Checkpoint Inhibitor and Radiation Therapy in Bulky, Node-Positive Bladder Cancer

Patients are eligible for the trial if they have bulky, clinically node-positive (cN+) bladder cancer and have either recently initiated (within ≤ 1 week) or are planned to initiate immune checkpoint inhibitor (ICI) therapy due to either 1) ineligibility for/refusal of platinum-based downstaging chemotherapy; or 2) failure to achieve a complete clinical response to platinum-based downstaging chemotherapy. Patients will initiate PULSAR treatment 1-2 weeks after initiating ICI. PULSAR will be administered in 3 fractions of 12 Gy each (36 Gy total) at 12-16 day intervals and patients will undergo radical cystectomy with bilateral extended pelvic lymph node dissection within 4-8 weeks after completion of PULSAR. ICI therapy will be administered according to the FDA-approved dosing route and schedule and will be continued during PULSAR treatments. PULSAR treatment will be initiated 1-2 weeks after the patient is initiated on an FDA-approved ICI agent. PULSAR will be administered in 3 fractions of 12 Gy each at 12-16 day intervals. Target areas will include the region of the bladder containing the primary tumor (confirmed, if necessary, on office flexible cystoscopy at UTSW) and to up to five targetable, pathologically enlarged bulky lymph nodes (as deemed feasible by the treating radiation oncologist). Non-enlarged pelvic lymph nodes will be spared to minimize adverse effects on the tumor immune response.