Active and Passive Immunization with an Anti-Methamphetamine Vaccine Attenuates the Behavioral and Cardiovascular Effects of Methamphetamine

BACKGROUND

Methamphetamine use disorder (MUD) is a growing health concern with no FDA-approved treatment. The present series of studies build upon our previous work developing an anti-methamphetamine (MA) vaccine for MUD. We determined the effects of a formulation that included tetanus-toxoid (TT) conjugated to succinyl-methamphetamine (TT-SMA) adsorbed onto aluminum hydroxide (alum) in combination with the novel Toll-Like Receptor-5 agonist, entolimod.

METHODS

Mice were vaccinated (0, 3, 6 weeks) with TT-SMA+alum and various doses of entolimod to determine an optimal dose for enhancing immunogenicity against MA. Functional effects were then assessed using MA-induced locomotor activation in mice. Experiments using passive immunization of antibodies generated by the vaccine tested its ability to attenuate MA-induced cardiovascular effects and alter the reinforcing effects of MA in an MA-induced reinstatement of a drug seeking model of relapse in male and female rats.

RESULTS

Antibody levels peaked at 10 weeks following vaccination with TT-SMA+alum combined with entolimod (1, 3 and 10 μg). MA-induced locomotor activation was significantly attenuated in vaccinated vs. unvaccinated mice and antibody levels significantly correlated with ambulation levels. Passive immunization decreased mean arterial pressure following MA dosing in rats of both sexes but did not alter heart rate. Passive immunization also attenuated the ability of MA to reinstate extinguished drug-seeking behavior in male and female rats. Results support further development of this vaccine for relapse prevention for individuals with MUD.

KMRC011, an agonist of toll-like receptor 5, mitigates irradiation-induced tissue damage and mortality in cynomolgus monkeys

In the study here, the potential applicability of KMRC011 - an agonist of toll-like receptor-5 - as a countermeasure for radiation toxicities was evaluated. Following a single 5.5 Gy total body irradiation (TBI, surface absorbed dose = 7 Gy) of Co⁶⁰ γ-rays, mortality rates and degrees of pathological lesions that developed over 80 days were compared in monkeys that received TBI only and a group that was injected once with KMRC011 (10 μg/kg) after TBI. Compared to the TBI-only hosts (80%), the death rate was significantly improved by the use of KMRC011 (40%), all deaths in both groups occurred in the period from Days 19-24 post-TBI. Further analysis of monkeys that survived until the end of the experiment showed that AST and ALT levels were elevated only in the TBI group, and that radiation-induced tissue damage was alleviated by the KMRC011 injection. Additionally, expression of cell death-related proteins was lower in tissues from the KMRC011-treated hosts than in those in the TBI-only group. Other measured parameters, including body weight, food uptake, and hematological values did not significantly differ between the two groups over the entire period. The results of this study, thus demonstrate that KMRC011 could potentially be used as a medical countermeasure for the treatment of acute radiation exposure.

Radioprotective effect of newly synthesized toll-like receptor 5 agonist, KMRC011, in mice exposed to total-body irradiation

Exposure to ionizing radiation leads to severe damages in radiosensitive organs and induces acute radiation syndrome, including effects on the hematopoietic system and gastrointestinal system. In this study, the radioprotective ability of KMRC011, a novel toll-like receptor 5 (TLR5) agonist, was investigated in C57BL6/N mice exposed to lethal total-body gamma-irradiation. In a 30-day survival study, KMRC011-treated mice had a significantly improved survival rate compared with control after 11 Gy total-body irradiation (TBI), and it was found that the radioprotective activity of KMRC011 depended on its dosage and repeated treatment. In a 5-day short-term study, we demonstrated that KMRC011 treatment stimulated cell proliferation and had an anti-apoptotic effect. Furthermore, KMRC011 increased the expressions of genes related to DNA repair, such as Rad21, Gadd45b, Sod2 and Irg1, in the small intestine of lethally irradiated mice. Interestingly, downregulation of NF-κB p65 in the mouse intestine by KMRC011 treatment was observed. This data indicated that KMRC011 exerted a radioprotective activity partially by regulating NF-κB signaling. Finally, peak expression levels of G-CSF, IL-6, IFN-γ, TNF-α and IP-10 induced by KMRC011 treatment were different depending on the route of administration and type of cytokine. These cytokines could be used as candidate biomarkers for the evaluation of KMRC011 clinical efficacy. Our data indicated that KMRC011 has radioprotective activity in lethally irradiated mice and may be developed as a therapeutic agent for radioprotection.

The Toll-like receptor 5 agonist entolimod suppresses hepatic metastases in a murine model of ocular melanoma via an NK cell-dependent mechanism

Uveal melanoma (UM) is the most common primary cancer of the eye in adults and progresses to metastatic disease predominantly of the liver in ∼50% of patients. In these cases, life expectancy averages just 9 months due to the lack of effective treatment options. The Toll-like receptor 5 (TLR5) agonist entolimod (former name CBLB502) rapidly activates TLR5-NF-κB signaling in hepatocytes and suppresses growth of both TLR5-expressing and non-expressing tumors in the liver through mobilization and activation of innate and adaptive immune mechanisms. The goal of this study was to explore the potential of entolimod as an immunotherapeutic agent against hepatic metastasis of UM using the TLR5-positive B16LS9 mouse model of ocular melanoma. Mice were given seven subcutaneous injections of vehicle or entolimod given 72 h apart started one day before, on the same day or three days after intraocular injection of B16LS9 cells. All tested regimens of entolimod treatment resulted in significantly reduced B16LS9 metastasis to the liver. Entolimod induced mobilization of natural killer (NK) cells to the liver and stimulated their maturation, differentiation and activation. Antibody-mediated depletion of NK cells from mice abrogated entolimod's antimetastatic activity in the liver and eliminated the entolimod-elicited in vitro cytotoxic activity of hepatic lymphocytes against B16LS9 cells. These results provide pre-clinical evidence of entolimod's efficacy against hepatometastasis of UM and support its further development as an anticancer immunotherapeutic drug.