GenSci143 in Participants With Advanced Solid Tumors

Inclusion Criteria:

* Voluntarily sign the ICF.
* Male or female participants ≥18 years old at the time of signing the ICF.
* Meet the requirements of tumor types as outlined below:

  1. Dose escalation: Participants with histologically or cytologically documented recurrent or metastatic advanced solid tumors, and who have progressed after standard therapy, are intolerant to standard therapy, or have no standard therapy available.
  2. Dose expansion:

Cohort 1: Participants with histologically or cytologically documented mCRPC，who had received at least one prior novel hormonal therapy (including but not limited to abiraterone, enzalutamide, darolutamide, apalutamide) and progressed on standard chemotherapy regimens, are intolerant to chemotherapy, or decline chemotherapy.

Cohort 2: Participants with histologically or cytologically documented other advanced solid tumors, and who have progressed after standard therapy, are intolerant to standard treatment, or have no standard therapy available.

* Life expectancy of ≥ 12 weeks.
* ECOG PS 0-1
* Have at least 1 evaluable tumor lesion according to RECIST v1.1. Participants with mCRPC who have bone only disease may be eligible on a case-by-case basis after discussion between the investigator and Sponsor
* Able to provide either archival or fresh biopsy formalin-fixed paraffin-embedded (FFPE) tumor samples.
* Adequate organ function at the time of screening, as outlined below:

  1. Hematology: Absolute neutrophil count (ANC) ≥ 1.5×109/L (1500/µL); platelet count (PLT)≥100×109/L (100,000/µL); hemoglobin (HGB) ≥ 90 g/L (9 g/dL) (have not received granulocyte colony-stimulating factor (G-CSF) within 7 days before the first dose of GenSci143, and have not received granulocyte-macrophage colony-stimulating factor (GM-CSF), blood transfusion, erythropoietin (EPO), platelet transfusion, thrombopoietin (TPO), or interleukin-11 (IL-11) within 14 days before the first dose of GenSci143).
  2. Liver function: Serum total bilirubin (TBIL) ≤ 1.5 upper limit of normal (ULN), and serum TBIL≤ 3×ULN in the presence of liver metastasis or documented Gilbert syndrome. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3×ULN if no liver metastasis; ALT and AST≤ 5×ULN in the presence of liver metastasis.
  3. Renal function: creatinine clearance (CLcr) ≥ 50 mL/min as calculated using the Cockcroft-Gault formula.
  4. Coagulation function: Prothrombin Time (PT), activated partial thromboplastin time (APTT), and international normalized ratio (INR) ≤ 1.5×ULN (or within target range if on anticoagulation therapy).
* Toxicities (other than alopecia) from previous anticancer therapy must have resolved to NCI-CTCAE v5.0 Grade ≤1.
* Women of childbearing potential (WOCBP) must have a serum pregnancy test negative within 7 days before the first dose of GenSci143. WOCBP must agree to use highly effective contraceptive methods and must not donate or retrieve ova for personal use from the time of informed consent until 6 months after the last dose of GenSci143. Male participants must agree to use highly effective contraceptive methods and must not freeze or donate sperm from the time of informed consent until 6 months after the last dose of GenSci143.

Exclusion Criteria:

* Participants with known spinal cord compression or active central nervous system (CNS) metastases, unless they are asymptomatic or have achieved post-treatment stability for \>4 weeks and discontinued corticosteroids for \>2 weeks before the first dose of GenSci143.
* History of other known malignancies within the past 3 years.
* Unstable thrombotic events requiring therapeutic intervention within 6 months before the first dose of GenSci143.
* Uncontrolled or clinically significant cardiovascular disease.
* Uncontrolled pleural fluid, pericardial effusion, or ascites requiring drainage, and/or diuretics within 2 weeks before the first dose of GenSci143.
* History of (non-infectious) interstitial lung disease (ILD)/pneumonitis that requires steroids, current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at Screening. Any autoimmune, connective tissue, or inflammatory disorders with suspected pulmonary involvement.
* Pregnant, breastfeeding, or planning to become pregnant.
* Known active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection.
* Known human immunodeficiency virus (HIV) infection
* Uncontrolled infection that requires systemic therapy with IV antibiotics, antivirals, or antifungals within 1 week before the first dose of GenSci143.
* Major surgery (excluding diagnostic surgery), radiotherapy, and immunotherapy within 4 weeks before the first dose of medication; Chemotherapy or antibody therapy within 3 weeks; Endocrine therapy and small molecule-targeted therapy within 2 weeks or 5 half-lives(whichever is shorter). Androgen-deprivation therapy with gonadotropin-releasing hormone (GnRH) analogues (either GnRH agonists or GnRH antagonists) was allowed for men with prostate cancer.
* Received any live vaccine within 4 weeks before the first dose of GenSci143 or intend to receive a live vaccine during the study.
* History of allogeneic hematopoietic stem cell transplantation (HSCT) or solid organ transplantation.
* Prior treatment with a topoisomerase inhibitor or an ADC that consists of a topoisomerase inhibitor.
* History of severe hypersensitivity reactions to GenSci143 and/or excipients in the drug product, or other monoclonal antibodies.
* Any illness (uncontrolled hypertension, serious diabetes mellitus, thyroid disorders, and psychiatric disorders, etc.) or other conditions that are not eligible for inclusion based on the investigator's judgment.