This is a randomized, controlled, open-label, multicenter phase 3 clinical study to evaluate the efficacy, safety and immunogenicity of 9MW2821 combined with Toripalimab versus standard chemotherapy in first-line locally advanced or metastatic urothelial cancer.

The study is planning to enroll approximately 460 participants with unresectable locally advanced or metastatic urothelial cancer who have not previously received systematic treatment.

Inclusion Criteria:

• Sign the informed consent form approved by IEC.
• Male or female subjects aged 18 to 80 years.
• ECOG status: 0 or 1.
• Histologically confirmed local advanced or metastatic urothelial cancer
• Previously untreated with local advanced or metastatic urothelial cancer
• At least one measurable lesion, according to RECIST V1.1.
• Adequate tumor tissues submitted for test
• Suitable for cisplatin/carboplatin-based chemotherapy assessed by investigator
• Life expectancy for more than 12 weeks.
• Adequate organ functions.
• Proper contraception methods.
• Willingness to follow the study procedures.

Exclusion Criteria:

• History of another malignancy within 3 years.
• History of autoimmune disease requiring systemic treatment within 2 years.
• History of clinically significant cardiac/cerebrovascular diseases or thrombosis within 6 months.
• Major surgery treated within 28 days; Any live vaccines got within 28 days; Radiotherapy or Intravesical therapy treated within 21 days; Traditional Chinese medicine or any potent CYP3A4 inducers/inhibitors taken within 14 days.
• Lots of pleural fluid and ascites, uncontrolled bone pain or spinal compression existed within 14 days; Systemic treatment with active infection within 7 days.
• Previously treated with PD-1, PD-L1, PD-L2, CTLA-4 inhibitors; Previously treated with ADCs which target Nectin-4 or are conjugated with payload MMAE; Organ transplantation or allogeneic hematopoietic stem cell transplantation in the past.
• Clinical significantly toxicity Grade ≥ 2 (except alopecia and pigmentation) related to previous treatment.
• Any situations adding the risk of severe dry eye, active keratitis or corneal ulcer, etc.
• Peripheral neuropathy Grade ≥ 2.
• Any other serious chronic or uncontrolled disease.
• Uncontrolled central nervous system metastases or carcinomatous meningitis.
• Active HBV/HCV/HIV infection, etc.
• Known allergic sensitivity to any of the ingredients of the study drug.
• History of drug abuse or mental illness.
• Other conditions unsuitable into the study.