Detailed Description:

This is a 2-part, multicenter, first-in-human (FIH), Phase 1/2a study in patients with a history of pathologically confirmed high-grade Ta or T1 NMIBC without CIS who have completed SOC previously, with recurrent papillary disease seen on cystoscopy, and who are undergoing TURBT without perioperative intravesical chemotherapy. All patients will receive relevant SOC therapy following TURBT. SOC will be administered in the adjuvant setting. Phase 1 is an open-label, single-treatment, dose-escalation study to evaluate the safety and tolerability of up to 4 increasing doses of intraoperatively administered STM-416 utilizing a 3+3 convention, with 3 to 6 patients enrolled in each STM-416 dose level, with a minimum of 6 patients enrolled at the highest dose level, for a total of approximately 24 patients. Phase 2a is a randomized, single-blind, single-treatment, dose-expansion study that will comprise 2 arms: TURBT + STM-416 Dose 1 followed by SOC versus TURBT + STM-416 Dose 2 followed by SOC.}}