BladderGATE: Atezolizumab + intravesical BCG (bacillus Calmette-Guerin) upfront combination in patients with high risk non-muscle invasive bladder cancer (NMIBC)—Phase I-II ONCOSUR study.

Abstract

595 Background: Intravesical Bacillus Calmette-Guerin (BCG) induction + BCG maintenance after transurethral resection is the current standard of care for patients (pts) with high-risk non-muscle invasive bladder cancer (NMIBC). Recurrence rate at 2 years and 5 years are around 30-40% and 70-80% respectively. Atezolizumab is a IgG1 monoclonal antibody targeting PD-L1 and is associated with long-term durable remissions in pts with metastatic urothelial cancer (MS. van der Heijden . Eur Urol 2021) and for pts with unresponsive NMIBC (PC. Black . Eur Urol 2023) with excellent results. Atezolizumab in combination with standard BCG could provide synergistic benefit for pts with NMIBC. BladderGATE (NCT04134000) is a phase Ib-II study which evaluates the safety and efficacy of upfront atezolizumab + intravesical BCG in pts with high-risk NMIBC. Methods: Pt had confirmed histopathology of high-risk NMIBC, BCG naïve or stopped >2 years ago, WHO PS 0-2 and adequate hematologic and organ function. Dose-escalation design to identify DLT and MTD (9 pts) and to evaluate safety and efficacy in an expansion cohort (30 pts) were programed. Pt received six weekly induction instillations, and maintenance instillations at 3, 6 and 12 months + intravenously atezolizumab 1200 mg every 3 weeks, up to 1 year. Urine/blood and tissue samples were collected for translational and biomarker correlative study. Primary objective is disease free survival. Secondary objectives include safety profile and quality of life. Results: Finally 36 pt were included, median age 70 years, 86% men, 61% of pt were former smokers, 22% smokers and 17% had never smoked, and tumor size was ≥3 cm in 44% of pt. With a 22 months median follow-up, 56% of pt had completed BCG treatment and 89% had received adequate BCG treatment (5 induction plus at least 2 maintenance instillations). Thirteen pts discontinued atezolizumab due to immune-related AEs (7 pts) (g2 dermatitis, g3 hepatitis, encephalitis, pneumonitis, myocarditis, adrenal insufficiency and psoriasis), due to early-relapse disease (3 pts) and progressive-disease (3 pts). All irAEs were solved and no toxic death were reported. Of the 36 pts analyzed, 6 pts showed local recurrence (17%), 5 pts with high-risk NMIBC (14%) and 1 pt with low-risk NMIBC, 1 pt with UTUC, and 3 pts with local muscle invasive bladder cancer progressive-disease (8 %). Preliminary 2-year disease free survival is 72.8% (95% CI: 56.1% - 89.5%). Conclusions: The combination strategy of atezolizumab + intravesical BCG upfront in high-risk NMIBC pts appears feasible and safe. A 14% of 2-years local recurrence-rate and 8% of local progressive-disease are promising results, pending to randomized Ph3 ALBAN study data (GETUG). Supported by Roche-Spain. Clinical trial information: NCT03425201 .