Abstract 5486: ENPP1 inhibitor ZX-8177 enhances anti-tumor activity of conventional therapies by modulating tumor microenvironment

Abstract

Abstract Emerging studies revealed that tumor derived 2’3’-cGAMP could act as an immune transmitter and directly trigger anti-tumor immunity. Damage associated molecular patterns, e.g. damaged genomic DNA, released from injured cancer cells can be converted into 2’, 3’-cGAMP by cGAS. Subsequently, cGAMP triggers STING pathway activation to produce type I interferons (IFNs) and other related innate immunity in the tumor microenvironment. Ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1), a membrane-bound nucleotide hydrolase, has been discovered as the predominant enzyme hydrolyzing 2’3’-cGAMP (Li, et al). Hence, ENPP1 blockade in the tumor milieu is a potential strategy against tumors by improving innate immunity response. In this report, we present a potent ENPP1 inhibitor ZX-8177. ZX-8177 showed an IC50 of 9.5 nM in a biochemical assay and an IC50 of 11 nM in MDA-MB-231 cell-based enzymatic assay. In a functional assay for evaluating efficacy of ZX-8177, the production of IFN-β1 by THP-1 cells was measured after the cells were cultured in the conditioned medium collected from MDA-MB-231 cells treated with or without ZX-8177. The interferon production assay showed an EC50 of 15 pM, suggesting that ZX-8177 effectively facilitated IFN-β1 production via cGAMP-STING axis. In CT-26 syngeneic mouse model, ZX-8177 treatment at 2 mg/kg, BID for 14 days can achieve around 37-60% tumor growth inhibition (TGI). No body weight loss was observed during treatment. Flow cytometry analysis indicated that ZX-8177 treatment resulted in a 2-3-fold increase in tumor-infiltrating NK (CD314+CD335+) cells, cytotoxic CD8 T cells (GranzB+CD8+), and M1-macrophages (CD206-MHCII+); and a decrease in M2-macrophages (CD206+MHCII-) (p< 0.05). Combination of Mitomycin C (0.5 mg/kg, i.p., BIW) and ZX-8177 (2 mg/kg, i.p., BID) in CT-26 model yielded synergistic anti-tumor efficacy (increased >30% TGI). The level of cGAMP in tumor tissue harvested from the combination treatment group was around 2-fold higher than that in the vehicle group. Furthermore, synergistic tumor inhibition of ZX-8177 and anti-PD-L1 antibody was also observed in MC38 mouse model. TGI of anti-PD-L1 antibody vs. combo treatment is 53% vs. 75%, p < 0.05. ZX-8177 has a favorable DMPK and safety pharmacology profile to support it as a clinical candidate for further development. Citation Format: Ying-ying Li, Zhiyuan Peng, Shuaijun Sun, Kun Guo, Deming Kong, Xiaomin Li, Yuning Xie, Siyu Shui, Yin Wang, Jinfu Yang, Xiaolin Alan Hao, Xiaoli (Shelley) Qin. ENPP1 inhibitor ZX-8177 enhances anti-tumor activity of conventional therapies by modulating tumor microenvironment [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 5486.