Advancing Clinical Trial Design for Non-Muscle Invasive Bladder Cancer

Standardization of the evaluation and surveillance of patients with BCG unresponsive high grade non-muscle invasive bladder cancer clinical trials

There are multiple ongoing and planned clinical trials that are evaluating novel therapies to treat patients with BCG-unresponsive high grade nonmuscle invasive bladder cancer (NMIBC). Importantly, there is considerable variation in surveillance strategies between these clinical trials, specifically with regards to the use of advanced imaging, enhanced cystoscopy, and mandatory biopsies, which could impact landmark efficacy assessments of investigational agents. To present guideline recommendations for the standardization of cystoscopic evaluation, surveillance, and efficacy assessments for patients with BCG-unresponsive NMIBC participating in clinical trials. On September 29, 2023 at the annual meeting of the International Bladder Cancer Network, a breakout session was convened, during which representatives from various disciplines discussed potential guidance statements with opportunity for discussion and comment. A set of statements regarding use of white light and enhanced cystoscopy were developed to help guide a pragmatic approach to surveillance and efficacy assessments of patients in clinical trials. The use of "for cause" and "mandatory" biopsies was also addressed. A standard approach to evaluation of patients within the context of clinical trials is necessary to accurately assess the efficacy of novel agents, especially within single arm trials that lack an appropriate comparator. Additionally, the utilization and timing of mandatory biopsies is critical, as these biopsies may impact both disease evaluations and the determination of duration of response.

Oncolytic adenoviral therapy plus pembrolizumab in BCG-unresponsive non-muscle-invasive bladder cancer: the phase 2 CORE-001 trial

Cretostimogene grenadenorepvec is a serotype-5 oncolytic adenovirus designed to selectively replicate in cancer cells with retinoblastoma pathway alterations, previously tested as monotherapy in bacillus Calmette-Guérin (BCG)-experienced non-muscle-invasive bladder cancer. In this phase 2 study, we assessed the potential synergistic efficacy between intravesical cretostimogene and systemic pembrolizumab in patients with BCG-unresponsive non-muscle-invasive bladder cancer with carcinoma in situ (CIS). Thirty-five patients were treated with intravesical cretostimogene with systemic pembrolizumab. Induction cretostimogene was administered weekly for 6 weeks followed by three weekly maintenance infusions at months 3, 6, 9, 12 and 18 in patients maintaining complete response (CR). Patients with persistent CIS/high-grade Ta at the 3-month assessment were eligible for re-induction. Pembrolizumab was administered for up to 24 months. The primary endpoint was CR at 12 months as assessed by cystoscopy, urine cytology, cross-sectional imaging and mandatory bladder mapping biopsies. Secondary endpoints included CR at any time, duration of response, progression-free survival and safety. The CR rate in the intention-to-treat population at 12 months was 57.1% (20 out of 35, 95% confidence interval (CI) 40.7-73.5%), meeting the primary endpoint. A total of 29 out of 35 patients (82.9%, 95% CI 70.4-95.3%) derived a CR at 3 months. With a median follow-up of 26.5 months, the median duration of response has not been reached (95% CI 15.7 to not reached). The CR rate at 24 months was 51.4% (18 out of 35) (95% CI 34.9-68.0%). No patient progressed to muscle-invasive bladder cancer in this trial. Adverse events attributed to cretostimogene were low grade, self-limiting and predominantly limited to bladder-related symptoms. A total of 5 out of 35 patients (14.3%) developed grade 3 treatment-related adverse effects. There was no evidence of overlapping or synergistic toxicities. Combination intravesical cretostimogene and systemic pembrolizumab demonstrated enduring efficacy. With a toxicity profile similar to its monotherapy components, this combination may shift the benefit-to-risk ratio for patients with BCG-unresponsive CIS. ClinicalTrials.gov Identifier: NCT04387461 .