A Single-arm, Multi-center, Phase II Exploratory Clinical Study to Evaluate the Efficacy and Safety of Trilaciclib in Preventing Myelosuppression Caused by Topoisomerase I Inhibitor Type ADC Drugs

Inclusion Criteria:

1. The patient voluntarily participated in this study, signed the informed consent form, had good compliance and cooperated with the follow-up;
2. Age greater than 18 years old, regardless of gender;
3. Malignant tumors diagnosed by histological or cytological examination;
4. Cancer patients whose tumors can be treated with topoisomerase I inhibitor type ADC drugs (Regucitinib, Gosatuzumab, Luconasuzumab, Deconzumab) as evaluated by the investigator;
5. Patients are allowed to have received systemic anti-tumor treatment in the past;
6. ECOG physical status score 0-2;
7. No gastrointestinal obstruction, such as gastric pyloric stenosis or intestinal obstruction;
8. Expected survival period ≥ 12 weeks;
9. Good organ and bone marrow function, defined as follows: Hematological system: Absolute neutrophil count (ANC) ≥ 1.5×109/L; Platelets (PLT) ≥ 90×109/L; Hemoglobin: ≥ 90 g/L; Liver function: Total bilirubin (TBIL) ≤ 1.5×ULN (for patients with Gilbert syndrome, ≤ 3×ULN); Aspartate aminotransferase ≤ 2.5×ULN (for patients with liver metastasis ≤ 5×ULN); Alanine aminotransferase ≤ 2.5×ULN (for patients with liver metastasis: ≤ 5×ULN); Albumin ≥ 30 g/L; Renal function: Creatinine ≤ 1.5×ULN; Creatinine clearance rate (only when creatinine \> 1.5×ULN is calculated): Endogenous creatinine clearance rate ≥ 50 mL/min (Cockcroft-Gault formula); Cardiac function: 12-lead electrocardiogram: No severe arrhythmia, and the mean corrected QT interval (QTc) by Fridericia method (for males) is \< 450 ms, QTc \< 470 ms (for females); Echocardiography: Left ventricular ejection fraction (LVEF) ≥ 50%;
10. Within 2 weeks before enrollment, no use of granulocyte colony-stimulating factor (g-csf), erythropoiesis-stimulating agents (ESAs), or bone marrow suppression prevention or correction-related drugs or treatments such as red blood cell (RBC) and/or platelet transfusion;
11. Exclude patients who have previously experienced infection or interstitial pneumonia; twelve For the fertile subjects, the serum pregnancy test was negative within 72 hours before the first use of the study drug, and they agreed to use effective contraceptive measures from the time of signing the informed consent form until 180 days after the last use of the investigational drug.

Exclusion Criteria:

* 1\. No history of myeloid leukemia, myelodysplastic syndrome or concurrent sickle cell disease; 2. Within one week before the blood test during the screening period, received hematopoietic growth factors, blood transfusion or platelet transfusion treatment; 3. Have any active autoimmune diseases or have a history of autoimmune diseases; 4. Within two weeks before the first administration, received systemic corticosteroids (daily \> 10mg prednisone or equivalent) or other immunosuppressive drugs (such as cyclophosphamide, azathioprine, methotrexate, thalidomide, TNF-α inhibitors, etc.) on a daily basis; 5. Within 4 weeks before enrollment, had a severe infection requiring intravenous antibiotics treatment or active infection; 6. Severe cardiovascular injury (greater than NYHA II grade congestive heart failure history), unstable angina pectoris or myocardial infarction within the past 6 months, or severe arrhythmia. At screening, QTcF interval \> 480 msec, for patients with implanted ventricular pacemaker, QTcF \> 500 msec; 7. Within 6 months before enrollment, had a stroke or cerebrovascular event; 8. Subjects with a recipient of allogeneic organ transplantation requiring immunosuppressive therapy; 9. Known human immunodeficiency virus (HIV) positive subjects; 10. Uncontrolled active hepatitis B (defined as a positive result for hepatitis B surface antigen HBsAG during the screening period, while the HBV DNA test value is higher than the upper limit of the laboratory department's normal value in the research center; subjects who tested HBV DNA content \< 500 IU/mL within 28 days before randomization and have received at least 4 weeks of local standard antiviral treatment and are willing to continue antiviral treatment during the study can be enrolled); active hepatitis C (defined as a positive result for hepatitis C surface antibody HCsAb during the screening period and positive HCV RNA) subjects; 11. Previously had concurrent other malignant tumors for ≤ 5 years, fully treated cervical carcinoma in situ, basal cell or squamous epithelial cell skin cancer, locally advanced prostate cancer after radical surgery, ductal carcinoma in situ after radical surgery. Patients who are not excluded if they have been fully treated; 12. Expected to need any other form of anti-tumor treatment during the study period; 13. Active brain metastasis; 14. Received traditional Chinese medicine or immunomodulatory drugs with anti-tumor indications within 2 weeks before the first administration; 15. Received live vaccines within 30 days before the first administration of the study treatment; 16. Any medical condition as determined by the investigator that makes the subject unsuitable for enrollment in the study.