In 106 pts (NSCLC=68, UC=38), median treatment duration was 113.0 days (NSCLC=113.0 days, UC=102.0 days) and was ongoing in 31.8% of pts. 56.6% of pts had treatment-related adverse events (TRAEs), 13.2% at grade 3–4...Objective response rate (ORR) was 20.9% (95% confidence interval [CI] 11.9–32.6%), and 32.1% and 45.5% in pts with PD-L1 tumor expression ≥1% and ≥50%, respectively. In the mITT UC population (n=38), 0% had a CR, 21.1% a PR (median duration 183.0 days), and 31.6% SD (median duration 118.5 days). ORR was 21.1% (95% CI 9.6–37.3%), and 40.0% and 50.0% in pts with PD-L1 tumor expression ≥1% and ≥50%, respectively. Survival data will be presented...In this update of SC PF-06801591 300mg q4w in pts with NSCLC or UC, the longer-term safety profile was consistent with previous reports. Durable antitumor activity was demonstrated.