Anti‐Methamphetamine Antibody Gene Therapy Ameliorates Methamphetamine‐induced Locomotor Effects in Mice for 8 Months after a Single Treatment

Abstract

There currently are no FDA‐approved pharmacological treatments to aid in treatment of methamphetamine (METH) substance use disorders. To address this, our laboratory has combined short chain variable fragments (scFvs) derived from antibodies with high binding affinity to METH with adeno‐associated viruses (AAV) to develop a long‐lasting potential therapy. These first generation gene therapies showed expression of the anti‐METH scFvs for at least 212 days but achieved an average serum concentration of less than 70.0 μg/ml in mice. We hypothesized that incorporating a constant region (Fc) derived from an IgG antibody would extend serum half‐life and increase circulating concentrations of the anti‐METH antibody fragment, thus providing greater levels of protection against METH in mice. To test this hypothesis, we cloned an anti‐METH scFv‐Fc encoding DNA sequence into custom expression plasmids and packaged into AAV serotype 8 viral vectors to make AAV‐7F9‐Fc. To test this new gene therapy, BALB/C mice were administered 1×1012 vector copies per mouse of either the AAV‐7F9‐Fc or empty AAV8 vector. Mice were allowed to reach peak AAV‐7F9‐Fc expression (~28 days, as determined by ELISA) before testing in locomotor studies. Locomotor activity was used to measure protection from the stimulant effects of METH. Briefly, after a 30‐minute baseline activity was recorded, mice were administered saline, 0.56, 1.0, 3.0, or 5.56 mg/kg METH sc, and locomotor activity was measured for 90 minutes. METH was administered consecutively with a two‐day washout period in between doses. This regimen was also performed on separate mice 7–8 months after administration of AAV‐7F9‐Fc therapy to test duration of protection. Our results show that by incorporating an IgG Fc moiety into the anti‐METH constructs, the average expression increased by over 30 fold compared to a our first generation scFvs to a peak serum concentration of 5.227.7 μg/ml, and mean of 2,116.1 μg/ml, and persisted over 239 days. The AAV‐7F9‐Fc mice showed significantly less locomotor activity (p < 0.05) than empty AAV8 treated mice at the 1.0 and 3.0 mg/kg METH doses. Furthermore, the AAV‐7F9‐Fc treated mice showed no significant activity differences from baseline at any of the METH doses administered. In a separate, long‐term study, 7–8 months after AAV‐7F9‐Fc treatment, mice showed significantly lower levels of locomotor activity at 0.56 and 1.0 mg/kg sc METH doses than the sham treated group. These data suggest our AAV‐7F9‐Fc can protect against stimulant effects of METH, and that the duration of action is at least 8 months in mice. Overall, these data suggest that 1) the addition of the IgG Fc region into the AAV‐scFv constructs resulted in dramatically higher anti‐METH antibody circulating concentrations than our first generation anti‐METH scFvs and 2) this higher antibody titer was able to provide protection against METH stimulant effects at low to moderate doses for at least 8 months in mice.Support or Funding InformationSupported by NIDA R01 DA036600 & NIGMS T32 GM106999This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.