Sesen Bio, Inc. reported positive preliminary efficacy data for the primary endpoint of its ongoing Phase 3 registration trial, the VISTA Trial, of Vicinium for the treatment of patients with high-grade non-muscle invasive bladder cancer. The data reported show clinically meaningful complete response rates in evaluable Carcinoma in situ patients at three, six, nine and 12 months of follow-up in the trial consistent with the data in the completed Phase 1 and Phase 2 clinical trials. Importantly, Vicinium continues to be generally well-tolerated in treated patients. Non-muscle invasive bladder cancer is a very prevalent cancer that can progress to become incurable. VISTA Trial Design: The Phase 3 VISTA Trial is a single-arm, multi-center clinical trial designed to support the approval of Vicinium for the treatment of patients with high-grade, BCG-unresponsive NMIBC. The trial enrolled a total of 133 patients across three cohorts based on histology and time to disease recurrence after adequate BCG: Cohort 1 (n=86): Carcinoma in situ patients with or without papillary disease whose cancer was determined to be refractory or recurred within six months of their last course of adequate BCG Cohort 2 (n=7): Carcinoma in situ patients with or without papillary disease whose cancer was determined to be refractory or recurred after six months, but less than 12 months, after their last course of adequate BCG Cohort 3 (n=40): patients with papillary disease without Carcinoma in situ whose cancer was determined to be refractory or recurred within six months of their last course of adequate BCG.