score: 0-2; * Planned to undergo at least two additional treatment cycles including T-DM1 administration, with the dose of T-DM1 in the current cycle consistent with the previous cycle; * Expected survival of ≥12 weeks and able to tolerate the current treatment regimen for at least two cycles or more; * Expected to have good compliance, able to follow up on treatment efficacy and adverse reactions as required by the protocol. Exclusion: * A history of other malignant tumors diagnosed within the past 3 years; * Patients with mental or neurological disorders who are unable to cooperate; * Patients who are scheduled to undergo or have previously undergone organ or bone marrow transplantation; * Patients with hematopoietic system disorders other than chemotherapy-induced thrombocytopenia (CTIT), including but not limited to leukemia, primary immune thrombocytopenia, myeloproliferative disorders, multiple myeloma, and myelodysplastic syndrome; * Patients with a history of any arterial or venous thrombotic events within the past 6 months prior to screening; * Severe bleeding manifestations within 2 weeks prior to screening, such as gastrointestinal or central nervous system bleeding; * Participation in a clinical trial of the same type of drug within 4 weeks prior to enrollment; * Pregnant or lactating women; * Patients with a history of hypersensitivity to the study drug; * Patients deemed ineligible by the investigator.