Neoadjuvant RC48 Plus Gemcitabine in HER2-Expressing MIBC

Objectives: To evaluate the non-inferiority of disitamab vedotin plus gemcitabine versus disitamab vedotin plus toripalimab in terms of the pathological complete response (pCR) rate as neoadjuvant therapy for muscle-invasive bladder cancer (MIBC). This study is designed to evaluate two parallel neoadjuvant treatment strategies followed by definitive local therapy and adjuvant treatment. Eligible patients will be assigned to either the Experimental Arm, receiving neoadjuvant Disitamab Vedotin (RC48) combined with Gemcitabine, or the Active Comparator Arm, receiving neoadjuvant RC48 combined with Toripalimab. Both neoadjuvant regimens are administered every two weeks for 3 to 6 cycles, contingent upon imaging-based tumor response. Following the neoadjuvant phase, patients from both arms will proceed to receive standard Radical Cystectomy (RC) combined with Pelvic Lymph Node Dissection (PLND) within four weeks of their final dose, with a trimodality therapy (TMT) bladder-sparing approach strictly restricted to a selected minority of patients. In the postoperative phase, eligible patients will receive adjuvant therapy consisting of RC48 plus Toripalimab for 6 cycles, followed by Toripalimab maintenance monotherapy for a duration of ≤ 1 year (or a maximum of 1 year).Patients post-RC require abdominopelvic/chest imaging q3-6m; non-RC patients need cystoscopy q3m and abdominopelvic/chest CT q3-6m. Follow-up staff should proactively contact patients q3m to record imaging findings and inquire about hematuria, stomal lesions, cough/chest pain, CNS symptoms, and accurately document recurrence/progression, metastasis, death with dates.