In this single-arm phase III trial, patients with primary low-grade upper tract urothelial carcinoma underwent 6 once-weekly instillations of UGN-101 (JELMYTO)...presented the key secondary endpoint of durability of response. 29/41 complete responders received at least one maintenance dose, with a median of 6 doses among these 29 patients. At 12 months, 23/31 patients (74.2%) had a persistent complete response. (This was 81.8% estimated 1-year persistent CR by Kaplan-Meier analysis, which would imply a ~48% 12 month CR rate overall.)