Bifunctional Behavior of Conformationally Constrained Methamphetamine Analogs: Unexpected Heteroclitic Immune Response and Antagonist Effects Altering Methamphetamine and Fentanyl Pharmacology

Methamphetamine addiction
is a growing global health
crisis with
no FDA-approved pharmacotherapies. Vaccination offers a promising
therapeutic strategy, yet clinical translation has been limited by
immune response inefficacy. Here, we evaluated three methamphetamine
vaccine candidates: H1, a conventional hapten based on
traditional drug–hapten–vaccine logic, and H2 and H3, two conformationally constrained analogs incorporating
pyrrolidine and azetidine scaffolds, respectively. The rigidified
hapten H2 produced an unprecedented heteroclitic immune
response, with mature antibodies binding methamphetamine with an order
of magnitude greater affinity than the immunizing scaffold. Although
vaccine haptens are rarely assessed for intrinsic bioactivity, the
pyrrolidine scaffold of H2, termed S1, exhibited
distinct pharmacology, which was markedly divergent from methamphetamine. S1 is also capable of mitigating not only methamphetamine
but also fentanyl-induced physiological effects. Methamphetamine conformational
constraint offers a new tool for methamphetamine vaccine development
as well as promising therapeutic agents for reversal of methamphetamine
behavior and fentanyl-induced toxicity.