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‹ Fri · 5 Jun 2026
Promising but preliminary

Methylation-based ctDNA monitoring in metastatic breast cancer during CDK4/6 inhibitor therapy

A molecular blood test tracked treatment response and predicted disease progression six months earlier than imaging in metastatic breast cancer, enabling faster treatment adjustments.

In 57 metastatic breast cancer patients on CDK4/6 inhibitor therapy, a tissue-agnostic methylation-based ctDNA measure (mTF) closely tracked radiographic response and predicted treatment outcome with dramatic effect size (HR 0.17 for ctDNA clearance). Molecular progression reliably preceded clinical progression by nearly 6 months, suggesting mTF could enable earlier treatment changes.

What the study was

Study design
Prospective serial ctDNA sampling cohort study
Population
57 patients with ER+/HER2- metastatic breast cancer receiving endocrine therapy + CDK4/6 inhibitor; 350 serial plasma timepoints
Sample size
57
Category
Diagnostics
Maturity
Exploratory
Journal
Nat Commun

Why it surfaced

Nat Commun; prospective serial sampling with strong HR (0.17) for ctDNA clearance; tissue-agnostic mTF measure is methodologically innovative. Limited by small n=57 and single-institution design. Prospective mTF-guided trial implications are clinically significant.

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