433. Micro-Utrophin as a Therapeutic Protein in rAAV Mediated Gene Therapy for Duchenne Muscular Dystrophy

Abstract

Late infantile neuronal ceroid lipofuscinosis (LINCL), a pediatric neurodegenerative lysosomal storage disorder, results from mutations in the CLN2 gene that lead to a deficiency in tripeptidyl peptidase (TPP-I) and consequent progressive destruction of neurons. Studies in our laboratory have demonstrated long term TPP-I expression in the CNS following CNS gene transfer of AAV2CUhCLN2 (an AAV2-based vector expressing the human CLN2 cDNA) in the rat and non-human primate. To prepare for a possible clinical trial, the present study tests the hypothesis that direct CNS injection of AAV2CUhCLN2 to the CNS of rats and non-human primates at doses scalable to humans has an acceptable long term safety profile. Fischer 344 rats were injected bilaterally in the striatum with 2 × 1010 particle units (pu) of AAV2CUhCLN2, using PBS as a control. At 13 wk, vector and PBS-injected rats were sacrificed (n=6 /group), and blood was collected and the brain and distant organs were assessed by histopathology. The data showed no significant differences between control and vector groups for complete blood count, blood chemistry, and neutralizing anti-AAV2 antibody levels. CNS administration of AAV2CUhCLN2 did not result in any pathological changes in the brain that were attributable to the vector, although microscopic changes were observed along the tract consistent with needle trauma. Changes observed in distant organs were of the type commonly observed in rats and occurred at similar frequencies in AAV2CUhCLN2 and PBS-injected animals. A total dose of 3.6 × 1010 or 3.6 × 1011 pu of AAV2CUhCLN2 was administered to the CNS of 18 African Green monkeys at 12 locations targeting the caudate nucleus, hippocampus and overlying cortices. Monkeys (n=3) at each dose were sacrificed at 1, 13, and 26 wk following injection. The controls consisted of sham-injected, PBS-injected, and AAV2CUNull-injected (3.6 × 1011 pu) monkeys. Using ANOVA analysis for repeated measurements, there were no significant differences among vector-injected and control groups in any parameter of the general assessment or comprehensive mammalian profile (blood chemistry panel, complete blood count) pre-administration, on the day of administration, and day 3, 7, 14, 28, 56, 91, 180 post-administration. There were no abnormal behaviors observed in any group in videotaped neurological assessment where behaviors was quantified prior to administration compared to day 7, 14, 28, 56, 91, 180 post-administration. Histopathological examination of the CNS demonstrated that injection of AAV2CUhCLN2 produced slight to mild and transient white matter edema (spongiosis) with reactive glial cells in the corona radiata of the cerebrum along the injection tract and in the surrounding white matter. This abmormality likely attributable to the vehicle, was not observed at 13 and 26 wk. Together with the long term gene expression following gene transfer, these findings support the initiation of clinical trials to assess the safety of AAV2CUhCLN2 administration to individuals with LINCL.