Trial Drug: Mitomycin C (MMC)

This study is designed to assess the antitumor efficacy and safety of pembrolizumab in combination with chemoradiotherapy (CRT) versus CRT alone in participants with muscle-invasive bladder cancer (MIBC). The primary hypothesis is that pembrolizumab + chemoradiotherapy is superior to placebo + chemoradiotherapy with respect to bladder intact event-free survival.