The NewroBus platform: engineered humanized anti-TfR1 nanobodies for efficient brain delivery.

Area of Science:

• Neuroscience
• Biotechnology
• Pharmacology

Background:

• The blood-brain barrier (BBB) restricts central nervous system (CNS) drug delivery.
• Receptor-mediated transcytosis via transferrin receptor 1 (TfR1) offers a physiological pathway for BBB transport.
• Developing targeted delivery systems is crucial for CNS therapeutics.

Purpose of the Study:

• To engineer human-specific nanobodies targeting TfR1 for enhanced CNS drug delivery.
• To ensure these nanobodies do not interfere with normal transferrin function and iron homeostasis.
• To create a versatile platform for delivering biologic therapeutics across the BBB.

Main Methods:

• Isolation and humanization of camelid single-domain antibodies against human TfR1.
• Optimization using computational and AI-guided algorithms for improved biophysical properties.
• In vivo assessment of BBB permeability and safety in TfR1 humanized rats.

Main Results:

• Picomolar affinity nanobodies (NewroBus) demonstrated efficient TfR1-mediated BBB transcytosis.
• NewroBus maintained TfR1 function, iron homeostasis, and showed no hematotoxicity.
• Fused NewroBus constructs achieved sustained CNS levels for over three days post-subcutaneous administration.

Conclusions:

• Humanized TfR1 nanobodies (NewroBus) provide a safe and efficient platform for biologic CNS delivery.
• The system preserves essential iron transport while enabling targeted drug transport.
• NewroBus offers a modular and versatile solution for overcoming BBB challenges in CNS therapeutics.