Inclusion Criteria:
* 1\) Histologically or cytologically confirmed locally advanced or metastatic solid tumors with disease progression (radiographic or clinical) after ≥1 line of prior standard therapy, unsuitable for/intolerant to standard therapy. Includes but not limited to: Gastrointestinal tumors (colorectal cancer, hepatocellular carcinoma, esophageal cancer, biliary tract cancer, pancreatic cancer, gastric cancer), Breast cancer, Non-small cell lung cancer (NSCLC), Small cell lung cancer (SCLC), Soft tissue sarcoma;
* 2\) ECOG performance status 0-2;
* 3\) ≥1 measurable lesion per RECIST v1.1 ;
* 4\) Adequate organ function meeting ALL criteria below:
1. Hematology (without transfusion/G-CSF support within 7 days):
Absolute neutrophil count (ANC) ≥1.5×10⁹/L Platelets ≥100×10⁹/L Hemoglobin ≥90 g/L
2. Biochemistry :
Total bilirubin (TBIL) ≤2×ULN ALT/AST ≤2.5×ULN (≤5×ULN if liver metastases present) Serum creatinine (Cr) ≤1.5×ULN Albumin ≥28 g/L
3. Urinalysis :
Urine protein \<2+ (dipstick) If protein ≥2+, 24h urinary protein ≤1.0 g
4. Coagulation (without anticoagulants):
PT/APTT/INR ≤1.5×ULN
* 5\) Life expectancy ≥12 weeks;
* 6\) Contraception : Females of childbearing potential or males with partners of childbearing potential must use effective contraception during treatment and for 6 months post-treatment;
* 7\) Signed informed consent and protocol compliance.
Exclusion Criteria:
* 1\) Tumor-Related Conditions
1. Known CNS metastases (except those radiologically stable ≥4 weeks after radiotherapy);
2. Other malignancies within past 5 years, excluding:
Cured basal/squamous cell skin cancer Localized low-risk prostate cancer Cervical/breast carcinoma in situ
3. Severe bone lesions from metastatic disease, including:
Uncontrolled bone pain Pathologic fractures at critical sites (within 6 months) or impending spinal cord compression;
4. Uncontrolled effusions requiring recurrent drainage (pleural/pericardial/ascites), per investigator assessment.
* 2\) Prior Anti-tumor Therapy
1. Prior systemic therapy with CTLA-4 inhibitors or other ICIs;
2. Any anti-tumor treatment within 4 weeks before first dose, including:
Surgery/chemotherapy/palliative radiotherapy to non-target lesions/hormonal/targeted/biologic/immunotherapy;
3. Treatment-related toxicities not recovered to CTCAE grade ≤1 (exceptions: alopecia/platinum-induced neuropathy ≤ grade 2).
* 3\) Comorbidities \& History
1. Arterial thromboembolism within 6 months (MI/unstable angina/stroke/TIA);
2. Symptomatic heart failure (NYHA class III-IV), unstable angina, or uncontrolled arrhythmia;
3. Severe pulmonary disease : ILD/COPD/symptomatic bronchospasm;
4. Active uncontrolled infection (≥CTCAE grade 2), including:
HIV Active HBV (DNA ≥500 IU/mL) HCV (Ab+ with detectable RNA) HBV/HCV co-infection;
5. History of neurologic/psychiatric disorders;
6. Recent or current substance abuse;
7. Prior allogeneic organ/hematopoietic stem cell transplantation.
* 4\) Hypersensitivity to study drug or its excipients.
* 5\) Active autoimmune disease requiring treatment or history within 2 years. Exceptions: Vitiligo/alopecia/psoriasis not needing systemic therapy Hypothyroidism managed only with hormone replacement Type 1 diabetes controlled solely with insulin.
* 6\) Pregnant/lactating women;
* 7\) Any uncontrolled systemic disease increasing study risk (per investigator);
* 8\) Other unsuitable conditions determined by investigator.
