New Ways to Build Muscle for Muscular Dystrophy GENE THERAPY to INHIBIT MYOSTATIN
MYOSTATIN • MYOSTATIN Gene discovered in mouse • Inhibition or loss leads to muscle enlargement 1997 Baby at 7 months without myostatin
• Human Gene found in 2004
Schuelke, Wagner, Stolz, et al N Engl J Med 2004
Can We Harness this as an approach for Gene Therapy ? Myostatin Inhibition
Circulating Propeptide Myostatin Complex
MM
SP
Propeptide Signal Peptide
Cleavage Myostatin Dimer Propeptide Complex
MM Follistatin
GASP1
MM
FLRG
P
ActRIIB
P
Alk4 /Alk5 co-receptor P P
Smad 2
Smad 3
P P
Smad Complex
Smad 4
Activation of target genes
nucleus
Candidate Genes for Myostatin Inhibition
Comparison of hindlimb Strength in C57/B6 mice
Follistatin Gene (DNA) 1
2
1
3
2
3
4
4
5
5
6b
6a
6b
FS344
SP
Adeno-associated Virus (AAV)
Treatment of muscular dystrophy mouse Control Control
Gene Gene Therapy Therapy
Injection of Leg Muscle 180 days
CK
None Gene Normal Therapy
Can the Mouse Studies Predict Safety and Efficacy in a Clinical Trial ? MOVING TO NON-HUMAN PRIMATE
FS344 Gene Transfer to Monkey
Follistatin Blood Levels Treated
Untreated
Thigh Circumference
Gene AAV1-FS Therapy
Control
Untreated
Low dose
high dose
The Clinical Problem • Quadriceps muscle weakness (Becker Muscular Dystrophy Sporadic Inclusion body myositis) • Frequent falls/ loss of ambulation • Clinical trial improving quadriceps muscle strength would result in a
“clinically meaningful outcome”
Resistant to Muscle Strength Training • Weight training • Electrical Stimulation • Anabolic Steroids
Ann Neurology March 11, 2008
• Wyeth sponsored 11 Center Trial (10 USA;1GB) Using MYO-029 antibody to myostatin – No Clinical Benefit – Muscle histology showed a trend toward increased muscle fiber size – Demonstrated safety of systemic delivery of a myostatin inhibitor in a clinical trial
Can Follistatin Gene Therapy be Done Safely ?
Clinical Chemistries Monkeys used in Pre-clinical Studies
IMMUNE RESPONSE
Full Examination of Non-Human Primates • Slides on each organ evaluated by a board certified veterinary pathologist blinded to treatment group (control vs FS) • No treatment-related abnormalities found in heart, liver, lung, spleen, kidney, testis, ovary and uterus (5 &15 months)
Cardiac Studies Post AAV1.FS344 Treatment 15 months
Moving Forward • FDA has given approval to move to a clinical trial • PPMD has supported studies in Becker muscular dystophy • Clinical trial will begin in December 2010 - January 2011
Clinical Trial Design
• Six BMD patients will undergo direct injection of AAV1.MCK.Follistatin into quadriceps muscles (1x1012 vg/muscle) • Patients will be followed for six months • Muscle biopsies will be done at 3 and 6 months
– Muscle size will be assessed and any signs of muscle inflammation/damage
• MRI of quadriceps at 3 and 6 months • Muscle strength and 6MWT will be assessed
Collaborators Brian Kaspar Louise Rodino K.Reed Clark Kevin Flanigan Zarife Sahenk Chris Walker
Support Parent Project Muscular Dystrophy The Myositis Association