Neoadjuvant RC48 Plus Gemcitabine in HER2-Expressing MIBC

Pathological Complete Response (pCR)

Defined as the absence of residual viable tumor cells (ypT0N0) in RC+PLND specimens. Assessed post-surgery. Method: A central pathology review committee performs centralized, blinded independent review of slides from all eligible patients. Sites ship de-identified slides and clinical forms to a central lab for uniform anonymization, QC, H\&E staining, and supplementary IHC if needed. All materials are fully de-identified, presented in random order without clinical data. Two senior uropathologists (associate professor level or above) read independently; consensus is final, otherwise a third senior pathologist adjudicates blindly. ypT and ypN are recorded.

Incidence of Grade ≥3 Treatment-Related Adverse Events (TRAEs) During Neoadjuvant Therapy

Defined as the proportion of patients in the safety set experiencing at least one Grade ≥3 TRAE (CTCAE v5.0) during neoadjuvant therapy. Assessed from the first cycle to 4 weeks after the last cycle, with comprehensive tests each cycle, a scheduled visit 1 week after the last dose of each cycle, and immediate evaluation upon any alert or complaint. Method: Uniform site training, structured eCRF recording of AE terms, dates, grades, relatedness, actions, outcomes. An independent Clinical Endpoint Committee (CEC) conducts centralized, blinded review of all Grade ≥3 events for final adjudication.

Clinical Complete Response (cCR)

Defined as no clinical evidence of residual tumor in primary and regional nodes after neoadjuvant therapy, assessed hierarchically: surgical patients based on pathological pCR (ypT0/Tis ypN0); non-surgical patients based on imaging CR per RECIST 1.1 (target lesions disappear, nodes \<10 mm, no new lesions). Assessed post-neoadjuvant. Method: Surgical patients use central pathology review (same as pCR); non-surgical patients use independent imaging review committee blinded to RECIST 1.1. A CEC reviews all data in blinded fashion, adjudicates cCR per hierarchy, ensuring uniformity.

Event-Free Survival (EFS)

Defined as time from neoadjuvant start to first occurrence of: ① disease progression (local/regional recurrence, distant metastasis, or definite clinical progression); ② death from any cause; ③ initiation of new anti-cancer therapy due to progression or toxicity. Censored at last known event-free assessment. Assessed at scheduled visits. Method: A central follow-up unit conducts structured symptom queries; any suspected event triggers medical evaluation. All potential event materials (imaging, records, symptom logs, death certificates) are submitted to an independent CEC for blinded adjudication of event and date, final for analysis.

Overall Survival (OS)

Defined as time from neoadjuvant start to death from any cause. Assessed at scheduled visits. Method: Central follow-up unit collects objective death documents from multiple sources. The independent CEC reviews all documents in a fully blinded manner, verifies and adjudicates the exact date of death, which serves as the final basis for OS calculation.