In a phase 3, single-arm multicenter registrational trial, the authors accrued patients with BCG-unresponsive NMIBC, defined as refractory or relapsing within 6 months (n = 126) and relapsing within 6 to 11 months (n = 7) after adequate BCG therapy. As with BCG, vicinium was administered in an induction phase followed by maintenance. During induction, vicinium was instilled for 2 hours twice weekly for 6 weeks, then weekly for 6 weeks. Disease-free patients at 3 months received maintenance every 2 weeks for up to 2 years. Patients were assessed every 13 weeks, with a response defined as negative cytology along with normal cystoscopy or absence of high-grade disease on biopsy.
With a data cut off of May 29th, 2019, in patients with CIS (n-89), the authors demonstrated a complete response rate at 3-months of 40%. For those with a complete response, the median duration of response was 9.4 months (95% CI, 5.1-NE) and 52% remained disease-free for 12 months after starting treatment.
In patients with papillary disease (n=38), the recurrence-free rates at 3, 6, 12, and 24 months were 71, 58, 50, and 37%, respectively. The median time to recurrence was 13.2 months (95% CI, 5.6-NE).
Overall, patients who responded at 3 months avoided radical cystectomy for much longer than those who did not respond: 34.0 vs. 20.7 months (p ≤ 0.001). Furthermore, the rate of cystectomy was only 10% (6 of 63) for patients who demonstrated response at 3-month versus 32% (18 of 56) for the non-responders.
While data remain immature, overall survival was 96% (95% CI, 92-100) at 2 years.
With respect to toxicity, vicinium was generally well-tolerated with 52% of patients experiencing treatment-related adverse events (AEs), the majority being grade 1-2, without significant differences between age groups. Three patients experienced four treatment-related severe AEs, including grade 4 cholestatic hepatitis, grade 5 renal failure, grade 3 acute kidney injury, and grade 2 pyrexia. Only 3% of the patients discontinued treatment due to AEs.
These data add vicinium to the rapidly growing armamentarium for patients with BCG-unresponsive NMIBC and may allow patients to delay radical cystectomy.
Presented by: Neal Shore, MD, FACS, Medical Director for the Carolina Urologic Research Center, Myrtle Beach, South Carolina
Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center, Nashville, TN, USA, Twitter: @WallisCJD, at the 2020 American Urological Association (AUA) Annual Meeting, Virtual Experience #AUA20, June 27-28, 2020.
Clinical Trial Information: NCT02449239 — Open-Label, Multicenter, Ph 3 Study to Evaluate the Efficacy and Tolerability of Intravesical Vicinium™ in Subjects With Non Muscle-Invasive Carcinoma in Situ and/or High-Grade Papillary Disease of the Bladder Treated With BCG