Toxicokinetics of a humanized anti-cocaine monoclonal antibody in male and female rats and lack of cross-reactivity.

A humanized monoclonal antibody h2E2 designed to bind cocaine with high affinity, specificity, and a long half-life (~7 d in rats) is being developed as a treatment for cocaine use disorder. We report here a pharmacokinetic (PK) study of h2E2 using male and female rats conducted under a Good Laboratory Practice (GLP) protocol over a dose range of 40 to 1200 mg/kg. The maximum concentration measured in rat plasma (Cmax) varied proportionately to the dose administered in both male and female rats. The terminal elimination half-lives (t1/2ß) were not significantly different in male and female rats at all doses tested. Importantly, this study reports pharmacokinetics for a humanized monoclonal antibody at a dose never tested before. h2E2 has a high affinity for cocaine, whereas low or no affinity was demonstrated for cocaine metabolites (all except cocaethylene), endogenous monoamines, and methamphetamine. This demonstrates its specificity and a potential lack of interactions with physiological and endocrine systems. A review of the clinical signs in single-dose toxicity studies in rats revealed no effects on the central nervous, respiratory, or cardiovascular systems following single intravenous doses of 40 to 1200 mg/kg. This study predicts that this monoclonal antibody may be safe and effective in humans.

A humanized anti-cocaine mAb antagonizes the cardiovascular effects of cocaine in rats.

The recombinant monoclonal anti-cocaine antibody, h2E2, sequesters cocaine in plasma increasing concentrations more than 10-fold. The increased levels of cocaine in the plasma could have detrimental peripheral effects, particularly on the cardiovascular system. We investigated the duration and magnitude of the effect of cocaine on the rat heart, and if h2E2 could antagonize that effect. Echocardiography was used to evaluate cardiac function under isoflurane anesthesia, while a tail-cuff was used to measure blood pressure. Cocaine was delivered intravenously and the rats were continuously monitored for a total of 45 min. Echocardiography measurements were recorded every 5 min and blood pressure measurements were recorded throughout the duration of the experiment using 30-s cycles. ECG recordings were taken simultaneously with the echocardiography measurements. An increase in ejection fraction was seen after the cocaine push with the maximum change occurring at 25 min. Treatment with h2E2 1 h before the cocaine push did not have any effect on cardiac parameters. Subsequent cocaine treatment had no effect on the ejection fraction, indicating that the antibody-bound cocaine does not affect the heart. This antagonism of cocaine's effects was greatly decreased after 1 week and entirely absent after 1 month. Cocaine in the presence of h2E2 is pharmacologically inert and h2E2 may have additional clinical utility for reversing cocaine effects on the cardiovascular system.

A Recombinant Humanized Anticocaine Monoclonal Antibody Alters the Urinary Clearance of Cocaine and Its Metabolites in Rats.

A recombinant humanized anticocaine monoclonal antibody, h2E2, has shown potential in the preclinical phases for the treatment of cocaine abuse. The standard tests for cocaine usage are the detection of benzoylecgonine (BE) and cocaine in the urine. This includes workplace drug screens as well as in clinical trials for potential treatments of cocaine abuse. By sequestering cocaine into the plasma compartment, h2E2 prevents cocaine from entering the brain. Due to the altered disposition of cocaine in the presence of h2E2, we investigated the effects of h2E2 on cocaine and metabolite levels in the urine of rats to clarify the use of BE as an endpoint measurement for effectiveness in future clinical trials. The urine concentrations of cocaine and metabolites were considerably altered in the presence of h2E2. After a single injection of h2E2 (120 mg/kg) and cocaine hydrochloride (0.56 mg/kg), the concentration of cocaine and BE excreted into the urine of rats decreased by 92% and 91%, respectively, from vehicle controls. Due to the significant decrease in urinary excretion, BE is not an appropriate indicator of cocaine usage in the presence of h2E2. Another endpoint measurement must be selected for the measurement of cocaine usage in the upcoming clinical trials of h2E2. In contrast to the effects on cocaine and BE urinary excretion, there was a 3-fold increase in ecgonine methyl ester (EME) in the presence of h2E2. Therefore, we conclude that EME is a more appropriate measurement of cocaine intake in the presence of h2E2.