T-Cell Engagers Based Bioassay for Evaluation of PD-1/PD-L1 Inhibitors Activity.

PD-1/PD-L1-based therapy has been named a revolution in cancer treatment. By the end of 2018, more than 100 anti-PD-1 and anti-PD-L1 antibodies were in various stages of development, and more than 2000 clinical trials with their use have been registered. Characterization of such antibodies requires a bioassay to determine their biological activity. In this study, we developed a cell-based bioassay for analyzing the activity of anti-PD-1 and anti-PD-L1 antibodies. We chose reporter system consisting of two cell lines and compared several approaches for activation of effector cell line based on superantigens, soluble anti-CD3 antibodies, transmembrane anti-CD3 antibodies, chimeric antigenic receptors (CARs) and bispecific T-cell engager antibodies. The bispecific T-cell engager antibodies offer several advantages over the other approaches. We characterized the bioassay and demonstrated its applicability for analyzing the activity of anti-PD-1 and anti-PD-L1 antibodies. The proposed bioassay can be useful in the development of new therapeutic agents and methods for their characterization.

Methods for Screening Live Cells.

Cell screening or, in other words, identification of cells with certain properties is now increasingly used in scientific and medical research, e.g., in diagnostics, drug testing, and production of cell clones with desired characteristics. In this review, we discuss existing methods of cell screening and their classification according to the cell presentation format. We describe the principles of the one-dimensional and two-dimensional formats and compare the main advantages and drawbacks of these formats. The first part describes the methods based on the 2D-format of cell presentation, when cells are immobilized in the same plane by various techniques. The second part describes the methods of the 1D-screening, when cells are aligned in a line in a stream of fluid and scanned one-by-one while passing through a detector. The final part of the review describes the method of high-performance cell analysis based on the merged gel technique. This technique combines the advantages of both 1D and 2D formats and, according to the authors, might become an effective alternative to many modern methods of cell screening.