Abstract CT036: CORE1: Phase 2, single arm study of CG0070 combined with pembrolizumab in patients with non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG)

Abstract Introduction: 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 of the combination. 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: Thus far, 10 patients are evaluable at the 3 m timepoint for efficacy. Assessment of these 10 pts demonstrates 100% CR at 3 mos. Six of the 10 pts have also reached the 6 m hallmark in a CR as well as 2 at the 12 mos timepoint. Treatment related AE have been limited to transient grade 1-2 local-regional genitourinary adverse events with no grade 3 or 4 treatment related AE reported date. Conclusions: This initial data on the efficacy and safety of CG0070 plus pembrolizumab for the treatment of BCG unresponsive NMIBC is encouraging. An update on the study will be provided at the time of presentation. Citation Format: Roger Li, Gary Steinberg, Paras Shah, Ed Uchio, Donald Lamm, Trinity Bivalacqua, Vignesh Packiam, Ashish Kamat, Michael Chisamore, John McAdory, Paola Grandi, Jee-Hyun Kim, James Burke. CORE1: Phase 2, single arm study of CG0070 combined with pembrolizumab in patients with non-muscle invasive bladder cancer (NMIBC) unresponsive to Bacillus Calmette-Guerin (BCG) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT036.