Idebenone (Catena/Raxone) Shows Promise in Phase III Study of Patients With Duchenne Muscular Dystrophy
Respiratory function endpoints corroborate previous positive data
The results of secondary respiratory-function endpoints from an on-going analysis of the pivotal phase III DELOS trial in patients with duchenne muscular dystrophy (DMD) have corroborated the positive outcome for the study’s primary endpoint. The data provide further supportive evidence of a treatment benefit for idebenone (Catena/Raxone, Santhera Pharmaceuticals) in DMD.
The new study data were reported May 22 at the Bio€quity Europe 2014 conference, held in Amsterdam.
As previously announced, the DELOS trial met its primary endpoint: the difference between idebenone and placebo in the change from baseline to week 52 in the peak expiratory flow (as percent predicted [PEF%p]). Hospital-based spirometry assessments showed that idebenone significantly reduced the annual decline in PEF%p by 66% compared with patients given placebo. The average annual decline in PEF%p was 3.1% for idebenone (baseline PEF%p: 53.1%; week 52: 50.1% [n = 30]; P = 0.13) compared with 9.0% for placebo (baseline: 54.3%; week 52: 45.3% [n = 27], P < 0.001), for a treatment-group difference in the change from baseline to week 52 of 5.96% (P = 0.04).
The results of secondary endpoints assessing respiratory function in all randomized and treated subjects have corroborated these primary findings. When measured weekly by the patient at home using the hand-held ASMA-1 device (secondary endpoint), idebenone significantly reduced the annual decline in PEF%p by 80% compared with patients given placebo. The ASMA-1 device showed that a significant 9.0% decline in PEF%p occurred between baseline and week 52 in the placebo group (n = 31; P < 0.001) compared with a non-significant decline of 1.8% in the idebenone group (n = 31; P = 0.44), for a treatment-group difference in the change from baseline to week 52 of 7.2% (P = 0.03).
Further, for the forced expiratory volume in 1 second (as percent predicted [FEV1%p]) — an additional endpoint for respiratory muscle strength — idebenone significantly reduced the annual decline by 78% compared with patients given placebo. The annual decline in FEV1%p in the placebo group was 10.7% compared with a decline of 2.4% in the idebenone group (P = 0.03).
Importantly, the outcome for forced vital capacity (as percent predicted [FVC%p]) — a measure of restrictive lung disease predictive of morbidity and mortality in DMD — also supported a treatment benefit of idebenone. The annual decline in FVC%p was reduced by 37% in idebenone-treated patients (9.0% decline in FVC%p in the placebo group vs. 5.7% decline in the idebenone group; P = 0.08).
The DELOS trial was a phase III, double-blind, placebo-controlled study that randomly assigned 64 patients with DMD who were not receiving concomitant corticosteroids to either idebenone tablets (900 mg [300 mg three times daily]; n = 31) or matching placebo (n = 33). The patients’ average age was 14.3 years. Five patients were ambulatory and 59 non-ambulatory at baseline. There were no eligibility criteria for mutational status.
The study was designed to assess the efficacy of idebenone in improving or delaying the loss of respiratory function in patients with DMD not using corticosteroids compared with placebo. The preservation of respiratory function is acknowledged by clinicians and by regulatory authorities as having major clinical importance for patients with DMD.
Source: Santhera Pharmaceuticals; May 22, 2014.