The United States patent 6,210,892 covers non-cleaving antisense compounds used to alter processing of wild-type cellular mRNA, particularly exon splicing, splice-site selection, polyadenylation, and mRNA stability. Its broadest claim is a functional method claim, not a composition claim directed to a specific oligonucleotide sequence, gene, protein, or drug. The patent’s nominal 20-year term expired in 2018, leaving no current blocking right from this patent. Its historical scope was significant for 2′-O-methoxyethyl antisense oligonucleotides, phosphorothioate-containing compounds, morpholinos, peptide nucleic acids, and exon-skipping methods.

United States Drug Patent 6,210,892: Scope, Claims, Expiration, and Antisense Patent Landscape

What does US Patent 6,210,892 cover?

US 6,210,892 covers methods of modulating the processing of a selected wild-type cellular mRNA by binding the mRNA with a non-cleaving antisense compound. The patent was assigned to Isis Pharmaceuticals, Inc., now Ionis Pharmaceuticals, and issued on April 3, 2001.[1]

The invention is directed to antisense compounds that bind an mRNA target without inducing RNase H or another cleavage mechanism. The claimed result is a change in how the target mRNA is processed.

The principal processing outcomes include:

Redirection of pre-mRNA splicing.
Exon inclusion or exon exclusion.
Reduced use of a 5′ splice site.
Alteration of the ratio of splice products.
Changes in membrane-bound versus soluble protein isoforms.
Modulation of polyadenylation.
Regulation of mRNA stability.

The claims identify several chemical platforms, including:

2′-O-methoxyethyl, commonly abbreviated 2′-MOE.
2′-dimethylaminooxyethoxy.
2′-dimethylaminoethoxyethoxy.
2′-acetamide.
Morpholino.
Peptide nucleic acid, or PNA.
Methylene methylimino backbones.
C-5 propyne nucleobases.
Phosphorothioate and other modified backbone linkages.

The patent therefore sits at the intersection of antisense chemistry and RNA-processing biology. It does not require a particular disease indication or therapeutic protein.

What is the scope of independent claim 1?

Claim 1 requires each of the following elements:

Claim element	Scope
Target	A selected wild-type cellular mRNA target
Agent	An antisense compound
Chemical structure	At least one specified modification, including 2′-MOE, morpholino, or PNA
Binding	Specific hybridization to the mRNA
Cleavage limitation	Binding does not elicit cleavage of the mRNA
Result	Modulation of processing of the mRNA

The claim is broad because it does not limit the target to a named gene, sequence, transcript, exon, receptor, or therapeutic indication. It also does not require a particular length of antisense compound, dose, route of administration, cell type, or formulation.

The claim is narrower than a general claim to antisense binding. A potentially relevant accused method must involve all of the following:

A wild-type cellular mRNA.
Specific antisense hybridization.
A non-cleaving mechanism.
One of the listed chemical modifications.
A measurable change in mRNA processing.

A compound that binds RNA but causes target cleavage through RNase H would fall outside the express non-cleavage limitation of claim 1. A compound that does not change processing would also fall outside the claim.

Which dependent claims cover exon skipping and splice-site redirection?

Claims 2 and 6 through 12 provide the principal splice-modulation coverage.

Claims	Claimed subject matter
2	Modulation of mRNA splicing
6	Redirection of splicing
7	Altered ratio of splice products
8	Exclusion of one or more exons
9	Targeting an exon to be excluded
10	Targeting an intron-exon junction
11	Targeting a region up to 50 nucleobases upstream from a 5′ splice site
12	Decreased use of the 5′ splice site

Claims 8 through 12 are particularly relevant to exon-skipping drugs. They describe a mechanism in which an antisense compound masks an exon, intron-exon junction, or splice-site region, causing the spliceosome to produce a different mature transcript.

The “up to 50 nucleobases upstream” limitation in claim 11 is a specific positional limitation. It does not mean that all antisense compounds used near splice sites fall within the claim. The accused sequence must satisfy the claimed location and the method must produce the claimed redirection or reduced 5′ splice-site use.

How do claims 28 through 30 address membrane and soluble receptors?

Claims 28 through 30 cover altered ratios of splice products that encode different protein forms, including membrane-bound and soluble forms.

Claim 29 limits the protein to a receptor, while claim 30 limits the receptor to a hormone or cytokine receptor. These claims are narrower than claim 1 and require a particular biological consequence: changing the relative amount of receptor isoforms produced by alternative splicing.

These claims could be relevant to antisense approaches intended to:

Increase a soluble receptor isoform.
Increase a membrane-bound receptor isoform.
Reduce production of one receptor form.
Change signaling by altering receptor localization or secretion.

The claims do not require a particular receptor, disease, antisense sequence, or commercial product.

What antisense chemistries are protected?

2′-O-methoxyethyl antisense compounds

Claims 3, 16 through 19, and related claims cover antisense compounds containing 2′-modified sugars, particularly 2′-O-methoxyethyl and 2′-dimethylaminooxyethoxy modifications.

Claim 3 requires the specified modification on substantially every sugar. Claim 19 identifies 2′-O-methoxyethyl and 2′-dimethylaminooxyethoxy as selected modifications.

These structural limitations were commercially important because 2′-MOE chemistry can improve:

Binding affinity.
Nuclease resistance.
Pharmacological duration.
Hybrid stability.
Compatibility with non-cleaving splice modulation.

The claims do not require that every 2′-MOE oligonucleotide be used for splicing. The relevant method claims still require target hybridization and modulation of mRNA processing.

Morpholino and peptide nucleic acid compounds

Claims 1, 25, and 31 expressly include morpholino and peptide nucleic acid technologies.

Claim 31 requires morpholino or PNA modification at substantially every backbone linkage. This is materially narrower than claim 1 and is directed to fully modified non-phosphodiester or non-phosphorothioate architectures.

Morpholino compounds are especially relevant to exon-skipping products such as eteplirsen, golodirsen, and casimersen. The patent’s claim language could historically have been relevant to a morpholino product used to redirect splicing, but the patent does not claim the sequences or chemical identities of those later products by name.

Backbone and nucleobase modifications

Claims 20 through 27 address modified backbone linkages and nucleobases.

The claimed backbone configurations include:

Mixed modified and phosphodiester linkages.
Mixed modified and phosphorothioate linkages.
Alternating modified and phosphorothioate or phosphodiester linkages.
Fully modified backbones.
Methylene methylimino linkages.
Morpholino linkages.
PNA linkages.

Claim 27 identifies a C-5 propyne nucleobase. This limitation may be relevant to high-affinity antisense chemistries, but it does not independently establish infringement. The target-binding and mRNA-processing limitations remain applicable.

How strong was the patent estate?

The patent was broad in technical concept but narrower in enforceability than its headline language suggests.

Strengths

It covered a non-cleaving antisense mechanism rather than a single target sequence.
It included multiple generations of antisense chemistry.
It reached exon exclusion, splice-site redirection, polyadenylation, and mRNA stability.
It included method claims that could cover treatment methods without requiring a particular disease.
It addressed both oligonucleotide and non-oligonucleotide antisense architectures.

Limiting features

Claim 1 requires a wild-type cellular mRNA.
The antisense compound must be specifically hybridizable.
The binding must not elicit cleavage of the target mRNA.
The method must actually modulate processing.
The claims do not cover every antisense use.
The patent does not claim a particular sequence, drug substance, formulation, or manufacturing process.
Dependent claims impose substantial structural or positional limitations.

The functional terms “modulation of processing,” “specifically hybridizable,” and “does not elicit cleavage” would have been important claim-construction issues. In litigation, infringement would likely turn on transcript-level evidence, mechanism-of-action evidence, compound structure, and the location of the antisense binding site.

When did US 6,210,892 lose exclusivity?

The patent issued from a nonprovisional application filed in 1998. Under the post-1995 United States patent-term rules, its nominal term ran approximately 20 years from the earliest effective nonprovisional filing date, subject to any patent-term adjustment.[2]

The patent’s enforceable term ended in 2018. It is therefore expired as of 2026. No generic, biosimilar, or antisense developer faces current infringement liability based solely on US 6,210,892.

Milestone	Date
Patent application filing	1998
Patent issued	April 3, 2001
Nominal 20-year term	2018
Current status	Expired
Current blocking value	None from this patent alone

Patent expiration does not eliminate the historical relevance of the patent’s disclosure. Its technical teachings can still affect prior-art analysis, obviousness arguments, freedom-to-operate reviews of later patents, and interpretation of related continuation patents.

What is the Orange Book status of US 6,210,892?

US 6,210,892 is not a drug-product patent listed in the FDA Orange Book. It is a general antisense method patent and does not identify an approved drug, active pharmaceutical ingredient, dosage form, strength, or specific commercial product.

The Orange Book generally lists patents submitted for approved drug products under the Hatch-Waxman framework.[3] This patent’s subject matter is instead relevant to platform technology and method-of-use analysis.

No Orange Book-listed patent status should be inferred for:

Eteplirsen.
Golodirsen.
Viltolarsen.
Casimersen.
Nusinersen.
Other antisense or RNA-targeting products.

Those products are evaluated against their own product-specific patent estates, regulatory exclusivities, and applicable FDA listings.

Does the patent create biosimilar risk?

No. US 6,210,892 does not create current biosimilar risk because it has expired and because its claims are not directed to a biologic reference product.

Antisense oligonucleotides generally do not follow the conventional biosimilar pathway used for protein biologics under section 351(k) of the Public Health Service Act. Depending on the product and regulatory characterization, follow-on developers may use an abbreviated new drug application, a 505(b)(2) application, or another FDA pathway.[4]

The patent could historically have been relevant to a follow-on antisense product if the product used a claimed chemistry and method of splice modulation. That relevance ended with patent expiration, although separate patents may continue to protect a sequence, composition, formulation, dosing regimen, conjugate, or manufacturing process.

How does the patent compare with modern exon-skipping drug patents?

US 6,210,892 is a platform patent. Modern exon-skipping portfolios are usually product-specific.

Patent category	Typical protected subject matter	Relationship to US 6,210,892
Platform method patent	Non-cleaving antisense modulation of mRNA processing	Broad technical foundation
Sequence patent	A defined antisense sequence targeting a defined exon or splice site	Usually narrower and product-specific
Composition patent	A defined oligonucleotide chemistry and sequence	Can remain enforceable after platform expiration
Formulation patent	Salt, buffer, concentration, container, or injectable formulation	Separate protection
Method-of-use patent	Treatment of a named disease or patient population	Separate protection
Manufacturing patent	Synthesis, purification, conjugation, or scale-up process	Separate protection
Regulatory exclusivity	FDA statutory exclusivity for a product	Separate from patent rights

Eteplirsen, golodirsen, viltolarsen, and casimersen all rely on exon-skipping concepts that are technically consistent with the patent’s disclosure. Their commercial protection, however, depends on later patents and regulatory exclusivities rather than the expired 6,210,892 patent.

Nusinersen is another relevant comparison because it is a splice-modifying antisense oligonucleotide with 2′-MOE and phosphorothioate-related chemistry. Its product-specific estate and regulatory status must be analyzed independently.

What formulation and manufacturing protection does US 6,210,892 provide?

The patent does not provide meaningful formulation or manufacturing protection.

The claims do not recite:

A defined injectable formulation.
A pH range.
An excipient.
A concentration range.
A vial or container system.
A purification method.
A solid-state form.
A conjugation process.
A manufacturing impurity profile.
A specific salt or counterion.

A developer could therefore avoid this patent, even before expiration, by using a different method or chemistry that did not satisfy the claimed limitations. Separate formulation and manufacturing patents would have carried the relevant commercial value.

Which companies and products were most exposed historically?

The principal historical exposure involved companies developing splice-modulating antisense compounds.

Company	Relevant product or platform	Technical overlap
Ionis Pharmaceuticals	2′-MOE antisense platform	Direct chemistry and mechanism overlap
Sarepta Therapeutics	Eteplirsen and casimersen	Morpholino exon skipping
NS Pharma	Viltolarsen	Morpholino exon skipping
Biogen and Ionis	Nusinersen	Splice modulation with 2′-MOE chemistry
Earlier antisense developers	Splice-switching and RNA-processing programs	Broad conceptual overlap

The patent’s expiration means that current competition is controlled by later patents, regulatory exclusivity, manufacturing scale, clinical data, reimbursement, and supply reliability.

What generic launch risks remain after patent expiration?

US 6,210,892 presents no current launch barrier. A follow-on developer would instead need to evaluate:

Product-specific composition claims.
Antisense sequence claims.
Formulation patents.
Dosing and treatment-method claims.
Conjugate or delivery patents.
Manufacturing and purification patents.
FDA exclusivity periods.
Clinical and analytical comparability requirements.
State-law substitution and reimbursement restrictions.
Supply-chain and production capacity.

For morpholino products, the most relevant risks are likely to arise from the sequence and composition of the oligonucleotide, not from this expired platform patent. For 2′-MOE products, the same distinction applies: the expired patent does not eliminate later patents covering a specific sequence, target, indication, or formulation.

What litigation and settlement issues matter?

The supplied patent claims do not establish a current litigation or settlement position. The patent’s expiration removes it as a basis for prospective injunctive relief or damages for post-expiration activity.

Historical litigation analysis should distinguish between:

Litigation involving US 6,210,892 itself.
Litigation involving continuation or divisional patents.
Litigation involving later sequence-specific patents.
Inter partes review or post-grant proceedings involving related patents.
Hatch-Waxman Paragraph IV disputes involving approved antisense products.
Contractual settlements and licenses concerning the broader Ionis platform.

A license to Ionis technology would not automatically establish a license to every later patent covering a commercial antisense product. Patent families, continuation claims, and field-of-use provisions must be reviewed separately.

What is the Paragraph IV risk associated with this patent?

There is no current Paragraph IV risk from US 6,210,892 because the patent is expired.

Historically, a Paragraph IV certification could have been relevant only if the patent had been listed for an approved drug and asserted against an ANDA applicant. This patent is a platform method patent and is not an Orange Book drug-product listing.

For current antisense products, Paragraph IV exposure must be assessed against product-specific Orange Book listings and the applicable FDA regulatory pathway. Morpholino and other complex oligonucleotide products may also raise scientific and regulatory issues that are distinct from conventional small-molecule ANDA litigation.

Key Takeaways

US 6,210,892 covers non-cleaving antisense modulation of wild-type cellular mRNA processing.
Its strongest technical applications are splice redirection, exon skipping, altered splice-product ratios, polyadenylation control, and mRNA-stability regulation.
Claim 1 is broad but requires specific hybridization, a listed antisense modification, non-cleaving activity, and actual processing modulation.
Claims 8 through 12 are the most relevant to exon-skipping and splice-site methods.
Claims 19, 25, and 31 address 2′-MOE, morpholino, PNA, and other modified antisense architectures.
The patent does not claim a specific drug, sequence, formulation, dosage regimen, or manufacturing process.
The patent expired in 2018 and creates no current blocking right.
It is not an Orange Book-listed drug patent.
Current commercial risk lies in later composition, sequence, formulation, method-of-use, manufacturing, and regulatory-exclusivity rights.
The patent remains relevant as historical prior art and as part of the technical foundation for modern splice-switching antisense products.

Frequently Asked Questions

Does US 6,210,892 cover eteplirsen?

It covers the general concept of non-cleaving antisense exon skipping and includes morpholino chemistry, but it does not claim eteplirsen by name or sequence. Because the patent expired in 2018, it does not currently block eteplirsen manufacture or sale.

Does US 6,210,892 cover nusinersen?

Nusinersen’s splice-modulating mechanism and modified antisense chemistry are technically related to the patent. Nusinersen’s freedom to operate depends on its own product-specific patents and regulatory rights, not on the expired 6,210,892 patent.

Can a company challenge this patent with an inter partes review?

An inter partes review is not commercially necessary for an expired patent because expired claims cannot ordinarily support a current injunction or post-expiration damages claim. A related unexpired continuation patent would require a separate validity analysis.

Does the patent protect antisense formulations?

No. The claims do not recite a defined formulation, excipient system, concentration, container, or administration vehicle. Formulation protection would have to come from a separate patent.

Does patent expiration eliminate all exon-skipping IP risk?

No. Expiration eliminates the risk from this patent, but later patents may protect the antisense sequence, target exon, chemical composition, indication, dosage regimen, formulation, manufacturing process, or delivery system.

References

United States Patent No. 6,210,892. (2001). Methods of modulating processing of selected mRNA targets. U.S. Patent and Trademark Office.
35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). Regulatory considerations for oligonucleotide therapeutics. Center for Drug Evaluation and Research.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	6271099	⤷ Start Trial
Australia	755515	⤷ Start Trial
Canada	2345354	⤷ Start Trial
European Patent Office	1119579	⤷ Start Trial
European Patent Office	1507005	⤷ Start Trial
Japan	2002526093	⤷ Start Trial
Japan	4223687	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,210,892

Summary for Patent: 6,210,892