https://orcid.org/0000-0001-6311-1451
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ABSTRACT
Rozanolixizumab is a humanized anti-neonatal Fc receptor (FcRn) monoclonal antibody (mAb) of the immunoglobulin G4 (IgG4) sub-class, currently in clinical development for the treatment of IgG autoantibody-driven diseases. This format is frequently used for therapeutic mAbs due to its intrinsic lower affinity for Fc gamma receptors (FcγR) and lack of C1q engagement. However, with growing evidence suggesting that no Fc-containing agent is truly “silent” in this respect, we explored the engagement of FcγRs and potential functional consequences with rozanolixizumab. In the study presented here, rozanolixizumab was shown to bind to FcγRs in both protein-protein and cell-based assays, and the kinetic data were broadly as expected based on published data for an IgG4 mAb. Rozanolixizumab was also able to mediate antibody bipolar bridging (ABB), a phenomenon that led to a reduction of labeled FcγRI from the surface of human macrophages in an FcRn-dependent manner. However, the presence of exogenous human IgG, even at low concentrations, was able to prevent both binding and ABB events. Furthermore, data from in vitro experiments using relevant human cell types that express both FcRn and FcγRI indicated no evidence for functional sequelae in relation to cellular activation events (e.g., intracellular signaling, cytokine production) upon either FcRn or FcγR binding of rozanolixizumab. These data raise important questions about whether therapeutic antagonistic mAbs like rozanolixizumab would necessarily engage FcγRs at doses typically administered to patients in the clinic, and hence challenge the relevance and interpretation of in vitro assays performed in the absence of competing IgG.
Abbreviations
| ABB | = | antibody bipolar bridging |
| CyTOF | = | cytometry time of flight |
| DC | = | dendritic cell |
| EDTA | = | ethylenediaminetetraacetic acid |
| FcγR | = | Fc gamma receptor |
| FcRn | = | neonatal Fc receptor |
| FCS | = | fetal calf serum |
| HUVEC(s) | = | human umbilical vein endothelial cell(s) |
| IFNγ | = | interferon-gamma |
| IgG | = | immunoglobulin G |
| IVIg | = | intravenous immunoglobulin |
| mAb(s) | = | monoclonal antibody(ies) |
| MFI | = | mean fluorescence intensity |
| NK | = | natural killer |
| PBMC(s) | = | peripheral blood mononuclear cell(s) |
| PBS | = | phosphate-buffered saline |
| PFA | = | paraformaldehyde |
| RPMI | = | Roswell Park Memorial Institute |
| SPR | = | surface plasmon resonance |
| TNFγ | = | tumor necrosis factor-alpha |
| WT | = | wild type |
Acknowledgments
The authors acknowledge the following scientists at UCB Pharma, Slough, UK, for the preparation of protein reagents used in the studies described: Geofrey Odede, Helen Brand, Sue Cross, and Shirley Peters. We also thank Veronica Porkess from UCB Pharma for editorial review and assistance. Editorial support was provided by James Pickford and Jo Cook, Ogilvy Health UK, and funded by UCB Pharma, in accordance with Good Publication Practice 2022 (GPP2022) guidelines (https://www.ismpp.org/gpp-2022).
Disclosure statement
All the studies reported here were funded by UCB Pharma. All authors except for NB & OQ were employees of UCB Pharma when all studies were carried out: OQ was an employee of Celentyx Ltd when some of the experiments were conducted and NB was an employee at Celentyx Ltd throughout the study; GM is now an employee of AstraZeneca UK; GC is now an employee of Dark Blue Therapeutics, and AM is now an employee of Exscientia.
Author contributions
OQ wrote the manuscript, designed the experiments, performed the experiments, and analyzed, interpreted, and critically reviewed the data; ES, RB, SW, RC, GM, AM, and GC designed the experiments, performed the experiments, and analyzed and interpreted the data; NB, SR, and BS designed the experiments and analyzed and interpreted the data; AS wrote the manuscript and analyzed, interpreted, and critically reviewed the data; DH analyzed, interpreted, and critically reviewed the data; all authors reviewed and approved the manuscript.
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/19420862.2023.2300155