At the 2026 MDA Clinical & Scientific Conference in Orlando, researchers from Atossa Therapeutics presented new preclinical data about (Z)-endoxifen and its potential use for Duchenne muscular dystrophy (DMD).
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What Is (Z)-Endoxifen?
(Z)-endoxifen is a compound related to Tamoxifen and belongs to a group of medicines called Selective Estrogen Receptor Modulators (SERMs).
Researchers believe it may influence biological pathways involved in:
- muscle inflammation
- fibrosis (muscle scarring)
- muscle regeneration
Unlike some Duchenne treatments that target specific genetic mutations, (Z)-endoxifen may potentially work across many Duchenne mutations, which could make it applicable to a broader group of patients.
The drug is currently not approved for Duchenne or any other condition.
(Z)-Endoxifen Improves Muscle Strength in Preclinical Study
The study used the mdx5Cv mouse model, one of the most widely used laboratory models for studying Duchenne disease progression.
The results showed several encouraging effects:
- The mdx5Cv Dystrophic mouse model, a trusted, reproducible standard for Duchenne muscular dystrophy (DMD) preclinical research, was used for this study
- (Z)-Endoxifen improved muscle strength and motor performance in both juvenile and adult dystrophic mice
- Treatment enhanced resistance to contraction-induced muscle injury
- Favorable changes were observed in body composition, including increased lean mass and reduced fat mass
- Key biochemical and histologic markers of muscle damage were reduced
- The therapy was well tolerated with no adverse findings observed during the study
Learn More: Biomarkers in DMD
Improvements in Muscle Strength and Performance
The study found that both young and adult dystrophic mice experienced improved muscle function after treatment with (Z)-endoxifen.
Key findings included:
- Increased muscle strength
- Better motor performance
- Greater resistance to muscle injury during contraction
These improvements suggest the therapy may help protect muscle fibers from damage.
Reduced Muscle Damage and Healthier Body Composition
Researchers also observed improvements in several biological markers linked to muscle damage.
The treatment showed:
- Lower levels of muscle damage biomarkers
- Healthier muscle tissue structure
- Increased lean muscle mass
- Reduced body fat
Together, these findings suggest the drug may help address multiple aspects of Duchenne disease progression.
Safety Findings
The therapy was well tolerated in the animal study, and researchers reported no significant adverse effects during treatment.
Although these results are encouraging, the research is still preclinical, meaning it was conducted in laboratory models and not yet in Duchenne patients.
What Happens Next?
The encouraging preclinical results support further research.
Future steps may include:
- Additional laboratory studies
- Safety testing
- Clinical trials in Duchenne patients
The U.S. FDA has already granted Orphan Drug Designation for (Z)-endoxifen in Duchenne muscular dystrophy, recognizing the urgent need for new therapies for this rare disease.
Why New Duchenne Treatments Are Still Needed
Duchenne muscular dystrophy is a rare genetic disease caused by mutations in the dystrophin gene. It leads to progressive muscle degeneration beginning in early childhood.
Children with Duchenne gradually lose muscle strength, which can lead to:
- Loss of walking ability
- Heart complications
- Breathing problems
Despite advances in treatments such as gene therapies and exon-skipping drugs, many families still need additional treatment options.
Follow This Page >>> All Clinical Trials for Duchenne
