Dickstein, Rian J.

TPS888 Background: There is currently no Food and Drug Administration (FDA)-approved treatment for intermediate-risk non–muscle-invasive bladder cancer (IR NMIBC), defined by the AUA as recurrence of low-grade (LG) Ta within 1 year, solitary LG Ta >3 cm, multifocal LG Ta, high-grade (HG) Ta (≤3 cm), and/or LG T1. Nadofaragene firadenovec-vncg is the first FDA-approved intravesical nonreplicating gene therapy for the treatment of adult patients with high-risk Bacillus Calmette Guérin (BCG)-unresponsive NMIBC with carcinoma in situ (CIS) with or without papillary tumors. In a nonrandomized, multicenter, open-label, repeat-dose, phase 3 study, 53.4% of participants (55/103) with CIS ± HG Ta/T1 achieved complete response 3 months after the first instillation. Nadofaragene firadenovec was well tolerated, with no grade 4/5 study drug-related AEs. Because maintenance treatment with nadofaragene firadenovec following tumor resection may improve clinical outcomes in patients with IR NMIBC, the ABLE-32 open-label randomized study is being conducted to evaluate the efficacy of nadofaragene firadenovec administered every 3 months versus observation in participants with IR NMIBC. Methods: This phase 3 study includes approximately 100 global sites with 454 anticipated participants. Adults diagnosed with new or recurrent IR NMIBC and having undergone transurethral resection of bladder tumor within 60 days prior to randomization are eligible. Participants will be randomly assigned 1:1 to receive nadofaragene firadenovec or continue observation. The nadofaragene firadenovec group will receive quarterly doses unless disease recurs or progresses. The observation group will be followed quarterly and may receive nadofaragene firadenovec if IR NMIBC recurs within 24 months. All participants will be evaluated for recurrence and progression using cytology, cystoscopy, and for-cause biopsy for up to 5 years. The primary endpoint is recurrence-free survival (RFS), from randomization to first documented recurrence, progression, or death. Secondary endpoints include RFS at 12 and 24 months and safety. Exploratory endpoints include effect on potential biomarkers and health-related quality of life. Final results are expected in 2031. Clinical trial information: NCT06510374 .

4601 Background: Cretostimogene grenadenorepvec is a type-5 oncolytic adenovirus designed to selectively replicate in bladder cancer cells with alterations in the retinoblastoma pathway. Additionally, the virus is engineered to express the GM-CSF transgene, resulting in a potent oncolytic immunotherapy mode of action. Cretostimogene monotherapy recently received Food and Drug Administration (FDA) Fast Track and Breakthrough Therapy Designations (BTD) in the BCG-Unresponsive, High-Risk, non-Muscle Invasive Bladder Cancer with Carcinoma in Situ (BCG-UR HR NMIBC with CIS) indication with a Complete Response (CR) at any time rate of 76%. This phase-2 study assessed the potential synergy between intravesical cretostimogene and pembrolizumab in patients with BCG-UR, HR NMIBC, with CIS, with or without Ta/T1 tumors. This combination has also received BTD from the FDA. Methods: 35 pts were treated with cretostimogene (1x1012 viral particles) in combination with pembrolizumab at a dose of 400 mg IV q6 weeks. Cretostimogene induction was given as 6 weekly intravesical instillations followed by 3 weekly maintenance doses at months 3, 6, 9, 12, and 18. Pts with persistent CIS or high-grade Ta tumors at the 3mo assessment were eligible for re-induction. Pembrolizumab was administered for up to 24mo. Response assessments included cystoscopy, urine cytology, cross-sectional imaging, and mandatory bladder mapping biopsies at 12mo. The primary endpoint was CR at 12mo. Secondary endpoints included CR at any time, duration of response (DOR), CR at 24mo, cystectomy-free survival, and safety. Exploratory endpoints included analyses of baseline viral receptor expression, free E2F levels, PD-L1 status, urinary cytokine panels and measures of viral replication. Results: 30/35 pts are evaluable per protocol for the primary endpoint. Five pts discontinued prior to the 12mo time point. The CR rate in the Intention to Treat (ITT) population at 12mo and any time, was 57% (20/35) (95% CI 40-73%) and 83% (29/35) (95% CI 66-93%), respectively. Median DOR has not been reached but exceeds 21mo. The current CR rate in the ITT population at 24mo is 46% (16/35) (95% CI 29-63%). Three pts have yet to reach the 24mo time point. Cystectomy-free survival at 21mo is 80%. Complete data on the ITT and evaluable patient cohorts will be presented. Analyses of treatment-related adverse events (AE) are consistent with the individual agents and demonstrate no synergistic toxicity. Conclusions: The efficacy and safety of cretostimogene plus pembrolizumab for treatment of BCG-UR, HR NMIBC with CIS demonstrates best-in-class CR and DOR compared to current FDA-approved therapies, with an acceptable AE profile. Further investigation of this promising combination therapy is warranted and may serve to address a considerable unmet need. Clinical trial information: NCT04387461 .