A phase Ib/IIa, open-label, multiple ascending-dose trial of domagrozumab in fukutin-related protein limb-girdle muscular dystrophy.

INTRODUCTION/AIMS: In this study we report the results of a phase Ib/IIa, open-label, multiple ascending-dose trial of domagrozumab, a myostatin inhibitor, in patients with fukutin-related protein (FKRP)-associated limb-girdle muscular dystrophy. METHODS: Nineteen patients were enrolled and assigned to one of three dosing arms (5, 20, or 40 mg/kg every 4 weeks). After 32 weeks of treatment, participants receiving the lowest dose were switched to the highest dose (40 mg/kg) for an additional 32 weeks. An extension study was also conducted. The primary endpoints were safety and tolerability. Secondary endpoints included muscle strength, timed function testing, pulmonary function, lean body mass, pharmacokinetics, and pharmacodynamics. As an exploratory outcome, muscle fat fractions were derived from whole-body magnetic resonance images. RESULTS: Serum concentrations of domagrozumab increased in a dose-dependent manner and modest levels of myostatin inhibition were observed in both serum and muscle tissue. The most frequently occurring adverse events were injuries secondary to falls. There were no significant between-group differences in the strength, functional, or imaging outcomes studied. DISCUSSION: We conclude that, although domagrozumab was safe in patients in limb-girdle muscular dystrophy type 2I/R9, there was no clear evidence supporting its efficacy in improving muscle strength or function.

Validity of the 6 minute walk test in facioscapulohumeral muscular dystrophy.

INTRODUCTION: In preparation for future clinical trials, we determined the reliability, relationship to measures of disease severity, and consistency across sites of the 6 Minute Walk Test (6MWT) in patients with facioscapulohumeral muscular dystrophy (FSHD). METHODS: Genetically defined and clinically affected FSHD participants at 2 sites performed the 6MWT, the Timed Up and Go, and the 30 foot Go/Timed 10 meter test as measures of mobility using standard procedures. RESULTS: Eight-six participants representing the full range of severity performed the 6MWT. The mean 6MWT distance was 404.3 meters (SD 123.9), with no difference between sites. The 6MWT was reliable (n = 25; intraclass correlation coefficient = 0.99) and demonstrated moderate to strong correlations with lower extremity strength, functional outcomes, and FSHD Clinical Score. CONCLUSIONS: The 6MWT is reliable and is associated with other measures of FSHD disease severity. Future directions include assessing its sensitivity to disease progression. Muscle Nerve 55: 333-337, 2017.

Bone health in facioscapulohumeral muscular dystrophy: A cross-sectional study.

INTRODUCTION: Herein we provide a comprehensive overview of bone health in facioscapulohumeral muscular dystrophy (FSHD). METHODS: Ninety-four adult individuals with FSHD type 1 from 2 sites were included in this cross-sectional study. Clinical characteristics and determinants of bone health were examined. Relationships between bone mineral density (BMD), strength, and function were explored. RESULTS: Nearly a third of subjects were deficient in vitamin D3 . Mean whole-body BMD z-score was -0.7; 11% of subjects had greater than age-related reductions in whole-body BMD (z-score < -2.0). Whole-body and regional BMDs were associated with strength and function. Thirty-six percent had a history of fractures. Likelihood of fractures was reduced for those with normal whole-body BMD (odds ratio = 0.25, 95% confidence interval 0.04-0.78). DISCUSSION: A diagnosis of FSHD is not necessarily predictive of reduced BMD or increased fracture rate. Given the considerable variability of bone health in the FSHD population, strength and function can serve as predictors of BMD. Muscle Nerve 56: 1108-1113, 2017.

Antisense oligonucleotide targeting DMPK in patients with myotonic dystrophy type 1: a multicentre, randomised, dose-escalation, placebo-controlled, phase 1/2a trial.

BACKGROUND: Myotonic dystrophy type 1 results from an RNA gain-of-function mutation, in which DM1 protein kinase (DMPK) transcripts carrying expanded trinucleotide repeats exert deleterious effects. Antisense oligonucleotides (ASOs) provide a promising approach to treatment of myotonic dystrophy type 1 because they reduce toxic RNA levels. We aimed to investigate the safety of baliforsen (ISIS 598769), an ASO targeting DMPK mRNA. METHODS: In this dose-escalation phase 1/2a trial, adults aged 20-55 years with myotonic dystrophy type 1 were enrolled at seven tertiary referral centres in the USA and randomly assigned via an interactive web or phone response system to subcutaneous injections of baliforsen 100 mg, 200 mg, or 300 mg, or placebo (6:2 randomisation at each dose level), or to baliforsen 400 mg or 600 mg, or placebo (10:2 randomisation at each dose level), on days 1, 3, 5, 8, 15, 22, 29, and 36. Sponsor personnel directly involved with the trial, participants, and all study personnel were masked to treatment assignments. The primary outcome measure was safety in all participants who received at least one dose of study drug up to day 134. This trial is registered with ClinicalTrials.gov (NCT02312011), and is complete. FINDINGS: Between Dec 12, 2014, and Feb 22, 2016, 49 participants were enrolled and randomly assigned to baliforsen 100 mg (n=7, one patient not dosed), 200 mg (n=6), 300 mg (n=6), 400 mg (n=10), 600 mg (n=10), or placebo (n=10). The safety population comprised 48 participants who received at least one dose of study drug. Treatment-emergent adverse events were reported for 36 (95%) of 38 participants assigned to baliforsen and nine (90%) of ten participants assigned to placebo. Aside from injection-site reactions, common treatment-emergent adverse events were headache (baliforsen: ten [26%] of 38 participants; placebo: four [40%] of ten participants), contusion (baliforsen: seven [18%] of 38; placebo: one [10%] of ten), and nausea (baliforsen: six [16%] of 38; placebo: two [20%] of ten). Most adverse events (baliforsen: 425 [86%] of 494; placebo: 62 [85%] of 73) were mild in severity. One participant (baliforsen 600 mg) developed transient thrombocytopenia considered potentially treatment related. Baliforsen concentrations in skeletal muscle increased with dose. INTERPRETATION: Baliforsen was generally well tolerated. However, skeletal muscle drug concentrations were below levels predicted to achieve substantial target reduction. These results support the further investigation of ASOs as a therapeutic approach for myotonic dystrophy type 1, but suggest improved drug delivery to muscle is needed. FUNDING: Ionis Pharmaceuticals, Biogen.