Study of IBI3020 Treatment in Participants With Late-Stage Solid Tumors

Inclusion Criteria: Participants must satisfy all of the following criteria to be enrolled into the study: 1. Participants have the ability to understand and give written informed consent for participation in this trial, including all evaluations and procedures as specified by this protocol; 2. Male or female participants ≥ 18 years old. For Part 1, age ≥ 18 years and ≤ 75 years; 3. Histologically or cytologically confirmed unresectable, locally advanced or metastatic solid tumors which have received available standard therapies and have disease progression, or unacceptable toxic effects, or contraindications; 4. At least 1 measurable lesion as defined per RECIST v1.1 within 28 days prior to the first dose of IBI3020; 5. Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0-1; 6. Minimum life expectancy of 12 weeks; 7. Adequate bone marrow and organ function confirmed at screening period; 8. Participants, both male and female, who are not of childbearing potential or who agree to use at least 1 highly effective method of contraception during the study. Exclusion Criteria: Participants who meet any of the following criteria will be disqualified from entering the study: 1. Previous treatment with CEACAM5-targeted therapy; 2. Prior anti-cancer therapy within the wash-out period; 3. Received live vaccines within 4 weeks or cancer vaccine within 3 months; 4. Potent cytochrome P450 3A4 (CYP3A4) inhibitors within 2 weeks or 5 half-lives; 5. Has adverse reactions resulting from previous anti-tumor therapies, which have not resolved to Grade 0 or 1 toxicity according to NCI CTCAE v5.0; 6. Known allergies, hypersensitivity, or intolerance to IBI3020 or its excipients; 7. Undergone major surgery within 4 weeks, or who have severe unhealed wounds; 8. Known symptomatic central nervous system (CNS) metastases; 9. Uncontrolled diseases or conditions; 10. History of pneumonitis requiring corticosteroids therapy, or history of clinically significant lung diseases; 11. History of thromboembolic event within 6 months; 12. Under neurological, psychiatric or social condition; 13. Women who are pregnant, have positive results in pregnancy test or are lactating; 14. Not eligible to participate in this study at the discretion of the investigator; 15. Participating in any other interventional clinical research.