GlycoConnect? immune cell engagers (GC?-ICEs). A non-genetic approach to targeted IL-15 immunotherapy

Abstract Engagement of T cell or NK cells to harness a patient’s immune system is a promising approach in immuno-oncology. An immunocytokine, i.e. a tumor-targeting antibody (fragment) genetically fused to an immunostimulatory cytokine, is specifically designed for this purpose. Fusion antibody-IL-15 immunocytokines, based on a variety of molecular architectures, are currently finding their way to the clinic with promising results. Here we demonstrate how GlycoConnect™, a site-specific conjugation technology anchoring on the native antibody glycan, can be applied for attachment of IL-15 without prior antibody engineering. The molecular architecture of the resulting immune cell engagers (ICEs) can be readily tailored to 2:2 or 2:1 ratio (anti-TAA:IL-15) to mitigate cytokine release syndrome. Moreover, we show how immunostimulatory activity can be regulated via linker design, either by tailoring of IL-15-antibody spacing or by generation of a conditionally active IL-15 format. Structural and functional studies will be presented to corroborate the architecture of these GC™-ICEs and in vitro and in vivo activity in a syngeneic mouse model. Citation Format: Remon van Geel, Floris van Delft. GlycoConnect™ immune cell engagers (GC™-ICEs). A non-genetic approach to targeted IL-15 immunotherapy [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 5606.