{
  "abstract": "Background Immunotherapy is a rapidly expanding field with a large range of therapeutics entering clinical development. In particular, cytokines have received significant attention due to their potential to counteract the immune suppressive tumor microenvironment and activate an anti-tumoral response. However, one persistent problem is the off-target activity of highly potent cytokines leading to significant dosage limitations during treatment. A variety of attempts have been made to mitigate these toxicity problems including antibody and albumin fusions as well as the design of cytokine mimics to limit off-target binding. 1 2 Despite these developments, cytokine mimics retain an intolerably high level of systemic toxicity in the clinic. To address this problem, we aimed to mask a previously disclosed cytokine mimic by modifying the binding site to mask the interaction with a key receptor complex.Methods and Results Through a screening process we discovered a mutant of this cytokine mimic which is a suitable candidate for this masking strategy. A simple modification of this cytokine mimic leads to a complete abolishment of binding to the relevant cytokine receptor as shown through binding assays. Upon modification of this mutant, the signalling capacity of the cytokine was also shown to be reduced significantly. To exploit this discovery, we have developed a small molecule linker which can mask the binding site of this highly potent cytokine mimic. Upon encountering a trigger, specific to the tumor microenvironment, this linker undergoes degradation to release the active protein. This release process has been demonstrated on both peptide and protein models and occurs quickly upon exposure to the specific trigger.Conclusions This masking strategy exploits bioconjugation chemistry to selectively modify the binding site of a cytokine to dramatically alter its binding capacity. Tumor-specific release of the active cytokine will target the effects of this potent protein to the tumour, limiting off-target toxicity and increasing dosage capacity.Acknowledgements We are grateful to the Yusuf Hamied Department of Chemistry, University of Cambridge for funding this PhD work.References Lode HN, Xiang R, Becker JC, Gillies SD, Reisfeld RA. Immunocytokines: a promising approach to cancer immunotherapy. Pharmacology & Therapeutics 1998;80(3):277–92.Silva DA, Yu S, Ulge UY, Spangler JB, Jude KM, Labão-Almeida C, Ali LR, Quijano-Rubio A, Ruterbusch M, Leung I, Biary T. De novo design of potent and selective mimics of IL-2 and IL-15. Nature 2019;565(7738):186–91.",
  "authors": [
    {
      "affiliations": [
        "University of Cambridge, Cambridge, UK"
      ],
      "name": "Elisabeth D Jones"
    },
    {
      "affiliations": [
        "University of Cambridge, Cambridge, UK"
      ],
      "name": "Bengt H Gless"
    },
    {
      "affiliations": [
        "Instituto de Medicina Molecular João Lobo Antunes, Lisboa, Portugal"
      ],
      "name": "Carlos Labão-Almeida"
    },
    {
      "affiliations": [
        "University of Cambridge, Cambridge, UK",
        "Instituto de Medicina Molecular João Lobo Antunes, Lisboa, Portugal"
      ],
      "name": "Gonçalo Bernardes"
    }
  ],
  "title": "856 Masking the activity of a potent cytokine mimic via site specific chemical modification",
  "uid": "14d0eab4-70ba-5bf1-87b9-c775ea0d978d"
}