Development of cell-based bioassays to advance individual and combination immunotherapy
Zhi-jie Jey Cheng, Jamison Grailer, Pete Stecha, Jun Wang, Mike Beck, Julia Gilden, Denise Garvin, Jim Hartnett, Dun Li, Mei Cong and Frank Fan
Promega Corporation, 2800 Woods Hollow Road, Madison, WI 53711, USA
Immune checkpoint receptors synergize with TCR-CD3 signaling to regulate cell cycle progression, cytokine production, T cell survival and effector functions. Blockade of immune checkpoints PD-1 or CTLA-4 has showed promising clinical results to enhance anti-tumor immunity, which has quickly extended the immune oncology research and development targeting many other immune inhibitory receptors (TIGIT, LAG-3, Tim-3) and co-stimulatory receptors (4-1BB, OX40, CD40, GITR). The optimal efficacy of immunotherapy will likely be achieved with designs that include combinations of different immunotherapeutic approaches, or immunotherapy combined with other cancer treatments. Here, we report the development of a suite of cell-based reporter bioassays to quantitatively measure the drug potencies for therapeutic antibodies designed to target single immune checkpoint receptor, or the drug potencies for bispecific antibodies or antibody cocktails in combination therapy targeting PD-1+TIGT, PD-1+CTLA-4, and PD-1+LAG-3. These assays consist of engineered T effector cells that express luciferase reporters driven by specific response elements responding to the signaling regulated by the T cell receptor and immune checkpoint target(s), and engineered artificial antigen presenting cells. These mechanism of action-based bioassays demonstrate high specificity, sensitivity and reproducibility and can serve as valuable tools in immunotherapy drug research and development.