• Patients included in this study must meet all of the following criteria:

‣ Age ≥ 18 years;

⁃ Histologically or cytologically confirmed HER2-expressing locally advanced unresectable (e.g., T4b, or N2-3) or metastatic urothelial carcinoma (la/mUC), including bladder, ureter, renal pelvis, and urethra. HER2 expression is defined as immunohistochemical (IHC) staining results of 1+ to 3+, and must be confirmed by the pathology department of Sun Yat-sen University Cancer Center according to ASCO/CAP guidelines.

⁃ Cohort 1: Patients who have received at least one prior systemic therapy, or relapsed/progressed within 12 months after the last treatment, or who could not tolerate treatment due to adverse events (AEs). Cohort 2: Patients who have not received prior systemic therapy or relapsed/progressed more than 12 months after neoadjuvant/adjuvant therapy, or those who could not tolerate treatment due to AEs. Cohort 3: Patients who have previously received platinum-based chemotherapy (including cisplatin, carboplatin, etc.), immunotherapy (including PD-1, PD-L1 inhibitors), and Disitamab Vedotin ;

⁃ At least one measurable target lesion according to RECIST 1.1 criteria;

⁃ ECOG performance status ≤ 2;

⁃ Adequate bone marrow, renal (calculated creatinine clearance \> 30 mL/min using the CG formula), hepatic, and coagulation function;

⁃ Expected survival ≥ 3 months;

⁃ The patient understands the study procedures and has provided written informed consent to participate in the study;

⁃ Female participants of childbearing potential must have a negative urine or serum pregnancy test within 7 days before the first administration of the study drug (Cycle 1, Day 1). If the urine pregnancy test is inconclusive, a blood pregnancy test is required.

‣ Both male and female participants must agree to use highly effective contraception (i.e., methods with a failure rate of less than 1% per year) and continue contraception until at least 180 days after the end of study treatment.