Inclusion Criteria:
The subject voluntarily participates in this study, signs the informed consent form, demonstrates good compliance, and agrees to follow-up.
Aged 18-75 years, regardless of gender.
Diagnosed with primary bladder cancer confirmed by histopathology or clinical diagnostic criteria, clinically assessed as unresectable, and having failed at least two prior lines of standard therapy.
Adequate organ function:
1. Hematologic system (no transfusion or hematopoietic growth factor therapy within 14 days prior to enrollment):
Absolute neutrophil count (ANC) ≥1.5×10⁹/L
Platelets (PLT) ≥60×10⁹/L
Hemoglobin (Hb) ≥90 g/L
2. Liver function:
Total bilirubin (TBIL) ≤1.5×ULN
Alanine aminotransferase (ALT) ≤3×ULN
Aspartate aminotransferase (AST) ≤3×ULN
Albumin ≥2.8 g/dL
3. Coagulation function:
Activated partial thromboplastin time (APTT) ≤1.5×ULN
International normalized ratio (INR) or prothrombin time (PT) within normal range
4. Renal function:
Serum creatinine ≤1.5×ULN, or
Creatinine clearance (Ccr) ≥50 mL/min (calculated using Cockcroft-Gault formula; applies only if creatinine \>1.5×ULN)
5. Thyroid function:
Thyroid-stimulating hormone (TSH) ≤1×ULN
Free triiodothyronine (FT3) ≤1×ULN
Free thyroxine (FT4) ≤1×ULN
6. Cardiovascular function:
Left ventricular ejection fraction (LVEF) ≥50% by echocardiography
AJCC Bladder Cancer Stage III or IV.
Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1.
At least one measurable lesion (according to mRECIST criteria).
Expected survival time ≥6 months.
Male subjects with partners of childbearing potential must use reliable and effective contraception from signing the informed consent form until 180 days after the last dose of the study drug. Male subjects with pregnant partners must use condoms and require no additional contraception methods.
Exclusion Criteria:
Prior treatments within 28 days before the first dose:
1. Chemotherapy, radiotherapy, biologic therapy, immunotherapy, targeted therapy, local therapy, or traditional Chinese medicine with明确抗肿瘤适应症 (clear antitumor indications).
2. Major surgical procedures or failure to recover from side effects of such surgeries (excluding minor procedures, e.g., appendectomy, tumor biopsy).
3. Participation in other interventional drug clinical trials (excluding observational studies or survival follow-up).
Failure to recover from prior antitumor therapy-related toxicities (except alopecia) (i.e., toxicity still \> Grade 1 or not returned to baseline).
Concurrent or history of other malignancies, except:
Curative basal cell or squamous cell skin cancer
Carcinoma in situ of the cervix
Papillary thyroid carcinoma
Ductal carcinoma in situ of the breast
Other malignancies with disease-free survival \>5 years
Uncontrolled diabetes despite optimal supportive care.
Presence of gastrointestinal bleeding, refractory ascites, hepatic encephalopathy, or hepatorenal syndrome.
History or presence of autoimmune diseases (e.g., rheumatoid arthritis).
Neurological diseases, diffuse leptomeningeal disease, or comorbid neurodegenerative disorders.
History or planned stem cell or organ transplantation during the study.
Any of the following within 6 months before the first dose:
1. Cerebrovascular accident, transient ischemic attack, symptomatic pulmonary embolism, or other clinically significant thromboembolic events.
2. Unstable angina, myocardial infarction, or symptomatic chronic heart failure.
3. Ventricular arrhythmias (e.g., ventricular tachycardia, ventricular fibrillation, torsades de pointes).
4. Coronary/peripheral artery bypass grafting.
5. Current or history of congestive heart failure (NYHA Class II-IV).
6. Uncontrolled hypertension despite medication (systolic BP ≥160 mmHg and/or diastolic BP ≥100 mmHg).
Active infections, including:
1. Clinically uncontrolled active infections within 7 days before the first dose (e.g., acute pneumonia, unexplained persistent fever).
2. Hepatitis B (HBsAg-positive and HBV-DNA \>1000 IU/mL; HBV carriers must receive antiviral therapy per local guidelines and commit to ongoing treatment during the study).
3. Hepatitis C (HCV antibody-positive).
4. HIV or Treponema pallidum (TP) infection.
Requirement for systemic corticosteroids (\>10 mg/day prednisone or equivalent) or other immunosuppressants.
Pregnancy or lactation.
Any uncontrolled concurrent condition (including psychiatric disorders or substance abuse) deemed by the investigator to compromise subject cooperation or trial participation, or any other reason making the subject unsuitable for the study.
