IPM Take
This is not just another liquid biopsy story. The sharper point is timing. Advanced breast cancer treatment decisions often wait for imaging, symptoms or later clinical assessment, which can mean weeks or months on a treatment that may not be working. ctDNA could give clinicians an earlier signal. But it should not become a routine switching trigger until prospective studies show that changing treatment based on ctDNA improves outcomes.
Executive Summary
Researchers at The Institute of Cancer Research, London analysed blood samples from 167 people with advanced breast cancer enrolled in the plasmaMATCH trial. ctDNA was measured before treatment and after four weeks. Low or undetectable ctDNA levels were associated with better treatment response and longer progression-free survival. The study included patients with targetable mutations receiving matched targeted therapies and patients with triple-negative breast cancer receiving olaparib plus ceralasertib. The researchers said larger validation studies are still needed before ctDNA-guided treatment adaptation becomes routine.
Why it matters
- Clinicians: Need evidence on whether early ctDNA changes should influence treatment continuation, switching or trial referral.
- Diagnostics / pathology: Should prepare for validated ctDNA workflows, including timing, assay quality, reporting and integration with clinical decision-making.
- Patients / advocates: Should watch whether liquid biopsy monitoring improves outcomes, not only whether it detects response earlier.
Before this type of monitoring, response to treatment in advanced breast cancer was usually judged through imaging, symptoms and later clinical assessment. That can delay the moment when clinicians know whether a therapy is helping.
What changed here is the use of ctDNA as an early, non-invasive response signal. In the plasmaMATCH analysis, ctDNA was measured at baseline and again after one treatment cycle. Patients with low ctDNA before treatment, or undetectable ctDNA after four weeks, tended to have better outcomes. ICR reported particularly strong associations between undetectable ctDNA at four weeks and longer progression-free survival in both treatment groups.
The affected population is people with advanced breast cancer receiving targeted or DNA-damage response therapies. For IPM, the implementation message is precise: ctDNA may help make treatment more adaptive, but routine use needs prospective validation, clear thresholds, reimbursement and agreement on what clinicians should do when ctDNA remains high.
