# Trials that include, and report, brain metastases in triple-negative breast cancer

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

## TL;DR

Nearly half of women with metastatic triple-negative breast cancer develop brain metastases and survive under five months after the diagnosis, yet the trials that set the standard mostly exclude active brain disease. Requiring a brain metastasis cohort in every phase 3, with intracranial response as an endpoint, would answer whether the new drugs reach the brain.

## Summary

Lin's Dana-Farber series found central nervous system metastases in 14 percent at first metastatic diagnosis and 46 percent before death, with a median survival of 4.9 months after the brain diagnosis and only 3 of 53 patients with controlled systemic disease, arguing that the problem is a lack of effective therapy rather than a sanctuary effect. The immunotherapy and antibody-drug conjugate trials generally admitted only treated, stable brain metastases and did not report intracranial endpoints; trastuzumab deruxtecan has shown intracranial activity in HER2-positive disease, and case series suggest sacituzumab govitecan crosses into brain lesions, but there is no randomised evidence in triple-negative disease. The bottleneck record for brain delivery describes the general problem.

## Fields

- Kind: Idea
- Last checked: 2026-09-24
- Tags: tnbc-evidence
- Hypothesis: Including a pre-specified cohort of patients with active or untreated brain metastases in first-line antibody-drug conjugate trials will show an intracranial objective response rate above 30 percent for at least one conjugate and will identify a group in whom systemic therapy can defer or replace whole-brain radiotherapy.
- Rationale: The population is large, the outcome is poor, the drugs plausibly penetrate, and exclusion leaves clinicians extrapolating; a cohort adds cost but no new molecule.
- Proposed test: A brain metastasis cohort with intracranial response by RANO-BM criteria and time to whole-brain radiotherapy in TROPION-Breast05 and IZABRIGHT-Breast01 or their successors; a dedicated randomised phase 2 of TROP2 conjugate versus physician's choice in active brain metastases; mandatory reporting of central nervous system recurrence in adjuvant trials.
- Maturity: early-clinical
- Actor: industry

## Sources

- Lin et al.: sites of distant recurrence in metastatic triple-negative breast cancer, high incidence of central nervous system metastases (Cancer 2008): https://europepmc.org/article/MED/18833576

## Connected records

- cancers: [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/)
- drugs: [Datopotamab deruxtecan](https://onco.cc/drugs/datopotamab-deruxtecan/), [Sacituzumab govitecan](https://onco.cc/drugs/sacituzumab-govitecan/), [Trastuzumab deruxtecan](https://onco.cc/drugs/trastuzumab-deruxtecan/)
- institutions: [Dana-Farber Brigham Cancer Center](https://onco.cc/institutions/dana-farber/)
- terms: [Brain metastases (intracranial disease)](https://onco.cc/terms/brain-metastases/)
- trials: [ASCENT-04 / KEYNOTE-D19](https://onco.cc/trials/ascent-04/), [IZABRIGHT-Breast01](https://onco.cc/trials/izabright-breast01/), [TROPION-Breast05](https://onco.cc/trials/tropion-breast05/)
- people: [Nancy U. Lin](https://onco.cc/people/nancy-lin/)
- bottlenecks: [Metastasis is understood least and studied last](https://onco.cc/bottlenecks/b-metastasis-biology/), [The brain: barrier and sanctuary](https://onco.cc/bottlenecks/b-brain-delivery/), [Trial design, endpoints and cost](https://onco.cc/bottlenecks/b-trial-design/)
- key papers: [Datopotamab deruxtecan in patients with untreated, advanced triple-negative breast cancer (TROPION-Breast02): a randomised, open-label, international, phase III trial](https://onco.cc/key-papers/paper-tropion-breast02-ann-oncol-2026/), [Sites of distant recurrence and clinical outcomes in patients with metastatic triple-negative breast cancer: high incidence of central nervous system metastases](https://onco.cc/key-papers/paper-lin-tnbc-cns-metastases-dfci-cancer-2008/)
- roadmaps: [Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem](https://onco.cc/roadmaps/tnbc-roadmap/)

---
JSON: https://onco.cc/api/v1/entities/idea-tnbc-brain-metastasis-trials.json