Romiplostim N01 for Injection for Secondary Prophylaxis of CIT in Breast Cancer

Inclusion Criteria: 1. Signed informed consent form. 2. Age 18 to 75 years, either sex. 3. Histologically or pathologically confirmed breast cancer. 4. Nadir platelet count \<50×10⁹/L in the previous treatment cycle; OR nadir platelet count ≥50×10⁹/L but \<75×10⁹/L in the previous chemotherapy cycle, plus at least one high-risk factor for bleeding as defined in the relevant guideline. 5. Platelet count \>100×10⁹/L at screening. 6. No prior exposure to romiplostim/romiplostim N01. 7. Prior receipt of one or more antineoplastic therapies, including but not limited to chemotherapy, radiotherapy, targeted therapy, and immunotherapy. 8. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2. 9. Life expectancy of ≥12 weeks. Exclusion Criteria: 1. Concomitant hematologic disorders; 2. Prior radiation therapy to long bones or flat bones, or currently receiving/planned to receive radiation therapy (local radiation to the breast is permitted); 3. Serious cardiac clinical symptoms or diseases within 6 months prior to screening; 4. Thrombotic predisposition or currently receiving thrombolytic and/or anticoagulant therapy; 5. Clinically significant bleeding symptoms within 2 weeks prior to screening, or definitive clinical manifestations of bleeding tendency; 6. Complications requiring emergency treatment, such as superior vena cava syndrome or spinal cord compression; 7. Significantly abnormal hepatic function: for patients without hepatic metastasis, ALT/AST \>3×ULN and TBIL \>3×ULN; for patients with hepatic metastasis, ALT/AST ≥5×ULN and TBIL ≥5×ULN; 8. Renal function abnormality: serum creatinine ≥1.5×ULN or eGFR ≤60 mL/min (by Cockcroft-Gault formula); 9. Receipt of romiplostim within 2 to 3 weeks prior to study drug administration; 10. Known or suspected hypersensitivity or intolerance to romiplostim N01 or its excipients (including cellulose-lactose, low-substituted hydroxypropyl cellulose, and magnesium stearate); 11. HIV infection; 12. Participation in any other clinical study of an investigational drug or device within 3 months prior to screening; 13. Pregnant or lactating women; 14. Any other condition that, in the investigator's opinion, may affect study results or lead to premature discontinuation of the study.