# TRAK-ER

Source: https://onco.cc/trials/trak-er/  
OnCo record `trak-er` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A UK-led trial that tests the blood of women with high-risk hormone-receptor-positive breast cancer every three months, and offers a change of treatment to those whose blood turns positive before scans show anything.

## Summary

TRAK-ER (NCT04985266), sponsored by the Royal Marsden with Invitae among its collaborators, has two phases: ctDNA surveillance with a tumour-informed assay from Labcorp, then randomisation of ctDNA-positive patients without radiological recurrence to palbociclib plus fulvestrant or standard endocrine therapy (tamoxifen, letrozole, anastrozole or exemestane), for up to 24 months. The registry lists 1,100 planned participants and an estimated primary completion in September 2027.

The surveillance phase reported in Annals of Oncology in 2026: of 912 patients who started surveillance, 12.0 per cent had ctDNA detected, panel design failed in 16.1 per cent, and 65.9 per cent of those detected on their first test already had radiological recurrence, against 26.6 per cent of those first detected later. The authors conclude that ultrasensitive assays are required to find relapse before it is clinically evident. The randomised treatment phase has not reported.

## Fields

- Kind: Trial
- Status: recruiting
- Last checked: 2026-11-04
- Also known as: TRAK ER
- Registry id: NCT04985266
- Phase: 2
- Setting: High-risk ER-positive, HER2-negative early breast cancer on adjuvant endocrine therapy with at least three more years planned: three-monthly tumour-informed ctDNA surveillance for up to three years; ctDNA-positive patients without radiological recurrence randomised to palbociclib plus fulvestrant or continued standard endocrine therapy
- Sponsor: Royal Marsden NHS Foundation Trust
- Enrolled: 1100
- Result: Surveillance phase: ctDNA detected in 12.0% (109 of 912); 65.9% of first-test detections had radiological recurrence at detection. Treatment phase not reported.
- Outcomes: Patient-level ctDNA detection during surveillance: Patients under ctDNA surveillance 12%; Radiological recurrence already present at first ctDNA detection: Detected on the first test 65.9% vs First detected on a later test 26.6%

## Sources

- ClinicalTrials.gov NCT04985266: https://clinicaltrials.gov/study/NCT04985266
- Cunningham et al., Ann Oncol 2026 (TRAK-ER surveillance): https://doi.org/10.1016/j.annonc.2026.10.1292

## Connected records

- trials: [c-TRAK TN](https://onco.cc/trials/c-trak-tn/), [TREAT ctDNA](https://onco.cc/trials/treat-ctdna/)
- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- technologies: [MRD / molecular residual disease testing](https://onco.cc/technologies/mrd-testing/)
- targets: [Estrogen receptor (ERα)](https://onco.cc/targets/estrogen-receptor/)
- drugs: [Anastrozole](https://onco.cc/drugs/anastrozole/), [Exemestane](https://onco.cc/drugs/exemestane/), [Fulvestrant](https://onco.cc/drugs/fulvestrant/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Palbociclib](https://onco.cc/drugs/palbociclib/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/)
- companies: [Invitae](https://onco.cc/companies/invitae/), [Labcorp](https://onco.cc/companies/labcorp/)
- institutions: [The Royal Marsden](https://onco.cc/institutions/royal-marsden/)
- terms: [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Minimal / molecular residual disease (MRD)](https://onco.cc/terms/mrd/), [Tumour-informed versus tumour-naive ctDNA assays](https://onco.cc/terms/tumour-informed-assay/)
- bottlenecks: [Naming which clone or phenotype is left after treatment](https://onco.cc/bottlenecks/b-subclone-attribution-residual-disease/)
- key papers: [Prospective circulating tumour DNA surveillance in patients with early high-risk hormone receptor positive, HER2-negative breast cancer in the TRAK-ER study](https://onco.cc/key-papers/paper-cunningham-trak-er-surveillance-ann-oncol-2026/)

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