A Study of AK131 in Patients With Advanced Solid Tumors

Inclusion Criteria: 1. Written and signed informed consent. 2. Eastern Cooperative Oncology Group (ECOG) Performance Score of 0 or 1. 3. Life expectancy ≥3 months. 4. Histologically or cytologically documented unresectable advanced or metastatic malignant tumor that has failed or intolerant of standard therapy, or for which no effective standard therapy is available. 5. Subject must have at least one measurable lesion according to RECIST Version1.1. 6. Adequate organ function. 7. Female subjects of childbearing potential and male subjects with female partners of childbearing potential must agree to use effective barrier methods of contraception during the study and for 120 days after last dose of study drug. Exclusion Criteria: 1. Any malignancy other than the disease under study within the past 3 years except for radically cured local cancers. 2. Being involved in another clinical study, except for observational clinical studies or follow-up period of interventional studies. 3. Receipt of any anti-CD73 treatment. 4. Anticancer therapy within 4 weeks prior to the first dose of investigational product. 5. Experienced a toxicity that led to permanent discontinuation of prior immunotherapy. 6. Subjects with spinal cord compression or active brain metastases, except for subjects with untreated and asymptomatic brain metastases or with stable brain metastases after treatment. 7. Subjects with pleural effusion, pericardial effusion, or ascites requiring repeated drainage. 8. Subjects whose imaging shows that the tumor has invaded important blood vessels or the investigator judges that the tumor is very likely to invade important blood vessels and cause fatal bleeding during the study. 9. Toxicities of prior anticancer therapy have not resolved to ≤ Grade 1. 10. Patients with clinically significant cardio-cerebrovascular disease. 11. Active autoimmune diseases or history of autoimmune diseases that may relapse. 12. History of interstitial lung disease or noninfectious pneumonitis. 13. Major surgery, trauma,unhealed wound, ulcer or fracture within 4 weeks prior to first dose of investigational product. 14. Any condition that required systemic treatment with corticosteroids or other immunosuppressive agents within 14 days prior to the first dose of investigational product. 15. Receipt of live attenuated vaccines within 4 weeks prior to the first dose of investigational product. 16. Known allergy or reaction to any component of the AK131 formulation. 17. Previous organ transplantation or allogeneic hematopoietic stem cell transplantation. 18. Any other conditions that, in the opinion of the Investigator, would interfere with evaluation of the investigational product or interpretation of subject safety or study results.