Successful Phase III VISTA trial of Vicinium to treat high-grade non-muscle invasive bladder cancer . Sesen Bio.Inc.

Sesen Bio, Inc. (formerly Eleven Biotherapeutics) has announced positive, three-month data from its ongoing Phase III VISTA Trial of Vicinium for the treatment of patients with high-grade non-muscle invasive bladder cancer (NMIBC) who have been previously treated with bacillus Calmette-Guérin (BCG). The efficacy data being reported are based on three-month follow-ups from 111 patients with high-grade NMIBC that is either carcinoma in situ (CIS), which is cancer found on the inner lining of the bladder that has not spread into muscle or other tissue, with or without papillary disease, or from patients with papillary disease without CIS, which is cancer that has grown from the bladder lining out into the bladder, but has not spread into muscle or other tissue.

“High-grade NMIBC is a devastating cancer that typically occurs later in life and for which treatment options are limited. Over the last 30 years, our industry has seen little innovation for the treatment of this prevalent cancer. The current standard-of-care, BCG, works in many patients, but many will also eventually relapse. For those patients who relapse or who don’t respond at all, the standard alternative is radical cystectomy. In a cystectomy, the bladder is removed along with surrounding lymph nodes and other organs that contain cancer. I am very encouraged by both the safety and these three-month efficacy data with Vicinium, and I look forward to continuing to work with the Sesen Bio team to help bring forward this potential treatment as a safe and effective option for my patients,” said Rian Dickstein, M.D. F.A.C.S., chief of urology, University of Maryland Baltimore Washington Medical Center; medical director of GU oncology, Tate Cancer Center at The University of Maryland Baltimore Washington Medical Center; clinical assistant professor, Department of Surgery, University of Maryland School of Medicine; director, bladder cancer program, Chesapeake Urology; and an investigator in the VISTA Trial.

Three-Month Efficacy Results: CIS (carcinoma in situ) Patients: In cohort 1 (Cohort 1 (n=87): patients with CIS with or without papillary disease whose cancer recurred within six months of their last course of BCG treatment.): 72 patients were evaluable for three-month data as of the April 20, 2018 data cut-off date. In these patients, treatment with Vicinium demonstrated a complete response rate of 39 percent. In evaluable patients in cohort 2 (Cohort 2 : patients with CIS with or without papillary disease whose cancer recurred after six months, but before 11 months, after their last course of BCG treatment) (n=5), treatment with Vicinium demonstrated a complete response rate of 80 percent. In an analysis assessing pooled CIS patients from cohorts 1 and 2 (n=77), based on final FDA guidance on treatment of BCG-unresponsive CIS NMIBC patients (defined as patients with recurrent CIS within 12 months of adequate BCG therapy), Vicinium treatment resulted in a complete response rate of 42 percent at three months.

Three-Month Efficacy Results: Papillary Patients : Patients with papillary disease without CIS were enrolled in cohort 3, but are not included in the primary endpoint assessment. At screening, all of these patients underwent mandatory resection of their tumors and upon starting treatment, were deemed to have no visible evidence of disease. As such, in this patient population, rates of disease recurrence and time to disease recurrence are standard criteria to evaluate response. In these evaluable patients (n=34), treatment with Vicinium demonstrated a 68 percent recurrence-free rate at three months.

To date, Vicinium has been well-tolerated in the VISTA Trial. In treated patients across cohorts (n=129), 72 percent of all adverse events were Grade 1 or 2.