The Amyloid Cascade After Lecanemab: Targets and Epitope Strategy

The approval of lecanemab (BAN2401) marks an inflection point in Alzheimer’s disease (AD) therapeutics, confirming that selective clearance of soluble amyloid beta (Aβ) aggregates can produce measurable clinical benefit. Patent filings retrieved from Eli Lilly and Company, Eisai R&D Management, F. Hoffmann-La Roche AG, and others converge on two canonical pathological hallmarks as primary intervention points: Aβ plaque accumulation and tau pathology. The amyloid cascade hypothesis — positing that Aβ deposition is an early, necessary event driving AD pathogenesis — remains the dominant framework across the patent filings in this dataset.

Aβ exists in multiple conformational states — monomers, oligomers, protofibrils, and insoluble fibrils — each representing distinct epitope targets for antibody design. The N-terminal epitope of Aβ (residues 3–7) is addressed by aducanumab; protofibril-selective antibodies such as lecanemab target soluble aggregated species; and anti-N3pGlu antibodies (donanemab, remternetug) target pyroglutamylated Aβ enriched in mature plaques. This epitope stratification is now the defining axis of competitive differentiation in the post-lecanemab pipeline, according to WIPO-registered filings reviewed in this analysis.

Biomarker-driven patient stratification is a parallel theme across filings. Eisai R&D Management filings emphasise amyloid PET, tau PET, Aβ42/40 ratios in CSF, and phosphorylated tau species (p-tau181, p-tau217, p-tau231, MTBR-tau243) as both selection and monitoring tools — reflecting a broader field shift toward precision patient identification consistent with frameworks outlined by the NIH National Institute on Aging.

Plaque-Selective Antibodies: N3pGlu Aβ and the Remternetug Generation

Eli Lilly and Company’s anti-N3pGlu Aβ program — encompassing donanemab and its next-generation successor remternetug (LY3372993) — represents the largest single cluster of patent activity in this dataset. Remternetug is characterised in retrieved Lilly JP filings (2025) as an IgG1 antibody achieving rapid amyloid clearance via microglia-mediated phagocytosis, with a longer half-life enabling less frequent dosing than donanemab. Donanemab clinical dosing regimens described in retrieved patents specify three doses of 700 mg every four weeks followed by 1,400 mg every four weeks, with a target of ≥15% improvement on the Integrated Alzheimer’s Disease Rating Scale (iADRS).

“N3pGlu Aβ is uniquely present in amyloid plaques but has low prevalence in vascular amyloid — enabling selective parenchymal plaque clearance with reduced CAA-related microhemorrhage risk.”

Eli Lilly and Company’s patent estate on N3pGlu Aβ spans at least 12 filings across JP, IL, AU, MX, CO, PE, SA, CN, EP, and WO jurisdictions, with prosecution activity running from 2018 through 2026. This geographic breadth — covering major pharmaceutical markets across Asia-Pacific, Latin America, the Middle East, and Europe — signals a deliberate strategy to create a compounding IP moat around the plaque-selective amyloid clearance mechanism.

A key mechanistic advantage of the N3pGlu target is its restricted distribution: N3pGlu Aβ is present in parenchymal amyloid plaques but has low prevalence in vascular amyloid. This selectivity is the basis for claims that anti-N3pGlu antibodies enable plaque clearance with reduced cerebral amyloid angiopathy (CAA)-related microhemorrhage risk relative to antibodies with broader Aβ epitope coverage. Tau PET baseline level is described in Lilly clinical filings as a patient selection criterion, indicating that tau burden at baseline is being incorporated into treatment eligibility frameworks.

Eisai R&D Management’s SC formulation patents for lecanemab describe a transition from IV induction dosing (10 mg/kg every two weeks) to subcutaneous maintenance dosing (250 mg weekly or biweekly), referencing ARIA vigilance protocols for the first 14 weeks of IV treatment and APOE4-associated ARIA risk elevation. One retrieved paper cites van Dyck et al., NEJM 2023, confirming clinical data on lecanemab in early AD — consistent with NEJM publication records.

Bispecific Antibodies and CNS Delivery Engineering

A distinct and high-value modality cluster in the post-lecanemab pipeline involves bispecific antibodies engineered to overcome the blood-brain barrier (BBB) penetrance limitations that constrain conventional monospecific anti-amyloid antibodies. F. Hoffmann-La Roche AG has filed patents on bispecific anti-Aβ/transferrin receptor (TfR) antibodies that leverage TfR-mediated transcytosis across the BBB to improve CNS biodistribution of the anti-Aβ component. Dosing in retrieved filings is described as 0.2–7.2 mg/kg IV every four weeks. Roche’s filing explicitly references aducanumab, lecanemab, donanemab, and gantenerumab as comparators, positioning the bispecific format as a next-generation alternative to approved agents.

Sinomab Bioscience Limited describes a complementary bispecific architecture: one arm targets an internalising antigen on neurological cell surfaces while the other engages toxic Aβ species. The explicit clinical rationale in Sinomab’s retrieved filings is to reduce ARIA-E (oedema) and ARIA-H (haemosiderin) vascular side effects relative to monospecific anti-amyloid agents — a safety-differentiation claim that addresses one of the most significant clinical barriers to broad adoption of anti-amyloid immunotherapy.

MedImmune Limited (AstraZeneca) has filed across WO, BR, KR, JP, and TW jurisdictions on MEDI1814, a fully human, effector-function-null monoclonal antibody with high selectivity for Aβ1-42/43 over Aβ1-40. A mechanistic claim described in retrieved filings as previously unestablished is that selective Aβ1-42 binding reduces neurofilament light chain (NfL) levels — establishing NfL as a downstream efficacy biomarker for neuronal axonal protection. This linkage between amyloid clearance and measurable axonal integrity is a significant translational signal, consistent with biomarker frameworks increasingly endorsed by regulatory bodies including the EMA.

Tau Therapeutics and Innate Immune Modulation

Tau is addressed as a secondary but strategically important target in this dataset, through both monoclonal antibody and antisense oligonucleotide (ASO) modalities. Genentech, Inc. retrieved JP filings describe humanised monoclonal anti-tau antibodies at 4,500 mg doses that preserve memory scores on ADAS-Cog11 in mild-to-moderate and moderate AD — representing a first-in-class claim for attenuating cognitive decline through tau immunotherapy. Axon Neuroscience SE’s filing covers antibodies targeting pathological tau-tau interaction epitopes, with utility in both AD and related tauopathies.

Biogen MA Inc. has filed on ISIS 814907, an ASO designed to reduce tau RNA and tau protein levels in patients with mild AD, mild cognitive impairment (MCI) due to AD, and frontotemporal dementia (FTD). This non-antibody, nucleic acid-based modality represents a distinct mechanistic approach to the tau axis, complementing the monoclonal antibody strategies pursued by Genentech and Axon Neuroscience. Eisai R&D Management filings on antimicrobial peptide (AMP) biomarkers reference tau species including MTBR-tau243, p-tau181, p-tau205, p-tau217, and p-tau231 as monitoring tools for anti-Aβ protofibril therapy response — demonstrating that tau biomarkers are being incorporated into anti-amyloid treatment protocols, not only standalone tau-targeting programmes.

TREM2 Agonists and IL-34 Inhibition

Neuroinflammation is emerging as a parallel mechanistic axis in the Alzheimer’s pipeline. Amgen Inc. has filed across WO, CA, JP, MX, and ID jurisdictions on TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) agonist-based treatment. Retrieved Amgen filings describe TREM2 dysfunction as a driver of impaired microglial surveillance in AD, with agonist therapy intended to restore microglial-mediated amyloid surveillance. Patient stratification in these filings includes a panel of biomarkers: APOE, B2M, BIRC5, BST2, C1QA/B/C, CCL2, CD63, CD74, CD81, and CXCL10, among others — a biomarker framework consistent with the precision medicine approaches now prevalent across the pipeline.

Eli Lilly and Company has separately filed on anti-IL-34 antibodies as an immune-mediated AD treatment strategy. IL-34 is positioned in these filings as a microglial survival and activation cytokine that, when antagonised, reduces neuroinflammation in concert with amyloid clearance by donanemab. Explicit combination use cases are described: donanemab plus anti-IL-34 to simultaneously clear N3pGlu Aβ plaques and suppress neuroinflammation in early symptomatic AD patients with established amyloid burden. This dual targeting rationale — combining amyloid clearance with neuroinflammation suppression — signals the next-generation combination strategy from Lilly’s AD franchise.

Combination Regimens and Subcutaneous Administration

Combination approaches and administration format innovations are accelerating as lifecycle management strategies across the post-lecanemab pipeline. Retrieved filings describe at least five distinct combination strategies, reflecting a field-wide recognition that single-target amyloid clearance may be insufficient for durable disease modification in a multifactorial disease.

• Donanemab + anti-IL-34 antibody (Eli Lilly): Simultaneous N3pGlu Aβ plaque clearance and neuroinflammation suppression in early symptomatic AD patients with established amyloid burden.
• Anti-amyloid antibody + NMDA receptor positive allosteric modulators (Sage Therapeutics): Targeting both synaptic dysfunction and amyloid pathology simultaneously, with CYP46A1 inhibitors as an alternative co-treatment. Patent evidence: JP, BR 2024.
• Lecanemab + scyllo-inositol (Frost assignee, WO 2024, JP 2025): A small-molecule adjuvant approach combining the anti-aggregation properties of scyllo-inositol with anti-amyloid immunotherapy in AD and MCI.
• Anti-amyloid antibody + curcumin analog TML-6 (Merry Life Biomedical, US 2022–2023): Positioning natural compound derivatives as immunotherapy adjuvants.
• TREM2 agonist + amyloid clearance antibody (implicit): The co-development of TREM2 agonists (Amgen) and amyloid clearance antibodies, combined with Lilly’s explicit neuroinflammation + amyloid dual targeting rationale, signals emerging interest in combinatorial approaches.

On administration format, multiple Eisai R&D Management filings describe IV-to-SC transition protocols for lecanemab, with SC maintenance dosing at 250 mg weekly or biweekly following IV induction. A broader prevention paradigm is also signalled: Eisai R&D Management filings describe treating amyloid-negative prodromal AD patients with reduced doses or frequencies of lecanemab to prevent amyloid positivity onset — representing a significant population expansion strategy beyond current treatment-focused indications. This prevention-oriented approach aligns with the growing body of evidence on pre-symptomatic AD intervention discussed in publications indexed by PubMed.

“Freedom-to-operate for future AD combination products will require careful analysis of intersecting method-of-treatment patents across Eisai, Lilly, and Sage Therapeutics.”

ARIA risk stratification — based on APOE4 genotype, amyloid PET, and MRI monitoring protocols — is being incorporated into treatment method claims across both Eisai R&D Management and Eli Lilly and Company filings. This signals that safety management innovations will be important components of commercial differentiation and freedom-to-operate analysis for any organisation seeking to enter the anti-amyloid immunotherapy space.

IP Landscape: Assignee Strategy and White-Space Signals

The post-lecanemab patent landscape is predominantly commercially led, with six major assignees accounting for the majority of retrieved filings. Academic and institutional output in this dataset is limited to a small number of literature records — a meta-analysis from Guangzhou University of Chinese Medicine on N-terminal anti-amyloid antibody clinical data, a CAD106 active immunisation paper from Indiana University, and an aducanumab commentary from Charles Darwin University — signalling that the current innovation frontier is patent-driven.

The tau axis is the most underpatented major target in this dataset relative to its biological significance. While retrieved results include anti-tau mAb (Genentech) and tau ASO (Biogen) filings, the tau patent estate appears substantially less densely covered than anti-amyloid approaches — representing a potential white-space opportunity for organisations developing tau-directed therapeutics, particularly in combination with approved amyloid-clearing agents. This observation aligns with the broader scientific consensus on tau’s role in AD progression as documented by bodies including the Alzheimer Europe consortium.

CNS delivery engineering via bispecific antibodies represents a further high-value frontier. Roche’s anti-Aβ/TfR bispecific platform — if validated clinically — could challenge IV-dosed monospecific antibodies by achieving equivalent plaque clearance at lower doses, potentially reducing ARIA incidence, with implications for second-line competition against approved agents. The combination IP acceleration across Eisai (lecanemab + antimicrobial peptide biomarkers), Lilly (donanemab + anti-IL-34), and Sage Therapeutics (anti-amyloid + NMDA PAM) means that freedom-to-operate for future AD combination products will require careful analysis of intersecting method-of-treatment patents across these assignees.