US Patent 11,771,734: Scope, Claims, Expiration and Elamipretide Patent Landscape for Barth Syndrome

US Patent 11,771,734 protects the use of elamipretide, also known as SS-31, for increasing or normalizing the 18:2 cardiolipin species in patients with Barth syndrome. The patent is a disease-specific method-of-use patent, not a composition-of-matter patent. Its commercial value depends on approval of elamipretide for Barth syndrome and the ability to demonstrate infringement through cardiolipin biomarkers, treatment records, or both.

The patent was issued on October 3, 2023. The patent owner is associated with Stealth BioTherapeutics, the developer of elamipretide. The expected nominal patent-term endpoint is in December 2037, subject to the official USPTO patent-term-adjustment calculation and any patent-term extension.

What does US Patent 11,771,734 protect?

The patent covers a method of treating a mammalian subject with Barth syndrome by administering the peptide:

D-Arg-2′6′-Dmt-Lys-Phe-NH2

This peptide is commonly called elamipretide or SS-31. The core independent claim requires four elements:

A method of treatment.
A mammalian subject having Barth syndrome.
Administration of a therapeutically effective amount of the specified peptide or an acceptable salt.
Increasing or normalizing the 18:2 cardiolipin species.

The patent does not broadly claim every use of elamipretide, every mitochondrial disease, or every cardiolipin-related therapy. The disease limitation and cardiolipin-species limitation materially narrow the claim.

Claim structure

Claim	Subject matter	Legal effect
1	Treatment of Barth syndrome by increasing or normalizing 18:2 cardiolipin with elamipretide or a pharmaceutically acceptable salt	Independent method-of-use claim
2	Human subject	Narrows claim 1 to human treatment
3	Oral, topical, systemic, intravenous, subcutaneous, intraperitoneal, or intramuscular administration	Express route-of-administration alternatives
4	Separate, sequential, or simultaneous administration of a cardiovascular agent	Combination-treatment claim
5	Acetate or trifluoroacetate salt	Salt-specific dependent claim

How should claim 1 be construed?

Claim 1 is a biomarker-linked therapeutic claim. It does not merely require administration of elamipretide to a Barth syndrome patient. It requires that the treatment increase or normalize the 18:2 cardiolipin species.

The likely technical reference is cardiolipin containing linoleoyl chains, particularly the tetralinoleoyl cardiolipin profile associated with mitochondrial membrane function. Barth syndrome results from pathogenic variants in TAZ, which impair cardiolipin remodeling and produce abnormal cardiolipin composition.

The claim therefore has both a disease component and a biochemical outcome component:

Disease: Barth syndrome.
Active agent: exact stereochemical peptide sequence.
Result: increased or normalized 18:2 cardiolipin.
Dose standard: therapeutically effective amount.

A competitor using a different mitochondrial-targeted peptide would not fall within the literal active-agent limitation. A competitor administering elamipretide for another indication, such as primary mitochondrial disease or heart failure, would not infringe unless the patient also has Barth syndrome and the claimed cardiolipin result is present.

Meaning of “18:2 cardiolipin species”

The phrase “18:2 cardiolipin species” is narrower than total cardiolipin. It identifies a molecular species or class based on the fatty-acid composition of cardiolipin. In a litigation setting, the scope would likely turn on:

The analytical method used to identify the species.
Whether “18:2” refers to each acyl chain or an aggregate fatty-acid notation.
Whether a cardiolipin measurement must show a specific numerical increase.
Whether “normalizing” means returning to a healthy reference range.
Whether a physician must measure the biomarker before and after treatment.

The absence of an explicit threshold creates potential claim-construction disputes. The patentee would likely argue that the specification and examples define the relevant cardiolipin species and provide appropriate measurement methods. An accused infringer could argue that the claim lacks an objective boundary if “increasing or normalizing” is not tied to a defined assay or reference range.

What is the scope of claim 2 for human treatment?

Claim 2 limits claim 1 to a human subject. It has direct relevance to commercial use because a marketed Barth syndrome product would be administered to humans.

Claim 1 already covers mammals generally, so claim 2 does not expand the patent. It provides a narrower human-treatment claim that may be easier to align with clinical-trial and prescribing evidence.

For infringement, claim 2 would require evidence that:

The patient has Barth syndrome.
The patient received elamipretide or a covered salt.
The use was directed to increasing or normalizing the claimed cardiolipin species.

What formulations and administration routes are protected?

Claim 3 covers administration orally, topically, systemically, intravenously, subcutaneously, intraperitoneally, or intramuscularly.

The claim is broad as to route but does not expressly claim:

A specific dosage.
A specific dosing interval.
A specific concentration.
A particular excipient.
A defined capsule, tablet, vial, or injectable formulation.
A particular pharmacokinetic profile.

The wording “systemically” may overlap with several listed routes and could be interpreted broadly. The listed routes provide alternative embodiments rather than separate independent inventions.

Are formulation patents protected by US 11,771,734?

No. Claim 3 is a route-of-administration limitation, not a conventional formulation claim. It does not independently protect a pharmaceutical composition containing elamipretide, a particular excipient system, a sustained-release product, or a specific dosage form.

A separate formulation patent could create an additional barrier if it claimed:

A stable elamipretide formulation.
A specific salt or counterion.
A defined injectable composition.
A solid oral dosage form.
A controlled-release delivery system.
A manufacturing or purification process.

Claim 5 provides some salt coverage, but it does not create a comprehensive formulation estate.

What does claim 4 protect regarding cardiovascular agents?

Claim 4 covers treatment in which a cardiovascular agent is administered separately, sequentially, or simultaneously with elamipretide.

The phrase “cardiovascular agent” is broad. Potentially relevant products could include therapies used for:

Cardiomyopathy.
Heart failure.
Arrhythmias.
Blood-pressure management.
Antithrombotic treatment.
Pulmonary vascular complications.

The claim does not identify a particular cardiovascular drug, dose, sequence, or treatment duration. Its practical enforcement value depends on how the term is construed and whether the patent specification supports the full breadth of the category.

A label that instructs use of elamipretide with standard cardiovascular therapy could create greater infringement exposure than a label limited to elamipretide monotherapy. The claim also reaches sequential administration, so a strict same-day combination requirement should not be necessary if the treatment sequence falls within the patent’s construction.

What does claim 5 protect about acetate and trifluoroacetate salts?

Claim 5 specifically covers the acetate and trifluoroacetate salts of elamipretide.

This claim is narrower than claim 1 because claim 1 already covers the peptide and “a pharmaceutically acceptable salt thereof.” Claim 5 identifies two salt forms expressly. Its value is evidentiary and formulation-specific:

It can support infringement where the commercial product uses acetate or trifluoroacetate.
It may provide a fallback claim if broader salt language is challenged.
It may overlap with separate salt, purification, crystallinity, or formulation claims in related patent families.

The claim does not cover every possible salt under its express language, although claim 1 may cover other pharmaceutically acceptable salts if they satisfy the broader claim requirements.

When does US Patent 11,771,734 expire?

The patent issued on October 3, 2023. Its expected nominal expiration is in December 2037, based on a priority chain beginning in December 2017 or an earlier related filing reflected in the patent family. The operative expiration date is the date shown in the USPTO Patent Center patent-term calculation after accounting for:

Patent-term adjustment.
Any terminal disclaimer.
Patent-term extension under 35 U.S.C. § 156.
Patent-term disclaimers associated with related patents.

The patent is therefore positioned as a potential post-approval barrier extending into the late 2030s. Because elamipretide was not FDA-approved for Barth syndrome as of the latest public regulatory records considered here, no Hatch-Waxman patent-term extension had been applied to this patent.

What is the FDA regulatory status of elamipretide?

Elamipretide was an investigational drug and had not received FDA approval for Barth syndrome in the public FDA records available through June 2024.

Stealth BioTherapeutics studied elamipretide in mitochondrial diseases, including Barth syndrome. Clinical development included the BLAZE study, which evaluated elamipretide in patients with Barth syndrome and included cardiolipin-related endpoints.[3]

The regulatory position affects the patent analysis:

There was no approved reference listed drug for an ANDA applicant to copy.
There was no conventional generic-launch pathway for elamipretide in Barth syndrome.
No Orange Book listing was expected for this unapproved indication.
A future NDA approval could create a later Orange Book listing if the patent met FDA listing requirements.
An applicant could pursue a 505(b)(2) pathway for certain products rather than a traditional ANDA, depending on the formulation and regulatory record.

What is the Orange Book status of US Patent 11,771,734?

US Patent 11,771,734 was not an Orange Book-listed patent for an approved elamipretide product as of June 2024.

Orange Book listing is tied to an approved drug application, not simply to patent ownership. If elamipretide later receives FDA approval, the sponsor could seek listing of eligible drug-substance, drug-product, or method-of-use patents. FDA listing would depend on the approved labeling and the statutory listing criteria.

The patent is particularly suited to potential method-of-use listing because its claims are directed to treatment of a defined disease with a defined active ingredient and a defined therapeutic outcome. Whether FDA would accept the listing would depend on the approved indication and labeling language.

Are there Paragraph IV challenges to this patent?

No public Paragraph IV challenge was identified for US Patent 11,771,734 through June 2024.

The absence of a Paragraph IV filing is consistent with the lack of an FDA-approved elamipretide reference product. A Paragraph IV dispute would become commercially relevant only after:

FDA approval of an elamipretide product.
Submission of an ANDA or another applicable abbreviated application.
Patent certification by a generic or follow-on applicant.
Notification to the patent owner and NDA holder.

A future challenger could attack the patent on several grounds:

Lack of enablement for all claimed administration routes.
Lack of written description for the full scope of “increasing or normalizing.”
Indefiniteness of the cardiolipin-species terminology.
Obviousness over earlier elamipretide mitochondrial-disease patents and Barth syndrome biology.
Inherency if cardiolipin normalization necessarily occurs during treatment.
Noninfringement based on failure to measure or achieve the claimed biomarker result.

How strong is the patent estate for elamipretide in Barth syndrome?

The patent has meaningful indication-specific value but is narrower than a composition patent.

Strength factor	Assessment
Active molecule	Strong identification of elamipretide through a specific peptide sequence
Disease limitation	Narrow but commercially aligned with Barth syndrome
Biomarker limitation	Creates technical specificity but may produce construction and proof disputes
Route coverage	Broad in claim 3
Combination coverage	Broad category in claim 4, subject to support and construction
Salt coverage	Useful fallback protection for acetate and trifluoroacetate
Composition-of-matter protection	Not provided by this patent
Generic vulnerability	Limited before product approval; potentially material after approval
Biosimilar vulnerability	Not applicable because elamipretide is a synthetic peptide drug rather than a biologic licensed through the biosimilar pathway
Regulatory leverage	Dependent on FDA approval and labeling
Commercial duration	Potential protection into approximately 2037

The key weakness is that claim 1 is outcome-dependent. A product claim would generally be easier to enforce because manufacture, sale, or use of the claimed composition can be demonstrated directly. Here, the patentee may need to establish the patient population, administration, and cardiolipin outcome.

The key strength is the disease-specific pairing of elamipretide and Barth syndrome. A competitor would need either to avoid the peptide, avoid the indication, avoid the claimed biomarker result, or establish invalidity.

How does this patent compare with composition and general mitochondrial-use patents?

US Patent 11,771,734 occupies the downstream, indication-specific portion of the elamipretide patent landscape.

Patent category	Typical claim focus	Relevance to elamipretide
Composition-of-matter	Peptide sequence, stereochemistry, or structural analogs	Broadest molecule-level protection
Mitochondrial-use patent	Treating mitochondrial dysfunction or oxidative stress	Broader disease coverage, less Barth-specific
Barth syndrome method patent	Treating Barth syndrome with elamipretide	Directly relevant to the claimed indication
Biomarker patent	Altering cardiolipin composition or a defined diagnostic marker	May create proof and assay overlap
Formulation patent	Injectable, oral, salt, stability, or delivery formulation	Can extend product protection beyond method claims
Manufacturing patent	Synthesis, purification, process controls, or scale-up	Can create supply-chain barriers
Combination patent	Elamipretide with cardiovascular or mitochondrial agents	Relevant to labeled combination use

The practical freedom-to-operate analysis must therefore review the entire family portfolio, not only US 11,771,734. A party could avoid this patent yet remain exposed under an earlier composition patent, a formulation patent, or a process patent.

What patent litigation and settlement risks exist?

No publicly identified litigation or settlement agreement was associated with US Patent 11,771,734 through June 2024.

The most likely future dispute would be a post-approval Hatch-Waxman case if an abbreviated applicant challenges an Orange Book listing. A second risk would involve a competing developer using elamipretide in a Barth syndrome clinical program or commercial label.

Potential dispute issues include:

Whether the accused patient population has genetically confirmed Barth syndrome.
Whether elamipretide is administered for the claimed cardiolipin objective.
Whether an increase in one cardiolipin species meets the claim.
Whether the accused formulation is a covered salt.
Whether cardiovascular co-therapy is part of the labeled regimen.
Whether the patent claims are invalid over prefiling clinical or scientific disclosures.

Settlement terms could include a delayed launch, a license for Barth syndrome only, a carve-out label, or restrictions on cardiolipin biomarker claims. No such agreement was publicly reported for this patent in the cited record.

What generic entry risks exist for elamipretide?

Near-term generic risk was low because no FDA-approved elamipretide reference product existed as of June 2024. After approval, the risk would depend on the product’s regulatory classification and the scope of listed patents.

A generic or follow-on applicant could pursue one of three commercial approaches:

Wait for expiration of the relevant composition and method patents.
Challenge listed patents through Paragraph IV certification.
Seek approval with a label that omits the Barth syndrome indication or cardiolipin-related use.

The third approach could reduce literal method-of-use exposure but would not eliminate risk if the product is marketed or promoted for the patented use. Physicians’ off-label prescribing alone generally presents a different infringement analysis from active manufacturer promotion.

What manufacturing and intellectual-property barriers remain?

US Patent 11,771,734 does not appear to be a manufacturing patent. It does not claim synthesis steps, purification parameters, analytical specifications, or production equipment.

Manufacturing barriers may still arise from other patents or trade secrets covering:

Solid-phase peptide synthesis.
Stereochemical control.
Dmt-containing peptide purification.
Salt formation.
Injectable stability.
Impurity control.
Scale-up and batch consistency.

For a synthetic peptide, biosimilar approval is generally not the relevant framework. The principal follow-on pathways would be an ANDA if the product qualifies as a duplicate of an approved reference drug, or a 505(b)(2) application for a materially different formulation, route, or clinical use.

What is the geographic coverage of the patent landscape?

US Patent 11,771,734 provides protection only in the United States. International protection must be assessed separately through the related PCT and national-phase filings.

The commercial landscape may include corresponding applications in:

European Patent Office jurisdictions.
United Kingdom.
Canada.
Australia.
Japan.
China.
Other markets where Barth syndrome treatment could be commercialized.

The existence, enforceability, and expiration of foreign counterparts will differ by jurisdiction. Patent-term adjustment, supplementary protection certificates, prosecution history, claim amendments, and national validation requirements can produce different outcomes from the US patent.

Key Takeaways

US Patent 11,771,734 is a Barth syndrome method-of-use patent for elamipretide, also known as SS-31.
Claim 1 requires both treatment with the specified peptide and an increase or normalization of the 18:2 cardiolipin species.
The patent does not claim elamipretide as a chemical composition.
Claim 3 covers multiple administration routes but does not claim a particular formulation, dose, or delivery device.
Claim 4 covers combination use with a cardiovascular agent administered separately, sequentially, or simultaneously.
Claim 5 specifically covers acetate and trifluoroacetate salts.
The expected nominal expiration is in December 2037, subject to the USPTO’s final term calculation.
Elamipretide had no FDA approval for Barth syndrome and no Orange Book-listed product associated with this patent as of June 2024.
No public Paragraph IV challenge, litigation, or settlement was identified through that date.
Biosimilar risk is not the primary issue because elamipretide is a synthetic peptide rather than a conventional biologic.
The patent’s commercial strength depends on approval, labeling, biomarker measurement, and the broader elamipretide composition, formulation, and manufacturing patent families.

FAQs About US Patent 11,771,734 and Elamipretide

Does US Patent 11,771,734 cover elamipretide for all mitochondrial diseases?

No. The claims are directed to subjects having Barth syndrome. Use for another mitochondrial disease would generally fall outside the literal disease limitation.

Can a competitor avoid claim 1 by not measuring cardiolipin?

Not necessarily. Failure to measure the biomarker may complicate proof, but it does not automatically establish noninfringement. The legal question is whether the claimed increase or normalization occurs and whether the accused use satisfies the claim construction.

Does the patent cover elamipretide acetate?

Yes. Claim 5 expressly identifies acetate as a covered salt. Claim 1 also includes pharmaceutically acceptable salts more generally, subject to the other limitations.

Is elamipretide eligible for a biosimilar application?

The biosimilar pathway is generally designed for biologic products. Elamipretide is a synthetic peptide drug, so a future follow-on product would more likely use an ANDA or 505(b)(2) pathway, depending on FDA classification and product differences.

Could a future FDA label create infringement risk under claim 4?

Yes. A label directing elamipretide use with cardiovascular therapy could increase exposure under claim 4, particularly because the claim covers separate, sequential, and simultaneous administration.

References

United States Patent and Trademark Office. (2023). US Patent No. 11,771,734 B2. United States Department of Commerce. https://patents.google.com/patent/US11771734B2/en
United States Patent and Trademark Office. (n.d.). Patent Center. United States Department of Commerce. https://patentcenter.uspto.gov/
ClinicalTrials.gov. (n.d.). A study of elamipretide in subjects with Barth syndrome. U.S. National Library of Medicine. https://clinicaltrials.gov/
Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files
Schlame, M. (2008). Cardiolipin synthesis and mitochondrial proliferation. Biochimica et Biophysica Acta, 1788(10), 2069-2077. https://doi.org/10.1016/j.bbamem.2009.03.010
United States Congress. (2012). Leahy-Smith America Invents Act, 35 U.S.C. §§ 101-376. https://uscode.house.gov/ӘА

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Stealth Biotheraps	FORZINITY	elamipretide hydrochloride	SOLUTION;SUBCUTANEOUS	215244-001	Sep 19, 2025		RX	Yes	Yes	11,771,734	⤷ Start Trial				METHOD FOR TREATING BARTH SYNDROME IN ADULT AND PEDIATRIC PATIENTS WEIGHING AT LEAST 30KG	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Canada	2916880	⤷ Start Trial
Canada	2916884	⤷ Start Trial
Canada	2916977	⤷ Start Trial
China	105407906	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 11,771,734

Which drugs does patent 11,771,734 protect, and when does it expire?

Summary for Patent: 11,771,734