Monoclonal Antibodies Engineered with Fc Region Mutations to Extend Protection against Fentanyl Toxicity

Area of Science:

• Pharmacology and Toxicology
• Immunology
• Drug Development

Background:

• Fentanyl and synthetic opioids are primary drivers of drug-related fatalities in the U.S.
• Monoclonal antibodies (mAbs) targeting fentanyl present a potential therapeutic strategy for opioid overdose and use disorder.
• Increasing the duration of action for anti-fentanyl mAbs is crucial for therapeutic efficacy.

Purpose of the Study:

• To enhance the efficacy and duration of an anti-fentanyl monoclonal antibody (mAb) by increasing its binding affinity to the neonatal Fc receptor (FcRn).
• To evaluate the in vitro and in vivo performance of engineered anti-fentanyl mAbs with modified Fc regions.

Main Methods:

• Engineered three sets of mutations in the Fc region of an IgG1 anti-fentanyl mAb (HY6-F9) to create variants (HY6-F9DF215, HY6-F9DHS, HY6-F9YTE).
• Compared mutant mAbs against wild-type (WT) HY6-F9mAb for fentanyl binding, thermal stability, and FcRn affinity in vitro.
• Assessed in vivo efficacy against fentanyl challenge and serum half-life in mice expressing human FcRn.

Main Results:

• Mutant mAbs demonstrated over a 10-fold increase in FcRn binding affinity compared to WT mAb.
• All FcRn-mutated mAbs provided protection against acute fentanyl toxicity and reduced brain fentanyl levels in mice.
• Serum half-lives in mice varied significantly, with HY6-F9DF215 showing a prolonged half-life of 26.4 days compared to WT (6.3 days).

Conclusions:

• Modifying anti-fentanyl mAbs for higher FcRn affinity can substantially increase their serum half-life while preserving therapeutic efficacy.
• These engineered mAbs represent a promising therapeutic avenue for managing fentanyl overdose and opioid use disorder.
• FcRn engineering offers a viable strategy to optimize the pharmacokinetic properties of antibody-based therapeutics.