# Use the brain's own transport door to carry antibody drugs across

Source: https://onco.cc/ideas/idea-bio2-transferrin-shuttle-adc/  
OnCo record `idea-bio2-transferrin-shuttle-adc` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The brain imports iron through the transferrin receptor. Antibody shuttle domains that bind that receptor raise brain exposure roughly ten to fifty-fold in primates and are already used in clinical Alzheimer's antibodies; the same engineering could carry antibody-drug conjugates or T-cell engagers to brain metastases.

## Summary

Transferrin receptor-binding shuttle domains raise brain exposure of antibodies roughly ten to fifty-fold in primates and are being used in clinical Alzheimer's antibodies and enzyme replacement therapies. Applying the same engineering to antibody-drug conjugates or T-cell engagers directed at brain metastasis antigens is a well-defined, if demanding, protein engineering task with a real precedent from another disease area.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: A shuttle-enabled HER2 antibody-drug conjugate achieves at least tenfold higher brain concentration than the parent molecule and produces intracranial responses in patients whose brain metastases progress on standard ADCs.
- Rationale: Shuttle engineering has moved from concept to clinical validation in neurology, so the platform risk is now largely retired. Brain metastases with retained antigen expression are a large, poorly served population where the only obstacle is delivery.
- Proposed test: Measure primate brain pharmacokinetics of shuttle versus parent conjugate, then run a phase 1 in HER2-positive brain metastasis with intracranial response and, where feasible, cerebrospinal fluid or resected-tissue drug measurement.
- Maturity: preclinical-evidence
- Actor: industry

## Sources

- Bottleneck evidence (The brain: barrier and sanctuary): Stupp et al., Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma (NEJM 2005): https://doi.org/10.1056/NEJMoa043330

## Connected records

- cancers: [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/), [Bispecific antibodies](https://onco.cc/technologies/bispecific-antibody/), [T-cell engagers (bispecific)](https://onco.cc/technologies/t-cell-engager/)
- targets: [HER2](https://onco.cc/targets/her2/), [HER3](https://onco.cc/targets/her3/), [TROP2](https://onco.cc/targets/trop2/)
- drugs: [Trastuzumab deruxtecan](https://onco.cc/drugs/trastuzumab-deruxtecan/), [Tucatinib](https://onco.cc/drugs/tucatinib/)
- terms: [Blood-brain barrier (BBB)](https://onco.cc/terms/blood-brain-barrier/), [HER2-positive brain metastases](https://onco.cc/terms/her2-brain-metastases/)
- bottlenecks: [The brain: barrier and sanctuary](https://onco.cc/bottlenecks/b-brain-delivery/), [The undruggable drivers](https://onco.cc/bottlenecks/b-undruggable-targets/)
- key papers: [Slamon 1989: HER2/neu in human breast and ovarian cancer](https://onco.cc/key-papers/paper-slamon-her2-breast-ovarian-science-1989/), [Yarden and Sliwkowski 2001: untangling the ErbB signalling network](https://onco.cc/key-papers/paper-yarden-sliwkowski-erbb-network-nrmcb-2001/)

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