SIDEROS, the largest ongoing trial in Duchenne

Santhera Completes Enrollment of Phase 3 SIDEROS Study with Puldysa® (Idebenone) in Duchenne Muscular Dystrophy (DMD)

Pratteln, Switzerland, May 20, 2020

Original press release

Santhera Pharmaceuticals announces the full recruitment of its Phase 3 SIDEROS study with idebenone in Duchenne muscular dystrophy (DMD). The sample-size and variability re-assessment performed according to study protocol demonstrated that with the currently enrolled patients the study has a very high power (>99%). Given the strong powering of SIDEROS, the Company is now assessing the potential of conducting an interim analysis to test for overwhelming efficacy with a view of completing the trial early.

With patient recruitment into the 18-month international SIDEROS trial in its final stages, Santhera performed the planned sample size and variability re-assessment in accordance with the study protocol to confirm adequate study power. This blinded analysis showed that variability is lower than anticipated per protocol and, with the current number of enrolled patients, the SIDEROS study has a very high power of over 99% to detect a treatment difference. On this basis, Santhera has taken the decision to complete enrollment into the SIDEROS trial. At present, approximately half of the recruited patients in SIDEROS have completed 18 months of treatment and about two-thirds of patients have completed 12 months of treatment.

Owing to the decision to complete enrollment of this advanced study, its very high power as well as the urgent unmet medical need, Santhera is assessing the potential of conducting an interim analysis to test for overwhelming efficacy with a view of completing the trial early. Such an interim analysis would be performed by the independent Data and Safety Monitoring Board (DSMB) to preserve the integrity of the study. If overwhelming efficacy is not established in the interim analysis, the study could continue as planned with the currently enrolled patients and the corresponding high power. However, if overwhelming efficacy is demonstrated, it would be considered unethical to continue with the blinded study and the Company would decide to end the study later this year. This would result in the acceleration of corresponding regulatory filings by approximately one year both in Europe and the US.


Gunnar Buyse, MD, Ph.D., Professor of Child Neurology at the University Hospitals Leuven (Belgium), SIDEROS Principal Investigator and Lead Investigator for Europe – “Santhera is the only company that has dedicated its clinical development program towards finding a treatment to preserve respiratory function in DMD. The large Phase 3 SIDEROS study was designed to confirm the efficacy of idebenone in patients with respiratory function decline who are concurrently taking glucocorticoids. We are truly excited that SIDEROS has completed recruitment and is on track to generate a comprehensive dataset in an area of such high unmet need.”


Oscar Henry Mayer, MD, Medical Director of the Pulmonary Function Testing Laboratory at the Children’s Hospital of Philadelphia and Lead Investigator for the US – “There are currently no approved treatments to slow the rate of respiratory function decline leading to respiratory failure, which remains a leading cause of premature death in young men at the advanced stages of DMD. By slowing the rate of respiratory function decline, we open the possibility of delaying the time to chronic respiratory failure and the need to assisted ventilation and reducing the risk of other life-threatening respiratory complications.”


Sjöblom Nygren, MD, Chief Medical Officer and Head of Development of Santhera – “We are delighted to have reached such an important milestone and wish to express our sincere thanks to patients and families, caregivers, physicians and study personnel for their support and commitment.”



SIDEROS, the largest currently ongoing clinical trial in DMD, is a double-blind randomized placebo-controlled Phase 3 study evaluating the efficacy of idebenone in delaying the loss of respiratory function in patients with DMD. Patients on any stable glucocorticoid treatment scheme and irrespective of the underlying dystrophin mutation or ambulatory status were randomized to receive oral idebenone (900 mg/day three times a day) or placebo for 18 months. The primary endpoint of the trial estimates the treatment difference in FVC%p (forced vital capacity % predicted). Patients completing the trial are offered the opportunity to enroll in an open-label extension study where all patients receive idebenone. The study is currently conducted in 62 sites in the United States, Europe and Israel. Further information is available at ClinicalTrials.gov NCT#02814019.

About idebenone

Idebenone is a synthetic molecular formula similar to coenzyme Q10. Chemically, it is an organic compound of the family of quinones that can slow the loss of respiratory function.

Mitochondria are specialized structures in the human body that serve as batteries, powering various functions of the cell and the organism as a whole.

Mitochondria produce the energy necessary for the cell functioning through a process called “cellular respiration” which requires oxygen and provides energy. During cellular respiration, some toxic forms of oxygen (called oxygen free radicals) can be produced. These free radicals must be neutralized by other substances to avoid cellular damage.

Idebenone is expected to act as a neutralizer of these toxic forms of oxygen. Thus, idebenone is expected to have an antioxidant effect, and consequently prevent cellular damage.

Idebenone is optimized to dissolve in water and lipids and able to cross the mitochondrial membrane.

Idebenone is a medicine that is under investigation for the treatment of DMD. It has not yet been approved by the U.S. FDA, and the safety and efficacy continue to be evaluated in clinical trials.

More about idebenone

About Santhera Pharmaceuticals

Santhera Pharmaceuticals is a Swiss specialty pharmaceutical company focused on the development and commercialization of innovative medicines for rare neuromuscular and pulmonary diseases with a high unmet medical need. Santhera is building Duchenne muscular dystrophy (DMD) product portfolio to treat patients irrespective of causative mutations, disease stage or age. A marketing authorization application for Puldysa® (idebenone) is currently under review by the European Medicines Agency. Santhera has an option to license vamorolone, a first-in-class anti-inflammatory drug candidate with a novel mode of action, currently investigated in a pivotal study in patients with DMD to replace standard corticosteroids. The clinical-stage pipeline also includes lonodelestat (POL6014) to treat cystic fibrosis (CF) and other neutrophilic pulmonary diseases, as well as omigapil and an exploratory gene therapy approach targeting congenital muscular dystrophies. Santhera out-licensed ex-North American rights to its first approved product, Raxone® (idebenone), for the treatment of Leber’s hereditary optic neuropathy (LHON) to Chiesi Group. For further information, please visit www.santhera.com. Raxone® and Puldysa® are trademarks of Santhera Pharmaceuticals.


EU Globe News Wire

Santhera’s SYROS Study Shows Long-term Efficacy with Idebenone in Slowing Respiratory Function Loss in Patients with Duchenne Muscular Dystrophy






Press release from Pfizer about gene therapy

Pfizer’s new phase 1b results of gene therapy in ambulatory boys with Duchenne muscular dystrophy (DMD) support advancement into pivotal phase 3 study

Read the press release here.

Friday, May 15, 2020
Pfizer Inc. announced updated Phase 1b clinical data on PF-06939926, an investigational gene therapy being developed to treat Duchenne muscular dystrophy (DMD). The preliminary data from 9 ambulatory boys with DMD, aged 6 to 12 indicate that the intravenous administration of PF-06939926 was well-tolerated during the infusion period, with encouraging efficacy and manageable safety events, even when considering those adverse events that were more severe in nature. The treatment provided durable and statistically significant improvements across multiple efficacy-related endpoints measured at 12 months post-infusion, including sustained levels of mini-dystrophin expression and improvements on the North Star Ambulatory Assessment (NSAA) rating scale, which is a validated measure of muscle function. Three serious adverse events (SAEs) were recorded, two of which reflected likely complement activation. While these two SAEs were severe in nature, all three events fully resolved within 2 weeks, providing encouragement that close monitoring and early intervention can help mitigate the effects of complement activation. This new dataset, which includes updated 12-month results on safety, dystrophin expression, and exploratory functional endpoints for 3 additional boys, was presented for the first time during a virtual oral session at the American Society of Gene & Cell Therapy (ASGCT) Annual Meeting.


Seng Cheng, Ph.D., Chief Scientific Officer, Pfizer Rare Disease Research Unit – “Based on the encouraging preliminary efficacy data and manageable safety events from our Phase 1b study, we believe we may have a potential breakthrough therapy for boys with Duchenne muscular dystrophy, a devastating disease for which there remains a significant medical need. We are advancing our Phase 3 program as quickly as possible and plan to begin dosing patients in the second half of 2020 pending regulatory approval. Our program has the potential to be the first DMD gene therapy Phase 3 trial start using a commercial-scale manufacturing process. If the program is successful, this manufacturing capability is expected to help position us to deliver this medicine to patients quickly following regulatory approval.”


Preliminary Safety Results

The primary endpoint of the Phase 1b study is to assess the safety and tolerability of this investigational gene therapy in ambulatory boys with Duchenne muscular dystrophy through 12 months following treatment. Based on the data to date, the most common adverse events (AEs) suspected to be related to PF-06939926 (occurring in >40% of patients) were vomiting, nausea, decreased appetite, and pyrexia (fever). There was no evidence of clinically relevant anti-dystrophin responses or hepatic dysfunction with the protocol-defined daily glucocorticoid regimen. Continue reading here.

Results from Secondary and Exploratory Endpoints

Secondary endpoints of the clinical study included measurement of mini-dystrophin concentration by liquid chromatography-mass spectrometry (LCMS) and distribution within muscle fibers by immunofluorescence.

Read more about: dystrophin concentration, dystrophin distribution and the functional assessment here.


Seng Cheng, Ph.D., Chief Scientific Officer, Pfizer Rare Disease Research Unit – “Taken together, we believe these data support the view that administration of PF-06939926 at a dose of 3E14 VG/kg can lead to the expression of potentially therapeutic levels of mini-dystrophin that may translate to a measurable improvement in muscle function and health in DMD patients. We also want to give our heartfelt thanks to all the patients, their families, the researchers, investigators, other clinicians and advocacy organizations for their passion, expertise and engagement in helping to advance clinical research and care for the Duchenne muscular dystrophy community.”


About PF-06939926

PF-06939926 is an investigational, recombinant adeno-associated virus serotype 9 (AAV9) capsid carrying a shortened version of the human dystrophin gene (mini-dystrophin) under the control of a human muscle specific promotor. The AAV9 capsid was chosen as the delivery vector because of its potential to target muscle tissue. Pfizer initiated the Phase 1b multi-center, open-label, non-randomized, ascending dose study of a single intravenous infusion of PF-06939926 in 2018. The goal of the study is to assess the safety and tolerability of this investigational gene therapy. Other objectives of the clinical study include measurement of dystrophin expression and distribution, as well as assessments of muscle strength, quality and function.


About Pfizer

Pfizer’s innovative portfolio focuses on the discovery and development of new medicines and vaccines. By focusing on the best science and patient experience, Pfizer’s leadership and significant investments support faster delivery of breakthrough medicines that can fulfill unmet needs.

Interesting link

La Fondation La Force talks with Dr. Jeffrey Chamberlain, a geneticist at the University of Washington, Seattle, about adenovirus-associated (AAV) micro-dystrophin gene replacement therapy.

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Latest edition of the Catabasis Connection newsletter

La Force is happy to share the latest edition of the Catabasis Connection newsletter with updates on edasalonexent and information that Catabasis shared at the MDA Virtual Poster Session.

Earlier this month, Catabasis shared data from three scientific posters during the Muscular Dystrophy Association (MDA) Virtual Poster Session. Learn more about edasalonexent and its potential to provide positive effects in Duchenne here.

In this newsletter you can read:

  • Boys with Duchenne demonstrate capsule swallowing abilities
  • Phase 3 PolarisDMD trial enrolled expected patient population
  • Age-normative growth and normal adrenal function observed with edasalonexent

About Edasalonexent (CAT-1004)

Edasalonexent (CAT-1004) is an investigational oral small molecule designed to inhibit NF-kB that is being developed as a potential foundational therapy for all patients affected by DMD, regardless of their underlying mutation. In DMD the loss of dystrophin leads to chronic activation of NF-kB, which is a key driver of skeletal and cardiac muscle disease progression. Our ongoing global Phase 3 PolarisDMD trial is evaluating the efficacy and safety of edasalonexent for registration purposes. Edasalonexent is also being dosed in the open-label extension trial GalaxyDMD. In our MoveDMD Phase 2 trial and open-label extension, we observed that edasalonexent preserved muscle function and substantially slowed disease progression compared to rates of change in a control period, and significantly improved biomarkers of muscle health and inflammation. The FDA has granted orphan drug, fast track, and rare pediatric disease designations and the European Commission has granted orphan medicinal product designation to edasalonexent for the treatment of DMD. For a summary of clinical results, please visit www.catabasis.com.

About Catabasis

The mission of Catabasis Pharmaceuticals is to bring hope and life-changing therapies to patients and their families. There lead program is edasalonexent, an NF-kB inhibitor in Phase 3 development for the treatment of Duchenne muscular dystrophy. For more information on edasalonexent and the Phase 3 trial, please visit www.catabasis.com.

About La Force DMD

The Force’s mission is to unite the DMD community to raise awareness around a common objective: that of providing access to new treatments as fast as possible and to participate in the funding of promising research projects. Where access to treatments for rare diseases is concerned, it is essential that our community be strong: each member must be an active spokesperson who helps raise awareness for DMD among the general public, as well as for the challenges associated with access to treatment.


Edasalonexent is an investigational drug that is not yet approved in any territory.