4511Background: The randomized, open-label Phase III IMmotion151 study met its coprimary endpoint in PD-L1+ patients (pts) with improvement in investigator-assessed PFS for atezo + bev vs sun (HR 0.74; median 11.2 vs 7.7 mo, P = 0.02). Encouraging efficacy was also observed in the intent-to-treat (ITT) population (HR 0.83; 11.2 vs 8.4 mo) (Motzer, ASCO-GU 2018). PROs were evaluated as secondary and exploratory endpoints to document pt perspective on overall clinical benefit for each tx. Methods: Pts received atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w (n = 454) or sun 50 mg PO QD 4 wk on/2 wk off (n = 461). Pts completed the MD Anderson Symptom Inventory (MDASI) and Functional Assessment of Cancer Therapy-Kidney Symptom Index 19 (FKSI-19) questionnaires on days 1 and 22 of each 6 wk cycle, at end of tx, and during survival follow-up. Prespecified concepts included symptom burden (MDASI symptom severity and symptom interference with daily living) and bother from tx side effects (FKSI-19 GP5 item). Health-re...