AbstractBackgroundThe pro-inflammatory cytokine,interleukin-18 (IL-18),plays an instrumental role in bolstering anti-tumor immunity. However,the therapeutic application of IL-18 has been limited due to its susceptibility to neutralization by IL-18 binding protein (IL-18BP),short in vivo half-life,and unfavorable physicochemical properties.MethodsIn order to overcome the poor drug-like properties of IL-18,we installed an artificial disulfide bond,removed the native,unpaired cysteines,and fused the stabilized cytokine to an IgG Fc domain. The stability,potency,pharmacokinetic and pharmacodynamic properties as well as efficacy of disulfide-stabilized IL-18 Fc-fusion (dsIL-18-Fc) were assessed via in vitro and in vivo studies.ResultsThe stability and mammalian host cell production yields of dsIL-18-Fc were improved,compared to the wild-type (WT) cytokine,while maintaining its biological potency and interactions with IL-18 receptor α (IL-18Rα) and IL-18BP. Recombinant fusion of the cytokine to an IgG Fc domain provided extended half-life. Notably,despite maintaining sensitivity to IL-18BP,dsIL-18-Fc was effective at activating both T and natural killer (NK) cells,and elicited a strong anti-tumor response,either as a single agent,or in conjunction with anti-programmed cell death-ligand 1 (anti-PD-L1) therapy.ConclusionsWe engineered IL-18 for reinforced stability,extended half-life,and improved manufacturability. The therapeutic benefit of dsIL-18-Fc,coupled with a more favorable manufacturability profile and enhanced drug-like properties,underscores the potential utility of this engineered cytokine in cancer immunotherapy.
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