This study will evaluate the efficacy and safety of intravenous RC48-ADC combined with JS001 in perioperative treatment of muscle-invasive bladder cancer.

Inclusion Criteria:

• Voluntary agreement to provide written informed consent.
• Male or female, Age ≥ 18 years.
• Predicted survival ≥ 12 weeks.
• Histologically confirmed diagnosis of muscle invasive bladder cancer (MIBC) .Naive of antitumor systematic treatment or radiotherapy.
• Have clinically non-metastatic bladder cancer (cT2-T4a, N0-1, M0) determined by imaging.
• Be deemed eligible for Radical Cystectomy (RC) + Pelvic Lymph Node Dissection (PLND).
• HER2 expressing (i.e. IHC 1+ 2+ or 3+) as confirmed by the local lab.
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.
• Adequate organ function, evidenced by the following laboratory results within 7 days prior to the study treatment.
• Male and female participants are eligible to participate if they agree to the contraception use as per study protocol.
• Willing to adhere to the study visit schedule and the prohibitions and restrictions specified in this protocol.

Exclusion Criteria:

• Has received other antitumor therapy before planned start of trial treatment.
• History of major surgery within 4 weeks of planned start of trial treatment.
• Diagnosed with HBsAg, HBcAb positive and HBV DNA copy positive, or HCVAb positive, or HIVAb positive.
• Has received a live virus vaccine within 4 weeks of planned start of trial treatment.
• NYHA Class III heart failure.
• Suffering from active infection requiring systemic treatment.
• Uncontrolled hypertension, diabetes, Interstitial lung Disease, or COPD;
• Treated with systemic treatment (e.g. immunomodulators, corticosteroids or immunosuppressants) for the autoimmune disease within 2 years prior to the study treatment.
• History of other malignancy within the previous 5 years, except for appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, or cancers with a similar curative outcome as those mentioned above.
• Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject's participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.
• Pregnancy or lactation.
• Assessed by the investigator to be unable or unwilling to comply with the requirements of the protocol.