CORE1: Phase 2, single-arm study of CG0070 combined with pembrolizumab in patients with nonmuscle-invasive bladder cancer (NMIBC) unresponsive to bacillus Calmette-Guerin (BCG).

Abstract

4597 Background: CG0070, is an Ad5-based oncolytic vaccine engineered to express GM-CSF and replicate selectively in tumor cells with mutated or deficient RB. The CG0070 mechanism of action includes cell lysis and immunogenic cell death which is enhanced in the presence of GM-CSF. In an open label ph. 2 study, an overall CR rate of 62% and a CR at 12 months (m) of 29% have been observed in patients with high risk NMIBC previously treated with BCG. IV pembrolizumab, was recently approved by the FDA for patients with BCG-unresponsive CIS (with or without papillary tumors) with an overall complete RR of 41% and a 12 m CR rate of ̃20%. This ph. 2 study will assess the potential synergy of the two agents in the treatment of BCG-unresponsive NMIBC. Methods: 35 pts with BCG-unresponsive CIS with or without concurrent Ta or T1 disease will be treated with intravescical CG0070 (1x1012 vp) in combination with pembrolizumab at a dose of 400 mg IV q6 weeks. CG0070 will be administered weekly x 6 as induction followed by weekly x 3 maintenance instillations at months 3, 6, 9, 12, and 18. Pts with persistent CIS or HG Ta at 3 m may receive re-induction with weekly x 6 of CG0070. Pembrolizumab will be administered up to 24 m. Assessment of response will include q 3 m cystoscopy with biopsy of areas suspicious for disease, urine cytology, CTU/MRU, and mandatory bladder mapping biopsies at 12 m. Recurrence of HG disease will be enumerated as disease recurrence. The primary endpoint of the study is CR at 12 m. Secondary endpoints will include CR at any time, progression free survival, duration of response, cystectomy free survival and the safety. Correlate assessments will include changes in the tumor immune microenvironment, systemic immune induction,viral replication and transgene expression. Baseline expression of PD-L1, coxsackie adenovirus receptor, E2F transcription factor as well as anti-Ad5 Ab titer will be correlated with tumor response. Results: A CR rate of 87.5% (14/16) at the 3 m assessment timepoint has been observed thus far. All patients in CR at 3 m remain in CR at downstream timepoints including: 9/9 at 6 m, 6/6 at 9 m, and 3/3 at 12 m. Treatment related AE have been generally limited to transient grade 1-2 local-regional genitourinary adverse events with no reports of grade 3, 4 or SAE attributed to treatment with CG0070/Pembroluzimab. Conclusions: This initial data on the efficacy and safety of CG0070 plus pembrolizumab for the treatment of BCG unresponsive NMIBC is encouraging. Additional data on efficacy as well as safety and biomarker (CAR, E2F, and PDL1) assessment will be presented for at least 25 of the projected 35 patients at the time of the conference. Clinical trial information: NCT04387461.