Preliminary results from phase Ib/II neoadjuvant CG0070 and nivolumab (N) for cisplatin (C)-ineligible muscle invasive bladder cancer (MIBC)

4574 Background: CG0070 is a replication-competent oncolytic adenovirus engineered to target RB deficient tumor cells and to express GM-CSF. CG0070 has previously demonstrated safety and efficacy against BCG-exposed high risk non-muscle invasive bladder cancer through tumor lysis and anti-tumor immune activation. We tested the safety and efficacy of CG0070 in combination with N as neoadjuvant therapy for MIBC in C-ineligible patients in this study (NCT04610671). Methods: C-ineligible pts with MIBC (cT2-4a, N≤1) were enrolled. Pts received 6 weekly intravesical CG0070 (1x1012vp) and 2 doses of N at wks 2 and 6, followed by radical cystectomy (RC). The primary objective is safety of CG0070+N as measured by CTCAEv5.0. Secondary objective is to assess pathologic response (PaR) (pT0N0). Exploratory objectives include the assessment of correlation between PaR with baseline 1) E2F expression; 2) immune infiltration; 3) PD-L1 expression; and 4) TLS expression. Results from a prespecified interim analysis following accrual of 15 patients is reported herein. Results: Between Nov 2020 and Jan 2022, 15 pts were enrolled with median age 75.5yrs, 73% male, 47% > cT2; 1 patient refused RC but was included in the ITT population. No DLTs were encountered. The overall rate of grade 3-4 AEs was 10/15 (75%), and the vast majority were related to RC (90%). Immune related AEs were seen in one pt, who had grade 2 autoimmune thyroiditis. There was no delay in time to RC and no unexpected surgical complications from treatment. PaR was observed in 6/13 (46%) evaluable pts, and an additional pt had negative post-treatment biopsy but refused RC. Conclusions: Neoadjuvant CG0070+N is safe and effective in C-ineligible pts with MIBC. This combination was well tolerated without any delays in RC and induced an overall response rate of 54%. Clinical trial information: NCT04610671. [Table: see text]