Preclinical potency and safety studies of an AAV2-mediated gene therapy vector for the treatment of MERTK associated retinitis pigmentosa.

Thomas J. Conlon, Wen Tao Deng, Kirsten Erger, Travis Cossette, Ji jing Pang, Renee Ryals, Nathalie Clément, Brian Cleaver, Issam McDoom, Shannon E. Boye, Marc C. Peden, Mark B. Sherwood, Corinne R. Abernathy, Fowzan S. Alkuraya, Sanford L. Boye, William W. Hauswirth

Research output: Contribution to journalArticlepeer-review

67 Scopus citations

Abstract

Abstract Proof of concept for MERTK gene replacement therapy has been demonstrated using different viral vectors in the Royal College of Surgeon (RCS) rat, a well characterized model of recessive retinitis pigmentosa that contains a mutation in the Mertk gene. MERTK plays a key role in renewal of photoreceptor outer segments (OS) by phagocytosis of shed OS tips. Mutations in MERTK cause impaired phagocytic activity and accumulation of OS debris in the interphotoreceptor space that ultimately leads to photoreceptor cell death. In the present study, we conducted a series of preclinical potency and GLP-compliant safety evaluations of an adeno-associated virus type 2 (AAV2) vector expressing human MERTK cDNA driven by the retinal pigment epithelium-specific, VMD2 promoter. We demonstrate the potency of the vector in RCS rats by improved electroretinogram (ERG) responses in treated eyes compared with contralateral untreated controls. Toxicology and biodistribution studies were performed in Sprague-Dawley (SD) rats injected with two different doses of AAV vectors and buffer control. Delivery of vector in SD rats did not result in a change in ERG amplitudes of rod and cone responses relative to balanced salt solution control-injected eyes, indicating that administration of AAV vector did not adversely affect normal retinal function. In vivo fundoscopic analysis and postmortem retinal morphology of the vector-injected eyes were normal compared with controls. Evaluation of blood smears showed the lack of transformed cells in the treated eyes. All injected eyes and day 1 blood samples were positive for vector genomes, and all peripheral tissues were negative. Our results demonstrate the potency and safety of the AAV2-VMD2-hMERTK vector in animal models tested. A GMP vector has been manufactured and is presently in clinical trial.

Original languageEnglish (US)
Pages (from-to)23-28
Number of pages6
JournalUnknown Journal
Volume24
Issue number1
DOIs
StatePublished - Mar 2013
Externally publishedYes

ASJC Scopus subject areas

  • Genetics(clinical)

Fingerprint

Dive into the research topics of 'Preclinical potency and safety studies of an AAV2-mediated gene therapy vector for the treatment of MERTK associated retinitis pigmentosa.'. Together they form a unique fingerprint.

Cite this