Identifying a Lead Candidate Anti-methamphetamine Monoclonal Antibody for IND-enabling Studies: Cross-reactivity and Locomotor Activity

Abstract ID 92838 Poster Board 303 Objectives: About 1.6 million people have methamphetamine (METH) use disorder (MUD) in the US. There are no direct antagonists approved to treat MUD and small molecule treatments have not produced clinically significant improvements. Behavioral interventions, such as cognitive-behavioral therapies and contingency management are effective in patients with MUD, but few individuals with MUD begin these therapies and retention rates are poor. InterveXion Therapeutics and our research team at UAMS have studied the effects anti-METH antibodies in reducing METH CNS effects as a model for treating MUD for many years. We are now developing a long-acting monoclonal antibody (mAb) that binds to METH with high affinity. Our research objective in this study was to identify the best candidate among a panel of humanized anti-METH binding variable regions by screening mAbs for in vitro specificity and efficacy in a METH-induced locomotor activity model. Methods: A panel of 8 mAbs (IS12-IS19) was chosen for these studies based on their affinity for METH and onset (ka) and offset (kd) rates of binding to METH. Cross-reactivity of the chosen mAbs was tested with several abused drugs, prescription medications, over-the-counter medications, and neurotransmitters. To determine the capacities of mAbs to reduce METH-elicited locomotor stimulation, 48 male Sprague-Dawley rats first received two injections of 0.56 mg/kg METH (sc) and their locomotor activity was video recorded for 4 h post-METH administration using Noldus EthoVision XT. Next, rats were assigned to receive one of eight mAbs (282 mg/kg; iv) and their locomotor response to 0.56 mg/kg METH was assessed 24 h and 96 h after mAb administration. The primary dependent measure in the locomotor activity experiment was the horizontal distance traveled (cm). We also quantified mAb levels in blood serum at <96 h and <264 h after mAb administration in the same sample of rats. Results:Cross-reactivity: mAbs have nanomolar affinity (kd or ki) for (+)-METH (range: 7.78 to 32.36 nM), (+)-amphetamine (170.91 to 1048.93 nM), (+)-3,4-methylenedioxymethamphetamine (9.91 to 65.54 nM), and selegiline (258.81 to 642.80 nM). Affinities for all other test compounds were >1 microM. Locomotor Activity: The mAb with the greatest affinity for METH (IS12) reduced 0.56 mg/kg METH-elicited locomotor stimulation (pre-mAb administration) by 39.44% when tested 24 h after mAb administration and by 18.17% when tested 96 h after mAb administration. Full data sets on cross-reactivity, locomotor stimulant effects, and blood titers of mAbs are forthcoming. Discussion: In this study, we identified IS12, which has the same variable region as the parent antibody, mAb7F9, as the mAb with the greatest affinity for METH and capacity to reduce METH-elicited locomotor stimulation. Our next step is to characterize the pharmacokinetic profile and duration of effect in reducing METH-elicited locomotor stimulation of IS12 produced as a pair of IgGs using two constant domain sequences that increase half-life. Funded by the NIH (NIDA: U01DA056240, PI: Misty Stevens, PhD). Test compounds were provided by the NIDA Drug Supply Program.