# Require every oncology candidate to publish how much reaches the brain

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

## TL;DR

Whether a drug gets into the brain is measured early in development but rarely published. Making that number public would show which existing drugs could treat brain disease.

## Summary

Unbound brain-to-plasma partition coefficients are routinely generated in preclinical development and almost never disclosed, so clinicians and academic groups cannot tell which approved drugs are worth testing in central nervous system disease. A disclosure requirement at investigational new drug or marketing authorisation stage, or a voluntary public registry, would create a searchable resource at near-zero cost.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: A public brain exposure registry identifies at least 20 approved oncology drugs with meaningful brain penetration that are not currently used for central nervous system disease, at least five of which merit trials.
- Rationale: Similar mandated disclosures, such as trial registration and results reporting, changed behaviour quickly once required. The data already exist inside companies, so the marginal cost of publication is trivial relative to the value of knowing.
- Proposed test: Ask ten companies to disclose historical brain exposure data for approved oncology drugs voluntarily; publish the registry and measure how many new central nervous system trials cite it within two years.
- Maturity: speculative
- Actor: policy

## 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

- collections: [ClinicalTrials.gov](https://onco.cc/collections/clinicaltrials-gov/), [DrugBank & ChEMBL](https://onco.cc/collections/drugbank-chembl/), [FDA Oncology Approvals (OCE) & Novel Drug Approvals](https://onco.cc/collections/fda-approvals/)
- terms: [Blood-brain barrier (BBB)](https://onco.cc/terms/blood-brain-barrier/)
- bottlenecks: [Failures are hidden](https://onco.cc/bottlenecks/b-negative-results/), [Knowledge reaches practice too slowly](https://onco.cc/bottlenecks/b-knowledge-diffusion/), [The brain: barrier and sanctuary](https://onco.cc/bottlenecks/b-brain-delivery/)

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