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

Pratteln, Switzerland, May 20, 2020 – Santhera Pharmaceuticals (SIX: SANN) announces 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 acceleration of corresponding regulatory filings by approximately one year both in Europe and the US.