tgAAG76, an adeno-associated virus delivered gene therapy for the potential treatment of vision loss caused by RPE65 gene abnormalities.

The gene therapy vector tgAAG76 (rAAV 2/2.hRPE65p.hRPE65) is in joint development by Targeted Genetics Corp, Moorfields Eye Hospital and the University of London. The vector is a recombinant adeno-associated virus vector that contains the human RPE65 gene under the control of the human RPE65 promoter region and the bovine growth hormone polyadenylation signal. The vector was designed for administration into the subretinal space of patients affected by a hereditary blinding disorder, Leber congenital amaurosis type 2, which is caused by mutations in the RPE65 gene. Interim results from an ongoing phase I/II clinical trial assessing tgAAG76 in three patients with Leber congenital amaurosis type 2 were considered to accomplish the primary outcome of the trial, which was the safety of the procedure, with no severe side effects observed to date. One of the three patients had a significant increase in sensitivity to light and the better capacity to ambulate an obstacle course under dim light conditions compared with baseline. Completion of the clinical trial was anticipated in the second half of 2010.