The development and characterization of an scFv-Fc fusion based gene therapy to reduce the psychostimulant effects of methamphetamine abuse

Abstract

Methamphetamine (METH) continues to be amongst the most addictive and abused drugs in the US. Unfortunately, there are currently no FDA approved pharmacological treatments for METH substance abuse disorder. As an alternative approach, we have previously explored the use of Adeno-associated viral (AAV) mediated gene transfer of an anti-METH monoclonal antibody. Here, we advance our approach by generating a novel anti-METH scFv-Fc fusion construct (7F9-Fc), packaged into AAV serotype 8 vector (called AAV-scFv-Fc), and tested in vivo and ex vivo. A range of doses (1 x 1010. 1 x 1011, and 1 x 1012 vector copies(vc)/mouse) were administered to mice, which exhibited a dose-dependent expression of 7F9-Fc in serum with peak circulating concentrations of 48, 1785, and 3,831 g/ml. The dose of 1 x 1012 vc/mouse was further tested in METH locomotor and biodistribution studies to determine the efficacy of the antibody protection. Expressed 7F9-Fc exhibited high affinity binding, 17 nM, to METH. Between days 21 and 35 after vector administration, the 7F9-Fc gene therapy significantly reduced the effects of METH in locomotor assays following administration of moderate and high doses of subcutaneous METH, 3.1 and 9.4 mg/kg respectively. On day 116 post-AAV administration, mice expressing 7F9-Fc sequestered over 2.5 times more METH into the serum than vehicle mice, and METH concentrations in the brain were reduced by 1.2 times compared to vehicle mice. Taken together, these data suggest that a AAV-delivered anti-METH Fc fusion antibody could be a design for persistently reducing concentrations of METH in the CNS.\n\nSignificance StatementIn this manuscript, we describe the use of a novel anti-METH scFv-Fc fusion protein delivered in mice using gene therapy. The results suggest that the gene therapy delivery system can lead to the production of enough antibody to mitigate METHs psychostimulant effects in mice over an extended time period.