367. Safety and Immunological Responses Following Intrapleural Administration of an AAV5 Vector Encoding Human α1-Antitrypsin to Non-Human Primates

Abstract

|[alpha]| 1-antitrypsin (|[alpha]|1AT), a 52 kDa serine proteinase inhibitor secreted by the liver, provides >95% of the functional anti-protease protection of the lower respiratory tract. |[alpha]|1AT deficiency is an autosomal recessive disorder associated with early-onset emphysema if serum |[alpha]|1AT levels are 1.6-fold the accepted therapeutic dose in humans. Importantly, the |[alpha]|1AT level in the bronchoalveolar lavage fluid (normalized to total protein) resulting from delivery of the AAV5CUh|[alpha]|1AT to the pleura was comparable to that found in the serum. In preparation for a clinical trial, the present study addresses the safety of administration of AAV5CUh|[alpha]|1AT to the pleural space of non-human primates at doses scalable to humans (evaluation of human |[alpha]|1AT levels in these animals is not technically feasible due to the 94% homology between African green monkey and human |[alpha]|1AT). The AAV5CUh|[alpha]|1AT vector (1013 gc/animal, n=3) and control (AAV5-luciferase, 1013 gc, n=1) were administered under fluoroscopy guidance in 5 ml of PBS into the right pleural space of juvenile African green monkeys, using an 22 gauge angiocatheter in the 5th or 6th intercostal space. Chest X-rays carried out immediately after vector administration, and at days 3,14 and 56 post-vector administration demonstrated the absence of pneumothorax, pleural effusion, pneumonia or any other pulmonary complications. Serum was collected at 3 time points (days-30,-15 and 0) prior to vector administration, to obtain baseline blood count and chemistry values, and at days 3, 14, 28, 56 and 91 post-vector administration. There were no significant differences (p>0.05 all parameters) between baseline (pre-vector administration) blood counts at any time point, except for transient increases in white blood cell count at days 3 and 14 post-vector administration (p=0.007), likely reflecting a physiological response to the procedure and/or vector administration. There were no significant differences in blood chemistry values at any time point, with the exception of serum Ca+ levels that decreased from initially high values into the range for adult African green monkeys. The anti-AAV5 neutralizing antibody titers post-vector administration ranged from 250 to 640 above background. Together with the long term gene expression following gene transfer to mice, these findings support the concept of a clinical trials to assess the safety of intrapleural administration of AAV5CUh|[alpha]|1AT to individuals with |[alpha]|1AT deficiency.