title: Safety and efficacy of subretinal readministration of a viral vector in large animals to treat congenital blindness.
abstract: Leber's congenital amaurosis (LCA) is a group of severe inherited retinal degenerations that are symptomatic in infancy and lead to total blindness in adulthood. Recent clinical trials using recombinant adeno-associated virus serotype 2 (rAAV2) successfully reversed blindness in patients with LCA caused by RPE65 mutations after one subretinal injection. However, it was unclear whether treatment of the second eye in the same manner would be safe and efficacious, given the potential for a complicating immune response after the first injection. Here, we evaluated the immunological and functional consequences of readministration of rAAV2-hRPE65v2 to the contralateral eye using large animal models. Neither RPE65-mutant (affected; RPE65(-/-)) nor unaffected animals developed antibodies against the transgene product, but all developed neutralizing antibodies against the AAV2 capsid in sera and intraocular fluid after subretinal injection. Cell-mediated immune responses were benign, with only 1 of 10 animals in the study developing a persistent T cell immune response to AAV2, a response that was mediated by CD4(+) T cells. Sequential bilateral injection caused minimal inflammation and improved visual function in affected animals. Thus, subretinal readministration of rAAV2 in animals is safe and effective, even in the setting of preexisting immunity to the vector, a parameter that has been used to exclude patients from gene therapy trials.
authors.affiliation: F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Defne
authors.initials: D
authors.lastname: Amado
authors.forename: Federico
authors.initials: F
authors.lastname: Mingozzi
authors.forename: Daniel
authors.initials: D
authors.lastname: Hui
authors.forename: Jeannette L
authors.initials: JL
authors.lastname: Bennicelli
authors.forename: Zhangyong
authors.initials: Z
authors.lastname: Wei
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Chen
authors.forename: Erin
authors.initials: E
authors.lastname: Bote
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Grant
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Golden
authors.forename: Kristina
authors.initials: K
authors.lastname: Narfstrom
authors.forename: Nasreen A
authors.initials: NA
authors.lastname: Syed
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Orlin
authors.forename: Katherine A
authors.initials: KA
authors.lastname: High
authors.forename: Albert M
authors.initials: AM
authors.lastname: Maguire
authors.forename: Jean
authors.initials: J
authors.lastname: Bennett
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000867:Anterior Chamber / Q000276:immunology; D057134:Antibodies, Neutralizing / Q000276:immunology; D001766:Blindness / Q000151:congenital* / Q000235:genetics / Q000628:therapy*; D002213:Capsid / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics / Q000627:therapeutic use; D000229:Dependovirus / Q000235:genetics*; D004285:Dogs; D004333:Drug Administration Routes; D005136:Eye Proteins / Q000235:genetics / Q000627:therapeutic use; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000008:administration & dosage* / Q000009:adverse effects*; D006801:Humans; D007109:Immunity / Q000276:immunology; D007150:Immunohistochemistry; D008875:Middle Aged; D011180:Postmortem Changes; D011323:Primates; D012160:Retina / Q000473:pathology*; D017186:Titrimetry; D016896:Treatment Outcome; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
chemical_list: D057134:Antibodies, Neutralizing; D002352:Carrier Proteins; D005136:Eye Proteins; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase