<p>Despite significant clinical progress, checkpoint blockade remains limited by variable response rates, resistance, and toxicity. Activating costimulatory receptors offers a promising alternative to enhance anti-tumor immunity. However, there is insufficient understanding of how to mimic physiological membrane-anchored costimulatory ligands. Here, we describe a strategy for developing effective agonists of the costimulatory receptor CD27 by increasing both antibody valency and FcγRIIB engagement. Engineered anti-CD27 antibodies capable of tetravalent binding to CD27 and selective FcγRIIB association exhibit potent T cell stimulatory activity and anti-tumor efficacy in pre-clinical models, compared to bivalent counterparts. The anti-tumor effects of the tetravalent antibody are mediated through CD8⁺ T cell activation without evidence of regulatory T cell depletion. Mechanistically, whereas the increase in avidity drives more efficient CD27 clustering, FcγRIIB engagement triggers polarization of receptor clusters to the cell-cell interface and reduces receptor internalization. This work provides a framework for developing more effective agonist-based T cell stimulatory therapies.</p>

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Harnessing multivalency and FcγRIIB engagement to augment anti-CD27 immunotherapy

  • Marcus A. Widdess,
  • Anastasia Pakidi,
  • Hannah J. Metcalfe,
  • H. T. Claude Chan,
  • Tatyana Inzhelevskaya,
  • Chris A. Penfold,
  • C. Ian Mockridge,
  • Steven G. Booth,
  • Sonya James,
  • Sean H. Lim,
  • Stephen A. Beers,
  • Mark S. Cragg,
  • Aymen Al-Shamkhani

摘要

Despite significant clinical progress, checkpoint blockade remains limited by variable response rates, resistance, and toxicity. Activating costimulatory receptors offers a promising alternative to enhance anti-tumor immunity. However, there is insufficient understanding of how to mimic physiological membrane-anchored costimulatory ligands. Here, we describe a strategy for developing effective agonists of the costimulatory receptor CD27 by increasing both antibody valency and FcγRIIB engagement. Engineered anti-CD27 antibodies capable of tetravalent binding to CD27 and selective FcγRIIB association exhibit potent T cell stimulatory activity and anti-tumor efficacy in pre-clinical models, compared to bivalent counterparts. The anti-tumor effects of the tetravalent antibody are mediated through CD8⁺ T cell activation without evidence of regulatory T cell depletion. Mechanistically, whereas the increase in avidity drives more efficient CD27 clustering, FcγRIIB engagement triggers polarization of receptor clusters to the cell-cell interface and reduces receptor internalization. This work provides a framework for developing more effective agonist-based T cell stimulatory therapies.