Abstract 1875: Novel cell-based bioassays for monoclonal antibody and bispecific molecules in PD-1 blockade monotherapy and combination therapy

Abstract

Abstract Programmed death 1 (PD-1) is an immune checkpoint (IC) receptor that negatively regulates T-cell immune function. Blocking the interaction of PD-1 with its ligand PD-L1 unleashes the immune system and enhances anti-tumor responses. Immunotherapy using PD-1 blockade has led to a paradigm shift in cancer drug discovery, due to its durable effect against a wide variety of cancers. However, despite its tremendous clinical success in cancer treatment, a significant fraction of patients and tumor types remain unresponsive to this therapy. This has led to the development of combination therapies combining PD-1 checkpoint inhibitors with a broad range of clinically active treatments including those targeting other IC receptors. A major challenge in immunotherapy drug development is the lack of quantitative and reproducible functional assays as existing methods rely heavily on primary immune cells and are highly variable. Here, we report the development of a suite of cell line-based reporter bioassays for monoclonal antibody targeting human PD-1/PD-L1, or bispecific molecules target PD-1/PD-L1 and a co-stimulatory receptor (e.g., 4-1BB, OX40, ICOS) or an immune inhibitory receptor (e.g., CTLA-4, LAG-3, TIGIT). A mouse PD-1/PD-L1 assay and a human PD-1/PD-L2 assay are also developed and can be used in parallel with human PD-1/PD-L1 assay to address preclinical study and assay specificity. Each of these assays consist of two engineered cell lines: a T effector cell line that express a luciferase reporter driven by specific promoter/response elements responding to the intracellular signals mediated by the T cell receptor (TCR), PD-1 and the second IC receptor, and an artificial antigen presenting cells (aAPCs). Particularly, the combination bioassays are able to measure the synergetic effect of PD-1 blockade with a second IC inhibitor receptor blockade or a costimulatory receptor activation. These reporter-based assays reflect the mechanisms of action for the therapeutic drugs of interest and are sensitive and quantitative. They are prequalified according to ICH guideline and demonstrated the performance characteristics (specificity, precision, accuracy, and linearity) to be used as potency assay for product release and stability studies during immunotherapy drug development and manufacture. Citation Format: Jamison Grailer, Julia Gilden, Jun Wang, Denise Garvin, Pete Stecha, Jim Hartnett, Steven Edenson, Frank Fan, Mei Cong, Zhi-jie Jey Cheng. Novel cell-based bioassays for monoclonal antibody and bispecific molecules in PD-1 blockade monotherapy and combination therapy [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 1875.