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Atossa Therapeutics Announces Acceptance of Manuscript Highlighting Utrophin-Modulation Potential of (Z)-Endoxifen in Duchenne Muscular Dystrophy

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Atossa Therapeutics (NASDAQ: ATOS)/b) announced acceptance of a review manuscript in on (Z)-endoxifen as a potential modulator of utrophin pathways in Duchenne muscular dystrophy (DMD).

The article outlines how (Z)-endoxifen may favor utrophin expression and function and proposes preclinical studies and biomarker development as next steps.

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Positive

  • Peer-reviewed manuscript on (Z)-endoxifen in DMD accepted for publication
  • Positions (Z)-endoxifen as a potential modulator of utrophin pathways
  • Highlights mutation-agnostic strategy via utrophin-mediated muscle stabilization
  • Defines concrete next steps, including preclinical evaluation and biomarker development

Negative

  • Current work is a mechanistic review without reported clinical efficacy data in DMD
  • Preclinical evaluation in dystrophin-deficient models is described as a future step

News Market Reaction – ATOS

+2.69%
+2.69% Session close to close

In the May 21 session, ATOS gained 2.69%, reflecting a moderate positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

This announcement adds mechanistic depth to Atossa’s Duchenne muscular dystrophy program by emphasiz...
Analysis

This announcement adds mechanistic depth to Atossa’s Duchenne muscular dystrophy program by emphasizing utrophin modulation as a mutation‑agnostic strategy for (Z)-endoxifen. It follows prior FDA designations in DMD and other rare diseases and builds on earlier DMD-focused publications. Historically, the stock reacted strongly to regulatory wins and key trial data but negatively to rising operating expenses of $9.9M in Q1 2026 and $37.1M in 2025. Watching future clinical data, financing actions, and expense trends remains important when contextualizing such scientific updates.

Historical Context

5 past events · Latest: May 14 (Positive)
Pattern 5 events
Date Event Sentiment 24h Move Catalyst
May 14 KOL event announcement Positive -0.2% Planned virtual KOL event on (Z)-endoxifen in ER-positive breast cancer.
May 08 Q1 2026 earnings Negative -1.2% Higher operating expenses and wider net loss for Q1 2026.
May 06 Phase 2 trial publication Positive +3.9% KARISMA trial showed significant MBD reduction with low-dose Endoxifen.
May 04 Rare disease designation Positive +9.9% FDA Rare Pediatric Disease designation for MAS with PRV potential discussed.
Mar 25 FY 2025 earnings Negative -13.1% Year-end results with higher $37.1M operating expenses versus 2024.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Recent news reactions have mostly aligned with the underlying tone, with four aligned moves and one divergence.

Recent Company History

Over the past few months, Atossa has focused on advancing (Z)-endoxifen across oncology and rare diseases. Key milestones included FDA Orphan Drug and Rare Pediatric Disease designations for Duchenne muscular dystrophy and McCune‑Albright Syndrome, plus positive Phase 2 KARISMA data showing meaningful reductions in mammographic breast density. Financial updates highlighted rising operating expenses (e.g., $37.1M in 2025, $9.9M in Q1 2026) and larger net losses. Today’s DMD-focused mechanistic manuscript builds on this strategy of broadening the scientific and regulatory foundation for (Z)-endoxifen applications.

Key Terms

utrophin, dystrophin, protein kinase C beta-1, estrogen receptor, +4 more
8 terms
utrophin medical
"The review centers on utrophin, a structural and functional homolog of dystrophin."
Utrophin is a naturally occurring protein that helps give muscle cells structural support by acting like a scaffold inside the cell. It matters to investors because many drug developers try to boost or mimic utrophin as a treatment strategy for genetic muscle-wasting diseases; if successful, those therapies could change a company’s clinical and commercial prospects much like fixing a damaged support beam restores a building’s stability.
dystrophin medical
"Utrophin may partially compensate for dystrophin deficiency by supporting sarcolemmal..."
Dystrophin is a large protein that acts like a structural support beam inside muscle cells, helping them withstand the stress of repeated use. It matters to investors because loss or shortage of dystrophin causes serious muscle-wasting diseases, so companies developing tests or treatments that restore or replace this protein can change patient outcomes and create significant commercial and regulatory value — but they also face scientific and approval risks.
protein kinase C beta-1 medical
"...processes, such as protein kinase C beta-1 signaling, estrogen receptor signaling..."
Protein kinase C beta-1 is an enzyme inside cells that functions like a biochemical switch, turning on and off pathways that govern cell growth, blood-vessel behavior and immune responses. For investors it matters because therapies that block or alter this switch are common drug targets for cancers, inflammatory and vascular conditions; clinical trial outcomes, safety findings or regulatory actions involving such drugs can materially affect a company’s pipeline value and stock performance.
estrogen receptor medical
"...such as protein kinase C beta-1 signaling, estrogen receptor signaling, calcium homeostasis..."
A protein inside or on the surface of cells that binds the hormone estrogen and changes how those cells behave, for example by turning certain genes on or off; think of it as a lock that estrogen (the key) fits into to flip a biological switch. Investors care because these receptors are common drug targets and diagnostic markers—knowing whether a disease involves estrogen receptors can affect treatment choices, regulatory approval prospects, and the commercial value of therapies and tests.
calcium homeostasis medical
"...estrogen receptor signaling, calcium homeostasis, inflammation, fibrosis..."
Calcium homeostasis is the body's system for keeping blood and cell calcium levels within a narrow, healthy range, like a thermostat that keeps a room at a steady temperature. For investors, disturbances or drugs that alter this balance matter because they can cause or treat diseases (bone, heart, nerve, or kidney problems), influence a therapy’s safety and effectiveness, and therefore affect clinical trial outcomes, regulatory approval, and commercial value.
fibrosis medical
"...calcium homeostasis, inflammation, fibrosis, mitochondrial function, and muscle regeneration."
Fibrosis is the process where excess scar tissue forms in an organ or tissue, often as a response to injury or long-term damage. This buildup can impair normal function, much like thickening insulation reduces the effectiveness of a wire. For investors, fibrosis is significant because it can signal ongoing health issues that may lead to increased medical costs or influence a company’s performance in healthcare-related sectors.
mitochondrial function medical
"...inflammation, fibrosis, mitochondrial function, and muscle regeneration."
Mitochondrial function describes how well mitochondria — the cell’s tiny power plants — produce energy and keep cells healthy. Investors watch it because many drugs, diagnostics and safety tests target or rely on healthy mitochondria; changes in mitochondrial function can signal a treatment’s effectiveness, side effects, or a new market opportunity in diseases tied to energy failure. Think of it as a company’s engine performance indicator for biological systems.
biomarker medical
"...next steps including preclinical evaluation... and biomarker development focused on utrophin expression..."
A biomarker is a measurable indicator found in the body, such as in blood or tissues, that provides information about health, disease, or how the body responds to treatment. For investors, biomarkers can signal the potential success or risk of medical products or therapies, influencing the value of related companies and industry trends. They act like signals or clues that help assess the progress of medical advancements and their market impact.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Review article accepted for publication in Degenerative Neurological and Neuromuscular Disease and builds on Atossa's previously published Duchenne Muscular Dystrophy (DMD) research

SEATTLE, May 20, 2026 /PRNewswire/ -- Atossa Therapeutics, Inc. (NASDAQ: ATOS) (Atossa or the Company), a clinical-stage biopharmaceutical company developing novel therapies in oncology and other areas of significant unmet clinical need, today announced that the manuscript titled, "(Z)-Endoxifen as a Potential Modulator of Utrophin Pathways in Duchenne Muscular Dystrophy: A Mechanistic and Transcriptomic Perspective," has been accepted for publication in Degenerative Neurological and Neuromuscular Disease.

The review centers on utrophin, a structural and functional homolog of dystrophin. Utrophin may partially compensate for dystrophin deficiency by supporting sarcolemmal and muscle-cell membrane stability when dystrophin is absent or deficient. The manuscript describes how (Z)-endoxifen, the primary active metabolite of tamoxifen, could create a cellular environment that favors utrophin expression, localization, and function, which could potentially influence disease-relevant processes, such as protein kinase C beta-1 signaling, estrogen receptor signaling, calcium homeostasis, inflammation, fibrosis, mitochondrial function, and muscle regeneration. The authors describe (Z)-endoxifen as a compelling mechanistic candidate in treating DMD and identified next steps including preclinical evaluation in dystrophin-deficient models and biomarker development focused on utrophin expression and localization, calcium handling, PKC activity, developmental myosin, transcriptomic signatures, and muscle composition imaging.

"This publication advances our scientific rationale for studying (Z)-endoxifen through the lens of utrophin biology, one of the most compelling mutation-agnostic strategies in DMD," said Dr. Steven C. Quay, M.D., Ph.D., President and Chief Executive Officer of Atossa Therapeutics. "DMD remains a devastating disease with significant unmet need, and we are encouraged by the mechanistic and transcriptomic evidence suggesting that (Z)-endoxifen may help support pathways involved in utrophin-mediated muscle stabilization and repair."

The new article builds on Atossa's previously published DMD manuscript in Degenerative Neurological and Neuromuscular Disease, "A Hypothesized Therapeutic Role of (Z)-Endoxifen in Duchenne Muscular Dystrophy" (L. Remmel, 2025), which introduced the broader rationale for evaluating (Z)-endoxifen in DMD. The accepted manuscript builds upon that work by placing greater emphasis on utrophin pathway biology as a potential unifying mechanism for (Z)-endoxifen's multi-pathway effects.

The manuscript was authored by H. Lawrence Remmel, Sandra S. Hammer, Scott M. Blackburn, and Steven C. Quay. The authors also acknowledge input from Dame Professor Kay E. Davies, CBE FRS FMedSci, Emeritus Fellow of Hertford College, Oxford.

About Duchenne Muscular Dystrophy

DMD is a rare, progressive neuromuscular disease caused by mutations in the DMD gene, which encodes dystrophin, a protein essential for maintaining muscle-cell structural integrity. Loss of functional dystrophin causes muscle fibers to become fragile and susceptible to contraction-induced damage, leading over time to progressive weakness, fibrosis, loss of ambulation, cardiomyopathy, respiratory failure, and premature death.

About Atossa Therapeutics

Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company developing innovative medicines in oncology and other areas of significant unmet need. The Company's lead product candidate, (Z)-endoxifen, is currently in development across several clinical settings.

(Z)-Endoxifen is a potent Selective Estrogen Receptor Modulator/Degrader (SERM/D) with demonstrated activity across multiple mechanisms of interest. Atossa is evaluating its potential applications in oncology and rare diseases. The Company's proprietary oral formulation has shown a favorable safety profile and pharmacology distinct from tamoxifen, including ER-targeted effects and PKC inhibition. Atossa's (Z)-endoxifen is not approved for any indication.

Atossa has previously received Orphan Drug and Rare Pediatric Disease (RPD) designations for (Z)-endoxifen for the treatment of DMD from the FDA. Upon approval of a qualifying marketing application, drugs with RPD designation may be eligible for a Priority Review Voucher (PRV), which can be used to obtain priority review for a future application or may be sold or transferred to another sponsor. In the last 18-24 months, disclosed PRV sales have ranged from $100-$205 million.

Atossa's (Z)-endoxifen program is supported by a growing global intellectual property portfolio, including multiple recently issued U.S. patents and numerous pending applications worldwide.

More information is available at https://atossatherapeutics.com.

Forward-Looking Statements

This press release contains certain "forward-looking statements" within the meaning of applicable securities laws, including, but not limited to, our expectations regarding the Company's development and regulatory strategy and related milestones, including the potential indications that the Company may pursue for (Z)-endoxifen, the potential role of (Z)-endoxifen in utrophin pathway modulation, expectations regarding the design, enrollment, data, timing, results and outcomes of the Company's clinical studies, the potential for (Z)-endoxifen to receive regulatory approval and the timing thereof, the Company's potential eligibility for and the value of a Rare Pediatric Disease Priority Review Voucher, and the potential market and growth opportunities for the Company. Words such as "expect," "potential," "continue," "may," "will," "should," "could," "would," "seek," "intend," "plan," "estimate," "anticipate," "believe," "design," "predict," "future," or other similar expressions or statements regarding intent, belief or current expectations, are forward-looking statements.

Forward-looking statements in this press release are subject to risks and uncertainties that may cause actual results, outcomes, or the timing of actual results or outcomes to differ materially from those projected or anticipated, including, without limitation, risks and uncertainties associated with: our ability to successfully execute our strategy to shorten our clinical development timelines and pursue a DMD indication or other indications for our lead program, (Z)-endoxifen; expected timing, completion and results of our preclinical studies, clinical trials and research and development programs; the unpredictable relationship between preclinical study results and clinical study results; the timing or likelihood of regulatory filings and approvals; the outcome or timing of necessary regulatory approvals; our ability to maintain compliance with Nasdaq listing requirements; our ability to establish and maintain intellectual property rights covering our products; the impact of general macroeconomic conditions on our business; our ability to raise capital; and other risks and uncertainties detailed from time to time in Atossa's filings with the SEC, including, without limitation, its Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q.

The market value of a PRV is variable and subject to a number of factors beyond our control and reported past PRV sale amounts are not necessarily indicative of PRV sale amounts in the future.

Forward-looking statements are presented as of the date of this press release. Except as required by law, we do not intend to update any forward-looking statements.

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SOURCE Atossa Therapeutics Inc

FAQ

What did Atossa Therapeutics (NASDAQ: ATOS) announce about (Z)-endoxifen and Duchenne muscular dystrophy on May 20, 2026?

Atossa announced acceptance of a review manuscript on (Z)-endoxifen as a potential utrophin-pathway modulator in Duchenne muscular dystrophy. According to Atossa, the article in Degenerative Neurological and Neuromuscular Disease details mechanistic and transcriptomic evidence supporting further evaluation in DMD.

How could (Z)-endoxifen potentially help patients with Duchenne muscular dystrophy (ATOS)?

(Z)-endoxifen may help by creating a cellular environment that favors utrophin expression, localization, and function. According to Atossa, this could affect pathways linked to calcium homeostasis, inflammation, fibrosis, mitochondrial function, and muscle regeneration relevant to Duchenne muscular dystrophy.

What is utrophin and why is it important in Atossa Therapeutics’ DMD research with (Z)-endoxifen?

Utrophin is a structural and functional homolog of dystrophin that may partially compensate when dystrophin is deficient. According to Atossa, the manuscript emphasizes utrophin biology as a potential unifying mechanism for (Z)-endoxifen’s multi-pathway effects in Duchenne muscular dystrophy.

What are the next research steps for Atossa’s (Z)-endoxifen program in Duchenne muscular dystrophy?

Next steps include preclinical evaluation of (Z)-endoxifen in dystrophin-deficient models and biomarker development. According to Atossa, biomarkers will focus on utrophin expression and localization, calcium handling, PKC activity, developmental myosin, transcriptomic signatures, and muscle composition imaging.

Does the new Atossa Therapeutics manuscript provide clinical trial data for (Z)-endoxifen in DMD?

No, the manuscript is a mechanistic and transcriptomic review and does not report clinical trial outcomes. According to Atossa, it advances scientific rationale and outlines future preclinical work rather than presenting patient-level efficacy or safety data in Duchenne muscular dystrophy.

How does this new DMD manuscript build on Atossa Therapeutics’ earlier (Z)-endoxifen publication?

The new manuscript builds on a prior hypothesis paper by placing greater emphasis on utrophin pathway biology. According to Atossa, it refines the mechanistic rationale by proposing utrophin modulation as a central explanation for (Z)-endoxifen’s multi-pathway effects in Duchenne muscular dystrophy.