Limb-girdle muscular dystrophy type 2D gene therapy restores alpha-sarcoglycan and associated proteins.
OBJECTIVE
alpha-Sarcoglycan deficiency results in a severe form of muscular dystrophy (limb-girdle muscular dystrophy type 2D [LGMD2D]) without treatment. Gene replacement represents a strategy for correcting the underlying defect. Questions related to this approach were addressed in this clinical trial, particularly the need for immunotherapy and persistence of gene expression.


METHODS
A double-blind, randomized controlled trial using rAAV1.tMCK.hSGCA injected into the extensor digitorum brevis muscle was conducted. Control sides received saline. A 3-day course of methylprednisolone accompanied gene transfer without further immune suppression.


RESULTS
No adverse events were encountered. SGCA gene expression increased 4-5-fold over control sides when examined at 6 weeks (2 subjects) and 3 months (1 subject). The full sarcoglycan complex was restored in all subjects, and muscle fiber size was increased in the 3-month subject. Adeno-associated virus serotype 1 (AAV1)-neutralizing antibodies were seen as early as 2 weeks. Neither CD4+ nor CD8+ cells were increased over contralateral sides. Scattered foci of inflammation could be found, but showed features of programmed cell death. Enzyme-linked immunospot (ELISpot) showed no interferon-gamma response to alpha-SG or AAV1 capsid peptide pools, with the exception of a minimal capsid response in 1 subject. Restimulation to detect low-frequency capsid-specific T cells by ELISpot assays was negative. Results of the first 3 subjects successfully achieved study aims, precluding the need for additional enrollment.


CONCLUSIONS
The finding of this gene replacement study in LGMD2D has important implications for muscular dystrophy. Sustained gene expression was seen, but studies over longer time periods without immunotherapy will be required for design of vascular delivery gene therapy trials.
Mendell
Jerry R
JR
Department of Pediatrics, Ohio State University, Columbus, OH, USA. Jerry.Mendell@nationwidechildrens.org
Rodino-Klapac
Louise R
LR
Rosales-Quintero
Xiomara
X
Kota
Janaiah
J
Coley
Brian D
BD
Galloway
Gloria
G
Craenen
Josepha M
JM
Lewis
Sarah
S
Malik
Vinod
V
Shilling
Christopher
C
Byrne
Barry J
BJ
Conlon
Thomas
T
Campbell
Katherine J
KJ
Bremer
William G
WG
Viollet
Laurence
L
Walker
Christopher M
CM
Sahenk
Zarife
Z
Clark
K Reed
KR
D000293:Adolescent; D018791:CD4 Lymphocyte Count; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002648:Child; D000229:Dependovirus / Q000276:immunology; D005260:Female; D015870:Gene Expression / Q000235:genetics; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007167:Immunotherapy / Q000379:methods; D008297:Male; D008565:Membrane Proteins; D018485:Muscle Fibers, Skeletal; D018482:Muscle, Skeletal / Q000378:metabolism; D049288:Muscular Dystrophies, Limb-Girdle / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D009500:Neutralization Tests; D049031:Sarcoglycans / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism
D008565:Membrane Proteins; D049031:Sarcoglycans