In a bold advancement for pediatric neuromuscular care, Atossa Therapeutics announces that the FDA has granted Rare Pediatric Disease (RPD) designation to (Z)-Endoxifen for Duchenne Muscular Dystrophy (DMD).
This designation broadens the (Z)-Endoxifen program into a challenging, life-threatening pediatric condition and could position Atossa to qualify for a future Priority Review Voucher (PRV) upon regulatory approval. PRVs can be used to speed up the review of another drug or sold or transferred to another sponsor, with recent disclosed sales ranging between $100 million and $160 million depending on the deal.
Atossa, a clinical-stage biopharmaceutical company focused on oncology and other areas of high unmet need, stated that the RPD designation represents an important regulatory milestone and a strong validation of the scientific basis for using (Z)-Endoxifen as a potential treatment option for DMD. Duchenne is one of the most devastating childhood diseases, and families urgently need safer, more effective alternatives beyond steroids and targeted genetic approaches. While oncology remains Atossa’s primary focus, this milestone highlights the potential of (Z)-Endoxifen as a versatile platform therapy that could generate non-dilutive value through the RPD program.
Janet Rea, MSPH, Atossa’s Senior Vice President of Research and Development, commented that RPD designation provides a clear regulatory framework and closer FDA collaboration as the company maps the clinical development path for DMD. She noted encouraging preclinical data and the potential of (Z)-Endoxifen as a differentiated mechanism—a potent SERM/D (Selective Estrogen Receptor Modulator/Degrader). Unlike exon-skipping therapies that target specific genetic mutations, (Z)-Endoxifen could offer a broader and more accessible treatment approach for boys with DMD. Rea also reflected on Atossa’s prior IND clearance for Exondys 51® (eteplirsen) and expressed enthusiasm for advancing the DMD program.
About Rare Pediatric Disease Designation: The FDA grants RPD designation to drugs aimed at serious or life-threatening conditions that primarily affect individuals from birth to 18 years old and that meet the FD&C Act’s definition of a rare disease. If a qualifying product advances to approval, it may be eligible for a PRV under the applicable law, subject to specific conditions and renewal status of the program.
The current regulatory landscape for PRVs hinges on ongoing legislative developments. The Mikaela Naylon Give Kids a Chance Act seeks to extend voucher authority through 2029 with retroactive effect, and the bill awaits Senate action. If renewed, RPD-designated drugs could be eligible for a PRV upon approval of a New Drug Application or Biologics License Application, provided they meet all statutory criteria. PRVs can be used by the sponsor or sold to another company.
About Duchenne Muscular Dystrophy: DMD is a rare X-linked neuromuscular disorder caused by mutations in the dystrophin gene. Symptoms typically emerge in early childhood and progress to muscle weakness, loss of ambulation, respiratory challenges, and cardiomyopathy. DMD remains fatal in early adulthood despite advances in treatment, underscoring a substantial ongoing need for safe, effective, and accessible therapies.
About (Z)-Endoxifen: This compound is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with activity across multiple mechanisms of interest. Atossa is exploring its potential in oncology and rare diseases. The company’s proprietary oral formulation has demonstrated a favorable safety profile and pharmacology distinct from tamoxifen, including ER-targeted effects and PKC inhibition. (Z)-Endoxifen is not yet approved for any indication.
Atossa’s program is supported by a growing global intellectual property portfolio, including recently issued U.S. patents and multiple pending applications worldwide.
About Atossa Therapeutics: Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company pursuing innovative medicines for oncology and other areas of significant unmet need. The company’s lead candidate, (Z)-Endoxifen, is being developed across multiple clinical settings. More information is available at atossatherapeutics.com.
Forward-looking statements: This release includes forward-looking statements about development plans, regulatory milestones, potential indications for (Z)-Endoxifen, and the PRV program. These statements involve risks and uncertainties that could cause actual results to differ materially, including regulatory timelines, trial outcomes, funding considerations, and changes in government policy affecting PRVs. Readers are cautioned not to rely on these statements, which speak only as of the date of this release. Atossa disclaims any obligation to update them except as required by law.
Source: Atossa Therapeutics Inc.
