The impact of glycosylation on immune checkpoint inhibitors
Abstract
Wider research context Programmed cell death 1 receptor (PD-1) and its ligand programmed cell death ligand 1 (PD-L1) are immune checkpoint proteins that regulate the immune system. Under physiological conditions their interaction results in T-cell immune suppression, but cancer cells can hijack this pathway to escape immune detection by expressing PD-L1. Immunotherapies targeting the PD-1/PD-L1 axis represent a major breakthrough in cancer treatment. Several PD-1 and PD-L1 antibodies are FDA approved. However, their efficacy remains variable and weakly predictable, and thus attempts for the development of non-mAb PD-1/PD-L1 inhibitors are being pursued. PD-1 and PD-L1 are highly glycosylated proteins but the role of specific glycans in their interaction is poorly understood. Studies on the impact of glycosylation have focused on experimental studies using glyco-(null) mutants. Also, there are no reports on the impact of glycosylation on antibodies whose mode of action is receptor blockade and should not require ADCC or CDC activity. Clearly, there is a knowledge gap between our current understanding of immune regulation and how it can be manipulated to enhance the clinical efficacy of immune checkpoint blockade therapies in cancer. Objectives and methods The proposed project aims to take advantage of the transient expression system in N. benthamiana and its suitability for glyco-engineering to produce immune checkpoint proteins and antibodies with defined and homogenous human-like glycans. These will be used to determine the functional impact of glycans in the PD-1/PD-L1 interaction. In addition, glyco-engineered plant-derived proteins will be assessed for their binding affinity and effector functions in vitro. We expect to be able to identify glycan-optimized proteins that can act as decoy/trap molecules to inhibit the binding of PD-L1 in tumor cells to PD-1 in T-cells. Level of originality An in-depth analysis of the role of glycosylation in PD-L1/PD-1 interactions is not yet available. Studies on the functional activity of glyco-optimized proteins are likely to provide major insights into glycan-dependent interactions that will help guide therapeutic applications in cancer treatment. This research represents a promising new and fast way of producing and validating therapeutic recombinant proteins that can cut the time it takes to achieve significant clinical and experimental advances in cancer immunotherapy. Primary researchers involved Alexandra Castilho, with 27 years of experience in molecular genetics and cell biology and 18 in the field of plant N-glycosylation will be responsible for the execution of the project in close collaboration with experts in the fields of glyco-proteomics (Johannes Stadlmann); plant molecular farming (Lukas Mach and Waranyoo Phoolcharoen), immunology (Peter Steinberger) and glycosylation in cancer therapy (Celso Reis).
Publikationen
Project staff
Alexandra Machado Ferreira Castilho
Dr. Alexandra Machado Ferreira Castilho
alexandra.castilho@boku.ac.at
Tel: +43 1 47654-94353
Project Leader
01.04.2022 - 30.09.2025