Interim data from the PURE-01 study, using pembrolizumab before radical cystectomy in muscle-invasive bladder cancer (MIBC), suggested that multiparametric magnetic resonance imaging (mpMRI) was able to predict the pathologic response. Owing to the availability of novel effective therapies in MIBC, the possibility to assess tumor response easily has become exceedingly important. The primary objective of the present study was to evaluate the association between individual and combined MRI sequences, and the pathologic response in the final PURE-01 population. Images were internally evaluated and the diagnostic performance was analyzed for separate sequences, along with their combination. From February 2017 to December 2019, 143 patients were enrolled in PURE-01, and 123 with suitable paired imaging assessments before and after pembrolizumab tests (N = 246 mpMRI in total) were analyzed in relation to the pathologic response. The area under the curve (AUC) of the combination of all sequences to predict ypT0ypN0 response was 0.74. By excluding dynamic contrast enhancement (DCE) assessment, the AUC was 0.74. When looking at ypT1/a/is ypN0 response, the AUC was 0.87 in both cases. Without DCE, 95% of patients with no evidence of disease resulted in ypT1/a/is ypN0 and 65% ypT0ypN0 responders. In conclusion, the final results confirmed the reliability of mpMRI and suggested the opportunity to avoid intravenous gadolinium contrast to personalize bladder-sparing strategies in radiologically complete responders. PATIENT SUMMARY: We evaluated the reliability of multiparametric bladder magnetic resonance imaging to predict the pathologic response to pembrolizumab administered before radical cystectomy in muscle-invasive bladder cancer. We observed that this radiologic examination is promising in the attempt to identify opportunities to spare the bladder in selected, radiologically defined complete responders. We also observed that the use of intravenous gadolinium contrast can be avoided in future studies. ClinicalTrials.gov, number NCT02736266.
Keywords: Biparametric magnetic resonance imaging; Bladder magnetic resonance imaging; Dynamic contrast enhancement; Multiparametric magnetic resonance imaging; Muscle-invasive bladder cancer; Noninvasive response assessment.
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