Background: The VI-RADS is a standardized reporting system that uses multiparametric magnetic resonance imaging (mpMRI) parameters to differentiate non muscle-invasive bladder cancer (NMIBC) from MIBC. Limited data on clinical response assessment to neoadjuvant therapy are currently available. In this study, we aimed to analyze the performance of VI-RADS to predict the pT0 or pT≤1 response post-neoadjuvant immunotherapy in MIBC. Methods: In PURE-01 study (NCT02736266) patients (pts) were staged with mpMRI before and after treatment (3 cycles of Pembrolizumab) prior to radical cystectomy (RC). Logistic regression models analyzed pre- and post-pembro VI-RADS, with clinical and tumor-related variables, against ypT≤1N0 (primary endpoint) and ypT0N0 (secondary endpoint). VI-RADS scores were dichotomized between 0-3 (0 = no evidence of disease) and 4-5 (5 = extension to extravescical fat). Event-free survival (EFS) and overall survival (OS) analyses based on VI-RADS were performed. Comprehensive genomic profiling and transcriptome-wide expression profiling data were matched with VI-RADS scores. Model performance was also tested in the ongoing NureCombo (nivolumab+nab-paclitaxel; NCT04876313) and SURE-01 (sacituzumab govitecan; NCT05226117) neoadjuvant studies. Results: In total, 110 patients treated with neoadjuvant pembrolizumab between 02/2017 and 07/2020 had centrally reviewed scans (N=220 mpMRI). Pre-pembrolizumab, 21 patients (19.1%) had no measurable disease (VI-RADS=0), 34 (30.9%) had a VI-RADS 1-3 score, and 55 (50%) had a VI-RADS 4-5 score. Both pre-pembrolizumab and post-pembrolizumab VI-RADS 0-3 scores were the only significant covariates that predicted the ypT≤1N0 endpoint on multivariable analyses (MVA): the strongest effect was seen with post-pembrolizumab VI-RADS 0-3 predicting the ypT≤1N0 response (odds ratio [OR]: 23.4, 95%CI: 7-95.3, p<0.0001). The area-under-the-curve (AUC) of this model was 0.90. Post-pembrolizumab VI-RADS 0-3 also predicted longer EFS (p<0.001) and OS (p=0.044). The scores of several gene signatures from baseline tumors differed between pre-pembrolizumab VI-RADS 0-3 and 4-5 categories. RAF1 mutations were enriched in pre-pembrolizumab VI-RADS 0-3 group (p=0.045). Conclusions: VI-RADS scores post-pembrolizumab revealed a robust association with pathological downstaging and survival. VI-RADS scores were also characterized by distinct biomarker features. These results indicate that VI-RADS is emerging as an important tool to design next-generation trials in MIBC. Clinical trial information: NCT02736266.