Durability of response of UGN-101: Longitudinal follow up of multicenter study.

Purpose: UGN-101, a reverse thermal mitomycin gel for upper tract instillation, recently became the first FDA approved treatment for upper tract urothelial carcinoma (UTUC). However, the durability of UGN-101 treatment has not been well described. Here we present long term outcomes from our multi-institutional cohort for patients who initially responded to treatment.

Materials and methods: We identified patients from a multi-institutional database with UTUC who had a negative endoscopic evaluation following either adjuvant or chemoablative UGN-101 induction. Recurrence and progression data for those patients was reviewed. Kaplan-Meier survival analysis was performed, stratified by relevant clinical features.

Results: We identified 56 renal units that met the inclusion criteria of which 93% had low-grade disease while 4 cases had high-grade UTUC. With a median follow-up of 23.5 months, 21.4% of renal units experienced a recurrence, with 65% of renal units recurrence-free at 36 months. Three patients experienced eventual progression of disease leading to mortality, however only 1 of these patients had presumed low-grade UTUC and did not undergo nephroureterectomy on recurrence due to solitary kidney.

Conclusions: UGN-101 treatment has excellent durability in patients who initially respond to the treatment. Further study is needed to better understand the long term outcomes of this novel therapy and also the risks/benefits of maintenance therapy in this setting. Caution should be used in patients with high-grade disease who appear to be at higher risk of relapse and death despite initial response.