{"entity":{"id":"idea-tnbc-brain-metastasis-trials","kind":"idea","name":"Trials that include, and report, brain metastases in triple-negative breast cancer","aka":[],"tldr":"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.","asOf":"2026-09-24","links":[{"label":"Lin et al.: sites of distant recurrence in metastatic triple-negative breast cancer, high incidence of central nervous system metastases (Cancer 2008)","url":"https://europepmc.org/article/MED/18833576"}],"tags":["tnbc-evidence"],"related":[],"cancers":["tnbc"],"sections":[],"technologies":["adc"],"targets":[],"drugs":["sacituzumab-govitecan","datopotamab-deruxtecan","trastuzumab-deruxtecan"],"companies":[],"institutions":["dana-farber"],"pathways":[],"terms":["brain-metastases"],"trials":["tropion-breast05","izabright-breast01","ascent-04"],"people":["nancy-lin"],"bottlenecks":["b-brain-delivery","b-metastasis-biology","b-trial-design"],"keyPapers":["paper-lin-tnbc-cns-metastases-dfci-cancer-2008","paper-tropion-breast02-ann-oncol-2026"],"journals":[],"dependsOn":[],"notes":[],"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.","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","cost":"medium","horizonYears":4},"route":"/ideas/idea-tnbc-brain-metastasis-trials/","neighbours":{"cancer":[{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"technology":[{"id":"adc","kind":"technology","name":"Antibody-drug conjugate (ADC)","route":"/technologies/adc/"}],"drug":[{"id":"datopotamab-deruxtecan","kind":"drug","name":"Datopotamab deruxtecan","route":"/drugs/datopotamab-deruxtecan/"},{"id":"sacituzumab-govitecan","kind":"drug","name":"Sacituzumab govitecan","route":"/drugs/sacituzumab-govitecan/"},{"id":"trastuzumab-deruxtecan","kind":"drug","name":"Trastuzumab deruxtecan","route":"/drugs/trastuzumab-deruxtecan/"}],"institution":[{"id":"dana-farber","kind":"institution","name":"Dana-Farber Brigham Cancer Center","route":"/institutions/dana-farber/"}],"term":[{"id":"brain-metastases","kind":"term","name":"Brain metastases (intracranial disease)","route":"/terms/brain-metastases/"}],"trial":[{"id":"ascent-04","kind":"trial","name":"ASCENT-04 / KEYNOTE-D19","route":"/trials/ascent-04/"},{"id":"izabright-breast01","kind":"trial","name":"IZABRIGHT-Breast01","route":"/trials/izabright-breast01/"},{"id":"tropion-breast05","kind":"trial","name":"TROPION-Breast05","route":"/trials/tropion-breast05/"}],"person":[{"id":"nancy-lin","kind":"person","name":"Nancy U. Lin","route":"/people/nancy-lin/"}],"bottleneck":[{"id":"b-metastasis-biology","kind":"bottleneck","name":"Metastasis is understood least and studied last","route":"/bottlenecks/b-metastasis-biology/"},{"id":"b-brain-delivery","kind":"bottleneck","name":"The brain: barrier and sanctuary","route":"/bottlenecks/b-brain-delivery/"},{"id":"b-trial-design","kind":"bottleneck","name":"Trial design, endpoints and cost","route":"/bottlenecks/b-trial-design/"}],"paper":[{"id":"paper-tropion-breast02-ann-oncol-2026","kind":"paper","name":"Datopotamab deruxtecan in patients with untreated, advanced triple-negative breast cancer (TROPION-Breast02): a randomised, open-label, international, phase III trial","route":"/key-papers/paper-tropion-breast02-ann-oncol-2026/"},{"id":"paper-lin-tnbc-cns-metastases-dfci-cancer-2008","kind":"paper","name":"Sites of distant recurrence and clinical outcomes in patients with metastatic triple-negative breast cancer: high incidence of central nervous system metastases","route":"/key-papers/paper-lin-tnbc-cns-metastases-dfci-cancer-2008/"}],"roadmap":[{"id":"tnbc-roadmap","kind":"roadmap","name":"Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem","route":"/roadmaps/tnbc-roadmap/"}]}}