Strategies to Screen and Evaluate Brain Targeting Antibodies Using an iPSC-Derived Blood-Brain Barrier Model

Area of Science:

• Neuroscience
• Biotechnology
• Pharmacology

Background:

• Antibodies targeting receptor-mediated transport (RMT) systems facilitate drug delivery across the blood-brain barrier (BBB) to the central nervous system (CNS).
• Engineering antibody binding properties aims to enhance brain uptake, but transport efficiency determinants are not fully understood.
• The study focuses on improving variants of the 46.1 antibody, previously shown to cross the BBB.

Purpose of the Study:

• To identify improved variants of the 46.1 antibody for enhanced BBB transcytosis.
• To develop and utilize in vitro phenotypic screening and quantitative transcytosis assays.
• To understand antibody properties influencing BBB transport efficiency.

Main Methods:

• Screening a random mutagenic 46.1 antibody phage display library using a human induced pluripotent stem cell (iPSC)-derived BBB model.
• Evaluating antibody variants for improved in vitro transcytosis after initial enrichment.
• Performing targeted histidine point mutations in complementarity-determining regions (CDRs) of the 46.1 antibody.

Main Results:

• Initial phage display screening yielded enriched variants, but these did not show improved soluble antibody transcytosis.
• Targeted mutations in CDRs led to the identification of a specific variant.
• The R162H variant demonstrated modestly improved in vitro transcytosis compared to the wild-type (WT) 46.1 antibody.

Conclusions:

• The R162H variant exhibits enhanced in vitro transcytosis, suggesting potential for CNS drug delivery.
• The developed iPSC-derived BBB screening and evaluation strategies can aid in engineering antibodies for CNS delivery.
• This work provides insights into optimizing lead antibodies for efficient brain penetration.