Abstracts that will be presented in World Muscle Society Meeting 2014

DMD/BMD Human Trials

Pilot study of flavocoxid in ambulant DMD patients

S. Messina, G.L. Vita, N. Licata, M. Sframeli, A. Bitto, M.G. Distefano, C. Barcellona, M. La Rosa,S. Romeo,  A. Ciranni, M. Aguennouz, F. Squadrito, G. Vita

Muscle degeneration in Duchenne muscular dystrophy (DMD) is exacerbated by the endogenousinflammatory response and increased oxidative stress. A key role is played by nuclear factor (NF)-κB. We previously showed that flavocoxid, a flavonoid with antioxidant and anti-inflammatory properties, ameliorates muscle pathology and function in mdx mice. This effect seemed to be mediated by the inhibition of NF-κB,tumor necrosis factor-α, cyclooxygenase-2/5-lipoxygenase and MAPKs expression in muscle. Moreover, flavocoxid has been shown to decrement serum levels of IL-1β and TNF-α in in vivo studies. Primary end-point of this pilot study was to evaluate safety and tolerability of flavocoxid administered daily per os for one year in ambulant DMD patients. We also evaluated function, muscle strength and quality of life. The effects of flavocoxid on selected biomarkers was also assessed. We enrolled 20 patients. We did not report any treatment-related adverse event and clinically meaningful change in laboratory findings. Serum expression analysis of inflammatory cytokines showed a significant reduction of TNF-α and IL-1β and oxidative stress markers (p < 0.05). The results of the multidimensional clinical evaluation showed an overall stabilization of clinical course, even in patients older than 7 years who showed a deterioration in the year before baseline. Moreover, a significant worsening of North Star Ambulatory Assessment was shown at 6 months after end of treatment compared to all trial time points (p < 0.05). We demonstrated that flavocoxid at this dosage is safe, also in pediatric age and in association with corticosteroids, and able to exert its biological effects on inflammatory pathways relevant to DMD pathogenesis.

CAT-1004, a novel anti-Inflammatory agent under development for treatment of Duchenne muscular dystrophy

J. Milne, J. Donovan, L. Sweeney, M. Sleeper, D. Hammers, M. Jirousek,  M. Curtis

 In DMD, inflammation is driven by elevated NF-κB in muscle and occurs early in life, with resident immune cells driving muscle degeneration. Corticosteroids block inflammation and delay loss of ambulation and onset of cardiac and respiratory failure, but chronic use has significant adverse effects. CAT-1004 is a novel compound that inhibits NF-κB and is in development to treat chronic inflammation in DMD. In the mdx mouse model, CAT-1004 reduced muscle inflammation and degenerating fibers, and increased regenerating muscle fibers. In the Golden Retriever Muscular Dystrophy (GRMD) model, a single dose of CAT-1004 reduced both baseline and lipopolysaccharide (LPS) induced NF-κB activity and production of plasma TNF-α. Long term mdx and GRMD studies have demonstrated improvement in muscle function such as diaphragm. In long term mdx mouse studies, cumulative distance run increased. Preclinical studies did not identify dose limiting toxicities of CAT-1004 at equivalent doses several-fold higher than clinical doses. Phase 1 clinical studies assessed single doses of CAT-1004 (300 mg to 6000 mg, n = 52) and multiple doses for 14 days (500 mg to 4000 mg, n = 44). In a single dose study (n = 9), CAT-1004 effects on NF-κB activity were evaluated after ex vivo stimulation of peripheral blood mononuclear cells with LPS. Safety was evaluated by adverse events, laboratories, physical exam and EKG. Subjects tolerated CAT-1004 well, with no clinically significant changes in EKG, physical exam, or laboratories. Most common adverse events were headaches and diarrhea. Biomarkers at both the gene and protein level demonstrated significant inhibition at multiple points in the NF-κB pathway following CAT-1004. A single dose of CAT-1004 produced a 70 percent reduction in NF-κB activity, in peripheral blood mononuclear cells. Phase 2 studies of CAT-1004 in DMD patients are planned. CAT-1004 may represent a steroid-sparing approach to slow muscle degeneration and improve function in DMD patients.

Utrophin modulators to treat Duchenne muscular dystrophy (DMD): Results from the Phase 1b safety and PK study in DMD boys dosed with SMT C1100

F. Muntoni, S. Spinty, H. Roper, I. Hughes, V. Ricotti, A. Bracchi, G. Horne, J. Tinsley

 The continual expression of utrophin protein by pharmacological maintenance of utrophin transcription indystrophin deficient muscle fibres is a potential disease modifying treatment for Duchenne muscular dystrophy (DMD). SMT C1100 is a small molecule utrophin modulator demonstrating significant benefit on the muscular dystrophy in the dystrophin deficient mdx mouse. Assessment of the in vitro and in vivo pharmacology plus the clean toxicology and safety data from the pre-clinical work led to the nomination of SMT C1100 as the first candidate for evaluation in DMD clinical trials. We previously reported that SMT C1100 successfully completed a Phase 1 healthy volunteer trial in which an oral paediatric formulation was deemed safe and well tolerated with plasma levels above those determined to be effective to modulate utrophin levels ex-vivo in DMD myoblasts and dystrophin deficient mdx mice. The first DMD paediatric patient trials of SMT C1100 started with an open-label, single and multiple oral dose finding Phase 1b study in DMD boys earlier this year. The purpose of the study was to determine whether increasing doses of SMT C1100 were safe, well tolerated and to understand the pharmacokinetic properties in patients with DMD. The boys were studied in 3 groups (Groups A to C), with each group consisting of 4 patients aged between 5 to 11 years. The doses for Groups A to C were administered in an escalating manner after safety review for each dose group. We will present the summary data from this trial.

Internal consistency and robustness of clinical efficacy data from the phase 2b study of ataluren (PTC124®) in nonsense mutation Duchenne muscular dystrophy

G.L. Elfring, A. Reha, R. Spiegel, S.W. Peltz, C. McDonald

Ataluren is an oral, investigational drug designed to promote ribosomal readthrough of premature stop codons in mRNA, leading to production of full-length, functional protein. In a Phase 2b, 48-week study in nonsense mutation Duchenne muscular dystrophy (nmDMD), ataluren 40 mg/kg/day was associated with slowing of ambulatory decline (measured by 6-min walk distance [6MWD]) vs placebo. Positive trends were also seen in timed function tests of stair-climbing, stair-descending, and walking/running 10 m. Treatment differences vs placebo were larger in an ambulatory decline phase subgroup (7–16 yrs old, oncorticosteroids, baseline 6MWD ¡Ý150 m but %-predicted 6MWD ¡Ü80%). Internal consistency and robustness of physical function outcomes were evaluated by statistical methods. Endpoint analyses were repeated 1000 times (Monte Carlo simulation), each time with 10% of patients in each arm excluded at random. Separately, endpoint analyses were performed after excluding one or more extreme results (best/worst exclusion) from each arm. These methods were applied to the overall study population and ambulatory decline phase subgroup. Monte Carlo simulation demonstrated that treatment differences in model-estimated mean change in 6MWD of ∼ 30 m in the overall study population and ∼45 m in the ambulatory decline phase subgroup, favoring ataluren vs placebo, were not driven by a small number of patients. Best/worst exclusion analysis confirmed these treatment differences were not distorted by outliers. Timed function test outcomes were consistent with 6MWD findings. Ambulatory decline in patients with nmDMD could potentially be delayed or stabilized with disease-modifying treatment. These analyses document the internal consistency and give evidence of robustness of the Phase 2b efficacy data for ataluren in nmDMD, confirming observations of relative stabilization of ambulatory measures of disease progression over 48 weeks with ataluren.

Follistatin Gene Therapy for Becker Muscular Dystrophy

J.R. Mendell,  Z. Sahenk, L.R. Rodino-Klapac, K.R. Clark, K.R. Lewis, K. Shontz, S. Al-Zaidy, L. Alfano, L.P. Lowes,, K. Berry, V. Malik C.J. Shilling, X.Q. Rosales, C.M. Walker, K.M. Flanigan,M. Hogan, B.K. Kaspar

Becker muscular dystrophy (BMD), a dystrophinopathy with milder skeletal muscle manifestations compared to Duchenne muscular dystrophy, characteristically demonstrates weakness of knee extensors (KE), accompanied by muscle atrophy and fibrosis. The weakness predisposes to gait impairment and loss of ambulation. Myostatin, a member of the TGF-β superfamily of signal peptides, is expressed in skeletal muscle, acting through the activin type IIB (ACTRIIB) receptor. Follistatin, a myostatin antagonist, inhibits this pathway resulting in muscle hypertrophy, and improved muscle strength. FS315 and FS288 are two isoforms of follistatin generated by alternative splicing. FS315 has no cell-surface affinity providing a safety margin avoiding pituitary–gonadal axis complications. FS344 is the precursor cDNA to FS315. When FS344 is delivered to mdx mice in adeno-associated virus (AAV1. CMV. FS344), muscle mass and strength increase. Similar findings are seen in non-human primates without safety concerns. Six BMD patients, 18 years and older with proven in-frame DMD gene mutations were enrolled in a clinical trial. The first 3 subjects received 12 intramuscular (IM) injections of AAV1. CMV. FS344 at a total dose of 6e11 vg/kg in the quadriceps muscles bilaterally. A second cohort received the same number of IM injections at higher total dose (1.2e12 vg/kg). Studies extending beyond one year in Cohort 1 and for six months in Cohort 2 showed no adverse events. The distance walked (meters) on the 6-min walk test (6MWT) was the primary functional outcome measure. At one year the distance walked by two subjects in Cohort 1 increased by 125 m and 58 m; subject 3 improved modestly by 9 m. In Cohort 2, one patient reaching the 6-month time point increased by 108 meters. For the entire group of BMD patients only a single patient declined in distance. Preliminary analysis of muscle biopsies favor increased muscle regeneration contributing to improved function.