- Email: [email protected]
56. Glaucoma-GT, a Novel Gene Therapy Treatment for Primary Open-Angle Glaucoma
CLINICAL GENE & CELL THERAPY 55. Preclinical Safety Studies for AAV2-MerTK Gene Therapy Vector for Retinitis Pigmentosa
Thomas J. Conlon,1 Wen-Tao Deng,2 Renee C. Ryals,2 Kirsten E. Erger,1 Travis L. Cossette,1 Shannon E. Boye,2 Isaam McDoom,2 Nathalie Clemente,1 Brian Cleaver,1 Mark Potter,1 Corinne Abernathy,3 Sanford L. Boye,2 William W. Hauswirth.2 1 Pediatrics, University of Florida, Gainesville, FL; 2Opthamology, university of Florida, Gainesville, FL; 3Clinical and Translational Science Institute, University of Florida, Gainesville, FL. Purpose. Efficacy of MERTK gene replacement therapy has been demonstrated using different viral vectors in the Royal College of Surgeons (RCS) rat, a well studied model of recessive retinitis pigmentosa (RP) that contains a mutation in the Mertk gene. MERTK is expressed in the RPE cells and plays a key role in renewal of photoreceptor outer segments (OS) by phagocyting shed OS tips. Mutations in MERTK cause impaired phagocytic activity and accumulation of OS debris in the interphotoreceptor space and ultimately result in retinal degeneration. The results of three separate Phase I clinical trials for Leber’s Congenital Amaurosis type 2 (LCA2) demonstrated the safety of AAV in human patients. AAV is well-suited for human gene therapy due to its low immunogenic profile. In the present study, we conducted a series of preclinical efficacy and safety evaluations of an AAV2 vector expressing human MERTK cDNA driven by a RPE-specific VMD2 promoter, including a formal GLP toxicology and biodistribution study. Methods. Efficacy of AAV2-VMD2-hMERTK vector was evaluated by subretinally injected into one eye of RCS rats and retinal function was assayed electroretinographically 2 months post-injection. Safety and biodistribution of the vector was assessed in SD rats by subretinal injection of BSS control and two different dosed of AAV vector at a total dose of 4x108 or 4x109 vg. The effect of the vector was investigated by electroretinogram, fundoscopic analysis, and gross anatomy in the injected eyes. Potential toxicity was studied by organ hispathology and clinical pathology at different time points up to 90 days post-injection. Results. Efficacy of the vector was demonstrated in RCS rat which showed significant improved ERG responses in treated eyes compared to contralateral untreated eyes. Delivery of AAV-MERTK in SD rat eyes at two different doses did not result in a change in ERG magnitude of rod and cone responses relative to BSS control injected eyes indicating that administration of AAV vector did not adversely affect retinal function. Fundoscopic analysis and gross anatomy of the injected eyes were normal compared to injected controls. There were no gross or microscopic findings or presence of transformed cells in the blood that were related to administration of the test article as assessed by histopathology and blood smear. All injected eyes and day 1 blood samples were positive for vector genomes and all peripheral tissues were negative. Conclusions. Our results demonstrate the efficacy and safety of the AAV2-VMD2hMERTK vector in animal models tested. A GMP vector has been manufactured and is presently in clinical trial. Supported by The Foundation Fighting Blindness.
56. Glaucoma-GT, a Novel Gene Therapy Treatment for Primary Open-Angle Glaucoma
Katie Binley,1 Scott Ellis,1 Vicky Scripps,1 Sharifah Iqball,1 Stuart Naylor,1 Kyriacos Mitrophanous.1 1 Oxford BioMedica (UK) Ltd, Oxford, United Kingdom. Glaucoma is the second leading cause of blindness worldwide, affecting around 70 million people, over 2.5 million people in the USA alone. It is characterized by irreversible degeneration of the optic nerve, usually associated with an elevated intraocular pressure (IOP). Prostenoid analogues such as Latanoprost are a first-line treatment for glaucoma due to their high level of efficacy and low risk of side-effects, but fail to halt disease progression in many patients due to non-adherence, which can be > 50%. Surgery is often Molecular Therapy Volume 21, Supplement 1, May 2013 Copyright © The American Society of Gene & Cell Therapy
required, which is expensive and only partially effective. There is therefore a real medical need for a novel drug that overcomes this issue of poor compliance. Initial proof-of-concept for this approach has been demonstrated (Barraza et al, 2010), and we are now moving this into a translational gene therapy platform for clinical evaluation. Glaucoma-GT is a gene therapy product aimed at lowering IOP via the prostenoid pathway: a single transcorneal administration leads to the expression of human cyclooxygenase-2 (COX-2) and prostaglandin F (FP) receptor in the front of the eye. COX-2 is a rate-limiting enzyme in the biosynthesis of prostaglandins, and both COX-2 and the FP receptor are down-regulated in glaucomatous eyes. Expression of both genes increases both prostaglandin 2 (PGF2) biosynthesis and signaling, increasing aqueous outflow and reducing longterm IOP. Gene transfer following transcorneal administration of EIAV-GFP vector was characterised in animal models. Various vector genome configurations were assessed for the production of PGF2 and activation of the FP receptor in in vitro assays. Further preclinical studies are currently ongoing and data from these will be presented. Transcorneal injection of EIAV vector led to the transduction of cells of the trabecular meshwork and corneal endothelium in vivo. Different configurations of expression cassette gave a broad range of PGF2 and FP activation, with CMV-COX-2-IRES-FP having the highest activity. We have demonstrated significant gene transfer following transcorneal administration of EIAV-GFP vector in animal models, and have optimised the therapeutic expression cassette to produce high levels of prostaglandin 2 and enhanced FP activation in in vitro studies. These vector configurations will be assessed for IOP lowering in a relevant animal model.
Clinical Gene & Cell Therapy 57. Acid alpha-Glucosidase Gene Replacement Therapy to the Diaphragm in Ventilator-Dependent Pompe Disease: One-Year Respiratory Motor Outcomes
Barbara K. Smith,1 Daniel Martin,1 Lee Ann Lawson,2 Cathryn S. Mah,2 Saleem Islam,3 Thomas Conlon J. Conlon,2 Dawn Phillips,3 Shelley Collins,3 Barry J. Byrne.2 1 Physical Therapy, University of Florida, Gainesville, FL; 2 Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL; 3Pediatrics and Surgery, University of Florida, Gainesville, FL.
Pompe disease is a neuromuscular disease caused by diminished or absent acid alpha-glucosidase (GAA) enzyme, which results in lysosomal glycogen accumulation in striated muscle and motor neurons. The early-onset form leads to severe cardiac hypertrophy and respiratory failure. The currently approved treatment for Pompe disease, recombinant enzyme replacement therapy, reduces the severity of cardiomyopathy and increases survival. However, many surviving patients experience progressive ventilatory insufficiency and may eventually require mechanical ventilation (MV). Preclinical data in the murine model of Pompe disease showed a diaphragmatic AAV-GAA vector corrected defects of phrenic motor function. Therefore, our objective was to initiate an open-label, Phase I/ II clinical study of AAV-GAA gene therapy to the diaphragm. We hypothesized AAV-GAA gene therapy would correct accumulation of muscle glycogen and promote retrograde transport of AAV-GAA to restore respiratory motor function. To date, five children (ages 2-15) with full-time MV dependence on chronic ERT have completed enrollment, received intramuscular rAAV1-CMV-GAA vector delivery into the diaphragm, and concluded follow-up ventilatory testing 365 days after dosing. No serious vector-related adverse events occurred and no clinically significant changes in safety labs were noted. Respiratory motor assessments showed improvements in maximum tidal volume and maximum voluntary ventilation in S23
Thomas J. Conlon,1 Wen-Tao Deng,2 Renee C. Ryals,2 Kirsten E. Erger,1 Travis L. Cossette,1 Shannon E. Boye,2 Isaam McDoom,2 Nathalie Clemente,1 Brian Cleaver,1 Mark Potter,1 Corinne Abernathy,3 Sanford L. Boye,2 William W. Hauswirth.2 1 Pediatrics, University of Florida, Gainesville, FL; 2Opthamology, university of Florida, Gainesville, FL; 3Clinical and Translational Science Institute, University of Florida, Gainesville, FL. Purpose. Efficacy of MERTK gene replacement therapy has been demonstrated using different viral vectors in the Royal College of Surgeons (RCS) rat, a well studied model of recessive retinitis pigmentosa (RP) that contains a mutation in the Mertk gene. MERTK is expressed in the RPE cells and plays a key role in renewal of photoreceptor outer segments (OS) by phagocyting shed OS tips. Mutations in MERTK cause impaired phagocytic activity and accumulation of OS debris in the interphotoreceptor space and ultimately result in retinal degeneration. The results of three separate Phase I clinical trials for Leber’s Congenital Amaurosis type 2 (LCA2) demonstrated the safety of AAV in human patients. AAV is well-suited for human gene therapy due to its low immunogenic profile. In the present study, we conducted a series of preclinical efficacy and safety evaluations of an AAV2 vector expressing human MERTK cDNA driven by a RPE-specific VMD2 promoter, including a formal GLP toxicology and biodistribution study. Methods. Efficacy of AAV2-VMD2-hMERTK vector was evaluated by subretinally injected into one eye of RCS rats and retinal function was assayed electroretinographically 2 months post-injection. Safety and biodistribution of the vector was assessed in SD rats by subretinal injection of BSS control and two different dosed of AAV vector at a total dose of 4x108 or 4x109 vg. The effect of the vector was investigated by electroretinogram, fundoscopic analysis, and gross anatomy in the injected eyes. Potential toxicity was studied by organ hispathology and clinical pathology at different time points up to 90 days post-injection. Results. Efficacy of the vector was demonstrated in RCS rat which showed significant improved ERG responses in treated eyes compared to contralateral untreated eyes. Delivery of AAV-MERTK in SD rat eyes at two different doses did not result in a change in ERG magnitude of rod and cone responses relative to BSS control injected eyes indicating that administration of AAV vector did not adversely affect retinal function. Fundoscopic analysis and gross anatomy of the injected eyes were normal compared to injected controls. There were no gross or microscopic findings or presence of transformed cells in the blood that were related to administration of the test article as assessed by histopathology and blood smear. All injected eyes and day 1 blood samples were positive for vector genomes and all peripheral tissues were negative. Conclusions. Our results demonstrate the efficacy and safety of the AAV2-VMD2hMERTK vector in animal models tested. A GMP vector has been manufactured and is presently in clinical trial. Supported by The Foundation Fighting Blindness.
56. Glaucoma-GT, a Novel Gene Therapy Treatment for Primary Open-Angle Glaucoma
Katie Binley,1 Scott Ellis,1 Vicky Scripps,1 Sharifah Iqball,1 Stuart Naylor,1 Kyriacos Mitrophanous.1 1 Oxford BioMedica (UK) Ltd, Oxford, United Kingdom. Glaucoma is the second leading cause of blindness worldwide, affecting around 70 million people, over 2.5 million people in the USA alone. It is characterized by irreversible degeneration of the optic nerve, usually associated with an elevated intraocular pressure (IOP). Prostenoid analogues such as Latanoprost are a first-line treatment for glaucoma due to their high level of efficacy and low risk of side-effects, but fail to halt disease progression in many patients due to non-adherence, which can be > 50%. Surgery is often Molecular Therapy Volume 21, Supplement 1, May 2013 Copyright © The American Society of Gene & Cell Therapy
required, which is expensive and only partially effective. There is therefore a real medical need for a novel drug that overcomes this issue of poor compliance. Initial proof-of-concept for this approach has been demonstrated (Barraza et al, 2010), and we are now moving this into a translational gene therapy platform for clinical evaluation. Glaucoma-GT is a gene therapy product aimed at lowering IOP via the prostenoid pathway: a single transcorneal administration leads to the expression of human cyclooxygenase-2 (COX-2) and prostaglandin F (FP) receptor in the front of the eye. COX-2 is a rate-limiting enzyme in the biosynthesis of prostaglandins, and both COX-2 and the FP receptor are down-regulated in glaucomatous eyes. Expression of both genes increases both prostaglandin 2 (PGF2) biosynthesis and signaling, increasing aqueous outflow and reducing longterm IOP. Gene transfer following transcorneal administration of EIAV-GFP vector was characterised in animal models. Various vector genome configurations were assessed for the production of PGF2 and activation of the FP receptor in in vitro assays. Further preclinical studies are currently ongoing and data from these will be presented. Transcorneal injection of EIAV vector led to the transduction of cells of the trabecular meshwork and corneal endothelium in vivo. Different configurations of expression cassette gave a broad range of PGF2 and FP activation, with CMV-COX-2-IRES-FP having the highest activity. We have demonstrated significant gene transfer following transcorneal administration of EIAV-GFP vector in animal models, and have optimised the therapeutic expression cassette to produce high levels of prostaglandin 2 and enhanced FP activation in in vitro studies. These vector configurations will be assessed for IOP lowering in a relevant animal model.
Clinical Gene & Cell Therapy 57. Acid alpha-Glucosidase Gene Replacement Therapy to the Diaphragm in Ventilator-Dependent Pompe Disease: One-Year Respiratory Motor Outcomes
Barbara K. Smith,1 Daniel Martin,1 Lee Ann Lawson,2 Cathryn S. Mah,2 Saleem Islam,3 Thomas Conlon J. Conlon,2 Dawn Phillips,3 Shelley Collins,3 Barry J. Byrne.2 1 Physical Therapy, University of Florida, Gainesville, FL; 2 Pediatrics and Powell Gene Therapy Center, University of Florida, Gainesville, FL; 3Pediatrics and Surgery, University of Florida, Gainesville, FL.
Pompe disease is a neuromuscular disease caused by diminished or absent acid alpha-glucosidase (GAA) enzyme, which results in lysosomal glycogen accumulation in striated muscle and motor neurons. The early-onset form leads to severe cardiac hypertrophy and respiratory failure. The currently approved treatment for Pompe disease, recombinant enzyme replacement therapy, reduces the severity of cardiomyopathy and increases survival. However, many surviving patients experience progressive ventilatory insufficiency and may eventually require mechanical ventilation (MV). Preclinical data in the murine model of Pompe disease showed a diaphragmatic AAV-GAA vector corrected defects of phrenic motor function. Therefore, our objective was to initiate an open-label, Phase I/ II clinical study of AAV-GAA gene therapy to the diaphragm. We hypothesized AAV-GAA gene therapy would correct accumulation of muscle glycogen and promote retrograde transport of AAV-GAA to restore respiratory motor function. To date, five children (ages 2-15) with full-time MV dependence on chronic ERT have completed enrollment, received intramuscular rAAV1-CMV-GAA vector delivery into the diaphragm, and concluded follow-up ventilatory testing 365 days after dosing. No serious vector-related adverse events occurred and no clinically significant changes in safety labs were noted. Respiratory motor assessments showed improvements in maximum tidal volume and maximum voluntary ventilation in S23