978 Stage-appropriate bioassays for assessing ADCP activity of therapeutic antibodies

• DOI: 10.1136/jitc-2023-sitc2023.0978
• Publication Date: 2023-10-31T14:23:31Z
• Authors: Julia K Gilden; Jonathan Mitchell; Pete Stecha; Jim Hartnett; Jamison Grailer; Frank Fan; Mei Cong
• Keywords: Neoplasms. Tumors. Oncology. Including cancer and carcinogens; RC254-282

<h3>Background</h3> Antibody-dependent Cellular Phagocytosis (ADCP) is an important mechanism of action (MOA) therapeutic antibodies designed to deplete tumor cells. ADCP mediated by effector cells such as monocytes and macrophages, induced via simultaneous binding FcγRIIa, FcγRI, or FcγRIIIa on a specific antigen target Traditionally, direct measurement relies ex vivo differentiation primary macrophages followed flow cytometry assays. These protocols are laborious produce highly variable results, due the diversity cell donors. <h3>Methods</h3> We have developed two novel plate-based bioassays for measuring activity antibodies, with utility at different stages in drug development process. For early phase programs, we created assay based NanoBiT split luciferase technology. Here, incubated engineered HiBiT-expressing At end incubation period, lysed HiBiT retained released complement LgBiT detection reagent, producing light proportion number present. Lysosomal degradation following results robust loss luminescence presence ADCP-inducing antibody. later reporter bioassay naturally phagocytic background, THP-1, where NanoLuc driven signaling through endogenously expressed Fc receptors. <h3>Results</h3> The Assay reproducible easy execute little hands-on time, can be used many common model It demonstrate both specificity making it ideal bridging assays.The THP-1 has been prequalified according ICH guidelines suitable potency stability studies quality-controlled settings. <h3>Conclusions</h3> Together, these assays expand toolbox characterization represent significant advancement reproducibility, workflow, biological relevance development.