Design and Characterization of Prodrugged Anti-CTLA-4 Antibodies

Area of Science:

• Biotechnology
• Immunology
• Pharmacology

Background:

• Therapeutic antibodies target specific molecules for treating diseases like cancer.
• Adverse events and limited pharmacokinetic (PK) profiles, including target-mediated drug disposition (TMDD), can restrict antibody therapies.
• Anti-CTLA-4 immunotherapy shows promise in solid tumors but faces safety limitations.

Purpose of the Study:

• To mask an anti-CTLA-4 antibody by conjugating polyethylene glycol (PEG) to reduce binding affinity and improve safety.
• To identify optimal conjugation sites within complementarity-determining regions (CDRs) and framework regions for effective masking.
• To evaluate the prodrugged antibody's stability, PK profile, and functionality in a preclinical model.

Main Methods:

• Conjugation of a large PEG molecule to specific sites on an anti-CTLA-4 antibody.
• Evaluation of multiple conjugation sites within CDRs and adjacent framework regions.
• Assessment of antibody binding to CTLA-4 and Fc gamma receptors (FcgRs).
• In vivo studies in a mouse model to determine stability and half-life.

Main Results:

• Identified an optimal conjugation site for maximizing masking efficiency and enabling enzyme-mediated functional restoration.
• The prodrugged antibody demonstrated reduced binding to CTLA-4 and FcgRs.
• Achieved high stability and an extended half-life in a mouse model.
• Successful bioconjugation and restoration of function upon enzymatic cleavage.

Conclusions:

• PEGylation at specific sites effectively masks anti-CTLA-4 antibody activity, reducing off-target interactions.
• This prodrug strategy enhances antibody stability and prolongs half-life, improving PK profiles.
• The developed technology holds potential for safer and more effective therapeutic antibody applications.