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Byron L Lam, Jennifer Verriotto, Ninel Gregori, Janet L Davis; Choroideremia Gene Therapy Phase II Clinical Trial: 6-Month Results. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3386.
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© ARVO (1962-2015); The Authors (2016-present)
Sustained visual acuity improvements following gene therapy with subfoveal 1010 gp adeno-associated virus (AAV) vector have been noted in some patients with choroideremia (CHM). We report the 6-month results of an open label Phase II study (NCT02553135) using the higher dose subfoveal 1011 gp AAV vector (AAV2-REP1).
Six patients, age ranging 32 to 72 years, with genetically-proven advanced stages of CHM were treated unilaterally in the worse eye with subfoveal 0.1 ml of 1011 gp of AAV2-REP1. The primary outcome consists of a change in best-corrected visual acuity (BCVA) using the Early Treatment for Diabetic Retinopathy Study (ETDRS) charts in the treated eye compared to the untreated eye. Secondary functional and anatomical measures included changes in microperimetry, autofluorescence, and optical coherence tomography.
At Baseline, the mean ETDRS BCVA was 65.3±8.8 (SD, range 56-77) letters in the 6 treated eyes and 77.0±4.2 (69-81) letters in the 6 unoperated eyes. The mean BCVA change at 6 month after gene therapy was 1.7±4.1 (range -1 to +10) letters in the treated eyes and 2.0±3.1 (range -2 to +6) in the unoperated control eyes. Patient P2 improved by 10 letters at 1 month and the improvement was sustained. No serious adverse event occurred in any patient. Patient P4, age 72 years, had worsening of mild pre-existing cataract after gene therapy surgery; cataract surgery at 6 month returned the BCVA to baseline. For patients P2 and P3, each developed a macular retinal hole in area of non-functioning retina where baseline OCT demonstrated pre-existing lamellar partial-thickness thinning.
Sustained visual acuity improvements occur in some patients with choroideremia shortly after subfoveal gene therapy using 1011 gp AAV2-REP1. The treatment continues to have a good safety profile.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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