PLA2R1 as the Dominant Autoantigen: Disease Architecture and Diagnostic Gaps

Primary membranous nephropathy (pMN) is an autoimmune glomerular disease in which pathogenic IgG4 autoantibodies target antigens expressed on glomerular podocytes, triggering subepithelial immune complex deposition, complement activation, and proteinuria. The M-type phospholipase A2 receptor (PLA2R1) is the dominant autoantigen, with approximately 70–82% of pMN patients carrying detectable anti-PLA2R autoantibodies. With roughly 3,000 new adult diagnoses annually in the United States and up to 40–50% of patients progressing to end-stage renal disease within 10–15 years, the clinical stakes of therapeutic innovation are high.

Within PLA2R1, retrieved patent filings from CHU de Nice and the French National Centre for Scientific Research (Centre National de la Recherche Scientifique) identify three structurally distinct antigenic domains — CysR, CTLD1, and CTLD7 — as the primary loci of autoimmune reactivity. CTLD1 and CTLD7 are more closely associated with active disease, and progressive epitope spreading from CysR toward CTLD1 and then CTLD7 correlates with worsening prognosis and lower likelihood of treatment-induced immunological remission. This epitope-spreading mechanism is not merely a diagnostic curiosity: it provides the mechanistic rationale for antigen-domain-specific therapeutic targeting, as pursued in the most recent academic-origin patent filings from Chang Gung University.

A significant diagnostic gap complicates treatment decisions: approximately 22–35% of pMN patients are seronegative for anti-PLA2R antibodies by standard assays. A patent from Aoshi Technology (Shenzhen) describes urinary detection of PLA2R splice variants — designated X1 at approximately 180 kDa, X3 at approximately 100 kDa, and X5 at approximately 85 kDa — combined with IgG4/PLA2R co-localization analysis, recovering positivity in the majority of conventionally seronegative patients. This urine-based approach signals a move toward non-invasive monitoring that could replace repeated kidney biopsies for treatment response assessment.

Beyond PLA2R, Mayo Foundation for Medical Education and Research has filed multiple patent applications extending the target landscape to include THSD7A, Semaphorin 3B (SEMA3B), NELL-1, protocadherin-7 (PCDH7), exostosins 1 and 2 (EXT1, EXT2), and protocadherin FAT1 — each defining a molecularly distinct subtype of membranous nephropathy. These emerging antigens are particularly relevant for the 22–35% of pMN patients who are PLA2R seronegative, a diagnostically and therapeutically underserved population according to WIPO-registered patent filings in this space.

Felzartamab and Anti-CD38 Therapy: Targeting the Plasma Cell Compartment

The most aggressively IP-protected therapeutic approach in the primary membranous nephropathy drug pipeline is felzartamab (MOR202), an anti-CD38 monoclonal antibody developed by MorphoSys AG. At least eight patent records across WO, US, CA, AU, IL, IN, JP, BR, and CL jurisdictions share the same core disclosure: that felzartamab administered at optimised dosage regimens is safe and efficacious for anti-PLA2R autoantibody-mediated membranous nephropathy.

The mechanistic rationale for anti-CD38 therapy is distinct from that of rituximab and other anti-CD20 agents. CD38 is constitutively expressed on long-lived bone marrow plasma cells — the antibody-secreting cells responsible for persistent production of pathogenic anti-PLA2R IgG4. Rituximab targets CD20, which is absent on mature plasma cells; this means B-cell depletion via anti-CD20 agents does not eliminate the plasma cell compartment that sustains circulating autoantibody titres. By targeting CD38, felzartamab addresses a mechanistic node downstream of B-cell differentiation that anti-CD20 approaches cannot reach, potentially achieving deeper and more durable immunological remission.

“Anti-CD38 targeting achieves a mechanistic node downstream of B-cell differentiation that is not addressed by anti-CD20 approaches, which spare mature plasma cells that are CD20-negative.”

MorphoSys AG’s multi-jurisdictional patent strategy — with national phase entries spanning North America, Europe, Asia-Pacific, and Latin America — constitutes the most coherent global IP enforcement framework for a single therapeutic agent in the pMN space. The specific description of “improved dosage regimens” across multiple national filings (including WO 2023/001804 and its national phase entries) is consistent with Phase II clinical trial activity, suggesting that clinical data was generated or is in generation. Drug developers evaluating plasma cell depletion strategies must navigate this IP landscape carefully, as the breadth of MorphoSys AG’s claims covers both the agent and the dosage regimen in anti-PLA2R-positive patients.

Next-Generation Anti-CD20 and BTK Inhibition: Rituximab Alternatives in the Pipeline

Rituximab’s non-inferiority to cyclosporine, demonstrated in the MENTOR trial and cited across multiple retrieved records, established anti-B-cell therapy as a clinical standard in primary membranous nephropathy. Two distinct approaches are now challenging and extending rituximab’s position: the type II anti-CD20 antibody obinutuzumab, and the BTK inhibitor zanubrutinib.

Obinutuzumab: Superior B-Cell Depletion in Refractory Disease

Genentech and F. Hoffmann-La Roche AG have filed extensive patent families disclosing the use of obinutuzumab — a type II anti-CD20 antibody — for membranous nephropathy, including explicit claims for primary membranous nephropathy. In contrast to rituximab (a type I anti-CD20 antibody), obinutuzumab produces more complete B-cell elimination through enhanced direct cell death induction and antibody-dependent cellular cytotoxicity. Patent filings from Genentech and Roche reference the Phase II NOBILITY trial (NCT02550652), which demonstrated superiority of obinutuzumab over placebo for complete and overall renal response at Week 52 in lupus nephritis, with the same methods extended explicitly to membranous nephropathy.

Critically, an academic paper from the Division of Nephrology at Cedars Sinai Medical Center documents clinical efficacy of obinutuzumab specifically in refractory membranous nephropathy patients who had failed rituximab. This constitutes a direct clinical signal within the dataset for obinutuzumab as a rituximab-alternative approach, supported by both patent and clinical literature evidence — the most clinically advanced combination of signals for any rituximab alternative in this analysis. According to data published by NEJM and reviewed by bodies including EMA, next-generation anti-CD20 agents represent a significant step forward in B-cell depletion depth for autoimmune nephropathies.

Zanubrutinib: Upstream BTK Inhibition Targeting the Full B-Cell Axis

BeiGene Switzerland GmbH and BeiGene, Ltd. have filed patent applications (PCT/CN2023/126500-series, published 2024–2026 across WO, IL, and BR) disclosing the use of zanubrutinib — a selective, covalent Bruton’s tyrosine kinase (BTK) inhibitor — for treating pMN, including patients with elevated glomerular basement membrane levels of PLA2R and/or THSD7A. BTK plays a critical role in B-cell receptor signalling and the downstream activation, differentiation, and autoantibody production by autoreactive B cells. By inhibiting BTK upstream of plasma cell generation, zanubrutinib may suppress both naïve B-cell activation and memory B-cell reactivation — a potentially broader mechanistic intervention than either anti-CD20 or anti-CD38 targeting alone.

BeiGene’s filings are structured for clinical use — patient selection criteria are based on GBM PLA2R/THSD7A levels, suggesting IND-enabling or early-phase clinical activity. However, no specific trial outcome data is presented in retrieved patent text, indicating that BTK inhibition in pMN is at an earlier development stage relative to anti-CD38 and anti-CD20 strategies. The commercial significance of BeiGene’s bet on upstream B-cell pathway inhibition is nonetheless substantial, given zanubrutinib’s established safety profile in oncology indications.

Antigen-Specific Antagonists and Precision Stratification: The Emerging Frontier

Direct antigen-specific intervention represents the most mechanistically targeted approach in the primary membranous nephropathy drug pipeline — and the most underexplored relative to its potential. Rather than depleting B cells or plasma cells systemically, these strategies aim to neutralise the pathogenic effector species (anti-PLA2R autoantibodies) at the molecular level or to induce antigen-specific immune tolerance.

CTLD1/CysR Domain Antagonists from Chang Gung University

Chang Gung University (Taiwan) has filed patents in both the US and EP (2025) disclosing antibody antagonists specifically designed to bind the CTLD1 or CysR domains of PLA2R1, thereby blocking the binding of pathogenic anti-PLA2R autoantibodies to the receptor. Alternatively, a recombinant protein designed to decoy and sequester circulating anti-PLA2R autoantibodies is also claimed. This competitive interference strategy does not deplete B cells or plasma cells but directly neutralises the pathogenic effector species — a disease-modifying approach that could be particularly valuable for patients intolerant of broad immunosuppression.

The foundational IP precedent for autoantibody sequestration via soluble PLA2R was established over a decade earlier by Le Centre National de la Recherche Scientifique and Boston Medical Center Corporation, whose patents (filed circa 2008–2009, subsequently granted in WO, CA, US, EP, and DK jurisdictions) proposed the administration of soluble PLA2R or its fragments to act as a decoy. Chang Gung University’s 2025 filings refine this concept with domain-specific precision informed by the intervening decade of epitope mapping research.

Tolerogenic Fusion Proteins and Epitope-Focused Polypeptides

A fusion protein strategy from Chengdu Diao Pharmaceutical Group discloses antibodies linked to PLA2R antigen epitope peptides — combining B-cell targeting with antigen-specific immune tolerisation in a single molecular scaffold. Separately, Peking University First Hospital has disclosed PLA2R-derived polypeptides (47 sequences) for therapeutic, preventive, and diagnostic use in pMN, including epitope-focused approaches linked to HLA-DRB1*1501 and HLA-DRB1*0301 alleles — a precision immunology approach that connects antigen-specific therapy to genetic risk stratification.

Precision Stratification for PLA2R-Seronegative Subtypes

Mayo Foundation for Medical Education and Research has filed a series of patent applications (WO, CA, 2020–2024) proposing rituximab, corticosteroids, and cyclosporine as treatments for molecularly stratified MN subtypes defined by new glomerular basement membrane antigens — NELL-1, Semaphorin 3B, PCDH7, EXT1/EXT2, and FAT1. These filings signal the emergence of a companion diagnostics/precision treatment paradigm for MN subtypes that are PLA2R-negative. The analogy to the stratification of inflammatory myopathies by myositis-specific antibodies — a model now endorsed by bodies including EULAR — is instructive: pMN will increasingly be managed as a family of antigen-defined diseases requiring different treatment protocols.

A drug delivery innovation from Guizhou University of Traditional Chinese Medicine describes ROS-responsive cationic polymer nanoparticles targeting podocytes for membranous nephropathy therapy — a glomerular-targeted delivery approach that could enhance the therapeutic index of any of the agents above by concentrating delivery at the pathological site, consistent with principles of targeted drug delivery reviewed by Nature in the context of nanomedicine for autoimmune nephropathies.

Patent Landscape and Strategic Implications for Drug Developers

The primary membranous nephropathy patent landscape is structured around a small number of high-conviction institutional actors, each occupying a distinct mechanistic niche. Understanding the IP architecture is essential for drug developers, biotech investors, and diagnostic companies evaluating entry points in this space.

Assignee Landscape by Innovation Focus

MorphoSys AG is the most prolific patent filer specifically for pMN treatment in this dataset, with at least eight patent records spanning nine jurisdictions — all centred on felzartamab/MOR202 anti-CD38 therapy. This constitutes the most coherent global IP enforcement strategy for a single therapeutic agent in this space. Genentech and F. Hoffmann-La Roche AG contribute the second largest patent cluster, covering obinutuzumab across US, WO, CA, AU, EP, MX, and JP for both lupus nephritis and membranous nephropathy — a dual-indication strategy suggesting shared clinical trial infrastructure. BeiGene represents an emerging entrant with recent priority dates (2023–2026), signalling active early-stage clinical development for zanubrutinib.

On the academic-institutional side, Mayo Foundation for Medical Education and Research is the dominant filer, with at least six WO/CA patent applications disclosing novel GBM antigens and companion immunosuppressive treatment strategies. Universite Cote d’Azur and CHU de Nice contribute enabling technology for precision treatment through PLA2R1 epitope profiling patents. Chinese academic and hospital institutions — including Peking University First Hospital, Aoshi Technology Shenzhen, and Hangzhou Saiji Biotechnology — contribute diagnostic and biomarker-focused patent activity primarily in the CN jurisdiction.

Strategic Recommendations by Stakeholder

• Drug developers targeting plasma cells: MorphoSys AG’s multi-jurisdictional patent strategy for anti-PLA2R-positive pMN creates significant barriers to entry. Any plasma cell depletion strategy must navigate the breadth of felzartamab claims covering both the agent and the dosage regimen.
• IP strategists evaluating anti-CD20 approaches: Genentech/Roche’s extensive patent family for obinutuzumab shows high degree of redundancy across jurisdictions. The combination of Phase II NOBILITY trial data and Cedars Sinai clinical reports makes obinutuzumab the most clinically advanced rituximab alternative with documented activity in refractory MN.
• Biotech companies exploring antigen-specific therapy: Chang Gung University’s CTLD1/CysR antagonist patents (US and EP, 2025) and the foundational CNRS/Boston Medical Center decoy protein IP represent potential partnership or in-licensing opportunities for disease-modifying approaches targeting patients intolerant of systemic immunosuppression.
• Diagnostic and companion diagnostics companies: Mayo Foundation’s expanding biomarker patent series creates a foundation for validated assays targeting the 22–35% of pMN patients who are PLA2R seronegative. Collaborative frameworks with Mayo to develop assays for THSD7A, NELL-1, SEMA3B, FAT1, EXT1/EXT2, and PCDH7 represent a significant commercial opportunity in precision nephrology.
• Academic researchers: Epitope immunodominance profiling methods from Universite Cote d’Azur and CHU de Nice are translational tools deployable in clinical trial stratification, enabling precision patient selection for any of the above therapeutic approaches.

The sequential or combination use of anti-CD20 and anti-CD38 agents — targeting B cells and plasma cells respectively — represents an implicit mechanistic logic in the patent landscape, though no explicit combination claims for these two modalities in pMN have been retrieved in this dataset. As the field matures, combination strategies informed by epitope profiling and antigen subtype identification are likely to emerge as the next frontier, consistent with trends in precision autoimmune therapy documented by institutions including NIH.