Inclusion Criteria:
1. Males or females aged 18 years or older (≥18 years).
2. Patients diagnosed with pathologically confirmed advanced solid tumors.
3. Subjects have at least one target lesion as assessed per the RECIST 1.1. Patients with only brain and/or bone lesions as target lesions are ineligible.
4. Agree to provide fresh or archival tumor tissue
5. Eastern Cooperative Oncology Group Performance Status (ECOG PS) score of 0 to 1 and no deterioration within 2 weeks before the first dose.
6. Have a life expectancy of at least 12 weeks.
7. Female subjects of childbearing potential are willing to take appropriate contraceptive measures and should not breastfeed from signing the informed consent until 6 months after the last dose; male subjects must agree to use barrier contraception (i.e. condoms) from signing the informed consent to 6 months after the last dose.
8. Female subjects must have a negative pregnancy test within 7 days prior to the first dose (for subjects with tumor related abnormal elevation of human chorionic gonadotropin \[HCG\], an ultrasound of uterus and appendages should be performed within 7 days prior to the first dose to rule out pregnancy), or demonstrate no risk for pregnancy.
9. Subject must be voluntarily enrolled in this clinical trial, be able to understand the study procedures and to sign written informed consent.
Exclusion Criteria:
1. Have received or is currently receiving the following treatment: B7-H4-targeted therapies; Have received any of cytotoxic chemotherapy drugs, investigational drugs, anti-tumor traditional Chinese medicines or other anti-tumor drugs within 14 days prior to the first dose of study drug; or need to continue these drugs during the study.
2. Presence of Grade ≥ 2 toxicities as per Common Terminology Criteria for Adverse Events due to prior anti-tumor therapy.
3. Presence of pleural/abdominal effusion requiring clinical intervention.
4. Known history of other primary malignancy.
5. Evidence of brain metastasis and/or cancerous meningitis
6. Inadequate bone marrow reserve or hepatic/renal functions.
7. Cardiological examination abnormality.
8. Severe, uncontrolled or active cardiovascular disorders.
9. Serious or poorly controlled diabetes.
10. Serious or poorly controlled hypertension.
11. Clinically significant bleeding symptoms or significant bleeding tendency within 1 month prior to the first dose of study treatment.
12. Serious infections within 4 weeks prior to the first dose.
13. Have received systemic glucocorticoid therapy for more than 7 days within 28 days prior to the first dose study treatment, or require chronic (≥ 7 days) use of systemic glucocorticoids during the study, or have other acquired, congenital immunodeficiency disorders, or a history of organ transplantation.
14. Presence of active infectious diseases such as hepatitis B, hepatitis C, tuberculosis, syphilis, or human immunodeficiency virus infection, etc.
15. Current hepatic encephalopathy, hepatorenal syndrome, or Child-Pugh Class B or more severe cirrhosis.
16. Any moderate or severe lung diseases that may interfere with the detection and treatment of drug-related pulmonary toxicity or may seriously affect respiratory function.
17. History of severe neurological or psychiatric disorder.
18. Pregnant or breast-feeding women or women who intend to become pregnant during the study.
19. Attenuated live vaccination within 4 weeks prior to the first dose.
20. Subjects with autoimmune disease that is active or is likely to recur.
21. Subjects with gastrointestinal fistula, visceral fistula, gastrointestinal perforation, or abdominal abscess, or with symptoms/signs of intestinal obstruction within 6 months prior to the first dose of study drug.
22. Subjects unlikely to comply with study procedures, restrictions and requirement as determined by the investigator.
23. Subjects with any condition that jeopardizes the safety of the patient or interferes with the assessment of the study, as judged by the investigator.
