Inclusion Criteria:
* Males or females aged 18 years or older (≥18 years).
* Patients diagnosed with pathologically confirmed advanced solid tumors.
* Subjects have at least one target lesion as assessed per the RECIST 1.1.
* Eastern Cooperative Oncology Group Performance Status (ECOG PS) score of 0 to 1 and no deterioration within 2 weeks before the first dose.
* Have a life expectancy of at least 12 weeks.
* 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.
* 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.
* Subject must be voluntarily enrolled in this clinical trial, be able to understand the study procedures and to sign written informed consent.
Exclusion Criteria:
* Have received or is currently receiving the following treatment: PARPi/B7-H4/B7-H3-targeted therapies;
* Have received or is currently receiving the following treatment: PARPi/B7-H4/B7-H3-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.
* Presence of Grade ≥ 2 toxicities as per Common Terminology Criteria for Adverse Events due to prior anti-tumor therapy.
* Presence of pleural/abdominal effusion requiring clinical intervention.
* Known history of other primary malignancy.
* Evidence of brain metastasis and/or cancerous meningitis
* Inadequate bone marrow reserve or hepatic/renal functions.
* Cardiological examination abnormality.
* Severe, uncontrolled or active cardiovascular disorders.
* Serious or poorly controlled diabetes.
* Serious or poorly controlled hypertension.
* Clinically significant bleeding symptoms or significant bleeding tendency within 1 month prior to the first dose of study treatment.
* Serious infections within 4 weeks prior to the first dose.
* 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.
* Presence of active infectious diseases such as hepatitis B, hepatitis C, tuberculosis, syphilis, or human immunodeficiency virus infection, etc.
* Current hepatic encephalopathy, hepatorenal syndrome, or Child-Pugh Class B or more severe cirrhosis.
* 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.
* History of severe neurological or psychiatric disorder.
* Pregnant or breast-feeding women or women who intend to become pregnant during the study.
* Attenuated live vaccination within 4 weeks prior to the first dose.
* Subjects with autoimmune disease that is active or is likely to recur.
* 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.
* Subjects unlikely to comply with study procedures, restrictions and requirement as determined by the investigator.
* Subjects with any condition that jeopardizes the safety of the patient or interferes with the assessment of the study, as judged by the investigator.
