Preclinical Efficacy and Selectivity of Vaccines Targeting Fentanyl, Alfentanil, Sufentanil, and Acetylfentanyl in Rats

Abstract

The ongoing public health emergency of opioid use disorders (OUD) and overdose in the United States is largely driven by fentanyl and its related analogues and has resulted in over 75 673 deaths in 2021. Immunotherapeutics such as vaccines have been investigated as a potential interventional strategy complementary to current pharmacotherapies to reduce the incidence of OUD and opioid-related overdose. Given the importance of targeting structurally distinct fentanyl analogues, this study compared a previously established lead conjugate vaccine (F 1 –CRM) to a series of novel vaccines incorporating haptens derived from alfentanil and acetylfentanyl (F 8, 9a, 9b, 10 ), and evaluated their efficacy against drug-induced pharmacological effects in rats. While no vaccine tested provided significant protection against alfentanil, lead formulations were effective in reducing antinociception, respiratory depression, and bradycardia elicited by fentanyl, sufentanil, and acetylfentanyl. Compared with control, vaccination with F 1 –CRM also reduced drug levels in the brain of rats challenged with lethal doses of fentanyl. These data further support investigation of F 1 –CRM as a candidate vaccine against fentanyl and selected analogues.

Efficacy and Selectivity of Monovalent and Bivalent Vaccination Strategies to Protect against Exposure to Carfentanil, Fentanyl, and Their Mixtures in Rats

“…The fentanyl-based hapten containing a tetraglycine linker (F 1 , or F(Gly) 4 ) was synthesized as previously described 20 and belongs to a series of F n haptens currently under development. 21,27 Carfentanil-Based Hapten (F 11 ). The synthesis of F 11 (Scheme 1) was initiated with the preparation of norcarfentanil from the previously described compound, N-benzylnorcarfentanil oxalate, 1.…”

“…The fentanyl-based hapten containing a tetraglycine linker (F 1 , or F­(Gly) 4 ) was synthesized as previously described and belongs to a series of F n haptens currently under development. , …”

“…Vaccines composed of F 1 conjugated to diphtheria cross-reactive material-197 (CRM) were previously shown to be effective in preventing fentanyl-induced antinociception, respiratory depression, bradycardia, and intravenous self-administration . Evaluation of F 1 -CRM alongside other conjugates containing a series of next-generation haptens (F 2–6 , and F 7–10 ) provided further evidence for this approach against fentanyl and selected analogs such as sufentanil, alfentanil, and acetylfentanyl. , In this series, the fentanyl-based hapten F 12 was synthesized but discarded early on from further screening (unpublished data). The F 11 and F 13 haptens are structurally different than other carfentanil-targeting haptens reported in the literature, , as the pendant phenethyl substituent has been replaced with linear amide-based linkers (Figure ).…”

Advancing humanized monoclonal antibody for counteracting fentanyl toxicity towards clinical development

“…Affinity and antigen selectivity measurements by BLI were performed with an Octet Red96e with biotinylated haptens derived from fentanyl (F 1 ), 18 , 31 acetylfentanyl (F 10 ), 31 and carfentanil (F 11 ). 32 Streptavidin-coated biosensors (Sartorius Catalog # 18–5020) were pre-incubated in 10 mM sodium phosphate, 0.15 M NaCl, 0.05% Tween-20, pH 7.5 (PBS-T) and loaded with 0.2 µg/mL of biotinylated hapten for 60 sec.…”

Mechanisms of Neurorespiratory Toxicity Induced by Fentanyl Analogs—Lessons from Animal Studies

“…In comparison to the controls, decreased post-exposure drug levels in the brain were observed in rats vaccinated with F1-CRM, a supported candidate vaccine against fentanyl and selected analogues. Lead vaccine formulations were highly effective in reducing the respiratory depression caused by fentanyl and other analogs, namely, sufentanil and acetylfentanyl [ 83 ], while due to their selectivity, they did not interfere with the pharmacological effects of commonly used anesthetics nor with methadone, naloxone, oxycodone or heroin [ 84 ]. Preclinical data obtained in rodents clearly encourage the translation of the fentanyl vaccine strategy to humans to fight against use disorders and toxicity.…”