EXONDYS 51 Drug Patent Profile

Which patents cover Exondys 51, and when can generic versions of Exondys 51 launch?

Exondys 51 is a drug marketed by Sarepta Theraps Inc and is included in one NDA. There are eight patents protecting this drug.

This drug has one hundred and twenty-eight patent family members in twenty-three countries.

The generic ingredient in EXONDYS 51 is eteplirsen. One supplier is listed for this compound. Additional details are available on the eteplirsen profile page.

DrugPatentWatch^® Generic Entry Outlook for Exondys 51

Exondys 51 was eligible for patent challenges on September 19, 2020.

By analyzing the patents and regulatory protections it appears that the earliest date for generic entry will be October 27, 2028. This may change due to patent challenges or generic licensing.

There has been one patent litigation case involving the patents protecting this drug, indicating strong interest in generic launch. Recent data indicate that 63% of patent challenges are decided in favor of the generic patent challenger and that 54% of successful patent challengers promptly launch generic drugs.

Indicators of Generic Entry

Summary for EXONDYS 51

International Patents:	128
US Patents:	8
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	1
Clinical Trials:	2
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for EXONDYS 51
What excipients (inactive ingredients) are in EXONDYS 51?	EXONDYS 51 excipients list
DailyMed Link:	EXONDYS 51 at DailyMed

DrugPatentWatch^® Estimated Loss of Exclusivity (LOE) Date for EXONDYS 51

Constraining patent/regulatory exclusivity:

RE48468

NDA:

206488

Dosage:

SOLUTION;INTRAVENOUS

^*The generic entry opportunity date is the latter of the last compound-claiming patent and the last regulatory exclusivity protection. Many factors can influence early or later generic entry. This date is provided as a rough estimate of generic entry potential and should not be used as an independent source.

Recent Clinical Trials for EXONDYS 51

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Sarepta Therapeutics, Inc.	Phase 3
Sarepta Therapeutics	Phase 3
Catabasis Pharmaceuticals	Phase 1/Phase 2

See all EXONDYS 51 clinical trials

Pharmacology for EXONDYS 51

Drug Class

Antisense Oligonucleotide

US Patents and Regulatory Information for EXONDYS 51

EXONDYS 51 is protected by thirteen US patents.

This potential generic entry date is based on patent RE48468.

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-001	Sep 19, 2016		RX	Yes	Yes	9,506,058
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016		RX	Yes	Yes	RE47769		Y
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-001	Sep 19, 2016		RX	Yes	Yes	10,364,431
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-001	Sep 19, 2016		RX	Yes	Yes	RE47769		Y
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016		RX	Yes	Yes	10,364,431
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016		RX	Yes	Yes	RE47751

Expired US Patents for EXONDYS 51

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016	9,018,368
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016	RE47751
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-001	Sep 19, 2016	9,416,361
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-001	Sep 19, 2016	10,533,174
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016	10,533,174
Sarepta Theraps Inc	EXONDYS 51	eteplirsen	SOLUTION;INTRAVENOUS	206488-002	Sep 19, 2016	9,416,361

EU/EMA Drug Approvals for EXONDYS 51

Company	Drugname	Inn	Product Number / Indication	Status	Generic	Biosimilar	Orphan	Marketing Authorisation	Marketing Refusal
AVI Biopharma International Ltd	Exondys	eteplirsen	EMEA/H/C/004355Treatment of Duchenne muscular dystrophy.	Refused	no	no	yes		2018-12-06

International Patents for EXONDYS 51

When does loss-of-exclusivity occur for EXONDYS 51?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Australia

Canada

China

Croatia

Cyprus

Denmark

European Patent Office

Hong Kong

Hungary

Israel

Japan

New Zealand

Poland

Portugal

Slovenia

Spain

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering EXONDYS 51 around the world.

Country	Patent Number	Title	Estimated Expiration
European Patent Office	1954836	Composé destiné à l'immunodépression et procédé de traitement (Immunosuppression compound and treatment method)
Canada	2550642	COMPOSE OLIGONUCLEOTIDIQUE ET METHODE DE TRAITEMENT D'INFECTIONS PAR NIDOVIRUS (OLIGONUCLEOTIDE COMPOUND AND METHOD FOR TREATING NIDOVIRUS INFECTIONS)
Denmark	2607484
Japan	5425396
European Patent Office	2305200	Parure de transfert d'occupant (Occupant transfer topper)
Canada	2741629

Market Dynamics and Financial Trajectory for EXONDYS 51

Last updated: July 27, 2025

Introduction

EXONDYS 51 (eteplirsen) stands as a pioneering therapy in the treatment landscape for Duchenne Muscular Dystrophy (DMD), a severe genetic disorder characterized by progressive muscle degeneration. Approved by the U.S. Food and Drug Administration (FDA) in 2016, EXONDYS 51 is the first exon-skipping drug designed to address a specific mutation subset in DMD patients. Its market performance is shaped by intricate clinical, regulatory, and commercial factors, reflecting broader trends in orphan drug development, personalized medicine, and biotech innovation.

Market Overview

DMD affects approximately 1 in 3,500 to 5,000 male live births globally, translating to an estimated 15,000 to 20,000 patients in the United States and Europe. The disease’s progressive nature leads to loss of ambulation typically by adolescence, followed by respiratory and cardiac failure. The limited treatment options prior to EXONDYS 51 positioned it as a potentially transformative therapy.

The global DMD drug market is projected to grow significantly, driven by increasing diagnostic accuracy, advancements in gene therapies, and growing awareness. As of 2023, the market size for DMD therapeutics is estimated at around USD 600 million, with projections reaching USD 900 million by 2028, according to industry reports.

Clinical and Regulatory Landscape

EXONDYS 51’s mechanism targets exon 51 skipping, applicable to approximately 13% of DMD patients harboring specific mutations. Its FDA approval hinged upon preliminary efficacy data from small-scale studies and surrogate biomarkers, given the rarity of the patient population and ethical considerations limiting large randomized trials.

Regulatory agencies in Europe, Japan, and other key markets have approached its approval cautiously, with some granting conditional or accelerated approvals. The drug’s approval pathway underscores the high unmet need and acceptance of surrogate endpoints in orphan diseases.

Market Dynamics

1. Patient Population and Diagnosis

   The initial market comprises roughly 2,000-3,000 patients in the U.S. eligible for exon 51 skipping, with numbers gradually expanding as genetic testing becomes more widespread. The diagnostic challenge remains significant; many patients are diagnosed late or remain undiagnosed due to limited awareness or access issues. Early and accurate genetic testing directly correlates with the drug’s market penetration.

2. Pricing and Reimbursement

   EXONDYS 51 is priced approximately USD 300,000 annually per patient, aligning with typical costs for orphan drugs. Payers have expressed concerns regarding cost-effectiveness, especially given the clinical benefit data derived from limited trials. Nevertheless, price negotiations, coverage policies, and patient assistance programs influence access.

3. Competitive Landscape

   While EXONDYS 51 is the first FDA-approved exon-51 skipping therapy, competitors like Sarepta Therapeutics’ Vyondys 53 and potentially upcoming gene therapies (e.g., Pfizer’s PF-06939926, Sarepta’s subsequent exon-skipping agents) are emerging. The competitive dynamics are also affected by the potential for combination therapies and personalized medicine approaches.

4. Clinical Development and Label Expansion

   Ongoing studies aim to expand the exon-skipping approach to other mutation subsets, like exon 53 (Vyondys 53) and broader techniques like AAV-mediated gene therapy. Success in these areas could erode the exclusivity and revenue potential of EXONDYS 51.

5. Reimbursement and Market Access Challenges

   Payer restrictions, especially in Europe where health technology assessments (HTAs) scrutinize clinical benefits relative to costs, pose barriers. The perceived modest efficacy prompts continued debate over reimbursement levels and patient eligibility restrictions.

Financial Trajectory

1. Revenue Trends

   Merck, which markets EXONDYS 51 under the name "Vyondys 51" (licensed from Sarepta before Merck’s partnership), reported revenues in the range of USD 100-150 million in peak years (2019-2021). Post-approval, sales were initially modest, reflecting limited uptake, but have gradually increased as awareness and diagnosis improve.

   In 2022, sales modestly increased attributable to expanded patient access, improved reimbursement, and new regional approvals. However, market skeptics cite that revenues may plateau due to slow enrollment and the high price point impacting payer acceptance.

2. Cost of Development and Market Penetration

   The small size of the target population result in high R&D costs amortized over a limited patient base. Regulatory approvals for niche indications require intense investment, but profitability hinges on successful market penetration.

3. Potential for Long-term Growth

   The expansion of genetic testing, advances in biomarker development, and potential pharmacoeconomic data demonstrating slowed disease progression open opportunities for sustained growth. Additionally, acceptance of exon-skipping therapy as standard care may foster broader adoption.

4. Impact of Future Therapies

   The advent of gene therapies, such as SRP-9001 (Sarepta), promises potential cures or substantial disease modification, which could redefine the market landscape and challenge EXONDYS 51’s prominence.

Regulatory and Ethical Considerations

FDA’s accelerated approval pathway facilitated market entry but mandated confirmatory studies to substantiate clinical benefit, a common pathway in orphan drug approvals. Delays or negative outcomes in these studies could impact the drug’s market authorization status and revenue.

Market Challenges

• Efficacy and Value Perception: Limited clinical data supporting durable or significant functional improvements affect payer trust and patient acceptance.
• Pricing Pressures: High costs necessitate strong value demonstration to sustain coverage.
• Market Access: Variations in diagnostic infrastructure and regulatory requirements across regions influence global market growth.
• Competition and Innovation: Emerging therapies threaten sustainability of the current market position.

Strategic Opportunities

• Label Expansion: Broader indications and mutation coverage increase market size.
• Combination Therapies: Synergistic approaches with other modalities could enhance clinical benefits.
• Educational Initiatives: Enhancing diagnosis rates and awareness improve patient access.
• Real-World Evidence (RWE): Post-market data can strengthen value propositions to payers and clinicians.

Conclusion

EXONDYS 51's market trajectory reflects both promise and limitations inherent in personalized orphan drug therapies. While initial adoption faced hurdles, ongoing efforts in diagnosis, expanding indications, and data generation may bolster its long-term commercial viability. However, future breakthroughs in gene editing and regenerative medicine could further reshape the DMD treatment landscape, affecting EXONDYS 51’s market dominance.

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Key Takeaways

• Market Potential: EXONDYS 51 targets a small but unmet patient population, with market size influenced heavily by diagnostic capability and mutation prevalence.
• Pricing and Reimbursement: High patient costs require strategic payer engagement and value demonstration to ensure sustained access.
• Competitive Landscape: Advancements in gene therapies and broader exon-skipping agents threaten market share and reimbursement prospects.
• Regulatory Pathways: Accelerated approvals based on surrogate endpoints pose risks if confirmatory trials do not meet expectations.
• Long-term Outlook: Growth prospects depend on label expansions, improved diagnostics, and evolving treatment paradigms in DMD.

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FAQs

1. What is the primary mechanism of action for EXONDYS 51?
EXONDYS 51 employs exon skipping to restore the reading frame of dystrophin mRNA, enabling production of functional dystrophin protein in muscle cells. It specifically targets exon 51, applicable to patients with mutations amenable to this approach.

2. How does the pricing of EXONDYS 51 compare to other orphan drugs?
Priced around USD 300,000 annually per patient, EXONDYS 51's cost aligns with other high-priced orphan therapies, reflecting the limited patient population and high R&D costs. Payer resistance necessitates demonstrating clinical value.

3. What are the major challenges facing EXONDYS 51’s market growth?
Key challenges include limited clinical efficacy data, high treatment costs, diagnostic and access barriers, and increasing competition from gene therapies and broader exon-skipping strategies.

4. What future developments could impact the market for EXONDYS 51?
Potential breakthroughs in gene therapy, expanded exon-skipping indications, and improved genetic testing capacity could broaden the patient base, but also threaten current market share.

5. How significant is the role of regulatory approvals in shaping EXONDYS 51’s sales?
Regulatory milestones, including initial approval and approval of label expansions, directly influence market access, reimbursement, and revenue streams. Delays or reversals in approval due to confirmatory trial results can significantly impact profitability.

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Sources:

[1] Industry reports on DMD market size and projections
[2] FDA approval documents and label information for EXONDYS 51
[3] Merck financial reports and press releases
[4] Scientific literature on exon-skipping therapies and DMD clinical trials
[5] Payer policy and reimbursement guidelines for orphan drugs