Abstract 5439: Development of a robust reporter-based T-cell activation assay for bispecific therapeutic antibodies in immunotherapy

Abstract Bispecific T-cell Engager (BiTE), which simultaneously targets CD3 on T cells and tumor-associated antigens to recruit cytotoxic T cells to cancer cells, has emerged as a promising immunotherapy approach to treat cancer. Current methods for bispecific antibody potency determination measure T-cell proliferation or cytokine release using primary peripheral blood mononuclear cells. They can be complex and highly variable. Here we report the development of a reporter-based T cell activation assay using two Jurkat cell lines stably expressing luciferase reporter driven by IL-2 promoter or NFAT-response element. Both Jurkat reporter cell lines showed robust reporter signal upon stimulation of crossed-linked CD3 antibody. These cell lines were developed in Thaw-and-Use format and showed similar assay performance as that from the cells fresh-from-culture. When tested with bispecific therapeutic antibody catumaxomab, we showed specific reporter response by co-culturing Jurkat reporter cells with cancer target cells endogenously expressing EpCAM, such as MDB-MA-231 and SK-BR-3 cells. No signal was observed without target cells or with EpCAM negative Raji cells. The assay can measure the relative potency for catumaxomab with good precision. It also can detect changes in biological activity for catumaxomab in stressed stability study, and therefore has appropriate stability-indicating property. In summary, the reporter-based T cell activation assay provides a simple and robust approach to quantitatively measure antibody potency for bispecific antibody. It can potentially serve as a potency bioassay for bispecific therapeutic antibodies during drug development and manufacture. Citation Format: Pete Stecha, Jamison Grailer, Zhi-jie Jey Cheng, Jim Hartnett, Frank Fan, Mei Cong. Development of a robust reporter-based T-cell activation assay for bispecific therapeutic antibodies in immunotherapy. [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 5439. doi:10.1158/1538-7445.AM2015-5439