The goal of these studies was to demonstrate the METH binding capacity and duration of function of chronic therapy with anti-METH monoclonal antibodies (mAb), vaccines, and combination of mAb and vaccine. We hypothesized that chronic anti-METH mAb7F9 treatment could significantly decrease METH-induced behavioral changes and significantly alter METH disposition through high affinity mAb binding of METH. For the first studies, rats were habituated to METH and then administered a loading dose of anti-METH mAb7F9 followed by two additional weekly maintenance doses. On seven occasions over the course of the first 21 days, rats were challenged with intravenous METH doses. Pharmacological outcomes were measured by analysis of changes in METH-induced behavior and METH serum concentrations over time. Results from the first 21 days showed that the mAb therapy initially reduced (p<0.05) total METH-induced distance traveled compared to vehicle-treated rats in two out of seven METH challenges, and reduced METH-induced rearing after four of seven METH challenges. Over time, the mAb7F9 related reduction in total METH-induced behavioral effects appeared to attenuate. However, METH binding in the serum was always significantly increased during the mAb dosing. To help understand the apparent discrepancy between the attenuated behavioral changes and constant pharmacokinetic results, we analyzed the data during the first and second hour of the approximately 2 hr effect of the 0.56 mg/kg METH dose. This analysis showed there were significant (p<0.05) decreases in horizontal locomotion compared to vehicle-treated animals at each 60-120 min time interval during the first 21 days of the study and a significant decrease in rearing at six of seven time points (p<0.05). These dated showed mAb7F9 was significantly shortening the duration of action of METH. In the second phase of this chronic study on day 24 and 28, three-fold higher METH challenge doses (1.68 mg/kg) were administered. Results showed that the duration of METH behavioral effects and brain concentrations were still substantially decreased compared to controls on days 24 and 28. Overall, these results showed that chronically dosed mAb7F9 continues to be efficacious over time, even when mAb7F9 binding capacity is substantially exceeded. The purpose of the second study was to determine if a combination treatment with two high affinity anti-METH mAbs could synergistically improve anti-METH effects. We hypothesized that a 50:50 mixture of anti-METH mAb7F9 and mAb4G9 could increase efficacy by increasing mAb serum binding of METH and amphetamine (AMP). This involved the simultaneous dosing of equal parts of anti-METH mAb7F9 and mAb4G9, at the same total mAb dose used in the first study. Results showed this treatment antagonized the pharmacological effects of multiple doses of METH, but it was substantially less effective than treatment with mAb7F9 alone. These data also suggest mAb7F9 would be more effective than mAb4G9 if used as a monotherapy. The final study tested the therapeutic safety and efficacy of dosing with mAb7F9 during active vaccination of rats with an anti-METH conjugate vaccine (MCV). We hypothesized that combining the immediate protection of anti-METH mAb7F9 with the long-lasting immune response from active immunization with an MCV could provide therapeutic advantages in onset of action, overall increased antibody concentrations at critical time points, and duration of antibody action. The therapeutic strategy was to achieve the immediate beneficial effects with the anti-METH mAb, without affecting the MCV's ability to safely stimulate an active immune response. For this experiment, two groups of animals were initially vaccinated with an MCV. One of these two MCV groups was also administered anti-METH mAb7F9 at weeks 6 and 7. The third group was not vaccinated, but received mAb7F9. Results showed that the mAb7F9-only and MCV-mAb7F9 combination therapy groups had significantly increased METH titers at week 8 and 9 after mAb7F9 dosing compared to the MCV-only group. At week 17, two weeks after the final MCV boost, the METH binding titers of the mAb7F9-MCV combination and MCV-only groups were not significantly different from each other, but were significantly elevated (p<0.05) compared to the mAb7F9 treated rats. This was due to the clearance of mAb7F9. At week 17, two hrs after a METH challenge, serum METH concentrations in the MCV-mAb7F9 and MCV-only treated rats were significantly increased compared to the mAb7F9-only treated rats. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of whole brain tissue showed significant decreases (0.05) in brain METH concentrations in both groups of MCV-treated animals compared to the mAb7F9-only treated group. All groups appeared to tolerate treatments without apparent health problems. Overall, the data suggest anti-METH mAb7F9 could be used to supplement anti-METH antibody capacity during the generation of anti-METH antibodies by active MCV immunization or as a supplement to an inadequate immune response to the MCV. These data support the hypothesis that mAb7F9 could provide early antibody protection without inhibiting the development of antibodies through active immunization with an MCV. These data also show mAb7F9 does not appear to affect longer-lasting production of antibodies though active immunization.
|Advisor:||Owens, S. Michael|
|Commitee:||Fantegrossi, William E., Gentry, W. Brooks, Gottschall, Paul E., Gurley, Bill J.|
|School:||University of Arkansas for Medical Sciences|
|School Location:||United States -- Arkansas|
|Source:||DAI-B 75/05(E), Dissertation Abstracts International|
|Keywords:||Combination therapy, Drug abuse, Methamphetamine, Monoclonal antibody, Vaccine|
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