SIDEROS trial community update from Santhera

May 20, 2020

Dear Duchenne community,

As you know from our previous updates, Santhera’s main focus in the U.S. in the first half of the year has been to bring the SIDEROS clinical study to full enrollment. We are pleased to announce today that the SIDEROS study is fully enrolled, with 254 participants ages 10-34 years old participating in the study. We would like to take this moment to express our deep appreciation to all of the families and young men participating in the SIDEROS study. Your commitment to the study, even in the midst of a global pandemic, has been nothing short of remarkable. It is because of you that the possibility exists to expedite timelines to bring this promising therapy to boys and men with Duchenne in the U.S. We also extend our gratitude to our advocacy partners, including but not limited to, Parent Project Muscular Dystrophy, CureDuchenne, Jett Foundation and Muscular Dystrophy Association, for their efforts to raise awareness about the SIDEROS study.

The SIDEROS study was originally estimated to need 266 participants and a pre-specified analysis was planned to be conducted to confirm this number as we neared full-enrollment. Upon conducting the analysis, we learned that the study population had less variability than expected and the study was powered higher than expected. “Power” is the probability of the experiment finding an effect if there is an effect to be found. A high-powered study means that whatever the results are, they are likely valid and not a result of chance. On the basis of this analysis, Santhera has taken the decision to now complete enrollment into the SIDEROS trial.

In light of the existing COVID-19 pandemic, patient safety and well-being remains our highest priority in all ongoing studies. We continue to support the current study participants and study site investigators for home or local assessments when necessary and requests for direct-to-patient shipping of study medication if needed. Trial participants should reach out directly to their study site team should they have any questions about attending study visits as the country begins to re-open.

In addition to announcing the full-enrollment of the SIDEROS study, Santhera also announced that we will work with the Food and Drug Administration (FDA) and regulatory authorities in Europe to assess the potential to conduct an interim analysis of the SIDEROS study. This means simply that the study’s Data and Safety Monitoring Board (DSMB) will conduct an analysis of the data at an earlier time point than initially planned. Approximately half of the SIDEROS study participants have completed a full 18 months of treatment and about two thirds have completed at least 12 months of treatment. If allowed to conduct an interim analysis, and if that analysis shows overwhelming efficacy, it would be considered unethical to continue with the blinded study. Santhera would then decide to end the study later this year and work with the FDA to pursue regulatory submission in the second quarter of 2021.

What does this mean for the Duchenne community in the U.S.?

Previous feedback from the FDA indicated that they would be open to a submission for approval upon the completion of the SIDEROS study and the results being positive. If the FDA endorses an interim analysis to be performed in the second half of 2020 and the interim analysis shows overwhelming efficacy, then Santhera could work towards a submission for approval in 2021, at least a year ahead of what was initially expected. If the trial continues as originally planned after the interim analysis, then 2022 is the earliest a submission for approval can be pursued in the U.S. All participants in the SIDEROS trial will continue to attend their study visits as planned until otherwise notified. At this time, the U.S. BreatheDMD expanded access program remains closed until an interim analysis is approved and conducted.

Once again, we express our appreciation to the study participants for their dedication to the SIDEROS study during what we recognize as a particularly stressful time for many families across the world. Thank you to the community for helping us achieve full enrollment of the largest ongoing study in DMD.

As a company, Santhera is unyielding in our pursuit of treatments to slow the progression of Duchenne muscular dystrophy. On behalf of Santhera, we will continue to keep you posted on our progress.

With warm regards, 

Dario Eklund                                                                                        Jodi Wolff

Chief Executive Officer                                                                        Head of Patient Advocacy – U.S