The research studies the safety and efficacy of high-dose recombinant human TPO in solid tumor patients with moderate or severe thrombocytopenia induced by chemotherapy. Patients with platelet count lower than 50 x 109/L will be enrolled and treated with high-dose rhTPO (300-600U/kg/day) until the platelets increased by 50 x 109/L compared to the baseline or above 100 x 109/L. During the study, the blood routine test will be regularly performed according to the clinical routine (at least once every two days). Finally, the clinical data will be collected and analyzed to validate the efficacy and safety of high-dose rhTPO therapy.

Chemotherapy-induced thrombocytopenia is a common toxic reaction of chemotherapeutic drugs, which may lead to dose reduction, delay or even termination of chemotherapy. Severe thrombocytopenia may cause bleeding and threaten patient's life. rhIL-11 and rhTPO are the only two drugs approved by China Food and Drug Administration for the treatment of chemotherapy-induced thrombocytopenia. The recommended dosage of rhTPO is 300U/kg. Clinical practice in the real world is full of changes and restraints. In the treatment of thrombocytopenia induced by chemotherapy, the actual dose of rhTPO is often below 300U/kg, due to factors such as Specs, economy and convenience. If the dose of rhTPO is insufficient, it can not give full play to the effect and thus can not achieve the purpose of rapid recovery of platelets. Previous clinical studies observed that the effect of rhTPO depends on the given dose. Dosage in the range of 75U-600U/kg of rhTPO were safe in human. While the 75U/kg dose group had no significant effect on the platelet count elevation, the platelet count in other three dose groups of 150U/kg, 300U/kg and 600U/kg increased by 24%, 32%, and 52% (P < 0.01). This research is a real-world study designed to verify the safety and efficacy of high-dose rhTPO in solid tumor patients with moderate or severe thrombocytopenia induced by chemotherapy. Patients with platelet count lower than 50 x 109/L will be enrolled and treated with high-dose rhTPO (300-600U/kg/day) until the platelets increased by 50 x 109/L compared to the baseline or above 100 x 109/L. During the study, the blood routine test will be regularly performed according to the clinical routine (at least once every two days) and the clinical data will be collected and analyzed. It is based on the patient's actual condition and the treatment measure is more consistent with the clinical practice. The results of this study are expected to provide new options and references for clinical treatment of thrombocytopenia induced by chemotherapy.

Inclusion Criteria:

• patients with malignant solid tumor
• moderate or severe chemotherapy-induced thrombocytopenia, platelet counts less than 50×109/L
• plan to use rhTPO
• be willing to adopt appropriate methods of contraception during the study period and 8 weeks after the end of the study; women of childbearing age must undergo pregnancy tests (serum or urine) within 7 days before entering the study and the result must be negative
• volunteer to participate in the study, sign the informed consent, and cooperate with good compliance

Exclusion Criteria:

• having other diseases that can lead to thrombocytopenia, such as aplastic anemia, myelodysplastic syndrome, leukemia, lymphoproliferative disease, immune thrombocytopenic purpura, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, thyroid disease, liver cirrhosis, hypersplenism, etc.
• using other non-chemotherapeutic drugs that can cause thrombocytopenia, such as sulfonamides, etc
• with long-term wound or great worry of gastrointestinal bleeding
• with venous thrombosis that need thrombolytic or anticoagulant therapy or high risk of venous thromboembolism
• with infection requiring antibiotic treatment
• History of immunodeficiency, including HIV positive, organ transplantation and other acquired/congenital immunodeficiency disorders
• patients with Hepatitis B(except inactive carrier) or Hepatitis C
• with serious heart disease or cerebrovascular disease
• with heart failure or heart failure history
• with severe anemia that requires long-term use of recombinant human erythropoietin
• congenital thrombocytopenia
• has been used medication for thrombocytopenia
• pregnancy or lactation
• participate in other clinical researchers at the same time
• not suitable to participate in the study in researchers'opinion