Mezzion Announces U.S. Patent Allowance Strengthening Udenafil Exclusivity in Fontan Patients

Key method-of-use patent expected to extend U.S. protection for JURVIGO^® (udenafil) into the early 2040s, pending FDA approval and extensions

FORT LEE, N.J., Dec. 3, 2025 /PRNewswire/ -- Mezzion Pharmaceuticals, Inc. (Mezzion), a clinical-stage rare disease biopharmaceutical company developing the first treatment specifically for people born with single ventricle congenital heart disease (SV-CHD) who are living with Fontan circulation, today announced that the United States Patent and Trademark Office (USPTO) has issued a Notice of Allowance for a key U.S. patent application from the company's 2020-filed FUEL patent family covering the use of udenafil to improve exercise capacity in Fontan patients.

The allowed patent includes broad, age-agnostic method-of-use claims covering chronic, twice-daily oral administration of udenafil (or a pharmaceutically acceptable salt) in Fontan patients to improve exercise capacity, with important dependent claims extending to additional cardiopulmonary exercise testing (CPET) endpoints.

The patent is expected to have a baseline expiration date of July 24, 2040. Subject to FDA approval of udenafil and regulatory review, Mezzion anticipates that the patent will be eligible for listing in the FDA's "Orange Book" and for patent term extension of up to five years, capped at 14 years from approval, with additional six-month pediatric exclusivity potentially extending U.S. protection into the early 2040s. Together, these protections, if granted, are expected to provide a long U.S. exclusivity runway and could delay meaningful generic competition into the next decade.

"This allowance marks a pivotal milestone in our long-term strategy for JURVIGO," said Dean Park, Chairman and CEO of Mezzion. "It reflects years of work with investigators, families and advocates in the Fontan community, and it helps ensure that, if approved, JURVIGO can be supported, studied and made available to people living with Fontan circulation for many years to come. A stronger and longer U.S. patent position gives us greater confidence to keep investing in the FUEL program and future innovations for the Fontan community."

Mezzion is developing JURVIGO^® (udenafil), a highly selective oral PDE5 inhibitor, as the first potential approved pharmacotherapy for approximately 70,000 individuals living with Fontan physiology worldwide. The Fontan community currently has no FDA-approved treatment options and faces high morbidity and mortality. Recent health-economic analyses from Additional Ventures and others estimate that complex congenital heart disease imposes an annual economic burden in the United States of approximately $74 billion. The ongoing global confirmatory Phase 3 FUEL-2 trial is currently enrolling patients in the U.S. and Asia, with European sites in start-up.

About Mezzion Pharmaceuticals
Mezzion Pharmaceuticals, Inc., a U.S.-based subsidiary of Mezzion Pharma Co., Ltd. (KOSDAQ: 140410), is a late-stage biopharmaceutical company focused on developing therapies for rare and underserved diseases. Mezzion is advancing JURVIGO^® (udenafil), an investigational oral PDE5 inhibitor, through a global Phase 3 program as a potential first-in-class therapy for patients with single ventricle congenital heart disease and Fontan physiology. JURVIGO is an investigational drug and has not been approved by the U.S. Food and Drug Administration (FDA) or any other regulatory authority, and its safety and efficacy have not been established. For more information, visit www.mezzion.com and www.FUEL2Study.com.

Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding the scope and duration of patent protection, potential Orange Book listing and patent term extension, regulatory approvals and the development and commercialization of udenafil. Actual results may differ materially from those expressed or implied due to risks and uncertainties, including changes in USPTO or FDA decisions or policies, the outcome and timing of clinical development, the possibility that regulatory approvals may be delayed or not obtained, and other factors. Mezzion undertakes no obligation to update forward-looking statements except as required by law.

Trademarks
JURVIGO^® is a registered trademark of Mezzion Pharma Co., Ltd.

Media Contacts:
John Presser, EVP, CBO: john.presser@mezzion.com
Mr. Sung-Il Noh, CFO: sung-il.noh@mezzion.com

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SOURCE Mezzion Pharmaceuticals, Inc