Abstract 4076: Interleukin-18 engineered for resistance to IL-18 binding protein (IL-18BP) and half-life extension to enhance its therapeutic potential

Abstract

Abstract Interleukin-18 (IL-18) possesses a unique combination of innate and acquired immune functions with high potential to be transformative in cancer immunotherapy of solid tumors. In clinical studies, recombinant wild-type IL-18 was limited by rapid upregulation of IL-18 binding protein (IL-18BP), which serves as a negative feedback checkpoint of the IL-18 pathway. As its name implies, IL-18BP tightly binds to IL-18, thereby blocking its ability to activate the IL-18 receptor. We have focused our protein engineering efforts to obtain variants of IL-18 that are resistant to IL-18BP suppression while retaining IL-18 biological activity. To further capitalize on the immunological effects of IL-18, the IL-18BP resistant variants were fused to half-life extension protein scaffolds for enhanced in vivo exposure. Rational protein design and combinatorial approaches were used to generate a pool of IL-18 variants that were screened for potency and resistance to IL-18BP. Several IL-18 variants showed undetectable binding to IL-18BP (up to 1 mM IL-18BP) and displayed a spectrum of potencies relative to recombinant wild-type IL-18. Importantly, these variants retained their full biological activity in the presence of super-physiological levels of IL-18BP, as tested with in vitro cell-based IFN-γ release assays. In vivo pharmacokinetic studies in mice compared several IL-18BP resistant variants fused to a half-life extension scaffold with a non-half-life enhanced IL-18BP resistant variant. The half-lives for the fusion proteins ranged from 15 - 30h, while the non-fused variant showed a half-live of 0.6h. Furthermore, the IL-18 variants displayed a more durable, Th1 immune response compared to a non-half-life enhanced variant. Thus, IL-18 variants with strong resistance to IL-18BP that are fused to a half-life extension protein scaffold displayed enhanced pharmacokinetic and pharmacodynamic properties in preclinical mouse models. These protein engineering modifications will enable us to select an appropriate development candidate with enhanced pharmaceutical properties to achieve the full therapeutic potential of IL-18 to assess in patients with cancer. Citation Format: Jean Chamoun, Clifford DiLea, Kristiana Dreaden, Pinar Gurel, Joshua Heiber, Robert G. Newman, Su-Ping Pearson, Chunhua Wang, Yanchun Zhao, Mark Whitmore. Interleukin-18 engineered for resistance to IL-18 binding protein (IL-18BP) and half-life extension to enhance its therapeutic potential [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4076.