A Clinical Study of YL205 in Patients With Advanced Solid Tumors

Inclusion Criteria:

• 1. Subjects who are informed of relevant information of the study prior toinitiation of the study and voluntarily sign and date on the informed consent form (ICF).

2. Age ≥18 years. 3) Be willing to follow and be able to complete all the studyprocedures. 4) Body mass index (BMI) within the range of 18 to 32 kg/m2, and bodyweight ≥45kg for female subjects.

5） Patients with histologically or cytologically confirmed locally advanced ormetastatic ovarian cancer (OC), non-squamous non-small cell lung cancer (NSQ NSCLC),renal cell carcinoma (RCC), endometrial cancer (EC), or other Napi2b-overexpressingtumors。 6) Patients with positive Napi2b test results at the central laboratory. 9)At least one radiologically evaluable lesion for subjects in Part 1; At least onemeasurable extracranial lesion (non-radiation fields) for subjects in Part 2 andPart 3.

10. Expected survival ≥3 months. 11) Female subjects of childbearing potential mustagree to take effective contraceptive measures and must not undergo egg donation oregg retrieval for their own use from screening throughout the study period and forat least 6 months after the last dose of the investigational drug. Male subjectsmust agree to take effective contraceptive measures and must not undergo spermcryopreservation or sperm donation from screening throughout the study period andfor at least 6 months after the last dose of the investigational drug.

11. subjects must provide tumor samples. 13) Subjects who are capable of and willingto comply with the visits and procedures stipulated in the study protocol.

Exclusion Criteria:

• 1. Subjects with a treatment history with drugs targeting Napi2b. 2) Subjects with ahistory of intolerance to topoisomerase I inhibitors or ADC therapy.

3. Subjects who are participating in another clinical study, with the exception anof observational (non-interventional) clinical study or the follow-up period of aninterventional study.

4. Subjects with an insufficient washout period from the previous anti-tumor therapyto the first dose.

5. Subjects who received radiotherapy, including palliative stereotacticradiotherapy on the abdomen, within 4 weeks prior to the first dose.

6. Subjects who received major surgery within 4 weeks prior to the first dose orthose who plan to receive major surgery during the study.

7. Subjects who received allogeneic bone marrow transplantation or solid organtransplantation.

8. Subjects who received systemic steroids or other immunosuppressive treatmentwithin 2 weeks prior to the first dose of the investigational drug.

9. Subjects who received any live vaccine within 4 weeks prior to the first dose orthose who plan to receive live vaccines during the study.

10. Subjects with a medical history of leptomeningeal carcinoma or cancerousmeningitis.

11. Subjects with brain metastasis or spinal cord compression. 12) Subjects withuncontrolled or clinically significant cardiovascular and cerebrovascular diseases.

12. Subjects who were diagnosed with Gilbert's syndrome. 14) Subjects withsignificantly symptomatic or unstable effusion in the third space requiring repeateddrainage.

13. Subjects with medical history of gastrointestinal perforation and/or fistulawithin 6 months prior to the first dose, or active gastric ulcers, duodenal ulcer,colitis ulcerative, or other gastrointestinal disorders that may cause hemorrhage orperforation in the opinion of the investigator.

14. Subjects with serious infection (Grade ≥3 as per NCI CTCAE v5.0) prior to thefirst dose.

15. Subjects with human immunodeficiency virus (HIV), active hepatitis B virus (HBV)or hepatitis C virus (HCV) infection; subjects with positive syphilis antibody and apositive titer result.

16. Subjects with unresolved toxicity caused by previous anti-tumor therapy. 20)Subjects with a history of serious allergic reactions to drugs, inactive ingredientsin drug products, or other monoclonal antibodies.

17. Female subjects who are pregnant as confirmed by a pregnancy test within 3 daysprior to the first dose, or lactating women.

18. Subjects who have any diseases, medical conditions, organ system dysfunction, orsocial conditions.

19. Subjects with multiple primary malignancies within 5 years prior to the signingof the ICF, except for fully resected non-melanoma skin cancer, radically treatedcarcinoma in situ, or other radically treated solid tumors.