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Safety and effects of the vector for the Leber hereditary optic neuropathy gene therapy clinical trial.

ABSTRACT: IMPORTANCE We developed a novel strategy for treatment of Leber hereditary optic neuropathy (LHON) caused by a mutation in the nicotinamide adenine dinucleotide dehydrogenase subunit IV (ND4) mitochondrial gene. OBJECTIVE To demonstrate the safety and effects of the gene therapy vector to be used in a proposed gene therapy clinical trial. DESIGN AND SETTING In a series of laboratory experiments, we modified the mitochondrial ND4 subunit of complex I in the nuclear genetic code for import into mitochondria. The protein was targeted into the organelle by agency of a targeting sequence (allotopic expression). The gene was packaged into adeno-associated viral vectors and then vitreally injected into rodent, nonhuman primate, and ex vivo human eyes that underwent testing for expression and integration by immunohistochemical analysis and blue native polyacrylamide gel electrophoresis. During serial follow-up, the animal eyes underwent fundus photography, optical coherence tomography, and multifocal or pattern electroretinography. We tested for rescue of visual loss in rodent eyes also injected with a mutant G11778A ND4 homologue responsible for most cases of LHON. EXPOSURE Ocular infection with recombinant adeno-associated viral vectors containing a wild-type allotopic human ND4 gene. MAIN OUTCOMES AND MEASURES Expression of human ND4 and rescue of optic neuropathy induced by mutant human ND4. RESULTS We found human ND4 expressed in almost all mouse retinal ganglion cells by 1 week after injection and ND4 integrated into the mouse complex I. In rodent eyes also injected with a mutant allotopic ND4, wild-type allotopic ND4 prevented defective adenosine triphosphate synthesis, suppressed visual loss, reduced apoptosis of retinal ganglion cells, and prevented demise of axons in the optic nerve. Injection of ND4 in the ex vivo human eye resulted in expression in most retinal ganglion cells. Primates undergoing vitreal injection with the ND4 test article and followed up for 3 months had no serious adverse reactions. CONCLUSIONS AND RELEVANCE Expression of our allotopic ND4 vector in the ex vivo human eye, safety of the test article, rescue of the LHON mouse model, and the severe irreversible loss of visual function in LHON support clinical testing with mutated G11778A mitochondrial DNA in our patients.

SUBMITTER: Koilkonda RD

PROVIDER: S-EPMC4266107 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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Safety and effects of the vector for the Leber hereditary optic neuropathy gene therapy clinical trial.

Koilkonda Rajeshwari D RD Yu Hong H Chou Tsung-Han TH Feuer William J WJ Ruggeri Marco M Porciatti Vittorio V Tse David D Hauswirth William W WW Chiodo Vince V Boye Sanford L SL Lewin Alfred S AS Neuringer Martha M Renner Lauren L Guy John J

JAMA ophthalmology 20140401 4

IMPORTANCE We developed a novel strategy for treatment of Leber hereditary optic neuropathy (LHON) caused by a mutation in the nicotinamide adenine dinucleotide dehydrogenase subunit IV (ND4) mitochondrial gene. OBJECTIVE To demonstrate the safety and effects of the gene therapy vector to be used in a proposed gene therapy clinical trial. DESIGN AND SETTING In a series of laboratory experiments, we modified the mitochondrial ND4 subunit of complex I in the nuclear genetic code for import into mi ...[more]

PMID: 24457989

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Project description:PurposeLeber hereditary optic neuropathy (LHON) is a disorder characterized by severe and rapidly progressive visual loss when caused by a mutation in the mitochondrial gene encoding NADH:ubiquinone oxidoreductase subunit 4 (ND4). We have initiated a gene therapy trial to determine the safety and tolerability of escalated doses of an adeno-associated virus vector (AAV) expressing a normal ND4 complementary DNA in patients with a G to A mutation at nucleotide 11778 of the mitochondrial genome.DesignIn this prospective open-label trial (NCT02161380), the study drug (self-complementary AAV [scAAV]2(Y444,500,730F)-P1ND4v2) was intravitreally injected unilaterally into the eyes of 5 blind participants with G11778A LHON. Four participants with visual loss for more than 12 months were treated. The fifth participant had visual loss for less than 12 months. The first 3 participants were treated at the low dose of vector (5 × 10(9) vg), and the fourth participant was treated at the medium dose (2.46 × 10(10) vg). The fifth participant with visual loss for less than 12 months received the low dose. Treated participants were followed for 90 to 180 days and underwent ocular and systemic safety assessments along with visual structure and function examinations.ParticipantsFive legally blind patients with G11778A LHON.Main outcome measuresLoss of visual acuity.ResultsVisual acuity as measured by the Early Treatment Diabetic Retinopathy Study (ETDRS) eye chart remained unchanged from baseline to 3 months in the first 3 participants. For 2 participants with 90-day follow-up, acuity increased from hand movements to 7 letters in 1 and by 15 letters in 1, representing an improvement equivalent to 3 lines. No one lost vision, and no serious adverse events were observed. Minor adverse events included a transient increase of intraocular pressure (IOP), exposure keratitis, subconjunctival hemorrhage, a sore throat, and a transient increase in neutralizing antibodies (NAbs) against AAV2 in 1 participant. All blood samples were negative for vector DNA.ConclusionsNo serious safety problems were observed in the first 5 participants enrolled in this phase I trial of virus-based gene transfer in this mitochondrial disorder. Additional study follow-up of these and additional participants planned for the next 4 years is needed to confirm these preliminary observations.

Project description:IMPORTANCE Establishing the natural history of G11778A Leber hereditary optic neuropathy (LHON) is important to determine the optimal end points to assess the safety and efficacy of a planned gene therapy trial. OBJECTIVE To use the results of the present natural history study of patients with G11778A LHON to plan a gene therapy clinical trial that will use allotopic expression by delivering a normal nuclear-encoded ND4 gene into the nuclei of retinal ganglion cells via an adeno-associated virus vector injected into the vitreous. DESIGN, SETTING, AND PARTICIPANTS A prospective observational study initiated in 2008 was conducted in primary and referral institutional practice settings. Participants included 44 individuals with G11778A LHON, recruited between September 2008 and March 2012, who were evaluated every 6 months and returned for 1 or more follow-up visits (6-36 months) as of August 2012. EXPOSURES Complete neuro-ophthalmic examination and main measures. MAIN OUTCOMES AND MEASURES Visual acuity, automated visual field testing, pattern electroretinogram, and spectral-domain optical coherence tomography. RESULTS Clinical measures were stable during the follow-up period, and visual acuity was as good as or better than the other visual factors used for monitoring patients. Based on a criterion of 15 or more letters from the Early Treatment Diabetic Retinopathy Study chart, 13 eyes of 8 patients (18%) improved, but 24 months after the onset of symptoms, any further improvements were to no better than 20/100. Acuity recovery occurred in some patients despite continued marked retinal nerve fiber layer thinning indistinguishable from that in patients who did not recover visual acuity. CONCLUSIONS AND RELEVANCE Spontaneous improvement of visual acuity in patients with G11778A LHON is not common and is partial and limited when it occurs, so improvements in vision with adeno-associated virus-mediated gene therapy of a synthetic wild-type ND4 subunit gene should be possible to detect with a reasonable sample size. Visual acuity appears to be the most suitable primary end point for the planned clinical trial.

Project description:PurposeLeber hereditary optic neuropathy (LHON), a maternally inherited disorder, results from point mutations in mitochondrial DNA (mtDNA). MtDNA is highly polymorphic in nature with very high mutation rate, 10-17 fold higher as compared to nuclear genome. Identification of new mtDNA sequence variations is necessary to establish a clean link with human disease. Thus this study was aimed to assess or evaluate LHON patients for novel mtDNA sequence variations.Materials and methodsTwenty LHON patients were selected from the neuro-ophthalmology clinic of the All India Institute of Medical Sciences, New Delhi, India. DNA was isolated from whole blood samples. The entire coding region of the mitochondrial genome was amplified by PCR in 20 patients and 20 controls. For structural analysis (molecular modeling and simulation) the MODELER 9.2 program in Discovery Studio (DS 2.0) was used.ResultsMtDNA sequencing revealed a total of 47 nucleotide variations in the 20 LHON patients and 29 variations in 20 controls. Of 47 changes in patients 21.2% (10/47) were nonsynonymous and the remaining 78.72% (37/47) were synonymous. Five nonsynonymous changes, including primary LHON mutations (NADH dehydrogenase subunit 1 [ND1]:p.A52T, NADH dehydrogenase subunit 6 [ND6]:p.M64V, adenosine triphosphate [ATP] synthase subunit a (F-ATPase protein 6) [ATPase6]:p.M181T, NADH dehydrogenase subunit 4 [ND4]:p.R340H, and cytochrome B [CYB]:p.F181L), were found to be pathogenic. A greater number of changes were present in complex I (53.19%; 25/47), followed by complex III (19.14%; 9/47), then complex IV (19.14%; 9/47), then complex V (8.5%; 4/47). Nonsynonymous variations may impair respiratory chain and oxidative phosphorylation (OXPHOS) pathways, which results in low ATP production and elevated reactive oxygen species (ROS) levels. Oxidative stress is the underlying etiology in various diseases and also plays a crucial role in LHON.ConclusionsThis study describes the role of mtDNA sequence variations in LHON patients. Primary LHON mutations of mtDNA are main variants leading to LHON, but mutations in other mitochondrial genes may also play an important role in pathogenesis of LHON as indicated in the present study. Certain alleles in certain haplogroups have protective or deleterious roles and hence there is a need to analyze a large number of cases for correlating phenotype and disease severity with mutation and mtDNA haplogroups.

Dataset Information

Safety and effects of the vector for the Leber hereditary optic neuropathy gene therapy clinical trial.

Publications

Safety and effects of the vector for the Leber hereditary optic neuropathy gene therapy clinical trial.

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