Abstract CT246: Consortium-IO: A safety and efficacy study of VE800 in combination with nivolumab in previously treated patients with select advanced metastatic cancers

Abstract

Abstract Background: Gut microbiome composition affects response to PD-1 blockade; and recent proof of concept studies suggest that gut microbiome manipulation is effective in reversing resistance to PD-1 blockade. VE800 is an oral live biotherapeutic consisting of 11 distinct non-pathogenic, non-toxigenic, commensal bacterial strains manufactured in lyophilized form. VE800 induces CD8+ T cell infiltrate into tumors; and significantly enhances anti-tumor activity of PD-1 blockade preclinically in multiple tumor models in a CD103+ dendritic cell and major histocompatibility (MHC) class I dependent fashion (Tanoue et al., 2019). Retrospective analysis of cancer patient's (pt) samples also suggests that greater VE800 strain abundance is associated with improved response to PD-1 blockade. The objective of this phase I study is to evaluate the safety, tolerability, and clinical activity of VE800 administered orally in combination with nivolumab in pts with select cancers. Methods: CONSORTIUM-IO (NCT04208958) is an open-label, first-in-human study evaluating VE800 and nivolumab combination in pts with anti-PD-1/PD-L1 relapsed/refractory melanoma, anti-PD-1/PD-L1 naïve gastric/gastroesophageal junction (GEJ) adenocarcinoma and anti-PD-1/PD-L1 naïve microsatellite-stable (MSS) colorectal cancer. Following a 5-day course of oral vancomycin 125mg QID, VE800 will be administered daily along with nivolumab (480mg Q4W). A single dose level of VE800 will be evaluated. In the interests of maximizing safety, a Simon 2-stage design will be used for each disease cohort. Although no dose-limiting toxicities (DLT) are expected, the first 3 pts will be enrolled serially 1 week apart; and safety data of the first 6 pts will be reviewed prior to further accrual. Pts will continue to receive VE800/nivolumab combination until disease progression or unacceptable toxicity. Primary endpoints include safety, tolerability; and clinical activity by objective response rate (ORR) per RECIST v1.1. Secondary endpoints include duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS); and metagenomic strain-level analysis of degree/duration of VE800 strain colonization. Exploratory endpoints include tumor and blood immunophenotyping, serum/stool metabolomics and global changes in fecal microbiome composition. CONSORTIUM-IO is currently actively enrolling pts. Citation Format: Diwakar Davar, Judy S. Wang, Michael Cecchini, Zev Wainberg, Martin Gutierrez, Anita Turk, Rose Szabady, Jason Norman, Bernat Olle, Bruce Roberts, Dmitri Bobilev. Consortium-IO: A safety and efficacy study of VE800 in combination with nivolumab in previously treated patients with select advanced metastatic cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT246.