# Blood-brain barrier (BBB)

Source: https://onco.cc/terms/blood-brain-barrier/  
OnCo record `blood-brain-barrier` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The tight seal around brain blood vessels that keeps most drugs out, one of the two main reasons brain cancer is so hard to treat.

## Summary

Endothelial tight junctions, efflux transporters (P-gp, BCRP), and pericytes exclude most antibodies and all but small, lipophilic small molecules. Glioblastoma disrupts the barrier heterogeneously (contrast enhancement) but infiltrating cells sit behind intact barrier. Strategies: lipophilic/small brain-penetrant drugs (temozolomide, lomustine, dordaviprone, vorasidenib), locoregional delivery (CAR-T, convection-enhanced), focused-ultrasound opening, LITT, and intra-arterial delivery.

## Fields

- Kind: Term
- Last checked: 2026-09-06

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Blood–brain_barrier
- Wikipedia: https://en.wikipedia.org/wiki/Blood–brain_barrier

## Connected records

- cancers: [Astrocytoma, IDH-mutant (grades 2 to 4)](https://onco.cc/cancers/idh-mutant-astrocytoma/), [Brain metastases (secondary brain tumours)](https://onco.cc/cancers/secondary-brain-tumours/), [Diffuse midline glioma, H3 K27-altered (including DIPG)](https://onco.cc/cancers/dipg-dmg/), [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [Medulloblastoma](https://onco.cc/cancers/medulloblastoma/), [Primary CNS lymphoma](https://onco.cc/cancers/primary-cns-lymphoma/)
- technologies: [CAR-T for glioma (IL13Rα2, GD2, EGFRvIII, multi-target)](https://onco.cc/technologies/glioma-car-t/), [Focused-ultrasound blood-brain barrier opening](https://onco.cc/technologies/bbb-focused-ultrasound/), [Laser interstitial thermal therapy (LITT)](https://onco.cc/technologies/litt/)
- terms: [Drug efflux pumps (ABC transporters)](https://onco.cc/terms/efflux-pump/)
- drugs: [Dordaviprone](https://onco.cc/drugs/dordaviprone/), [Entrectinib](https://onco.cc/drugs/entrectinib/), [Lomustine (CCNU)](https://onco.cc/drugs/lomustine/), [Methotrexate](https://onco.cc/drugs/methotrexate/)
- trials: [CheckMate 143](https://onco.cc/trials/checkmate-143/), [CheckMate 498](https://onco.cc/trials/checkmate-498/), [CheckMate 548](https://onco.cc/trials/checkmate-548/)
- ideas: [A skull ultrasound implant that opens the barrier at every cycle](https://onco.cc/ideas/idea-bio2-implanted-ultrasound-repeat-dosing/), [Build a human model of the barrier that guards the brain fluid](https://onco.cc/ideas/idea-bio2-blood-csf-barrier-model/), [Deliver drugs and cells to the brain through the nose](https://onco.cc/ideas/idea-bio2-intranasal-delivery/), [Design protein degraders small enough to get into the brain](https://onco.cc/ideas/idea-bio2-brain-penetrant-glue-degraders/), [Focused-ultrasound BBB opening to deliver ADCs and radioligands to glioma](https://onco.cc/ideas/idea-fus-plus-adc-glioma/), [Require every oncology candidate to publish how much reaches the brain](https://onco.cc/ideas/idea-bio2-brain-exposure-disclosure/), [Robot-placed catheters and live imaging for drug infusion into brain tumours](https://onco.cc/ideas/idea-bio2-robotic-convection-delivery/), [Ultrasound-assisted blood test instead of a brain biopsy](https://onco.cc/ideas/idea-bio2-sonobiopsy/), [Use the brain's own transport door to carry antibody drugs across](https://onco.cc/ideas/idea-bio2-transferrin-shuttle-adc/)
- bottlenecks: [The brain: barrier and sanctuary](https://onco.cc/bottlenecks/b-brain-delivery/)
- pathways: [Organ tropism: seed and soil](https://onco.cc/pathways/organ-tropism-seed-soil/), [The blood-brain barrier & brain metastasis](https://onco.cc/pathways/blood-brain-barrier-metastasis/)

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