LAUSR

4502Background: Comorbidities and renal impairment preclude many with advanced UC from receiving chemotherapy. Initial results from the phase 2 KEYNOTE-052 (NCT02335424) trial suggested first-line pembro is active and safe in cisplatin-ineligible advanced UC. We present updated efficacy and safety data (all pts have ≥6 mo follow-up) and evaluate biomarkers correlated with outcomes. Methods: Eligibility criteria included cisplatin-ineligible (ECOG PS 2, CrCl ≥30- < 60 mL/min, grade ≥2 neuropathy/hearing loss, NYHA Class 3 heart failure), advanced UC, and no prior systemic chemotherapy. Pts received pembro 200 mg IV Q3W. Imaging was performed at wk 9, then Q6W for the first year, and Q12W thereafter. Primary end point was confirmed ORR (RECIST v1.1, independent review). Efficacy and safety were assessed in the 370 pts with ≥1 pembro dose. The associations of an 18-gene expression profile (GEP) and IHC PD-L1 combined positive score (CPS) with ORR were evaluated. Results: As of the Dec 19, 2016, data cutoff, ...