Pharmacological Profiling of Antifentanyl Monoclonal Antibodies in Combination with Naloxone in Pre- and Postexposure Models of Fentanyl Toxicity

Abstract

The incidence of fatal drug overdoses in the United States is an alarming public health threat that has been exacerbated by the COVID-19 pandemic, resulting in over 100,000 deaths between April 2020 and April 2021. A significant portion of this is attributable to widespread access to fentanyl and other synthetic opioids, alone or in combination with heroin or psychostimulants such as cocaine or methamphetamine. Monoclonal antibodies (mAb) offer prophylactic and therapeutic interventions against opioid overdose by binding opioids in serum, reducing distribution of drug to the brain and other organs. Here, we investigated the efficacy of a lead anti-fentanyl mAb, clone HY6-F9, in reversal and prevention of fentanyl-induced toxicity compared to the opioid receptor antagonist naloxone (NLX) in rats. In post-exposure models, rats were challenged with fentanyl, followed by HY6-F9, NLX, or both. HY6-F9 reversed fentanyl-induced antinociception, respiratory depression, and bradycardia, and rats retained protection against additional challenges for at least 1 week. Although intravenous NLX reversed fentanyl-induced respiratory depression more rapidly than mAb alone, kinetics of reversal by intravenous mAb were similar to subcutaneous NLX. Co-administration of mAb and NLX provided greater protection than individual treatments against high doses of fentanyl. Prophylactic administration of mAb reduced the ED 50 of NLX approximately 2-fold against 2.25 mg/kg fentanyl. Finally, mAb sequestered fentanyl and its metabolite norfentanyl in serum, and reduced brain concentrations of fentanyl. These results support the translation of mAb as medical interventions alone or in combination with NLX to prevent and reverse fentanyl-related overdose. Significance statementFentanyl-related overdoses have increased dramatically in the US and worldwide. Currently, approved pharmacotherapies for treatment of opioid use disorder and reversal of overdose are not sufficient to curb the incidence of opioid-related deaths. Additionally, fentanyl and its potent analogs present a potential risk from use in deliberate poisoning or chemical attacks. This study demonstrates the use of mAb as a countermeasure to fentanyl-induced toxicity in pre-and postexposure scenarios, supporting their use in combination with the opioid antagonist NLX.

Advancing humanized monoclonal antibody for counteracting fentanyl toxicity towards clinical development

“…All mAbs significantly reduced brain fentanyl and increased fentanyl concentration in serum, though HY11-6B2_Ch was least effective at sequestering fentanyl in serum. Because HY6-F9_Mu has previously shown efficacy in rats, 19 , 40 the efficacy of HY6-F9_Ch was also compared to HY6-F9_Mu in rats ( Figure 3 ). Rats were passively immunized with 40 mg/kg of HY6-F9_Mu or HY6-F9_Ch, and 24 hours later challenged with 0.1 mg/kg fentanyl.…”

“…Anti-fentanyl murine mAb and chAb isolated by other groups have been shown to prevent fentanyl-induced antinociception and brain distribution at similar mAb and fentanyl doses to those used here. 20 , 21 Meanwhile, HY6-F9_Mu has been shown to prevent fentanyl effects in both mice and rats, 19 and to reverse respiratory depression in rats, 40 a more clinically relevant measure for fentanyl overdose than antinociception. However, as murine and chimeric mAbs are unsuitable for human use due to ADA responses, 26–28 humanization is essential for clinical advancement.…”

“…These mAbs offer a promising new treatment for counteracting the effects of synthetic opioid-induced toxicity by providing an alternative to treatment with naloxone, or via dual administration of mAb and naloxone. 40 Further clinical development of the lead α-fentanyl mAbs described herein will grant a first-in-class opportunity to assess the clinical potential of a mAb-based therapeutic at preventing the loss of life caused by synthetic opioids.…”

An Epitope-Focused Trypanosome-Derived Vaccine Platform Elicits High-Affinity Antibodies and Immunity Against Fentanyl Effects

“…Figures 1A and B) (Raleigh et al, 2019;Robinson et al, 2020;Crouse et al, 2022). After sortase A-mediated conjugation of fen-sort to the surface VSG (Fent-VAST), sortagging efficiency was assessed by flow cytometry using a mouse anti-fentanyl mAb (Baehr et al, 2020(Baehr et al, , 2022. This revealed that 100% of the trypanosomes had been decorated with the fent-sort (Figure 2A).…”

“…These strategies have also been used to generate mAbs against a variety of target drugs of abuse including fentanyl. Notably, fentanyl-specific mAbs are effective in both preventing and reversing fentanyl's pharmacological effects in rodent models, further highlighting the promise of immunotherapeutics in the opioid space (Smith et al, 2019;Baehr et al, 2020Baehr et al, , 2022Ban et al, 2021). While promising indeed, there remains a lack of clinical output in this space and a desperate need for additional intervention options.…”