ABSTRACTS PRESENTED IN ANNUAL MEETING OF
AMERICAN ACADEMY OF NEUROLOGY, CHICAGO, 2008/APRIL
Randomized, Double-Blind, Controlled Study To Compare
Efficacy and Tolerability of Standard Daily Prednisone Regime with a Novel
Intermittent High Dose Regime in Ambulant Boys with Duchenne Muscular Dystrophy
Diana Escolar, Craig McDonald, V. Viswanathan, Chennai, India,
Andrew J. Kornberg, Melbourne, Australia, Tulio Bertorini, Memphis, TN, Yoram
Nevo, Jerusalem, Israel, Timothy Lotze, Houston, TX, Monique Ryan, Westmead,
Australia, Paula Clemens, Robert Leshner, Alan Pestronk, Lauren Morgenroth,
Pittsburgh, PA, Angela Zimmerman, Adrienne Arrieta, Erik Henricson, Davis, CA,
Jill P. T. Mayhew, Julaine Florence, Tina Duong, Lei Nei, Fenming Hu,
Washington, DC, Ana Tesi-Rocha, Arlington, VA, Anne Connolly, Saint Louis, MO
OBJECTIVE: This study evaluated the hypothesis that high dose prednisone
given over 2 days of the week has similar efficacy but fewer side effects than
the standard daily prednisone regime. BACKGROUND: DMD is a progressive
lethal muscle disorder. Daily prednisone treatment at 0.75 mgs/day results in
increased function and prolonged ambulation. Weight gain, behavioral problems
and growth deceleration have hindered its acceptance as standard treatment.
DESIGN/METHODS: Double-blind, controlled, randomized 12 month study
comparing prednisone 0.75 mgs/kg/day with weekly 10 mg/kg divided over two days.
Participants were steroid naive DMD boys, ages 4 to 10. Co-primary outcome
measures for efficacy and tolerability were quantitative total muscle strength
and body mass index. Secondary outcomes included QMT arm and leg scores, grip,
MMT, timed function, FVC, height, weight, bone density, cataract formation,
blood glucose, blood pressure and behavioral changes. Primary analysis was
comparison of QMT score improvement and of BMI changes between groups at 12
months. RESULTS: Seventy six patients were enrolled, 64 randomized and 55
completed the protocol. Mean age was 7.296 (sd=1.78). There were no significant
differences in baseline characteristics between groups. After 12 months of
treatment the improvement on the total QMT score did not differ between groups
(-0.05 (CI= -0.15, 0.05) p=0.34) nor did all other efficacy measures. BMI
increased in both groups, with a significant difference between groups (higher
in daily) at 3 months (p= 0.04), that lost significance at 12 months (p=0.07).
There was a significantly greater increase in growth in the intermittent dose
regime group (p=0.004) and no difference in weight. CONCLUSIONS/RELEVANCE:
This study confirms that an intermittent dose regimen of prednisone can be
equally efficacious to daily steroids, with a lesser effects on growth
retardation and BMI. Other results on adverse events, including behavior,
cataract formation and bone density will be presented. Supported by: Muscular
Dystrophy Association, NIH (NCRR).
Genotype Analysis Predicts Dilated Cardiomyopathy in Becker
Muscular Dystrophy
Rita W. Kaspar, Westerville, OH, Hugh D. Allen, Donna McCarthy, John
T. Kissel, Kevin M. Flanigan, Salt Lake City, UT, Jerry R. Mendell, Federica
Montanaro, Columbus, OH
OBJECTIVE: To identify dystrophin mutations predictive of dilated
cardiomyopathy in patients with Becker muscular dystrophy (BMD) or X-linked
dilated cardiomyopathy (XLDCM). BACKGROUND: BMD is caused by dystrophin
gene mutations resulting in skeletal and cardiac muscle degeneration. When
cardiac manifestations are out of proportion to skeletal muscle symptoms, the
disorder is diagnosed as XLDCM. Dystrophin mutations predictive of XLDCM have
been suggested, but representative examples from the literature are insufficient
in number to establish with certainty. Defining the clinical presentations of
specific mutations is crucial for risk classification, early detection and
treatment to prolong survival. DESIGN/METHODS: BMD and XLDCM patients
with dystrophin deletion/missense mutations and with cardiac histories were
collected from databases at Nationwide Childrens
Hospital, The Ohio State University, the Utah Dystrophinopathy Project, the
Leiden Open Variation Database, and published case reports. Phenotype-genotype
correlations were established based on age, skeletal muscle and cardiac
manifestations, and echocardiograms. Statistical analysis was performed using
Mann-Whitney U tests. RESULTS: Data from 126 patients were analyzed.
Deletions in the N-terminus domain of dystrophin resulted in the earliest mean
age of cardiac involvement (23 years) compared to mutations affecting the rod
domain (41 years) or the hinge 3 region (39 years). Mutations affecting the
spectrin repeats in the rod domain which preserve hinge 3 lead to an earlier
onset (31 years) of cardiomyopathy than mutations which remove hinge 3 (47 years)
(p<0.05). Mutations affecting the spectrin repeats preserving hinge 3 were
subdivided based on whether they disrupted (out-of-phase) or preserved (in-phase)
the spectrin repeats structure. Out-of-phase mutations predisposed to early
onset (25 years) cardiomyopathy compared to in-phase mutations (37 years) (p<0.05).
CONCLUSIONS/RELEVANCE: This genotype-phenotype analysis included the
largest number of BMD patients to date. The results define dystrophin mutations
predisposing to cardiomyopathy and enable clinicians to provide early
intervention for at-risk patients that could improve the disease natural history.
Palliative Care Services in Families of Patients with Duchenne
Muscular Dystrophy
Shree Pandya, Rochester, NY, John Meaney, Jennifer Andrews, Melinda
Davis, Palliative Care Group MDSTARNet, Tucson, AZ
OBJECTIVE: To describe the palliative care services families of patients
with Duchenne muscular dystrophy (DMD) currently receive. BACKGROUND:
Improvements in care have led to prolonged survival in patients with DMD.
Palliative care services that address physical pain and emotional, social, and
spiritual needs may benefit individuals with DMD and their families. DESIGN/METHODS:
A questionnaire was administered to families of patients with DMD born prior to
January 1, 1982, and born or residing in one of four sites participating in the
Muscular Dystrophy Surveillance, Tracking, and Research Network (MDSTARNet).
RESULTS: Thirty-four families completed the questionnaire, which included
45% of the families that could be contacted. Twenty-five (73.5%) were white,
non-Hispanic and 9 were Hispanic (26.5%). In most families (22, 65%), the
individual with DMD was living. Most families (84.8%) had never heard the term
palliative care. Of six palliative care services, only Attendant Care and
Skilled Nursing Services showed much usage, with 44% and 50% of respondents
indicating receipt of these respective services. Other services were received
much less frequently: Pastoral Care (27%), Respite Care (18%), Pain Management
(12%), and Hospice Care (6%). Less than 25% of respondents (8/34) reported
having any type of directive document in place. A living will, advance directive
and Durable Medical Care Power of Attorney are considered important documents in
disease management of individuals with a life-threatening illness. Only 2 (6%)
of families had guardianship papers in place for the care of their son with DMD
in the event of incapacitation or death of the parent. CONCLUSIONS/RELEVANCE:
These data suggest the need for improved counseling and education of families
about palliative care services. Supported by: Funded through a contract
agreement with the Association of University Centers on Disabilities for AUCD
RTOI 2004-03-03.
Immediate Release Oral Pentoxifylline Is Poorly Tolerated
in Duchenne Muscular Dystrophy Boys
Carolina Tesi-Rocha, Nancy Kuntz, Rochester, MN, Paula Clemens,
Pittsburgh, PA, Susan Iannaccone, Dallas, TX, Alan Pestronk, Angela Zimmerman,
Erik Henricson, Sacramento, CA, Adrienne Aarieta, Lei Nei, Bruce Markle, Anne
Connolly, Saint Louis, MO, Diana Escolar, Washington, DC
OBJECTIVE: The objective of this open label pilot study of oral,
immediate release pentoxifylline was to assess the tolerability, safety and
efficacy on muscle strength and function in Duchenne Muscular Dystrophy (DMD).
BACKGROUND: Severe to complete dystrophin deficiency produces the DMD
phenotype. Untreated DMD boys demonstrate progressive, eventually fatal, muscle
weakness. In relevant animal models, pentoxifylline slows disease progression.
DESIGN/METHODS: This was an open label, prospective study with a 3 month
lead in period followed by 12 months of treatment with a 20mg/kg/day dose of
pentoxifylline (maximal dose 598 mg/day). Study subjects were 4-9 year old
steroid-naive DMD boys. The primary efficacy measure was a total quantitative
muscle testing (QMT) score. Secondary and exploratory endpoint measures were
manual muscle strength (MMT), arm and leg QMT, timed function tests, muscle MRI,
serum TNF-
and TGF-
levels and adverse event profiles. RESULTS: Of twenty patients screened,
17 enrolled and 9 completed the protocol. Age range was 4.3-8.5 years (mean 6.0,
median 5.8). QMT and MMT measures did not show a significant change during the 3
month lead-in or 12 month treatment period. Five of 8 patient withdrawals were
due to intolerable adverse events. Eleven of 17 patients experienced nausea and
vomiting. Two patients experienced moderate (grade 3) to severe (grade 4)
leucopenia. CONCLUSIONS/RELEVANCE: The immediate release oral formulation
of pentoxifylline is not well tolerated in children with DMD. The 12% incidence
of leucopenia in this study was higher than the reported incidence rate in
adults (<1%). Leucopenia improved post drug withdrawal. The 65% incidence of
vomiting was also higher than reported in adults (4.5%). The lack of
deterioration in strength and function over 12 months in steroid naive DMD
children (mean age 6 years) suggests a possible beneficial effect on disease
progression and warrants further study with a different formulation of
pentoxifylline.
Double-Blind Randomized Controlled Trial of SNT-MC17/Idebenone
in Duchenne Muscular Dystrophy
Gunnar M. Buyse, Luc Mertens, Marleen van den Hauwe, Daisy Thijs,
Imelda J. M. De Groot, Nijmegen, Netherlands, Ulrike Schara, Neuss, Germany,
Berten Ceulemans, Antwerp, Belgium, Thomas Meier, Liestal, Switzerland, Nathalie
Goemans, Leuven, Belgium
OBJECTIVE: This 12-month study has evaluated the efficacy and
tolerability of treatment with SNT-MC17/idebenone (450 mg/day) compared to
placebo in children with Duchenne muscular dystrophy (DMD). BACKGROUND:
Idebenone supports mitochondrial respiratory chain function and reduces
oxidative stress, pathways that are involved in DMD pathogenesis. Previous
long-term blinded controlled preclinical studies in the homologous mdx
mouse have indicated that idebenone is cardioprotective and improves exercise
performance in murine dystrophin-deficiency. DESIGN/METHODS: 21 DMD
patients (8-16 y) with cardiac dysfunction were enrolled in the double-blind
randomized placebo-controlled trial. Comedication with glucocorticoids was
allowed at stable dosage; use of ACE-inhibitors was excluded. Thirteen patients
received SNT-MC17 as a daily dose of 450 mg for 52 weeks, 8 patients were
randomized to the placebo group. RESULTS: All subjects completed the
study; the frequency and type of adverse events was comparable in the active and
placebo treatment groups indicating good safety and tolerability of SNT-MC17.
The primary endpoint was the change in peak systolic radial strain of the left
ventricular inferolateral wall, the region of the heart which in DMD is affected
early and most severely. For the observed cases, patients on SNT-MC17 improved
by 17.313.2%
from baseline (22.99.1%)
to week 52, while patients on placebo improved by 7.512.0%
from baseline (33.79.7%;
p= 0.066 comparison SNT-MC17 vs placebo). Secondary outcome measures
included respiratory function tests. Whereas SNT-MC17 treatment was associated
with improvement in peak flow (30.854.4
L/min) and peak flow % predicted (2.813.8%)
during the 52 week study period, patients on placebo deteriorated in peak flow
(- 13.851
L/min; p= 0.039) and peak flow % predicted (- 8.513.8%;
p= 0.042). CONCLUSIONS/RELEVANCE: This the first indication of clinical
efficacy with SNT-MC17/idebenone on functional cardiac and respiratory
parameters in DMD. The results provide the basis for the planning of further
clinical development studies with SNT-MC17/idebenone in DMD.
Implementation of a Newborn Screening Program for Duchenne
Muscular Dystrophy (DMD)
Roula Al-Dahhak, Christopher J. Shilling, Marlinda S. Iyer, Diane
Dunn, Kandice Roush, Susan Gailey, Deborah Cragun, Natalie Street, Atlanta, GA,
Nancy Leslie, Cincinnati, OH, William Becker, Robert Weiss, Salt Lake City, UT,
Jerry Mendell, Columbus, OH
OBJECTIVE: Introduce a comprehensive newborn screening paradigm for
Duchenne muscular dystrophy (DMD). BACKGROUND: The incidence of DMD is
presumed to be 1:3500 newborn males, however, this has not been confirmed in an
outbred population. Only small cohorts of newborns have been screened based on
creatine kinase (CK) testing. The most useful, exacting and baby friendly
paradigm includes testing both CK and DNA on the dried blood spots (DBSs) taken
within the first 24 to 48 hours of life. DESIGN/METHODS: DBSs obtained
within the newborn period were used to test for CK combined with a rapid direct
method of sequence analysis of the dystrophin gene referred to as SCAIP
sequencing. RESULTS: The first goal of this study was to establish a
range of CK from 40,000 anonymous newborn male DBSs (250 + 111).
Mutational analysis was tested on DBSs taken from 8 boys with known DMD
mutations. Blood was obtained from the finger simulating heel stick samples
obtained in the newborn period. Samples were analyzed blindly using
modifications of SCAIP and matched successfully with known mutations. Once
having established a CK testing range based on >3SD above the mean and a DNA
confirmational method on DBSs, the second goal was achieved with implementing a
newborn screening program in 6 birthing hospitals in central Ohio and Cincinnati
areas. To date we have enrolled over 6000 newborn males. CONCLUSIONS/RELEVANCE:
A successful paradigm for screening newborns for DMD has been established that
will provide a definitive diagnosis of DMD in the newborn period. Survey of over
500 participants reveals a high degree of enthusiasm (>99%) for participation in
this program. The long-term benefits include: 1) prevention of an unsuspecting
second child with DMD; 2) establishing a registry for early intervention for
clinical trials; and 3) determining the incidence of DMD in newborn males in an
outbred population. Supported by: Center for Disease Control and Prevention.
A Gene Therapy Approach To Treat Cardiomyopathy in the mdx
Mouse Model of Duchenne Muscular Dystrophy (DMD)
Louise Rodino-Klapac, Mandar S. Joshi, Chrystal L. Montgomery, Kim
M. Shontz, John Anthony Bauer, K. Reed Clark, Jerry Mendell, Columbus, OH
OBJECTIVE: At least 95% of DMD patients develop a cardiomyopathy,
critical to their long-term prognosis. Most evolving strategies for replacing
the missing dystrophin protein in skeletal muscle are not applicable to the
heart. Our goal is to use adeno-associated virus (AAV) to replace the mutant
gene. BACKGROUND: Dystrophinopathy victims historically died from
respiratory complications while cardiac failure appeared catastrophically
related to the stress of respiratory infections. Contemporary methods now
protect the respiratory system related to improved equipment, antibiotics and
vaccines; consequently, the progressive cardiomyopathy of DMD mandates attention.
We have previously shown AAV serotype 8 to efficiently transduce skeletal muscle
when delivered through the vasculature, and therefore chose to test its
efficiency in transducing cardiac muscle of mdx mice, a model with similar
lesions to DMD patients. DESIGN/METHODS: Using AAV8 carrying green
fluorescent protein (GFP) as a marker gene we treated mdx mice at the neonatal
stage (P2) [2 x 1011 vector genomes (vg)] by intraperitoneal
injection, or at 8 weeks-old by intravenous tail vein injections (8 x 1011
vg). Hearts were harvested and stained for GFP four weeks post delivery. In
addition, we developed a testing paradigm to serially measure in vivo
cardiovascular function in mdx using echocardiography and electrocardiography (ECG).
RESULTS: Gene delivery to mdx mice resulted in 73% gene expression in mdx
mice treated with AAV8.GFP treated as adults and 65% expression in neonates. In
addition, using our previously described methods, we observed a 52% reduction in
left ventricular fractional shortening % (FS%) in the mdx mice as compared to
the wild-type controls (52.05-2.77
vs. 27.513.06;
Ctrl vs. mdx; p<0.05). CONCLUSIONS/RELEVANCE: Together these data support
treatment of the cardiomyopathy of neonatal or adult mdx mice using rAAV8 to
deliver a therapeutic dystrophin transgene while concurrently monitoring cardiac
performance using serial, non-invasive outcome measures similar to those used in
the clinic.
Pentoxifylline Treatment Fails To Rescue Muscle Strength
and Function Deterioration in Prednisone-Treated Duchenne Muscular Dystrophy
Diana Escolar, Ksenija Gorni, Pavia, Italy, Ana Tesi-Rocha,
Arlington, VA, Jean Mah, Calgary, AB, Canada, Yoram Nevo, Jerusalem, Israel,
Andrew Kornberg, Parkville, Australia, Hannah Kolski, Edmonton, AB, Canada,
Tulio Bertorini, Memphis, TN, Anne Connolly, Nancy Kuntz, Rochester, MN, Paula
Clemens, Angela Zimmerman, Lauren Morgenroth, Pittsburgh, PA, Jill Mayhew,
Julaine Florence, Saint Louis, MO, Lei Nei, Fenming Hu, Tina Duong, Erik
Henricson, Davis/Sacramento, CA, Robert Leshner, Washington, DC, Alberto
Dubrovsky, Buenos Aires, Argentina
OBJECTIVE: This clinical trial was conducted to evaluate the additive
effect of Pentoxyfylline to prednisone by stabilizing or improving muscle
strength and function in DMD. BACKGROUND: Treatment of DMD with
prednisone results in slowing, but not prevention, of deterioration of muscle
strength and function. Pentoxyfylline is an anti-inflammatory and anti-fibrotic
drug that prevents muscle strength deterioration by 51% in the exercised mdx
mouse model of the disease. If these effects translate to human, a combination
therapy could halt disease progression, or produce a steroid sparing effect.
DESIGN/METHODS: This was a randomized, controlled, double-blind 12 months
study of Pentoxyfylline in steroid-treated DMD boys over the age of 7. The
primary objective of the study was to determine whether daily treatment with PTX
could significantly improve total QMT score at 12 months compared to patients
receiving placebo. Secondary endpoints were QMT arm and leg scores, grip, MMT
score, timed function, quality of life and exploratory surrogate outcome
measurements of levels of TGF-
and TNF-.
Safety laboratory assessments and adverse events were collected. RESULTS:
Based on preliminary results, seventy three patients were enrolled, 64
randomized and 57 completed the protocol. Mean and median age were 10.07 and 9.5
respectively. Baseline characteristics between groups were not statistically
significant. Total QMT score changes at 12 months was not significantly
different between groups (p=0.5). None of the secondary strength and functional
endpoints differed between groups at 12 months. The PTX group presented with
increase incidence of coagulation, skin and mild gastrointestinal side effects.
CONCLUSIONS/RELEVANCE: This study has shown that Pentoxyfylline treatment,
although well tolerated over a year, has no effect in slowing disease
progression over prednisone in DMD boys. Supported by: The Federation to
Erradicate Duchenne and NIH (NCRR).
Imatinib Attenuated Skeletal Muscle Dystrophy in mdx
Mice
Ping Huang, Xinyu S. Zhao, Matthew Fields, Richard M. Ransohoff, Lan
Zhou, Cleveland, OH
OBJECTIVE: To test anti-inflammatory and anti-fibrotic effects of
imatinib on mdx mice, a mouse model of Duchenne muscular dystrophy (DMD).
BACKGROUND: DMD is the most common genetic muscle disease. DMD is lethal
and currently untreatable. Muscle necrosis, inflammation, and fibrosis are
prominent pathological features, and pharmacotherapy to ameliorate these
pathological changes may represent an important therapeutic approach for DMD.
Imatinib is an anti-neoplastic therapy that selectively inhibits the tyrosine
kinase activity of c-abl, c-kit, and PDGF receptors (PDGFRs). It is also a
promising anti-inflammatory and anti-fibrotic therapy as demonstrated by its
substantial inhibition of inflammation and fibrosis of liver, kidney, lung, or
skin in various animal models of disease. DESIGN/METHODS: We treated
mdx mice with intraperitoneal injection of imatinib at the peak of limb
muscle inflammation and at the onset of diaphragm fibrosis; controls received
PBS vehicle or were left untreated. Muscle necrosis and inflammation were
quantified by measuring serum CK activity and percentage of CD45 immunoreactive
area, respectively. Muscle fibrosis was evaluated by collagen III immunostaining.
Muscle function was assessed by measuring hindlimb grip strength.
Phosphorylation of the tyrosine kinase targets of imatinib was studied by
Western blot. RESULTS: Compared with control mdx mice,
imatinib-treated mdx mice showed striking pathological and functional
benefit. Serum CK level, diaphragm and quadriceps inflammation areas, and
diaphragm fibrosis were markedly reduced. Hindlimb grip strength was
significantly improved. Reduced clinical disease was accompanied by suppression
of TNF-alpha and IL-1beta mRNA expression, and inhibition of c-abl and PDGFR
phosphorylation. CONCLUSIONS/RELEVANCE: 1) Imatinib therapy for DMD may
hold promise for ameliorating muscle necrosis, inflammation, and fibrosis. 2)
Imatinib likely exerts its therapeutic effects on mdx mice by inhibiting
c-abl and PDGFR signaling and downstream inflammatory cytokine and fibrotic gene
expression. Supported by: 1K08 NS049346-01A2 (LZ).
How Frequently Are Corticosteroids Used in Boys with
Dystrophinopathy in the USA: Data from the MDSTARnet
Emma Ciafaloni, Shree Pandya, Dennis J. Matthews, Aurora, CO,
Katherine James, Denver, CO, Katherine D. Mathews, Iowa City, IA, Tim M. Miller,
Tucson, AZ, MDSTARnet, Rochester, NY
OBJECTIVE: To review the use of corticosteroids for the treatment of
Duchenne Muscular Dystrophy (DMD) in clinical practice from 1991 to 2005 in a
large population- based cohort in the USA. BACKGROUND: Corticosteroids
are the only pharmacological treatment that has been shown to have positive
effect on muscle strength and function in DMD in three randomized controlled
trials and a 3 year follow up open study. These studies were published in 1991.
DESIGN/METHODS: The Muscular Dystrophy SurveillanceTracking and Research
Network (MD STARnet) is a population-based surveillance system funded by the
Centers for Disease Control to identify all cases of Duchenne /Becker Muscular
Dystrophy (DBMD) born since 1982 and/or residing within Arizona, Colorado, Iowa
and Western New York State. A pooled database containing clinical information
abstracted from medical records on 433 individuals was analyzed. RESULTS:
The proportion of boys receiving corticosteroids increased from 27% in 1991 to
44% in 2005. The proportion of boys receiving corticosteroids in 2005 by state
is: NY: 57 % (clinic A= 75%; clinic B= 5 %), CO: 29%, AZ: 38%, IA: 50 %. Mean
age when corticosteroids are started is 7.4 years (median= 7; range 3-18). Mean
duration of treatment is 57 months. Most common reasons for discontinuing
corticosteroids are: weight gain, behavioral side effects and becoming
wheelchair bound. Most common reasons for changing corticosteroids dose are:
weight gain, behavioral side effects and parents
request. CONCLUSIONS/RELEVANCE: The proportion of DMD boys taking
corticosteroids has increased in the past 15 years but is overall still less
than 50%. Large variability in practice remains between States and between
Neuromuscular Clinics. We plan a repeat analysis in 2 years to assess the impact
of the AAN Practice Parameter on the use of corticosteroids in DMD published in
2005. Supported by: MDSTARnet is funded by the Centers for Disease Control and
Prevention grant # 1U01DD00019001.
Long-Term Enhancement of Skeletal Muscle Mass and Strength
by Single Gene Administration of Myostatin Inhibitiors
Brian Kaspar, Amanda Haidet, Liza Rizo, Chalonda Handy, Paul Martin,
Zarife Sahenk, Jerry Mendell, Columbus, OH
OBJECTIVE: To determine the safety and efficacy of adeno-associated virus
expressing follistatin (FS-344), for muscle enhancement in a mouse model for
Duchenne Muscular Dystrophy and wild-type animals. BACKGROUND: Increasing
the size and strength of muscles represents a promising therapeutic strategy for
musculoskeletal disorders. Significant interest has focused on myostatin, a
negative regulatory factor of muscle growth. Inhibition of myostatin
significantly increases muscle mass. Several proteins including follistatin (FS),
follistatin-related gene (FLRG) and growth and differentiation factor-associated
serum protein 1 (GASP-1) inhibit myostatin. DESIGN/METHODS: 1x1011
particles of AAV1 vectors expressing Follistatin, FLRG, or GASP-1 were injected
bilaterally into hindlimbs of mdx or wild-type mice and followed for 6-months or
2 years. RESULTS: Wild-type mice injected in the hindlimbs with of
AAV1-FS, FLRG, or GASP-1 showed increased overall body mass, with 30% increase
in hindlimb and forelimb grip strength compared to AAV1-GFP controls. Overall
strength increase was greatest for animals receiving AAV1-FS followed by
AAV1-FLRG and then AAV1-GASP-1. We next tested the potential of AAV1-FS to
increase muscle mass and strength and delay muscle deterioration in the mdx
mouse model. Mdx animals were injected at 3 weeks of age and followed for 6
months with AAV1-FS. Animals showed a 30-50% increase in skeletal muscle mass,
enhanced muscle grip strength, and decreased serum creatine kinase levels
compared to controls. Histology demonstrated myofiber hypertrophy locally and at
remote sites to the injection. No adverse organ pathology was detected. Mdx
animals treated with AAV1-Follistatin at 6.5 months of age also showed increased
muscle strength, demonstrating the ability to improve strength in aged animals.
CONCLUSIONS/RELEVANCE: Inhibition of myostatin by myostatin inhibitory
proteins, in particular follistatin represents a promising therapeutic strategy
warranting consideration for clinical trials in human muscle diseases. Supported
by: The Myositis Association, Roger Stevens, Project A.L.S. and The Muscular
Dystrophy Association.
Fidelity of Gamma-Glutamyl Transferase in Differentiating
Skeletal Muscle from Liver Damage
Xiomara Rosales, Mary Chu, Christopher Shilling, Cheryl Wall,
Gregory Pastores, New York, NY, Jerry Mendell, Columbus, OH
OBJECTIVE: To validate that gamma-glutamyl transferase (GGT) is a
flawless biomarker distinguishing liver and skeletal muscle damage.
BACKGROUND: Serum creatine kinase (CK) is recognized to be a valuable
biomarker for distinguishing myopathic and neurogenic disorders. Accompanying
the leak of CK from skeletal muscle are other intracellular enzymes, including
aspartate aminotransferase (AST), alanine aminotransferase (ALT), pyruvate
kinase, and lactic dehydrogenase. The initial interpretation of an elevated AST
and ALT is a derivation from liver, frequently leading to liver biopsy. Many
clinicians ignore the fact that muscle breakdown is an established cause for
hypertransaminasemia. GGT is a membrane-bound enzyme produced in the liver, with
little or none from skeletal muscle. We tested the validity of GGT as a marker
to differentiate skeletal muscle from liver damage in an environment of
unrestrained activity. DESIGN/METHODS: Duchenne muscular dystrophy
subjects (n=28) with proven dystrophin mutations were enrolled (equally divided
between ambulatory and non-ambulatory, and approximately one-half taking
corticosteroids). Normal males (n=20) served as controls. Initial GGT and CK
samples were taken between 8 and 9 am and redrawn 8 hours later. Subjects
resumed normal play or left the clinic between blood draws. RESULTS: Not
a single DMD patient, ambulatory or non-ambulatory, taking corticosteroids or
not, showed a GGT outside the range of normal at any time point. CK levels at
the same time points ranged from 14 to 200 times the normal subjects.
CONCLUSIONS/RELEVANCE: Some have challenged the value of GGT as a
distinguishing marker for liver disease in myopathic disorders. We found its
value to be impeccable despite an environment greatly predisposed to leak
intracellular enzymes into the serum. The importance of this first and only
evidence-based study establishes an essential role: 1) for GGT in the management
of patients required to take hepatotoxic drugs for inflammatory muscle diseases;
and 2) for monitoring myopathic patients participating in clinical trials.