The purpose of this research program is to develop safe and effective treatments for hereditary neurological disorders. Specific research accomplishments in the past year include the following: (1) continuation of a randomized, controlled trial of exercise in spinal and bulbar muscular atrophy (SBMA), (2) continuation of a protocol for evaluation of skeletal and cardiac imaging with a trial of oligonucleotide therapy in Duchenne muscular dystrophy (DMD). SBMA is an X-linked, adult onset motor neuron disease. We are nearing completion of a study to examine the safety and efficacy of exercise in SBMA patients.
We aim to enroll 80 men with genetically confirmed SBMA. This is a randomized, evaluator blinded, trial with 25 subjects in each exercise arm. Following informed consent, the subjects undergo initial medical and physical evaluations followed by a series of neurological tests and blood work over a two-day outpatient visit at the NIH. The subjects provide blood work for analysis of hormonal levels and assessment of any potential muscle damage. On the second day of their visit, the subjects are randomized and taught a series of either functional or stretching exercises that they engage in as part of the study and control arms, respectively. Following the baseline visit to NIH, the subjects are monitored throughout the study with telephone contacts and other measures including video recording to monitor their progress and compliance. The subjects return to the NIH at the end of a 12 week period at which time the physical and laboratory testing is repeated. The primary outcome measure used is the Adult Myopathy Assessment Tool . Secondary outcome measures are QMA, the Timed Up and Go test, a quality of life measure (SF-36v2), adverse event questionnaires, a Computerized Dynamic Posturography assessment of balance, accelerometer measurements of exercise effort, and progressive height sit-to-stand testing. Several exploratory biomarkers that may be affected by exercise are being evaluated, including insulin-like growth factor-1 (IGF-1), IGF binding protein 3, testosterone, growth hormone, and creatine kinase. Beck Depression Inventory testing is also being used to determine if the subjects mood is affected by exercise. DMD is the most frequent inherited fatal childhood disease. Antisense oligonucleotide-induced exon skipping is a promising therapeutic strategy for DMD that is currently being explored in clinical trials. Magnetic resonance imaging (MRI) and ultrasound imaging methods are sensitive to key processes in dystrophic muscle such as edema and fat infiltration and therefore could serve as a biomarker of disease progression and therapeutic response. We are completing a study protocol to explore the potential of these imaging biomarkers for assessing the effects of the oligonucleotide GSK2402968 in ambulatory boys with DMD. The primary objective is to assess longitudinal changes in skeletal muscle structural MRI measures reflecting fat and edema in the lower extremities in ambulatory boys with DMD receiving GSK2402968 or placebo. We have enrolled 9 ambulatory boys with DMD. 20 healthy volunteer/control boys matched for the age-range have been recruited to obtain comparative data for the imaging studies. This prospective study of skeletal muscle, cardiac, and diaphragm imaging at the NIH was offered to subjects participating in a phase 2, double blind, exploratory parallel-group, placebo-controlled clinical study in ambulatory subjects with DMD resulting from a mutation that can be corrected by exon 51 skipping induced by GSK2402968. Subjects traveled with a family member to the NIH for MRI and ultrasound assessments during the screening phase of the parent study and additionally, if randomized, then at the following time points in the parent study: at 12 weeks, and 24 weeks during the blinded treatment period;and finally, after completion of 24 weekpost-treatment phase (at 48 weeks). If not randomized, the subjects had a one-time evaluation during the screening phase of the parent study. Data has also been obtained from healthy boys for comparisons to allow exploration of MRI and ultrasound measures specific to pathology in the ambulatory boys with DMD. The primary outcome measure for the study is MRI-detected change in skeletal muscle fat in the lower extremities from baseline in boys with DMD receiving GSK2402968 or placebo. Secondary outcome measures include changes in the following outcome measures at 12, 24, and 48 weeks from baseline in boys with DMD receiving GSK2402968 or placebo: relative muscle fat/water assessed by skeletal muscle MRI T1 imaging, muscle edema assessed by T2 imaging, and cardiac function and myocardial fat and edema as measured by cardiac MRI. Exploratory outcome measures include changes in muscle water diffusivity as assessed by diffusion MRI;the effects of exercise on selected MRI measures in leg muscles, muscle ultrasound to monitor changes in skeletal muscle volume, echogenicity, and stiffness;and MRI assessment of diaphragm motion.
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