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

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

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

5) Subjects who received radiotherapy, including palliative stereotactic radiotherapy 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 or those who plan to receive major surgery during the study.

7) Subjects who received allogeneic bone marrow transplantation or solid organ transplantation.

8) Subjects who received systemic steroids or other immunosuppressive treatment within 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 or those who plan to receive live vaccines during the study.

10) Subjects with a medical history of leptomeningeal carcinoma or cancerous meningitis.

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

13) Subjects who were diagnosed with Gilbert's syndrome. 14) Subjects with significantly symptomatic or unstable effusion in the third space requiring repeated drainage.

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

16) Subjects with serious infection (Grade ≥3 as per NCI CTCAE v5.0) prior to the first dose.

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

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

21) Female subjects who are pregnant as confirmed by a pregnancy test within 3 days prior to the first dose, or lactating women.

22) Subjects who have any diseases, medical conditions, organ system dysfunction, or social conditions.

23) Subjects with multiple primary malignancies within 5 years prior to the signing of the ICF, except for fully resected non-melanoma skin cancer, radically treated carcinoma in situ, or other radically treated solid tumors.