Sesen Bio’s Vicineum for Non-Muscle Invasive Bladder Cancer Receives FDA Priority Review

The Food and Drug Administration (FDA) accepted Sesen Bio’s Biologics License Application (BLA) for Vicineum for the treatment of high-risk, BCG-unresponsive non-muscle invasive bladder cancer (NMIBC). The agency also gave the application Priority Review and, according to a press release, does not plan to hold an advisory committee meeting regarding the BLA.

“We have been meeting with the FDA regularly for the past two years on the application for Vicineum,” said Dr. Thomas Cannell, president and chief executive officer of Sesen Bio, in a press release. “We understand the FDA’s position and guidance very clearly and have found the review process to be collaborative and engaging. … We remain focused on the patient and our mission to save and improve lives and expect to continue to make progress around the world in the coming months.”

The company previously reported outcomes of the phase III VISTA trial, which recruited 133 patients in three cohorts. The study included patients with BCG-unresponsive NMIBC who had completed ≥2 courses of full-dose BCG and recurred with papillary NMIBC ≤30 weeks or carcinoma in situ ≤50 weeks after last BCG. Vicineum was instilled into the bladder for two hours at 30 mg doses twice a week for six weeks, followed by weekly for six weeks and then every two weeks for up to two years. Patients underwent evaluation per urine cytology, cystoscopy, and pathology of biopsy of any suspicious lesion. The primary efficacy endpoints were complete response rate (CRR) and duration of response for patients in the first cohort. Secondary efficacy endpoints were time to disease recurrence for patients in the third cohort, and for the entire study population, time to cystectomy, progression-free survival, event-free survival, and overall survival (OS).

By May 2019, data were available for cohorts one (n=82) and two (n=7). Cohort one included patients with CIS with or without papillary disease that was determined to be refractory or recurred within six months of their last course of adequate BCG. The CRRs were: three months, 39%; six months, 26%; nine months, 20%; and 12 months, 17%. Cohort two included patients with CIS with or without papillary disease that was determined to be refractory or recurred after six months, but less than or equal to 11 months, after their last course of adequate BCG. CRRs in this cohort were 57%, 57%, 43%, and 14%, respectively.

When the two cohorts were pooled together, the CRRs were: three months, 40% (95% confidence interval [CI], 30-51%); six months, 28% (95% CI, 19-39%); nine months, 21% (95% CI, 13-31%); and 12 months, 17% (95% CI, 10-26%).

At data cutoff, the researchers anticipated that 90% of the entire cohort would remain progression-free for ≥2 years, 96% of patients were estimated to have OS ≥2 years; 95% of all adverse events (AEs) were grade 1 or 2. The most prevalent treatment-related AEs were dysuria (14%), hematuria (13%) and urinary tract infection (12%).