Abstract 6336: Heterodimeric Fc-fused IL12 shows potent antitumor activity and low toxicity

Abstract

Abstract Background: Interleukin-12 (IL12) is a heterodimeric pro-inflammatory cytokine (70 kDa) composed of two different polypeptide chains: an α-chain (p35 subunit) and a β-chain (p40 subunit). IL12 could induce the proliferation and cytotoxicity of T and NK cell and production of interferon-γ (IFN-γ), promote the differentiation of T helper 1 (TH1) cells and regulate innate resistance and adaptive immunity. However, the clinical efficacy of IL12 has been hindered for its high dose-related toxicities and short serum half-life. Here we have developed a heterodimeric Fc-fused IL12, HK054-V, with reduced potency to improve tolerability and prolong half-life. Methods: We assessed the binding, bioactivity, anti-tumor efficacy and safety of HK054-V. The binding ability of IL12-Fc lead variants to activated PBMCs was analyzed by flow cytometry. The bioactivity of HK054-V was determined by assessing the activated T-cell proliferation and IFN-γ production in human PBMCs, and STAT-4 phosphorylation in a reporter gene assay. A murine surrogate, mHK054-V, was engineered to mimic HK054-V to evaluate the antitumor efficacy in MC38 and CT26 syngeneic tumor mouse models. Cytokine release assay was conducted by incubating HK054-V with peripheral blood mononuclear cells (PBMCs) from healthy donors. The safety profiles and pharmacokinetic (PK) behavior of HK054-V were characterized in non-tumor-bearing Balb/c mice. Results: HK054-V is a heterodimeric Fc-fused IL12, which was designed with reduced potency. HK054-V was observed to stimulate the proliferation of activated T cells and NK cells and induce production of IFN-γ in a dose-dependent manner. HK054-V could activate pSTAT4 signal in luciferase reporter gene assay and showed up to 100-fold reduction of potency compared to wild-type IL12-Fc. Human IL12 is inactive in mice, so in vivo anti-tumor activity was assessed by a murine surrogate, mHK054-V. mHK054-V demonstrated anti-tumor efficacy in syngeneic mouse models and was better tolerated than WT mIL12-Fc. Furthermore, mHK054-V has improved PK and therapeutic index in mice. Conclusion: These data demonstrate that HK054-V, a heterodimeric Fc-fused IL12 with reduced potency, retain strong anti-tumor efficacy with a favorable tolerability profile, which may provide a practical alternative to the systemic administration of IL12 for antitumor therapy. Citation Format: Yang Huang, Wenting Liu, Dayan Zhang, Pengfei Zhou, Weiming Zhou, Xiaoli Zeng, Qun Zhao, Liangwei Li, Guodong Shen, Liansheng Cheng. Heterodimeric Fc-fused IL12 shows potent antitumor activity and low toxicity. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6336.