Combatting Synthetic Designer Opioids: A Conjugate Vaccine Ablates Lethal Doses of Fentanyl Class Drugs

Abstract

Fentanyl is an addictive prescription opioid that is over 80 times more potent than morphine. The synthetic nature of fentanyl has enabled the creation of dangerous 'designer drug' analogues that escape toxicology screening, yet display comparable potency to the parent drug. Alarmingly, a large number of fatalities have been linked to overdose of fentanyl derivatives. Herein, we report an effective immunotherapy for reducing the psychoactive effects of fentanyl class drugs. A single conjugate vaccine was created that elicited high levels of antibodies with cross-reactivity for a wide panel of fentanyl analogues. Moreover, vaccinated mice gained significant protection from lethal fentanyl doses. Lastly, a surface plasmon resonance (SPR)-based technique was established enabling drug specificity profiling of antibodies derived directly from serum. Our newly developed fentanyl vaccine and analytical methods may assist in the battle against synthetic opioid abuse. Fentanyl is an effective synthetic opioid that is used legally as a schedule II prescription pain reliever. However, fentanyl presents a significant abuse liability due to the euphoric feeling it induces via activation of μ-opioid receptors (MOR) in the brain; the same pharmacological target as the illegal schedule I opioid, heroin.[1] Excessive activation of MOR results in respiratory depression which can be fatal.[2] Fentanyl exceeds the potency of heroin by >10-fold, and morphine by >80-fold posing a significant risk of overdose when it is consumed from unregulated sources.[3] Furthermore, the ease of fentanyl synthesis enables illegal production and the creation of designer drug analogues.[4] The fact that the pharmacology of these analogues has yet to be properly characterized makes them particularly dangerous, especially when certain modifications, even methyl additions, can increase potency, notably at the 3-position (Figure 1 The basis of this strategy involves active vaccination of a protein-drug conjugate to generate an in vivo 'immunoantagonist', which effectively minimizes concentrations of the target drug at the sites of action. As a result, the vaccine reduces the addiction liability and overdose potential of the specific drug. In this work, we report the first instance of an efficacious fentanyl conjugate vaccine. Upon immunization, this vaccine successfully stimulated endogenous generation of IgG antibodies with specificity for fentanyl class drugs. Moreover, mouse antiserum showed nanomolar affinity for a variety of fentanyl analogues by SPRanalytical methods. When mice were dosed with potentially lethal quantities of fentanyl analogues, the vaccine imparted significant protection. No other vaccines to date have demonstrated blockade of the acutely lethal effects of any drugs of abuse. Importantly, our research efforts have yielded significant progress for mitigating the pharmacodynamic effects of fentanyl class drugs. In developing a fentanyl vaccine, hapten design presented the initial and possibly the most crucial challenge. As ...

Efficacious Vaccine against Heroin Contaminated with Fentanyl

“…Heroin titers increased in vaccination groups containing Her-KLH after a subsequent boost between week 3 and week 5; however, fentanyl titers in the individual Fent-KLH vaccine decreased slightly over time, but exhibited increased antibody affinity by surface plasmon resonance (SPR, Table 2). We have observed this phenomenon for several antidrug vaccines, including a fentanyl vaccine, 7 an oxycodone vaccine, 14 and a methamphetamine vaccine, 8 and this may be the result of a shortened vaccination schedule. 15 Antibody titers detected in the admixture were approximately half the level detected in the individual Her-KLH vaccine, as predicted based on the amount of Her-KLH immunoconjugate employed in each group (Table 1), but antibody affinity remained at similar levels.…”

“…Future plans will be to increase copy numbers of both immunoconjugates, 22 and with more efficacious carrier proteins, like tetanus toxoid, the admixture vaccine should approach efficacy seen with the singular vaccines. 7,11 Nonetheless, the current admixture vaccine protects against both heroin and fentanyl and may provide a future therapy to combat accidental exposure to fentanyl-contaminated heroin.…”

“…11 Moreover, we have also disclosed a fentanyl immunoconjugate vaccine, which shifted the fentanyl dose–effect curve in antinociceptive testing 30-fold in mice. 7 To our knowledge, this is the first and only report of a fentanyl conjugate vaccine, which demonstrated an ability to act as a “synthetic opioid pan-vaccine,” mitigating the effects of not only fentanyl, but also six other closely related fentanyl derivatives.…”

Enhancing Efficacy and Stability of an Antiheroin Vaccine: Examination of Antinociception, Opioid Binding Profile, and Lethality

“…36 Diluted mouse serum from day 38 was incubated with serial dilutions of heroin, 6-AM, methadone, oxycodone, naloxone, buprenorphine, norbuprenorphine, naltrexone, and morphine and injected into a Biacore 3000 containing a Her-BSA-loaded sensor chip. The heroin–BSA conjugate was immobilized on the sensor chip using a NHS, EDC-mediated coupling reaction.…”

Biologics to treat substance use disorders: Current status and new directions

“…45 Combination of CpG and alum also showed preclinical efficacy for vaccines directed against the prescription opioid fentanyl. 109 These data suggest that addition of CpG to alum adjuvant improves the quantity, quality, and function of the post-vaccination Ab response, and that this approach will likely improve other vaccines for SUD.…”