Inclusion Criteria:

          1. Voluntary participation and informed consent

          2. Male or female, ≥ 18 years of age

          3. Expected survival ≥ 12 weeks

          4. Locally advanced or metastatic but unresectable urothelial carcinoma with
             histopathological confirmation (including urothelial carcinoma originating from renal
             pelvis, ureters, bladder, or urethra)

          5. Subjects diagnosed with unresectable, locally advanced or metastatic disease who
             develop disease progression on or after receiving a platinum containing regimen

          6. At least one measurable lesion based on RECIST version 1.1 (≥ 20 mm as measured by
             conventional CT, ≥ 10 mm as measured by Spiral CT, and have not undergone radiotherapy
             for the measurable lesion). Tumor lesions previously treated with radiotherapy are
             considered measurable if progression is demonstrated at the time of enrollment

          7. HER2-expressing status confirmed by the central laboratory: IHC 2+ or 3+; Subject is
             able to provide specimens from primary or metastatic lesions for HER2 tests

          8. ECOG performance status score: 0 or 1

          9. Adequate cardiac, bone marrow, hepatic and renal functions (based on normal reference
             ranges of the clinical trial site):

               -  Left ventricular ejection fraction (LVEF) ≥ 50%

               -  QTcF < 470 ms

               -  Hemoglobin ≥ 9.0 g/dL without transfusion

               -  Absolute neutrophil count (ANC) ≥ 1.5 x 109/L

               -  Platelets count ≥ 100 x 109/L

               -  Total serum bilirubin ≤ 1.5 x upper limit of normal (ULN)

               -  Without liver metastasis: ALT and AST ≤ 2.5 x ULN; With liver metastasis: ALT and
                  AST ≤ 5 x ULN

               -  Serum creatinine ≤ 1.5 x ULN or creatinine clearance (CrCl) ≥ 50 mL/min as
                  calculated by the Cockcroft-Gault equation

         10. Willingness to avoid pregnancy or fathering children based on the criteria below:

               1. Women of non-childbearing potential (i.e., surgically sterile with a hysterectomy
                  and/or bilateral oophorectomy OR chemically sterile OR ≥ 12 months of amenorrhea
                  in the absence of chemotherapy, anti-estrogens, or ovarian suppression). Women of
                  non-childbearing potential need not undergo pregnancy testing

               2. Women of childbearing potential who have a negative urine or serum pregnancy test
                  at Screening and before the first dose of study drug on Cycle 1, Day 1, and who
                  agree to take appropriate precautions to avoid pregnancy (with approximately 99%
                  certainty) from Screening through 6 months after the last dose of study drug

               3. Men who agree to take appropriate precautions to avoid fathering children (with
                  at least 99% certainty) from Screening through 6 months after the last dose of
                  study drug

         11. Subject must be willing and able to comply with the trial procedure and the follow-up
             schedule.

        Exclusion Criteria:

          1. Known hypersensitivity to disitamab vedotin for injection or any of its components

          2. Received anti-tumor treatment (including chemotherapy, radiotherapy, targeted therapy,
             immunotherapy etc.) or participated in another clinical study within 4 weeks prior to
             the start of the study, or toxicity from a previous treatment that has not returned to
             Grade 0-1 (except for Grade 2 alopecia)

          3. Received treatment with other antibody-drug conjugates (such as enfortumab vedotin,
             trastuzumab emtansine, etc.)

          4. Major surgery that has not fully recovered within 4 weeks prior to dose administration

          5. Received live vaccines (except for vaccines for COVID-19 )within 4 weeks prior to dose
             administration or plan on receiving any vaccine (except for vaccines for COVID-19 )
             during the course of the study

          6. Other serious, uncontrolled concomitant diseases that may affect protocol compliance
             or interpretation of outcomes, including active opportunistic infections or advanced
             (severe) infections, uncontrolled diabetes, cardiovascular diseases (NYHA Class III-IV
             heart failure, Grade II or more severe heart block, myocardial infarction, unstable
             arrhythmia or unstable angina within the past 12 months, cerebral infarction within
             the past 6 months, etc.) or pulmonary diseases (interstitial pneumonia, obstructive
             pulmonary disease, or history of symptomatic bronchospasm), and deep vein thrombosis
             or pulmonary embolism within the past 6 months

          7. History of other malignant tumors within 5 years prior to dose administration, except
             for:

               -  Localized, low-risk prostate cancer (subjects with stage ≤ T2b, Gleason score ≤
                  7, and prostate-specific antigen (PSA) ≤ 20 ng/mL (if measured) at diagnosis, who
                  have undergone radical treatment and have no PSA recurrence may participate in
                  this study);

               -  Malignancies that can be cured after treatment (including but not limited to
                  adequately treated thyroid cancer, cervical carcinoma in situ, basal or squamous
                  cell skin cancer, or radical treatment of ductal carcinoma in situ of the breast)

          8. Central nervous system metastasis and/or carcinomatous meningitis. Subjects who have
             undergone treatment for brain metastasis may be eligible, provided that: the subject
             has been in stable condition for at least 6 months; no radiographic evidence of
             disease progression within 4 weeks prior to the first dose; all neurological symptoms
             have returned to baseline levels; no new or growth of brain metastasis; and the
             subject has discontinued radiation, surgery or steroid therapy at least 28 days prior
             to the first dose. This does not include subjects with carcinomatous meningitis, who
             are not eligible even if clinically stable

          9. Active autoimmune diseases that require systemic therapy (such as the use of
             disease-modifying drugs [e.g., methotrexate, sulfasalazine, leflunomide,
             hydroxychloroquine], corticosteroids, or immunosuppressives) over the past 2 years.
             Replacement therapies (such as thyroxine, insulin, or physiological replacement of
             glucocorticoids due to renal or pituitary deficiency) are allowed

         10. Received allogeneic hematopoietic stem cell transplantation or solid organ
             transplantation

         11. Pleural effusion or ascites with symptoms or requiring symptomatic treatment

         12. Pregnant or breastfeeding women

         13. Positive HIV test, with a lower CD4+ count (<350 cells/μL)

         14. Subjects with uncontrolled hypertension (systolic blood pressure > 180 mmHg and/or
             diastolic blood pressure >100 mmHg)

         15. Subjects with active Hepatitis B and/or Hepatitis C:

               -  For subjects with positive HBsAg, only those whose HBV DNA < 500 IU/mL are
                  eligible.

               -  As for subjects with positive anti-HCV, only those who have a negative HCV RNA
                  PCR test are eligible

         16. Active tuberculosis

         17. Any other disease, metabolic disorder, or abnormal finding upon physical examination
             or laboratory examination that makes the subject unsuitable for receiving the
             investigational drug, affects the interpretation of study outcomes, or poses risks to
             subject safety, as determined by the investigator

         18. A positive real-time reverse transcriptase polymerase chain reaction (RT-PCR) test for
             SARS CoV-2.

         19. Clinical signs and symptoms consistent with SARS-CoV-2 infection (e.g., fever, dry
             cough, dyspnea, sore throat, fatigue) or positive SARS-CoV-2 test result within 2
             weeks prior to screening.

         20. Severe course of COVID-19 (e.g., extracorporeal membrane oxygenation, mechanically
             ventilated).

         21. Subject compliance is questionable