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In 1,039 Japanese patients with resected colorectal cancer, a positive Signatera test at week 4 carried a tenfold higher recurrence risk, and only ctDNA-positive patients appeared to benefit from adjuvant chemotherapy.
GALAXY is the prospective observational arm of the Japanese CIRCULATE platform. Patients with stage II-IV resectable colorectal cancer had serial tumour-informed ctDNA testing (Signatera) after surgery, with treatment at physician discretion.
ctDNA positivity at 4 weeks post-surgery was the strongest predictor of recurrence (HR about 10). Among ctDNA-positive patients, adjuvant chemotherapy was associated with markedly better disease-free survival (HR about 6.6 in favour of treatment), whereas ctDNA-negative patients showed no apparent benefit. Clearance of ctDNA during adjuvant therapy predicted good outcomes.
The study is the largest prospective MRD dataset in colorectal cancer and the basis for the randomised VEGA and ALTAIR trials.
The blood test stratifies risk far better than stage or pathology. It supports treating ctDNA-positive patients and suggests ctDNA-negative patients gain little from chemotherapy, but because treatment was not randomised the de-escalation claim needs the randomised trials that are now under way.
Shares Jeanne Tie, Take ctDNA-guided de-escalation beyond stage II, and stop escalating on a positive result until a trial says it helps, Tumour-informed versus tumour-naive ctDNA assays, DYNAMIC: a blood test safely halved chemotherapy use after surgery for stage II colon cancer.
Shares Variant allele frequency (VAF), Continuous and near-continuous ctDNA monitoring, Tumour-informed versus tumour-naive ctDNA assays, CIRCULATE-Japan (GALAXY / VEGA / ALTAIR).
Shares Natera, Tumour-informed versus tumour-naive ctDNA assays, Signatera, ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment.
Shares Natera, Tumour-informed versus tumour-naive ctDNA assays, CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), Signatera.
Shares Jeanne Tie, ctDNA-guided adjuvant therapy as the default in stage II-III colon cancer, Formally qualify tumour-DNA blood tests as a surrogate endpoint for adjuvant trials, Take ctDNA-guided de-escalation beyond stage II, and stop escalating on a positive result until a trial says it helps.
Shares Continuous and near-continuous ctDNA monitoring, Tumour-informed versus tumour-naive ctDNA assays, ctDNA MRD positivity (molecular residual disease after curative treatment), Signatera.
Shares Variant allele frequency (VAF), Natera, ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment, Minimal / molecular residual disease (MRD).
Shares Variant allele frequency (VAF), Natera, ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment, Dormant cells and minimal residual disease.