Value of a Marker Lesion in Non-Muscle-Invasive Bladder Cancer Patients Treated with Interleukin-2 Instillations: A Randomized Controlled Multicentre Trial

Purpose: To compare the effect of intravesical interleukin-2 (IL-2) instillations with and without a marker lesion on time to recurrence (TTR) in non-muscle-invasive bladder cancer (NMIBC) patients. Methods: A prospective randomized, controlled trial was conducted. Patients with multiple non-muscle-invasive tumours were randomized for a complete or incomplete transurethral resection (TURBT), followed by 3 IL-2 instillations. The primary end point was TTR. Results: These are the results of an interim analysis, which was performed due to slow accrual after which the study was closed prematurely. Twenty-eight patients were randomized of which 17 were eligible on an intention-to-treat basis. Median TTR or last follow-up was 3 months (interquartile range [IQR] 3–10 months) for the complete and 4 months (IQR 3–8 months) for the incomplete TURBT group. The TTR between the 2 groups did not differ significantly (log-rank, p = 0.54). ­Conclusions: These data do not support the hypothesis that a marker lesion enhances the therapeutic effect of IL-2 instillations in patients with NMIBC.