Atossa Therapeutics has earned Rare Pediatric Disease (RPD) designation from the U.S. Food and Drug Administration for its experimental therapy, (Z)-Endoxifen, aimed at Duchenne Muscular Dystrophy (DMD). This RPD status broadens the company’s development plan for (Z)-Endoxifen to include a serious pediatric neuromuscular condition and may qualify the program for a Future Priority Review Voucher once a qualifying drug approval occurs.
The designation, granted to drug candidates targeting serious or life-threatening diseases that primarily affect individuals from birth through age 18, can pave the way to a Priority Review Voucher (PRV) upon successful regulatory approval. PRVs can be used to speed up a separate future application or sold or transferred to another sponsor. Over the past year or two, disclosed PRV transactions have ranged between $100 million and $160 million.
Steven Quay, M.D., Ph.D., Atossa’s President and Chief Executive Officer, described the designation as a meaningful regulatory milestone and a robust validation of the underlying science supporting (Z)-Endoxifen’s potential in DMD. He noted that DMD is a devastating childhood illness and stressed the need for options beyond steroids and gene-targeted therapies. Although Atossa’s primary focus remains oncology, this milestone underscores (Z)-Endoxifen’s promise as a versatile platform therapy that could generate non-dilutive value through the Rare Pediatric Disease program.
Janet Rea, MSPH, Atossa’s Senior Vice President of Research and Development, commented that RPD designation provides a clearer regulatory framework and increased FDA interaction as the company maps the clinical development path for DMD. She highlighted encouraging early preclinical results and described (Z)-Endoxifen as a differentiated mechanism—a potent SERM/D with potential applicability across cancer and rare diseases. Unlike exon-skipping approaches, (Z)-Endoxifen does not target a specific genetic defect, which could translate into a broader treatment reach for boys with DMD. Rea also referenced Atossa’s prior IND clearance for Exondys 51® (eteplirsen) and expressed enthusiasm for advancing the (Z)-Endoxifen program further.
About Rare Pediatric Disease Designation
FDA’s RPD designation targets serious or life-threatening diseases affecting individuals from birth to 18 years old that fit the definition of a rare disease under the FD&C Act. The landscape for PRVs is currently shaped by regulatory rules and potential extensions. The timing and availability of new PRV awards depend on legislative actions, such as proposals to extend voucher authority, which have seen progress in Congress but require final enactment.
If the program is renewed, drugs granted RPD designation may become eligible for a PRV upon successful approval of a New Drug Application or Biologics License Application, provided they meet statutory criteria. PRVs can be utilized by the sponsor to accelerate another submission or sold or transferred to another party.
About Duchenne Muscular Dystrophy
Duchenne Muscular Dystrophy is a rare, progressive X-linked neuromuscular disorder caused by mutations in the dystrophin gene. Symptoms typically appear in early childhood and include progressive muscle weakness, loss of the ability to walk, breathing difficulties, and heart muscle disease. DMD remains fatal, usually in early adulthood, and there remains a substantial unmet need for safe, effective, and accessible treatments.
About (Z)-Endoxifen
(Z)-Endoxifen is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with activity across several mechanisms of interest. Atossa is exploring its potential in oncology and rare diseases. The company’s oral formulation has shown a favorable safety profile and pharmacology distinct from tamoxifen, including targeted estrogen receptor effects and PKC inhibition. (Z)-Endoxifen is not approved for any indication at this time.
Atossa’s (Z)-Endoxifen program is supported by a growing global IP portfolio, with multiple recently issued U.S. patents and numerous applications pending worldwide.
About Atossa Therapeutics
Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company developing innovative medicines for oncology and other areas with high unmet medical need. The lead candidate, (Z)-Endoxifen, is being evaluated across several clinical contexts. More information is available at atossatherapeutics.com.
Forward-Looking Statements
This release contains forward-looking statements under securities laws, including expectations about development timelines, regulatory strategies, potential indications for (Z)-Endoxifen, prospects for regulatory approvals, eligibility for a PRV, market opportunities, and other risks. These statements involve risks and uncertainties and are subject to change. Factors that could cause actual results to differ include the timing and success of preclinical and clinical studies, regulatory approvals, potential extensions of the RPD PRV program, Nasdaq compliance, intellectual property matters, macroeconomic conditions, capital needs, and other risks described in Atossa’s SEC filings.
The value of a PRV is variable and influenced by factors outside the company’s control, and past PRV sale prices should not be assumed indicative of future values.
This information is current as of the date of release. Atossa does not undertake an obligation to update forward-looking statements unless required by law.
SOURCE Atossa Therapeutics Inc.
