New Ways to Build Muscle for Muscular Dystrophy

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