Abstract: TH-PO0418
Engineering Phospholipase A2 Receptor Fc-Fusions with Reduced Heparin Interaction Improves Pharmacokinetic Properties
Session Information
- Glomerular Diseases: Autoimmune Diseases
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Jacobowitz, Joseph R., Merida Biosciences, Cambridge, Massachusetts, United States
- Palanati, Amoolya, Merida Biosciences, Cambridge, Massachusetts, United States
- Patterson, Troy D., Merida Biosciences, Cambridge, Massachusetts, United States
- Shu, Yanqun, Merida Biosciences, Cambridge, Massachusetts, United States
- Huggins, Danielle, Merida Biosciences, Cambridge, Massachusetts, United States
- Donaghey, Julie, Merida Biosciences, Cambridge, Massachusetts, United States
- Schweitzer, Lawrence, Merida Biosciences, Cambridge, Massachusetts, United States
- Gutierrez, Dario A., Merida Biosciences, Cambridge, Massachusetts, United States
- Capili, Allan D., Merida Biosciences, Cambridge, Massachusetts, United States
Background
Autoantibody-driven diseases arise when immune tolerance to self-antigens breaks down, triggering a pathological humoral response against the body's own tissues. Recent work has demonstrated that autoantibodies can be specifically neutralized and degraded in vivo by Fc-fusions that link these self-antigens to an Fc with enhanced FcgRIIb affinity and selectivity. We adapted this approach to the treatment of Primary Membranous Nephropathy (PMN). For 70% of patients, PMN is driven by autoantibodies targeting the Phospholipase A2 Receptor (PLA2R), with CysR being the immunodominant domain of the receptor. Here, we show that the pharmacokinetics of a CysR Fc-fusion can be improved through the design of variants with reduced polyreactivity to negatively charged heparin.
Methods
To identify positive patches that mediate polyreactive interactions with heparin, we used AlphaFold2 to predict the structure of CysR and visually inspected the surface charge distribution. We used a combination of rational design and ProteinMPNN to generate variants that neutralize or obstruct these regions of CysR. To assess polyreactivity, we used ELISAs to compare differences between variants’ abilities to interact with heparin, a representative negatively charged glycosaminoglycan. We used both ELISAs and CryoEM-based structural studies to assess these variants’ binding to patient-derived monoclonal autoantibodies. Finally, we tested the impact on in vivo pharmacokinetics using humanized FcgR/FcRn mice.
Results
We observed three positively charged patches on the surface of CysR and identified a single patch that, when neutralized, has reduced interaction with heparin. This variant has improved pharmacokinetics but is significantly impaired in its ability to bind patient-derived monoclonal autoantibodies. In a second round of design, we generated a variant with an additional glycosylation site proximal to the heparin binding patch and show this variant also has reduced heparin binding and improved pharmacokinetics while retaining interaction with patient-derived monoclonals.
Conclusion
The variants described herein enhance the in vivo half-life of therapeutic PLA2R Fc-fusions which may enable a more favorable dosing schedule for PMN patients. Moreover, these design strategies may be applied to other therapeutic proteins to similarly improve their pharmacokinetic properties.