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There are still no approved medications for treating patients who abuse methamphetamine. Active vaccines for treating abuse of nicotine and cocaine are in clinical studies, but have not proven effective seemingly due to inadequate anti-drug antibody production. The current studies aimed to optimize the composition, adjuvant and route of administration of a methamphetamine conjugate vaccine, ICKLH-SMO9, in mice with the goal of generating significantly higher antibody levels. A range of hapten epitope densities were compared, as were the adjuvants Alhydrogel and a new Toll-like receptor 4 (TLR4) agonist called GLA-SE. While methamphetamine hapten density did not strongly affect the antibody response, the adjuvant did. Glucopyranosyl lipid A in a stable oil-in-water emulsion (GLA-SE) produced much higher levels of antibody in response to immunization compared with Alhydrogel; immunization with GLA-SE also produced antibodies with higher affinities for methamphetamine. GLA-SE has been used in human studies of vaccines for influenza among others and like some other clinical TLR4 agonists, it is safe and elicits a strong immune response. GLA-SE adjuvanted vaccines are typically administered by intramuscular injection and this also proved effective in these mouse studies. Clinical studies of the ICKLH-SMO9 methamphetamine vaccine adjuvanted with GLA-SE have the potential for demonstrating efficacy by generating much higher levels of antibody than substance abuse vaccines that have unsuccessfully used aluminum-based adjuvants.

Previously, our laboratory produced a high affinity, anti-phencyclidine (PCP) murine monoclonal antibody (mAb6B5) that also binds other PCP-like arylcyclohexylamines. In this project, mAb6B5 is engineered into a mouse/human chimera (ch-mAb6B5) to assess the feasibility of developing it into a medication for PCP and PCP-like drug abuse. To create ch-mAb6B5, the light and heavy chain constant regions of mAb6B5 were replaced with human kappa and IgG(2) constant regions in order to decrease its potential immunogenicity in humans. To be an effective anti-PCP medication, ch-mAb6B5 must retain the critical immunochemical binding properties of mAb6B5. Expression vectors containing ch-mAb6B5 light chain and heavy chain cDNA were constructed and expressed in the murine myeloma cell line P3X63-Ag8.653. Immunoassays confirm that ch-mAb6B5 is indeed a chimera, composed of mAb6B5's PCP-binding variable domains and human kappa and IgG constant regions. Radioimmunoassays show that ch-mAb6B5 has the same drug-binding profile as mAb6B5. Ch-mAb6B5 and mAb6B5 bind PCP with a K(D) of 0.67 nM and 1.17 nM (respectively) and bind PCP-like arylcyclohexylamines 1-[1-(2-thienyl)cyclohexyl]piperidine and N-ethyl-1-phenylcyclohexylamine with similar specificity. Additionally, ch-mAb6B5 and mAb6B5 have the same calculated isoelectric points and molecular weights, critical properties in antigen-antibody interactions. These data demonstrate that mouse/human ch-mAb6B5, a "more human" version of murine mAb6B5, retains mAb6B5's unique drug-binding properties. This work supports our continued efforts to develop ch-mAb6B5 into a medication for PCP and PCP-like drug abuse - introducing the intriguing possibility of using a single therapeutic mAb for treating a class of abused drugs.