Inclusion Criteria:
* Subjects must meet all of the following inclusion criteria to be enrolled in the study：
1. Age ≥ 18 years, gender is not limited.
2. Patients with histopathologically confirmed metastatic lung cancer.
3. Receiving platinum- or gemcitabine-based (21-day chemotherapy cycles) antineoplastic therapy with an anticipated treatment of ≥ 2 cycles.
4. ECOG PS score 0-2.
5. Platelet count \< 75 × 10\^9/L in previous cycle due to same lung cancer treatment regimen.
6. PLT between 100-200 × 10\^9/L prior to enrollment.
7. Primary organ function normal:
① Bone marrow hematopoiesis: ANC ≥ 1.5×10\^9/L; hemoglobin ≥ 8 g/dL;
② Liver and kidney function: total bilirubin ≤ 1.5 ULN; ALT, AST ≤ 2.5 ULN; if liver metastasis is present, ALT, AST ≤ 5 ULN; serum creatinine ≤ 1.5 ULN or creatinine clearance \> 60 mL/min (Cockcroft-Gault);
③ Coagulation function: activated partial thromboplastin time (APTT) and international normalized ratio (INR) ≤ 1.5 ULN
8. Expected survival ≥ 3 months.
9. Female subjects of childbearing potential must have a negative blood pregnancy test within 7 days prior to the first dose and not breastfeeding and must agree to use effective contraception during the trial and for 7 days after the last dose of study drug; male subjects with partners of childbearing potential should be surgically sterilized or agree to use effective contraception during the trial and for 7 days after the last dose of study drug and are not allowed to donate sperm during the study.
10. Voluntarily join this study, sign informed consent form, have good compliance and are willing to cooperate in follow-up.
Exclusion Criteria:
* Subjects will not enter this study if they have any of the following characteristics or conditions:
1. Pregnant or lactating women.
2. Inability to understand the investigational nature of the study or lack of informed consent.
3. Associated hematopoietic disorders, including but not limited to leukemia, primary immune thrombocytopenia, myeloproliferative disorders, multiple myeloma, and myelodysplastic syndrome.
4. Other diseases causing thrombocytopenia other than thrombocytopenia caused by anti-tumor therapy (CTIT) within 6 months before screening, including but not limited to chronic liver disease, hypersplenism and infection.
5. Presence of active uncontrolled infection.
6. Tumor bone marrow invasion or bone marrow metastasis.
7. Any arterial or venous thrombosis (stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis, or pulmonary embolism) within 6 months prior to Screening, or clinical symptoms and history suggestive of thrombophilia.
8. Cardiac disorders, including Grade 3/4 congestive heart failure, cardiac arrhythmia or myocardial infarction requiring medication, or cardiac arrhythmia known to increase the risk of thrombotic events (eg, atrial fibrillation), or prolongation of the subject 's corrected QT interval (QTc) within 3 months prior to Screening.
9. Thrombocytopenia not due to antineoplastic therapy.
10. Known hypersensitivity to TPO.
11. Patients accompanied by severe bleeding symptoms or with clear clinical manifestations of bleeding tendency, such as gastrointestinal tract or cerebral hemorrhage.
12. Concurrent use of other drugs that may affect platelet count (traditional Chinese medicine, proplatelet, antiplatelet, etc.)
13. Other conditions not suitable for inclusion in the study judged by the investigator.
