This section highlights FDA-related milestones and regulatory updates for drugs developed by Avidity Biosciences (RNA).
Over the past two years, Avidity Biosciences has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
AOC, AOC, AOC, del-desiran, Delpacibart, and del-zota. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
AOC 1001 - FDA Regulatory Timeline and Events
AOC 1001 is a drug developed by Avidity Biosciences for the following indication: Myotonic Dystrophy type 1 (DM1).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- AOC 1001
- Announced Date:
- October 3, 2024
- Indication:
- Myotonic Dystrophy type 1 (DM1)
Announcement
Avidity Biosciences, Inc. announced that the U.S. Food and Drug Administration (FDA) has removed the partial clinical hold on delpacibart etedesiran (del-desiran/AOC 1001), an investigational treatment designed to address the root cause of myotonic dystrophy type 1 (DM1).
AI Summary
The U.S. Food and Drug Administration (FDA) has removed the partial clinical hold on Avidity Biosciences’ investigational treatment, delpacibart etedesiran (del-desiran/AOC 1001). This treatment targets the root cause of myotonic dystrophy type 1 (DM1) by lowering the levels of DMPK mRNA, a key factor in the disease’s progression. Del-desiran uses a novel approach combining a monoclonal antibody that binds to the transferrin receptor with a siRNA that specifically targets the problematic mRNA.
The FDA’s decision allows the ongoing Phase 3 HARBOR trial to continue evaluating the safety and effectiveness of del-desiran in DM1 patients. DM1 is a progressive neuromuscular disease that currently has no approved therapies, making this development a significant step toward finding a treatment for those affected by this challenging condition.
Read Announcement- Drug:
- AOC 1001
- Announced Date:
- May 8, 2024
- Indication:
- Myotonic Dystrophy type 1 (DM1)
Announcement
Avidity Biosciences, Inc. announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to delpacibart etedesiran (AOC 1001), the company's lead clinical development program, for the treatment of myotonic dystrophy type 1 (DM1). Delpacibart etedesiran, abbreviated as del-desiran, is an investigational treatment designed to address the root cause of DM1, an underrecognized, progressive and often fatal neuromuscular disease with no approved therapies.
AI Summary
The U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to delpacibart etedesiran (AOC 1001), also known as del-desiran. This decision is a key step forward for Avidity Biosciences’ lead clinical development program aimed at treating myotonic dystrophy type 1 (DM1). DM1 is a severe, progressive neuromuscular disease that can be fatal and currently has no approved treatment options. Unlike other approaches, delpacibart etedesiran is designed to target the root cause of the disease, which may help improve outcomes for patients. The Breakthrough Therapy designation by the FDA reflects the drug’s promising potential to address significant unmet medical needs, and it is expected to accelerate the research and development process, bringing the treatment closer to patients who desperately need new solutions.
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AOC 1020 - FDA Regulatory Timeline and Events
AOC 1020 is a drug developed by Avidity Biosciences for the following indication: Facioscapulohumeral Muscular Dystrophy (FSHD).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- AOC 1020
- Announced Date:
- June 12, 2024
- Indication:
- Facioscapulohumeral Muscular Dystrophy (FSHD)
Announcement
Avidity Biosciences, Inc. announced positive initial AOC 1020 data from the Phase 1/2 FORTITUDE™ trial demonstrating unprecedented and consistent reductions of greater than 50% in DUX4 regulated genes, trends of functional improvement, and favorable safety and tolerability in people living with facioscapulohumeral muscular dystrophy (FSHD).
AI Summary
Avidity Biosciences announced encouraging initial results from the Phase 1/2 FORTITUDE™ trial for delpacibart braxlosiran (AOC 1020), an investigational therapy for facioscapulohumeral muscular dystrophy (FSHD). The data showed unprecedented and consistent reductions of over 50% in DUX4 regulated genes at a four‐month assessment in patients treated with a 2 mg/kg dose. These gene expression reductions indicate that the therapy directly targets the underlying cause of FSHD. In addition to the biomarker improvements, trends also pointed to functional benefits such as enhanced muscle strength and improved reachable workspace, along with positive patient and clinician reported outcomes. The treatment was well tolerated, with only mild to moderate adverse events observed. Based on these promising results, Avidity plans to speed up the initiation of registrational cohorts in its ongoing FORTITUDE™ trial.
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AOC 1044 - FDA Regulatory Timeline and Events
AOC 1044 is a drug developed by Avidity Biosciences for the following indication: Designed to deliver phosphorodiamidate morpholino oligomers (PMOs).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- AOC 1044
- Announced Date:
- August 9, 2024
- Indication:
- Designed to deliver phosphorodiamidate morpholino oligomers (PMOs)
Announcement
Avidity Biosciences, Inc. announced positive AOC 1044 5 mg/kg data demonstrated unsurpassed delivery of phosphorodiamidate morpholino oligomers (PMO) concentrations to skeletal muscle, statistically significant increase of 25% of normal in dystrophin production and statistically significant increase of 37% in exon 44 skipping in people living with Duchenne muscular dystrophy mutations amenable to exon 44 skipping (DMD44) in the Phase 1/2 EXPLORE44™ clinical trial.
AI Summary
Avidity Biosciences, Inc. announced positive Phase 1/2 EXPLORE44™ trial results for delpacibart zotadirsen (AOC 1044) in patients with Duchenne muscular dystrophy mutations amenable to exon 44 skipping (DMD44). At a 5 mg/kg dose, the treatment delivered unsurpassed concentrations of phosphorodiamidate morpholino oligomers (PMO) to skeletal muscle. The trial data showed a statistically significant 37% increase in exon 44 skipping and a 25% boost in dystrophin production—reaching 25% of normal levels—with some patients achieving up to 54% of normal dystrophin. Additionally, creatine kinase levels were reduced by over 80% compared to baseline, indicating an improvement in muscle health. The data suggest that delpacibart zotadirsen may offer a transformative treatment approach for DMD44 by enhancing muscle function and slowing disease progression, with a favorable safety and tolerability profile supporting further development and regulatory review.
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del-desiran - FDA Regulatory Timeline and Events
del-desiran is a drug developed by Avidity Biosciences for the following indication: for Treatment of Myotonic Dystrophy Type 1.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- del-desiran
- Announced Date:
- April 8, 2025
- Indication:
- for Treatment of Myotonic Dystrophy Type 1
Announcement
Avidity Biosciences, Inc. announced that the Japan Ministry of Health, Labour and Welfare (MHLW) has granted Orphan Drug designation (ODD) to delpacibart etedesiran (del-desiran) for the treatment of myotonic dystrophy type 1 (DM1), an investigational treatment designed to address the root cause of DM1, an underrecognized, progressive and often fatal neuromuscular disease with no approved therapies.
AI Summary
Avidity Biosciences announced that Japan’s Ministry of Health, Labour and Welfare (MHLW) has granted Orphan Drug designation to its investigational treatment, delpacibart etedesiran (del-desiran), for myotonic dystrophy type 1 (DM1). DM1 is a rare, progressive neuromuscular disease with no approved therapies, and del-desiran is designed to tackle the root cause by reducing harmful DMPK mRNA levels in patients.
This designation, the first for a DM1 treatment in Japan, highlights the urgent need for effective therapies. It also supports Avidity’s global development plans, which include a Phase 3 trial known as HARBOR. The decision reinforces the potential of del-desiran to improve outcomes for people living with DM1, while providing benefits like prioritized regulatory consultations and fee reductions to help speed up its clinical development and eventual approval.
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Delpacibart Braxlosiran - FDA Regulatory Timeline and Events
Delpacibart Braxlosiran is a drug developed by Avidity Biosciences for the following indication: In People Living with Facioscapulohumeral Muscular Dystrophy.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- June 11, 2025
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc. announced that the company will be presenting two oral and one poster presentations at the 32nd Annual FSHD Society International Research Congress, being held June 12-13, 2025, in Amsterdam, the Netherlands.
AI Summary
Avidity Biosciences, Inc. announced it will showcase its latest research at the 32nd Annual FSHD Society International Research Congress in Amsterdam on June 12-13, 2025. The company will deliver two oral presentations and one poster presentation, highlighting important advancements in therapies for facioscapulohumeral muscular dystrophy (FSHD).
Dr. Jeffrey M. Statland will present topline data from the dose escalation cohorts of the Phase 1/2 FORTITUDE trial investigating delpacibart braxlosiran (del-brax). Meanwhile, Dr. Stephen Tapscott will share findings on a novel DUX4-regulated circulating biomarker, offering new insights into FSHD diagnostics. These presentations reflect Avidity’s ongoing commitment to advancing RNA therapeutics through its innovative Antibody Oligonucleotide Conjugates (AOCs). For more details, the research sessions will be available on the company’s website.
Read Announcement- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- June 9, 2025
- Estimated Event Date Range:
- April 1, 2026 - June 30, 2026
- Target Action Date:
- Q2 2026
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc announced that topline data from FORTITUDE™ biomarker cohort in Q2 2026 .
AI Summary
Avidity Biosciences, Inc. has announced promising progress in its Phase 1/2 FORTITUDE program for del-brax, a novel treatment for Facioscapulohumeral Muscular Dystrophy (FSHD). The topline data from the dose escalation cohorts have shown significant improvements in muscle strength, functional mobility, and patient-reported outcomes while also demonstrating rapid and meaningful biomarker reductions. Building on these findings, the company plans to submit a Biologics License Application (BLA) for accelerated approval in the second half of 2026. Crucially, topline data from the FORTITUDE biomarker cohort, with its primary endpoint focused on lowering KHDC1L—a novel DUX4-regulated circulating biomarker—are expected in Q2 2026. These results underscore del-brax’s potential to directly target the underlying cause of FSHD, offering hope for improved quality of life to patients with this progressive and currently untreatable condition.
Read Announcement- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- June 9, 2025
- Estimated Event Date Range:
- July 1, 2026 - December 31, 2026
- Target Action Date:
- H2 2026
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc. announced that Planning accelerated approval BLA submission in H2 2026
AI Summary
Avidity Biosciences recently announced its plan to submit a Biologics License Application (BLA) for accelerated approval in the second half of 2026. The company is advancing its investigational therapy, delpacibart braxlosiran (del‐brax), designed to target the disease-causing DUX4 gene in patients with facioscapulohumeral muscular dystrophy (FSHD). This therapy aims to treat the root cause of FSHD, which leads to progressive muscle weakness and loss of function.
The decision to pursue an accelerated approval pathway follows promising early clinical data from the FORTITUDE study, where del‐brax showed consistent improvements in muscle strength, mobility, and patient-reported outcomes compared to placebo. Avidity hopes that building on these encouraging results will support the accelerated BLA submission and provide an effective treatment option for patients battling FSHD.
Read Announcement- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- June 9, 2025
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc. announced the accelerated approval regulatory pathway in the United States is open for delpacibart braxlosiran (del-brax) in the treatment of facioscapulohumeral muscular dystrophy (FSHD).
AI Summary
Avidity Biosciences recently announced that the accelerated approval regulatory pathway in the United States is now open for its investigational therapy, delpacibart braxlosiran (del-brax), for treating facioscapulohumeral muscular dystrophy (FSHD). Del-brax is designed to target the underlying cause of FSHD by directly inhibiting the DUX4 gene, which is linked to the progressive loss of muscle strength and function. Early clinical data from the FORTITUDE study showed promising signs of improved muscle function and strength for participants receiving del-brax compared to those on placebo.
Based on these positive results, Avidity is pursuing a faster review process for del-brax, with plans to submit a Biologics License Application (BLA) in the second half of 2026. This regulatory pathway could potentially speed up the availability of the first approved treatment for FSHD, offering new hope to thousands affected by this rare, debilitating condition.
Read Announcement- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- June 9, 2025
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc. announced that it has initiated its global, confirmatory, Phase 3 FORWARD™ study intended to support a subsequent full approval package for del-brax for people living with FSHD in the U.S. and additional countries around the world.
AI Summary
Avidity Biosciences, Inc. has launched its global, confirmatory Phase 3 FORWARD™ study for del-brax, an investigational therapy designed to treat facioscapulohumeral muscular dystrophy (FSHD). The study aims to support a full regulatory approval package for del-brax in the United States and other countries around the world. Del-brax targets the gene DUX4, which is responsible for the progression of FSHD, a debilitating neuromuscular disease that leads to significant muscle weakness and loss of function. With promising early data indicating improvements in muscle strength, mobility, and quality of life, this Phase 3 trial marks a crucial step forward in confirming the drug’s clinical benefits. Avidity’s strategy focuses on providing new treatment options for people living with FSHD, addressing unmet medical needs and potentially changing the treatment landscape for this rare disorder.
Read Announcement- Drug:
- Delpacibart Braxlosiran
- Announced Date:
- March 31, 2025
- Indication:
- In People Living with Facioscapulohumeral Muscular Dystrophy
Announcement
Avidity Biosciences, Inc. announced the completion of enrollment in the biomarker cohort in the Phase 1/2 FORTITUDE™ clinical trial of delpacibart braxlosiran (del-brax) in people living with facioscapulohumeral muscular dystrophy (FSHD).
AI Summary
Avidity Biosciences, Inc. recently reached a key milestone by completing enrollment in the biomarker cohort of its Phase 1/2 FORTITUDE™ clinical trial. This phase is studying delpacibart braxlosiran (del-brax) in 51 participants with facioscapulohumeral muscular dystrophy (FSHD), a rare disease that causes progressive muscle weakness. The biomarker cohort is designed to support a potential accelerated approval pathway in the U.S., focusing on changes in DUX4 gene expression, which is linked to the muscle degeneration seen in FSHD.
Early data have shown promising results, including significant reductions in DUX4-regulated gene activity and trends toward improved muscle function. Avidity Biosciences plans to share additional data and key regulatory updates in the near future, moving closer to bringing the first approved therapy for FSHD to patients who currently have no treatment options.
Read Announcement
del-zota - FDA Regulatory Timeline and Events
del-zota is a drug developed by Avidity Biosciences for the following indication: for people living with Duchenne Muscular Dystrophy amenable to exon 44 skipping (DMD44).
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- del-zota
- Announced Date:
- March 17, 2025
- Indication:
- for people living with Duchenne Muscular Dystrophy amenable to exon 44 skipping (DMD44).
Announcement
Avidity Biosciences, Inc. announced positive del-zota topline data from the Phase 1/2 EXPLORE44® trial in people living with Duchenne muscular dystrophy amenable to exon 44 skipping (DMD44) demonstrating consistent, statistically significant improvements in dystrophin, exon skipping and creatine kinase as well as favorable safety and tolerability across the dose cohorts.
AI Summary
Avidity Biosciences recently announced positive topline results from the Phase 1/2 EXPLORE44® trial testing del-zota in patients with Duchenne muscular dystrophy (DMD) who are amenable to exon 44 skipping (DMD44). The data showed consistent and statistically significant improvements in key biomarkers, including increases in dystrophin production and exon skipping, along with a notable reduction in creatine kinase levels, a marker of muscle damage. In addition, del-zota demonstrated favorable safety and tolerability across different dose groups. These promising results suggest that del-zota effectively delivers the treatment components to skeletal and cardiac muscles, offering new hope for patients and families affected by DMD. The positive outcomes underscore the potential of this innovative therapy as it advances toward a planned Biologics License Application submission later this year, marking a significant milestone in the development of new RNA-based treatments for rare neuromuscular diseases.
Read Announcement- Drug:
- del-zota
- Announced Date:
- March 12, 2025
- Indication:
- for people living with Duchenne Muscular Dystrophy amenable to exon 44 skipping (DMD44).
Announcement
Avidity Biosciences, Inc. announced that the company will be presenting one oral and two poster presentations at the 2025 MDA Clinical & Scientific Conference (MDA) in Dallas, Texas, being held March 16-19, 2025 and will host an investor and analyst webcast event on March 17, 2025.
AI Summary
Avidity Biosciences, Inc. announced that it will present one oral and two poster presentations at the 2025 MDA Clinical & Scientific Conference in Dallas, Texas, from March 16-19, 2025. The oral presentation, scheduled for March 19, 2025, will feature topline data from the EXPLORE44 trial, which evaluates del-zota treatment in patients with Duchenne Muscular Dystrophy amenable to exon 44 skipping. Additionally, the company will showcase two poster presentations during the conference. Avidity will also host an investor and analyst webcast event on March 17, 2025, at 8:00 a.m. ET, where management will discuss the latest topline data from the EXPLORE44 trial. These presentations and webcast aim to highlight advances in RNA therapeutics and provide insight into how Avidity’s Antibody Oligonucleotide Conjugates (AOCs™) are being developed to address rare neuromuscular diseases.
Read Announcement
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