8-K: Avidity Biosciences Reports Unprecedented Del-zota Trial Data

Avidity Biosciences announced positive one-year data from its del-zota trials for Duchenne Muscular Dystrophy, showing significant functional improvements and biomarker changes, and plans for a year-end BLA submission.

Summary

• Avidity Biosciences reported positive one-year data from participants treated continuously with delpacibart zotadirsen (del-zota) in the EXPLORE44 and EXPLORE44-OLE trials for Duchenne Muscular Dystrophy (DMD44).
• The data demonstrated reversal of disease progression and unprecedented improvement compared to baseline and natural history across multiple functional measures.
• Participants showed statistically significant increases of approximately 25 percent of normal in dystrophin production, restoring total dystrophin up to 58 percent of normal.
• Creatine kinase (CK) levels reduced by greater than 80 percent compared to baseline and were sustained at near normal levels for up to 16 months, with 50 percent of participants having CK levels within the normal range at one year.
• Functional improvements were observed in 4-Stair Climb, 10-Meter Walk/Run Test, Time to Rise from Floor, North Star Ambulatory Assessment (stable vs. decline in natural history), and Performance of Upper Limb.
• Del-zota continued to demonstrate favorable long-term safety and tolerability as of the June 2025 data cutoff, with most treatment emergent adverse events (TEAEs) being mild or moderate.
• The company remains on track to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) at year-end 2025, which is the first of three planned BLA submissions over a 12-month period.
• The board of directors approved an amendment to the 2022 Employment Inducement Incentive Award Plan, increasing the authorized number of shares reserved for issuance from 4,500,000 to 8,000,000.

Sentiment

Score: 9

Explanation: The filing presents highly positive clinical trial data for del-zota, showing unprecedented functional improvements and strong biomarker responses in a rare and severe disease. The clear path to BLA submission by year-end 2025 and plans for global approval indicate significant progress and potential for the company.

Positives

• Del-zota demonstrated reversal of disease progression and unprecedented improvement compared to baseline and natural history across multiple functional measures in DMD44 patients.
• Statistically significant increases of approximately 25 percent of normal in dystrophin production were observed, restoring total dystrophin up to 58 percent of normal.
• Creatine kinase (CK) levels rapidly reduced by greater than 80 percent compared to baseline and were sustained at near normal levels throughout the duration of evaluation (up to 16 months).
• 50 percent of participants had CK levels within the normal range at one year of treatment.
• Ambulatory participants improved from baseline in 4-Stair Climb by 2.1 seconds, while the natural history group declined by 2.7 seconds.
• Ambulatory participants improved from baseline in 10-Meter Walk/Run Test by 0.7 seconds, while the natural history group declined by 1.5 seconds.
• Ambulatory participants improved from baseline in Time to Rise from Floor by 3.2 seconds, while the natural history group declined by 1.6 seconds.
• North Star Ambulatory Assessment (NSAA) scores remained stable in del-zota treated participants, while the natural history group declined by 2.4 points.
• Performance of Upper Limb (PUL2) improved from baseline by 1.5 points, while the natural history group declined by 0.7 points, with similar improvements seen in both ambulatory and non-ambulatory participants.
• Del-zota continued to demonstrate a favorable long-term safety and tolerability profile, with most treatment emergent adverse events (TEAEs) being mild or moderate.

Negatives

• One participant discontinued from the EXPLORE44-OLE trial following an event of hypersensitivity.

Risks

• Results of clinical trials are not necessarily predictive of future results.
• Requests for data by the FDA or other regulatory authorities may result in significant additional expense and timing delays.
• Data delivered to regulators may not be satisfactory or support a successful BLA submission, registration, or accelerated approval.
• Inability to establish a novel biomarker as a surrogate endpoint reasonably likely to predict clinical benefit could hinder approval.
• Additional participant data related to del-zota that continues to become available may be inconsistent with previously reported data.
• Unexpected adverse side effects or inadequate efficacy of del-zota may delay or limit its development, regulatory approval, and/or commercialization, or may result in clinical holds, recalls, or product liability claims.
• The company's approach to the discovery and development of product candidates is unproven, and there is no guarantee of developing products of commercial value.
• Potential delays in the commencement, enrollment, and completion of clinical trials and data readouts therefrom.
• Even if approved, the company may not be able to execute successful product launches.
• Dependence on third parties in connection with clinical testing and product manufacturing.
• Regulatory developments in the United States and foreign countries, including acceptance of INDs and similar foreign regulatory submissions, and the proposed design of future clinical trials.
• Fast Track and other designations by the FDA may not lead to a faster development or regulatory review or approval process.
• Ability to obtain and maintain intellectual property protection for product candidates and proprietary technologies.
• The company may exhaust capital resources sooner than expected and fail to raise additional needed funds.
• Natural history data used for comparison may not be precisely matched to del-zota patient data or representative of the DMD44 patient population in other ways.

Future Outlook

Avidity Biosciences is on track to submit a Biologics License Application (BLA) for del-zota to the U.S. FDA by year-end 2025, marking the first of three planned BLA submissions over a 12-month period. The company is also preparing for a confirmatory study to support full global approval and is building commercial infrastructure to ensure access to del-zota, with a potential launch in 2026. Functional data further reinforce the potential for accelerated approval.

Management Comments

• Del-zota has shown unprecedented functional improvement on all key measures demonstrated at one year across EXPLORE44 & EXPLORE44-OLE.
• Compelling biomarker data of muscle health, including rapid, significant, and sustained creatine kinase (CK) reductions, were observed.
• Del-zota continues to exhibit favorable safety and tolerability, with most TEAEs being mild or moderate.
• The company is on track for BLA submission by year-end 2025 and a potential launch in 2026.
• Avidity is committed to commercial readiness to ensure access and has a deep commitment to the patient community.
• The company is finalizing Phase 3 confirmatory study design and preparing a global development pathway.

Industry Context

Avidity Biosciences is positioning del-zota as a potentially transformative treatment for Duchenne Muscular Dystrophy (DMD), specifically targeting the ~900 patients in the U.S. with mutations amenable to exon 44 skipping (DMD44). The positive clinical data, particularly the reversal of disease progression and significant biomarker improvements compared to natural history, suggest a strong competitive profile in the rare disease space. This development follows the company's progress with delpacibart etedesiran (Del-desiran) for DM1 and delpacibart braxlosiran (Del-brax) for FSHD, both of which are on track to be the first globally approved drugs for their respective indications, highlighting Avidity's broader strategy in revolutionizing RNA therapeutics delivery for rare neuromuscular diseases.

Comparison to Industry Standards

• Del-zota demonstrated improvement in 4-Stair Climb (2.1 seconds improvement) compared to a decline in the DMD44 natural history group (2.7 seconds decline) from the PRO-DMD-01 database (N=22 for natural history, N=10 for del-zota).
• Del-zota showed improvement in 10-Meter Walk/Run Test (0.7 seconds improvement) compared to a decline in the DMD44 natural history group (1.5 seconds decline) from the PRO-DMD-01 database (N=22 for natural history, N=10 for del-zota).
• Del-zota improved in Time to Rise from Floor (3.2 seconds improvement) compared to a decline in the DMD44 natural history group (1.6 seconds decline) from the PRO-DMD-01 database (N=19 for natural history, N=6 for del-zota).
• North Star Ambulatory Assessment (NSAA) scores remained stable for del-zota treated participants, whereas the DMD44 natural history group declined by 2.4 points from the PRO-DMD-01 database (N=20 for natural history, N=10 for del-zota).
• Performance of Upper Limb (PUL2) improved by 1.5 points for del-zota treated participants compared to a decline of 0.7 points in a separate published natural history study (Brogna et al, Children (Basel), 2023) (N=27 for natural history, N=17 for del-zota).

Corporate Governance

Stakeholder Impact

• **Shareholders:** Likely positive impact due to strong clinical data, clear regulatory path, and potential for accelerated approval, which could lead to increased share price and future revenue streams.
• **Patients (DMD44):** Highly positive impact as del-zota demonstrated reversal of disease progression and significant functional improvements, offering a potential new treatment option for a severe, rare disease with high unmet medical need.
• **Employees:** Positive impact through the increase in the authorized share pool for the Employment Inducement Incentive Award Plan, enhancing compensation and retention incentives.
• **Regulatory Authorities (FDA):** The company is on track for BLA submission, indicating active engagement and progress towards regulatory review and potential approval.

Next Steps

• Submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) at year-end 2025.
• Prepare for a confirmatory study to support full global approval for del-zota.
• Present additional data from the EXPLORE44 program at upcoming scientific congresses.
• Execute on plans for a potential commercial launch of del-zota in 2026.
• Continue to build commercial infrastructure and ensure access to del-zota.

Key Dates

Recommendation

The filing presents exceptionally strong positive clinical data for del-zota in Duchenne Muscular Dystrophy, demonstrating unprecedented functional improvements and significant biomarker changes compared to natural history. The clear and imminent path to BLA submission by year-end 2025, coupled with plans for global approval and commercial launch, significantly de-risks the asset and points to a substantial market opportunity in a high-unmet-need rare disease. While risks inherent in drug development remain, the reported efficacy and safety profile warrant a strong buy recommendation for long-term investors.

Keywords

Duchenne Muscular Dystrophy, DMD44, del-zota, Avidity Biosciences, RNA therapeutics, clinical trial, BLA, FDA, exon skipping, dystrophin, creatine kinase, EXPLORE44, EXPLORE44-OLE