The Glomerular Disease Burden: IgAN and FSGS Pathobiology

IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS) are leading glomerular causes of chronic kidney disease and end-stage renal disease worldwide, sharing a high-unmet-need profile defined by proteinuria, progressive eGFR decline, and a historically limited therapeutic toolkit. Understanding the distinct but overlapping mechanisms of each disease is essential for interpreting the current patent landscape.

IgAN pathobiology is described in multiple retrieved patents as a “two-hit” process. Aberrantly galactose-deficient IgA1 (Gd-IgA1) acts as a self-antigen, triggering autoantibody formation and immune complex deposition in the mesangial region. This is followed by complement activation, mesangial cell proliferation, and progressive glomerular injury. Downstream NF-κB signalling and PDGF-mediated mesangial pathways are also cited as contributors. According to retrieved patent filing disclosures, approximately 20–50% of IgAN patients progress to ESRD within 20–30 years.

FSGS pathobiology is characterised by primary podocyte injury and depletion. Circulating permeability factors — most prominently soluble urokinase plasminogen activator receptor (suPAR) — are identified in the retrieved dataset as pathogenic mediators. Retrieved results from Walden Biosciences, the University of California, and the University of Miami establish that elevated serum suPAR activates podocyte β3 integrin, driving proteinuria and glomerulosclerosis. Genetic risk factors, specifically APOL1 variants, are cited in Genzyme filings as modifying disease susceptibility in primary FSGS.

Complement Pathway Inhibition: The Most Patent-Dense Therapeutic Space

Complement pathway inhibition represents the single largest cluster of retrieved patent results in this dataset, with MASP-2 inhibitory antibodies constituting the dominant IP family. The University of Leicester, in partnership with Omeros Corporation, has filed an extensive international portfolio spanning WO, AU, US, CA, CN, SG, JP, MX, ES, and OA jurisdictions — at least 12 retrieved records — covering anti-MASP-2 monoclonal antibodies for IgAN and related proteinuric glomerular diseases.

The mechanism involves selective inhibition of MASP-2-dependent complement activation, specifically blocking the lectin pathway while leaving the classical C1q-dependent pathway intact. Retrieved claims describe reduction of renal tubulointerstitial inflammation, anti-fibrotic effects demonstrated in the unilateral ureteral obstruction (UUO) mouse model, and proteinuria reduction as primary endpoints. Dosing regimens described include intravenous administration of approximately 4 mg/kg once weekly for at least 12 weeks, targeting MASP-2 epitopes defined by SEQ ID NO:67 (heavy chain) and SEQ ID NO:70 (light chain). The specificity of these dosing parameters and inclusion/exclusion criteria is consistent with IND-enabling or Phase I/II clinical protocol design.

“New entrants to complement inhibition in IgAN must design around MASP-2 epitope claims SEQ ID NO:67/70 — or differentiate through alternative pathway targets such as Factor B, Factor H, or C3.”

Beyond MASP-2, alternative pathway targeting is represented by Alexion Pharmaceuticals (AstraZeneca), which has filed patents describing kidney-active fusion proteins containing Factor H catalytic domains — including VHH (single-domain camelid antibody) elements and Factor H-related protein 5 (FHR5) domain constructs — for diseases mediated by complement alternative pathway (CAP) activation, specifically naming FSGS, IgAN, MCD, and C3 glomerulopathy. Q32 Bio has filed WO and TW patents covering compounds targeting renal diseases characterised by complement system dysregulation and/or C3d deposition, with preclinical data shown in the Passive Heymann Nephritis (PHN) model. Novartis has filed a CN patent describing the use of iptacopan (a Factor B inhibitor) for IC-MPGN, expanding the patent landscape for complement alternative pathway inhibitors in nephrology. According to WIPO, complement-directed biologics represent one of the fastest-growing patent categories in rare renal disease globally.

SGLT2 Inhibitors: From Diabetes to Non-Diabetic Glomerular Disease

SGLT2 inhibitors represent the most commercially advanced renoprotective modality in this dataset for IgAN-associated CKD, with AstraZeneca’s dapagliflozin filings extending explicitly to non-diabetic IgAN and FSGS. AstraZeneca has filed patents in CN and JP for dapagliflozin specifically in CKD patients with and without type 2 diabetes, with explicit indication extensions to IgAN-associated CKD, CKD related to chronic glomerulonephritis, and FSGS-associated proteinuric CKD.

The renoprotective mechanism of SGLT2 inhibitors in glomerular disease operates through glomerular haemodynamic effects — specifically reducing intraglomerular pressure via tubuloglomerular feedback — alongside anti-inflammatory and anti-fibrotic mechanisms. AstraZeneca’s JP patent (2023) explicitly references treatment of “IgA nephropathy (also known as Berger’s disease)” in the context of CKD methods in patients without type 2 diabetes, consistent with a clinical regulatory filing strategy following the broader DAPA-CKD programme. Findings from the DAPA-CKD trial, widely cited in the nephrology literature and discussed by NEJM, established dapagliflozin’s benefit across CKD subgroups including non-diabetic patients.

Boehringer Ingelheim has filed multiple patents (CN, HK, TW) covering empagliflozin for CKD prevention in periadiposity-related glomerulosclerosis and IgAN. A Taiwanese National Defense Medical College patent identifies SGLT2 expression itself as a biomarker for diagnosing CKD and monitoring treatment response in FSGS and IgAN. Joslin Diabetes Center has filed CN and JP patents proposing SGLT2 inhibitors as indicated therapy when patients are identified — through FGF20, ANGPT1, or TNFSF12 biomarker screening — as being at risk of progressive renal decline, signalling an emerging precision medicine framework. According to the European Medicines Agency, SGLT2 inhibitors have received expanded regulatory approvals for CKD, further validating this patent expansion strategy.

Emerging Targets: suPAR, Endothelin, and Novel Biologics

Beyond complement and SGLT2, the retrieved dataset reveals a cluster of biologically well-supported but commercially fragmented targets — most notably suPAR, the endothelin-A receptor, and a range of podocyte-directed biologics — each with distinct mechanistic rationales and assignee profiles.

suPAR-Targeting Biologics in FSGS

Soluble urokinase plasminogen activator receptor (suPAR) is identified in the retrieved dataset as a circulating permeability factor uniquely elevated in FSGS. Its downstream target is podocyte β3 integrin, and its activation drives proteinuria and glomerulosclerosis. At least four distinct assignees are independently pursuing suPAR-directed strategies: Walden Biosciences (WO and JP patents for isolated anti-suPAR antibodies across FSGS, IgAN, lupus nephritis, and membranous nephropathy), the University of California (pending US patent for anti-uPAR/CD87 and anti-suPAR antibodies specifically for FSGS), the University of Miami (active JP patent demonstrating that ex vivo suPAR removal from circulation can halt or slow disease onset by preventing podocyte β3 integrin activation), and Massachusetts General Hospital. This fragmentation suggests consolidation or licensing activity could be strategically valuable.

Endothelin Receptor Antagonism (ERA)

Chinook Therapeutics (acquired by Novartis) has filed patents in CN and JP covering atrasentan — a selective endothelin-A receptor antagonist — for both IgAN and FSGS. Claimed endpoints include reduction of renal inflammation and fibrosis, proteinuria reduction, eGFR stabilisation, reduction of ESRD onset, and reduction of disease flares. Mesangial PDGF pathway inhibition (PIK3R1, PDGFRA, NFKBIA) is cited as a mechanistic component in IgAN mesangial cells. The specificity of dosing language, patient exclusion criteria, and clinical endpoints in Chinook’s filings is consistent with ongoing Phase II/III clinical development.

Novel Biologics: SLIT2, TRPC6, Anti-CD38, and Anti-APRIL

Everest Medicines (China) Co., Ltd. has filed WO and CN patents for anti-SLIT2 antibodies targeting FSGS, glomerular disease, and proteinuria, with podocyte function preservation as a stated endpoint. Boehringer Ingelheim has filed WO and TW patents for TRPC6 (transient receptor potential cation channel C6) inhibitors — a channel expressed in podocytes — for FSGS treatment. ChemoCentryx (now Amgen) holds active JP patents for C5aR antagonists (including avacopan-class molecules, Formula I compounds) for FSGS treatment across primary, secondary, and genetic subtypes. For IgAN, MorphoSys (now Novartis) filed a CN patent for anti-CD38 antibodies (including felzartamab/MOR202) targeting depletion of CD38-expressing plasma cells and reduction of circulating immune complexes and mesangial IgA deposits. Westlake Biosciences has filed a CN patent for anti-APRIL antibodies, exploiting APRIL’s role in driving pathological IgA production. Research published in Nature journals has highlighted podocyte biology as a central focus for next-generation FSGS therapeutics, consistent with the SLIT2 and TRPC6 patent activity observed here.

Combination Strategies and the Next IP Frontier

Combination therapy patents are emerging as the next frontier in the IgAN and FSGS landscape, with several filings explicitly designed to capture additive or synergistic renoprotection across complementary mechanisms. Single-agent studies alone may not define the eventual standard of care.

The most advanced combination patent in this dataset is AstraZeneca’s 2025 CN filing for a fixed-dose combination (FDC) of zibotentan (endothelin receptor antagonist) and dapagliflozin (SGLT2 inhibitor) for high-proteinuria CKD, explicitly covering biopsy-confirmed IgAN and FSGS-associated CKD as target populations. The rationale is dual haemodynamic (SGLT2) plus anti-inflammatory/anti-fibrotic (ET-A blockade) mechanisms offering additive renoprotection. This FDC signals an imminent combination product strategy that IP teams and competitors should monitor for Freedom-to-Operate considerations.

Resolute Biosciences’ TW patent describes a combination of a BET bromodomain inhibitor with an SGLT2 inhibitor for improving eGFR in kidney disease, representing an emerging epigenetic plus SGLT2 combination approach. Multiple University of Leicester filings reference co-administration strategies permitting corticosteroid dose reduction, pointing toward a steroid-sparing combination strategy for steroid-dependent IgAN. Additional CN and AU filings from the University of Leicester describe anti-MASP-2 antibodies as an adjunct to renal replacement therapy, reducing dialysis/plasmapheresis frequency, or as bridge therapy in transplant candidates — a potentially high-value perioperative strategy.

Strategic Implications for Drug Developers and IP Teams

The retrieved patent dataset reveals a landscape in which complement inhibition and SGLT2 inhibition are the dominant therapeutic pillars, but where the competitive dynamics, IP barriers, and combination strategies differ substantially between them. Several strategic implications stand out for drug developers, IP strategists, and licensing professionals.

Complement inhibition is the most heavily patent-protected space in IgAN. The University of Leicester/Omeros multi-jurisdictional MASP-2 antibody estate spans at least 9 jurisdictions and covers both proteinuria reduction and anti-fibrotic claims. New entrants must design around the MASP-2 epitope claims (SEQ ID NO:67/70) and the broader MASP-2-dependent complement activation mechanism, or differentiate through alternative pathway targets (Factor B, Factor H, C3).

SGLT2 inhibitors represent the most commercially advanced renoprotective modality in this dataset for IgAN-associated CKD. The zibotentan plus dapagliflozin FDC signals an imminent combination product strategy. IP teams should monitor Freedom-to-Operate implications of this filing for any overlapping development programmes.

suPAR targeting in FSGS is biologically well-supported but commercially fragmented. At least four distinct assignees (Walden Biosciences, University of California, University of Miami, Massachusetts General Hospital) are pursuing independent approaches to suPAR neutralisation or depletion. Consolidation or licensing activity could be strategic given the orthogonal mechanism relative to complement and SGLT2 approaches.

APOL1-genotype-stratified FSGS therapy (TGFβ antagonism, Genzyme/Sanofi) represents a precision medicine niche with limited competition in this dataset. The absence of an approved FSGS pharmacotherapy despite extensive IP activity underscores ongoing unmet need and potential first-mover advantages for agents advancing through stratified trial designs. According to FDA guidance on rare kidney diseases, genotype-stratified trial designs are increasingly supported as a pathway for accelerated approval.

“Combination therapy IP — ERA+SGLT2, MASP-2+steroid sparing, BET+SGLT2 — is emerging as the next frontier, suggesting single-agent studies alone may not define the eventual standard of care in IgAN and FSGS.”

Combination therapy IP is emerging as the next frontier. Drug developers and IP strategists should evaluate combination patent claims and data package requirements for regulatory submission in both IgAN and FSGS. The patent activity observed across ERA+SGLT2, MASP-2+steroid sparing, and BET+SGLT2 combinations suggests that the eventual standard of care in these diseases is likely to be multi-mechanistic.