Abstract LB214: Discovery of EPIM-001, a tumor targeted engineered IL2 with biased IL2Rβ agonist activities

Abstract

Abstract Background: The cytokine Interleukin 2 (IL2) has been approved for cancer treatment. However, its application has been limited due to severe toxicities associated with its high concentration administration. These side effects are attributed to the strong binding of IL2 to its receptor IL2Rα which is enriched on regulatory T Cells and Lung epithelial cells. We have engineered IL2 to significantly reduce IL2Rα binding and enhance IL2Rβ binding. We further developed EPIM-001, a bi-functional IL2Rβ agonist and Anti-PDL1 biologic, aiming to treat a broad set of solid tumors with improved therapeutic index. Methods: We used mSCAFold࣪, a unique protein engineering platform to redefine and improve pharmacologic properties of the cytokine through structure-based rationally designed libraries and mRNA display selection. The optimal IL2 candidate with enhanced IL2Rβ and reduced IL2Rα binding was engineered with an internally discovered anti-PD-L1 antibody to generate EPIM-001, a bispecific IL2/PD-L1 biologic drug candidate. EPIM-001 was characterized in vitro for receptor binding activity, immune cell activation, proliferation, and tumor cell killing assays. In vivo efficacy was evaluated in xenograft humanized mouse models, and PK/PD and toxicity has been studied in Non-Human Primates (NHPs). Results: We have shown that EPIM-001 is a strong agonist of IL2Rβ, with significantly reduced binding to IL2Rα. It demonstrated much stronger CD8+ T cells and NK cell activation and proliferation compared WT-IL2, whilst only weaker activation and minimal proliferation with Tregs. In vitro cell killing assays showed that EPIM-001 promoted better immune cell killing of PD-L1 expressing target cells than WT IL2. In xenograft in vivo studies, EPIM-001 has shown significant tumor growth inhibition against the human lung cancer cell line H1975, which whilst expressing high levels of PD-L1, does not respond to PD-L1/PD-1 blockade. Furthermore, in the human breast cancer cell line MDA-MB-231, EPIM-001 showed stronger tumor growth inhibition compared to Keytruda. PK/PD and toxicity studies in NHPs showed that EPIM-001 is well tolerated. EPIM-001 greatly expanded CD8+ T cells, whilst having minimal effect on TRegs and Eosinophils associated with toxicity. Conclusions: EPIM-001 is a promising immune modulating drug candidate that selectively activates CD8+ T cells and NK Cells with strong anti-tumor activity and safe profile for both immune checkpoint sensitive and insensitive PD-L1 positive tumors. Citation Format: Kehao Zhao, Sam Hassan, Yan Chen, Jenna Nguyen, Ning Jiang, Gening Zhang, Irene Li, Ryan Feng. Discovery of EPIM-001, a tumor targeted engineered IL2 with biased IL2Rβ agonist activities [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 LB214.