ctDNA-guided adjuvant chemo in resected stage II colon cancer

When ctDNA-positivity justifies escalation and ctDNA-negativity justifies de-escalation of adjuvant chemotherapy after resection of stage II colon cancer, traceable to the trial spine (CIRCULATE-Japan, DYNAMIC, GALAXY, BESPOKE-CRC).

(colon cancer) AND (circulating tumor DNA OR ctDNA OR minimal residual disease) AND adjuvant AND stage II

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• anchor nod_ca77eb54-7919-407b-b3b1-4cb0f7d13c0d Tie J, Cohen JD, Lahouel K, et al. "Circulating Tumor DNA Analysis Guiding Adjuvant Therapy in Stage II Colon Cancer" (the DYNAMIC trial). N Engl J Med. 2022;386(24):2261-2272. A randomized controlled trial testing a ctDNA-guided approach to adjuvant chemotherapy decisions in stage II colon cancer: post-surgical ctDNA status (assayed at weeks 4 and 7) was used to direct whether adjuvant chemotherapy was given, versus standard clinicopathologic management. The landmark prospective evidence for the sub-topic's central question of whether MRD-by-ctDNA can safely de-escalate adjuvant therapy in stage II disease.
• anchor nod_6055e3f3-efa0-4781-b965-58d9c0d3e28e Nakamura Y, Watanabe J, Akazawa N, et al. "ctDNA-based molecular residual disease and survival in resectable colorectal cancer" (the CIRCULATE-Japan GALAXY observational study). Nat Med. 2024;30(11):3272-3283. A large prospective multicenter observational registry (n=2,240; stage II-III colon cancer and stage IV colorectal cancer undergoing curative-intent resection) measuring tumor-informed ctDNA across the molecular-residual-disease (MRD) window and during/after adjuvant chemotherapy. ctDNA positivity in the MRD window was associated with markedly inferior disease-free and overall survival, and sustained versus transient ctDNA clearance under adjuvant chemotherapy stratified outcomes. The principal observational evidence in the sub-topic's trial spine complementing the DYNAMIC randomized trial: it characterizes the prognostic and predictive behavior of ctDNA/MRD that motivates ctDNA-guided escalation (on positivity) and de-escalation (on sustained clearance/negativity) of adjuvant therapy. Note the population is broader than resected stage II colon cancer (it includes stage III and stage IV); its bearing on the sub-topic's stage II question is via the MRD biology it establishes, not a stage II-specific randomized comparison.
• excerpt nod_3eff4ffc-dcba-437b-aaa0-0bb7d999e2f8 From GALAXY (Nakamura et al., Nat Med 2024;30:3272-3283; PMID 39284954), the updated 23-month-follow-up analysis (n=2,240; stage II-III colon and stage IV CRC) reports that sustained ctDNA clearance under adjuvant chemotherapy (ACT), versus transient clearance, is associated with a dramatic separation in 24-month outcomes: 24-month DFS 89.0% vs 3.3% and 24-month OS 100.0% vs 82.3%. This is the central empirical observation in GALAXY that bears on the sub-topic's question: clearance dynamics under ACT — not just baseline MRD status — stratify outcomes, supplying the observational rationale for ctDNA-guided escalation (when clearance fails to sustain) and de-escalation (when sustained negativity is achieved/maintained) of adjuvant therapy. Caveat for the stage II colon focus: this clearance contrast is reported pooled across the GALAXY cohort (stage II-III colon + stage IV CRC), so its applicability to the sub-topic's specific population is via MRD biology rather than a stage-II-restricted estimate.
• excerpt nod_11726864-69d3-4156-bd40-c5d641ed2083 DYNAMIC's pre-specified de-escalation finding: in stage II colon cancer randomized 2:1 to ctDNA-guided vs standard clinicopathological management (N=455; ctDNA assayed at weeks 4/7 post-resection), adjuvant chemotherapy use was substantially reduced in the ctDNA-guided arm (15% vs 28%) while 2-year recurrence-free survival met the pre-specified noninferiority criterion (lower 95% CI bound −4.1 percentage points vs noninferiority margin of −8.5 pp). This is the strongest randomized evidence directly addressing the sub-topic's central question — whether ctDNA-negativity in the MRD window justifies de-escalation of adjuvant chemotherapy after resection of stage II colon cancer. Scope match is exact (stage II colon cancer, post-resection MRD window via weeks 4/7 ctDNA, adjuvant decision as outcome of guidance), so unlike the GALAXY/BESPOKE observational anchors, no population caveat is needed. Note: the chemotherapy-use difference is the secondary endpoint that operationalizes "de-escalation"; the noninferior RFS is the primary endpoint that licenses it. Both pieces are needed to interpret the trial's bearing.
• anchor nod_0ee5b925-e844-4dd9-96cd-e18e80680db5 Kasi PM, Sawyer S, Guilford J, et al. "BESPOKE study protocol: a multicentre, prospective observational study to evaluate the impact of circulating tumour DNA guided therapy on patients with colorectal cancer." BMJ Open. 2021;11(9):e047831. The peer-reviewed design paper for BESPOKE CRC (ClinicalTrials.gov NCT04264702), a multicenter prospective observational study of stage II/III/IV colorectal cancer using a tumor-informed ctDNA assay to characterize the impact of ctDNA-guided decisions on adjuvant chemotherapy choice and downstream recurrence outcomes. Establishes the design that the sub-topic's spine names alongside CIRCULATE-Japan, DYNAMIC, and GALAXY: post-resection ctDNA assessment in the MRD window plus longitudinal surveillance, with adjuvant chemotherapy decisions left to clinicians and ctDNA dynamics treated as the prognostic/predictive readout. Notes on bearing: this is the protocol paper, not the trial readout; the interim analysis is currently in abstract form (JCO 2024;42(3 suppl):9, ASCO GI) and is expected to be superseded by a full primary publication, at which point a propose_supersedes is the natural follow-up. Like CIRCULATE-Japan/GALAXY, BESPOKE-CRC is observational rather than randomized, and its population is broader than resected stage II colon cancer (includes stage III and stage IV); its bearing on the sub-topic's stage II question is via the ctDNA-MRD biology and the observed clinician/patient adjuvant-decision behavior it documents, not a stage II-specific randomized comparison.
• excerpt nod_cc8f4dd3-6e2b-40a4-b1b5-537033bc98e7 BESPOKE-CRC protocol prespecifies adjuvant-treatment decisions as a primary endpoint: the study will observe how tumor-informed ctDNA testing changes clinicians' adjuvant chemotherapy choices (not a randomized de-escalation/escalation mandate like DYNAMIC). For the sub-topic, this anchor documents the observational spine's design intent—linking post-resection ctDNA dynamics to real-world adjuvant use and asymptomatic recurrence detection across stage I–IV CRC—while a secondary endpoint explicitly compares survival in MRD-negative patients who receive adjuvant chemotherapy versus active surveillance, which is the closest protocol-level analogue to the stage II de-escalation question (but not stage II–specific and not randomized). Population caveat remains: enrollment is stage I–IV and observational, so bearing on resected stage II colon cancer is inferential pending readout/supersede of interim abstracts.
• synthesis nod_d3956d56-a89d-4a34-8b1c-bf32ea235890 Across the trial spine, two complementary evidence types address ctDNA-guided adjuvant modulation after curative-intent resection. DYNAMIC (stage II colon cancer RCT) directly licenses de-escalation when ctDNA is negative in the post-resection MRD window: fewer patients received adjuvant chemotherapy (15% vs 28%) without compromising 2-year RFS under a prespecified noninferiority design. GALAXY (observational CIRCULATE-Japan registry; stage II–III colon and stage IV CRC) does not randomize treatment but shows that ctDNA clearance dynamics under adjuvant chemotherapy stratify outcomes sharply—sustained versus transient clearance separates 24-month DFS/OS—supporting the biological premise that ctDNA negativity/clearance marks a lower-risk subgroup where intensified or prolonged therapy may be unnecessary, while failure to clear marks escalation need. Joint reading for the sub-topic: DYNAMIC supplies the stage II–specific causal policy test for withholding chemotherapy when MRD-negative; GALAXY supplies mechanistic/prognostic reinforcement and escalation logic when MRD persists or clears only transiently, with explicit population caveats because GALAXY is not stage II–restricted. Neither node alone answers both de-escalation licensure and escalation rationale; together they frame ctDNA-guided adjuvant decisions as bidirectional (omit when negative/sustainedly clear; treat when positive or poorly clearing) pending further stage II–restricted observational/randomized readouts (e.g., BESPOKE-CRC, ongoing RCTs).

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