Abstract 5440: Novel PD-1 blockade bioassay to assess therapeutic antibodies in PD-1 and PD-L1 immunotherapy programs

Abstract

Abstract Programmed death receptor-1 (PD-1) and its ligand (PD-L1) are among the few important immunotherapy targets for cancer. Current PD1 assays measure cell proliferation or cytokine production in primary T cells which are tedious, have high assay variation and small assay window. To enable quantitative potency measurement for key anti-PD-1 drugs in the market or in clinical trials such as pembrolizumab and nivolumab, as well as anti-PD-L1 drugs in clinical trials such as MPDL3280A and BMS-936559, here we report the development of a robust bioluminescent cell-based PD1 blockade bioassay. For this, we built a PD-1 effector cells in Jurkat cells which stably express human PD-1 and a NFAT-RE-luciferase reporter, and a PD-L1 positive artificial Antigen Presenting Cells (PD-L1+ aAPC) in CHO-K1 cells which stably express PD-L1 and an engineered TCR activator. Once these two cell types were co-cultivated, transcriptional activation of NFAT pathway in PD-1 effector cells, mediated by binding of TCR complex with TCR activator in PD-L1+ aAPC, is significantly suppressed by PD-1/PD-L1 engagement. This inhibition can then be specifically reversed by co-incubation of PD-1 or PD-L1 blocking antibodies in dose-dependent manner, but not by the antibody for other immune checkpoint receptors such as anti-CTLA4 ipilimumab. We further developed both PD-1 effector cells and PD-L1+ aAPC in Thaw-and-Use format so the cells can be plated for assay without the need of cell culture. The resultant PD-1 assay using Thaw-and-Use cells brings the benefit of convenience, low day-to-day variation, and easy lab-to-lab assay transfer. We demonstrate the assay is able to measure relative potency for antibody biologics, and also can detect potency changes for stressed antibody samples. In summary, the reporter-based PD-1 blockade assay provides a valuable tool for both drug screening and characterization in early drug discovery, and lot release and stability study in drug manufacture for therapeutic antibody drug candidates in PD-1 and PD-L1 immunotherapy programs. Citation Format: Zhi-Jie Jey Cheng, Natasha Karassina, Jamison Grailer, Jim Hartnett, Frank Fan, Mei Cong. Novel PD-1 blockade bioassay to assess therapeutic antibodies in PD-1 and PD-L1 immunotherapy programs. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5440. doi:10.1158/1538-7445.AM2015-5440