Combining Immunotherapy and Radiation Therapy to Help Patients Avoid Bladder Removal After Treatment Shrinks Muscle Invasive Bladder Cancer, BRIGHT Trial

Inclusion Criteria: * Participants must have histologic evidence of cT2-T4aN0M0 muscle invasive urothelial carcinoma of the bladder within 180 days prior to starting neoadjuvant therapy (NAT) * Participants must have had CT chest/abdomen/pelvis (C/A/P), MRI C/A/P or PET within 60 days prior to starting NAT to determine cT2-T4aN0M0 * Participants must have undergone TURBT with biopsy of areas of prior disease and systematic biopsies (left and right lateral, dome, posterior wall and trigone) and radiologic staging showing clinically T0-T1 disease within 60 days after the last dose of NAT. At least 4 out of 5 systematic biopsies must be performed * NOTE: This TURBT must be within 90 days prior to registration. Registration must be within 90 days after the last dose of NAT * Participants must have imaging of the chest, abdomen, and pelvis performed using CT or MRI preferably with contrast. Fludeoxyglucose F-18 (FDG) PET-CT can also be used for staging. If FDG PET-CT is used, then it is at the discretion of the investigator if they want to additionally obtain diagnostic CT or MRI with contrast within 60 days after the last dose of NAT * Participants with lymph nodes ≥ 1.0 cm in the shortest cross-sectional diameter on imaging (CT or MRI of abdomen and pelvis) after completion of NAT must have a PET-CT within 70 days prior to registration. A biopsy in the setting of negative PET-CT is not required unless there is strong clinical suspicion for nodal involvement with tumor. Parti…