ctDNA MRD positivity (molecular residual disease after curative treatment)
A ctDNA MRD test looks for the tumour's own mutations in blood after surgery. Detection predicts relapse months before scans, and in 2026 the FDA approved Signatera as the companion test selecting bladder cancer patients for adjuvant atezolizumab.
Overview
Tumour-informed assays (Signatera, RaDaR, NeXT Personal) sequence the tumour first and track a personalised set of variants in plasma; tumour-naive assays (Guardant Reveal) use mutations and methylation without a tumour sample. A positive result is any detection above the assay's calling threshold, reported as detected or not detected with a level. IMvigor011 showed a survival benefit for atezolizumab over placebo in ctDNA-positive muscle-invasive bladder cancer after cystectomy, and the FDA list carries Signatera CDx as the companion diagnostic for Tecentriq in that setting (P260004, 15 May 2026); the Tecentriq label read on 20 May 2026 predates the indication text in the openFDA copy, so the threshold here is quoted from the FDA list. In colorectal cancer the DYNAMIC trial and the ongoing CIRCULATE trials use ctDNA to guide adjuvant chemotherapy. As a genome-wide readout it sits under no target.
A positive ctDNA test after surgery means traces of the cancer's DNA are still in your blood and relapse is likely without more treatment. In muscle-invasive bladder cancer a positive Signatera result now selects a year of atezolizumab; in bowel cancer it is used in trials and by some teams to decide on chemotherapy. A negative result is reassuring but not a guarantee, and testing is usually repeated over time.
Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.
Detection of tumour-derived DNA in plasma above the assay's validated calling threshold after curative treatment (Signatera: two or more of 16 patient-specific variants detected), reported as MRD-positive with a mean tumour molecules per millilitre level.
“Circulating tumor DNA (ctDNA) molecular residual disease (MRD): Signatera CDx (Natera, Inc.) Muscle Invasive Bladder Cancer (MIBC) - Plasma TECENTRIQ (atezolizumab), TECENTRIQ HYBREZA BLA 761347 P260004 (05/15/2026)”
FDA: List of FDA-Authorized Companion Diagnostic Devices| Threshold | Drug | Cancer | Regulator | Source |
|---|---|---|---|---|
| ctDNA MRD-positive by Signatera CDx after cystectomy FDA companion diagnostic row P260004 (15 May 2026) for Tecentriq in muscle-invasive bladder cancer; the atezolizumab label copy read on DailyMed on 23 Sept 2026 (effective 20 May 2026) is the label version to check for the indication text. | Atezolizumab | Bladder & urothelial cancer | FDA | label |
| Device | Maker | Indication and sample | Drug | PMA / 510(k) |
|---|---|---|---|---|
| Signatera CDx | Natera | Muscle Invasive Bladder Cancer (MIBC) - Plasma | Atezolizumab | P260004 (05/15/2026) |
Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.
- NCT04660344 · 2025IMvigor011
- no registry id · 2023CIRCULATE-Japan (GALAXY / VEGA / ALTAIR)
- ACTRN12615000381583 · 2022DYNAMIC
- NCT04486378A Phase II Clinical Trial Comparing the Efficacy of RO7198457 Versus Watchful Waiting in Patients With ctDNA-positive, Resected Stage II (High Risk) and Stage III Colorectal Cancer
- NCT06564844A Phase III, Randomised Study of Adjuvant Dato-DXd in Combination With Rilvegostomig or Rilvegostomig Monotherapy Versus Standard of Care, Following C
- NCT07023289A Study to Assess Adverse Events and Change in Disease Activity in Adult Participants Receiving Intravenously Infused Telisotuzumab Adizutecan Alone o
- NCT04264702BESPOKE CRC
- NCT05174169CIRCULATE-US
- NCT04385368MERMAID-1
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