Sustained alpha‐sarcoglycan gene expression after gene transfer in limb‐girdle muscular dystrophy, type 2D

Abstract

Objective The aim of this study was to attain long-lasting alpha-sarcoglycan gene expression in LGMD2D subjects mediated by adeno-associated virus (AAV) gene transfer under control of a muscle specific promoter (tMCK) Methods rAAV1.tMCK.hSGCA (3.25 × 1011 vg) was delivered to the extensor digitorum brevis (EDB) muscle of three subjects with documented SGCA mutations via a double-blind, randomized, placebo controlled trial. Control sides received saline. The blind was not broken until the study was completed at 6 months and all results reported to the oversight committee. Results Persistent alpha-sarcoglycan gene expression was achieved for six months in two of three LGMD2D subjects. Markers for muscle fiber transduction other than alpha-sarcoglycan included expression of major histocompatability complex I (MHC I), increase in muscle fiber size, and restoration of the full sarcoglycan complex. Mononuclear inflammatory cells recruited to the site of gene transfer appeared to undergo programmed cell death demonstrated by TUNEL and caspase-3 staining. A patient failing gene transfer demonstrated an early rise in neutralizing antibody titers and T cell immunity to AAV validated by enzyme-linked immunospot (ELISpot) on the second day post gene injection. This was in clear distinction to other participants with satisfactory gene expression. Interpretation The findings of this gene replacement study in LGMD2D subjects have important implications not previously demonstrated in muscular dystrophy. Long-term, sustainable gene expression of alpha-sarcoglycan was observed following gene transfer mediated by AAV. The merit of a muscle specific tMCK promoter, not previously used in clinical trial was evident, and the potential for reversal of disease was displayed.

Immune responses to AAV vectors: overcoming barriers to successful gene therapy

“…on May 12, 2018. by guest www.bloodjournal.org From clinical outcome was more difficult to establish. Furthermore, several factors appear to influence the outcome of gene transfer in muscle, including upregulation of MHC I expression in some settings, 100,101 apoptosis of reactive T cells, 101,103 immunomodulatory properties of the transgene product 17,98,104 as well as transgene immunogenicity (vide infra), and baseline levels of inflammation within the target tissue. 105 Additional studies are needed to identify determinants that may lead to a destructive immune response following AAV vector administration to muscle and to establish whether IS is needed (eg, when large doses of AAV vectors are administered).…”

“…[131][132][133][134] In the clinic, direct intramuscular gene transfer using AAV vectors has been explored for a number of indications, including hemophilia B, 18,26 lipoprotein lipase deficiency, 16,48 a 1 -antitrypsin deficiency, 17,98,135 and muscular dystrophies. [99][100][101][102] In addition, cardiac muscle has also been targeted through an intravascular approach, for cardiac failure. 19 Immune responses against the therapeutic transgene were not detectable in most of these studies.…”

CpG-depleted adeno-associated virus vectors evade immune detection

“…Adeno-associated virus (AAV) vector efficiently transduces dividing or nondividing muscle cells through both local and systemic administration, providing multiple strategies to treat musculoskeletal diseases. While thought to be minimally immunogenic -an attribute that allows for sustained transgene expression from AAV vectors in some experimental models -adaptive immune responses have been observed and, in some cases, implicated in the loss of transgene expression (1)(2)(3)(4)(5)(6).…”

Phase I/II Trial of Adeno-Associated Virus–Mediated Alpha-Glucosidase Gene Therapy to the Diaphragm for Chronic Respiratory Failure in Pompe Disease: Initial Safety and Ventilatory Outcomes

“…These preclinical findings suggest that rAAV gene therapy can influence neural GAA activity in Pompe disease. In addition, others have reported an acceptable safety profile for AAV1-mediated gene delivery in human clinical trials (Brantly et al, 2006;Mendell et al, 2010). As such, we initiated a phase I/II clinical trial of rAAV1-hGAA intramuscular gene transfer to the diaphragm.…”