Abstract 5022: MEDOCC-CrEATE trial: Feasibility of measuring circulating tumor DNA after surgery to guide adjuvant chemotherapy in stage II colon cancer patients

Abstract Introduction: Patients with stage II colon cancer not classified as high risk (pT4 microsatellite stable) do not receive adjuvant chemotherapy (ACT) according to Dutch guidelines. However, 15-20% of patients with stage II colon cancer experience a disease recurrence, indicating that there is an unmet clinical need to identify patients who could benefit from adjuvant treatment. Observational studies demonstrate that postoperative circulating tumor DNA (ctDNA) is indicative of minimal residual disease (MRD) and a strong prognostic biomarker for disease recurrence. Aim: The MEDOCC-CrEATE trial aims to assess 1) the proportion of stage II colon cancer patients with detectable postoperative ctDNA accepting ACT and 2) whether ctDNA-guided ACT reduces 2-year recurrence rate (RR). Methods: MEDOCC-CrEATE is an interventional trial following the ‘trial within cohorts’ design. Participants of the Prospective Dutch Colorectal Cancer cohort with stage II colon cancer and no indication for ACT randomized to the intervention arm undergo postoperative tumor-informed ctDNA testing using next-generation sequencing of 33 genes through the PGDx elio™ liquid biopsy assay. If ctDNA is detected, they are offered 4 cycles of adjuvant capecitabine plus oxaliplatin. Patients in the intervention arm who test ctDNA negative and patients in the control arm receive standard of care follow-up. For all patients, blood is collected every 6 months for 3 years to monitor disease recurrence. The primary endpoint is the proportion of patients with detectable postoperative ctDNA willing to receive ACT. Secondary endpoints include 2-year RR, disease-free and overall survival, quality of life and cost-effectiveness of ctDNA-guided ACT. The study is powered for 2-year RR, randomizing 660 patients to each study arm in order to treat 30 patients in the intervention arm with detectable postoperative ctDNA, assuming 5% ctDNA detection and 10% noncompliance. Results: Logistics for timely multicenter collection of tumor tissue and blood have been optimized across 28 Dutch hospitals. At present, 240 patients have been randomized. Of the 119 patients in the intervention arm, 98 provided consent for immediate postoperative ctDNA analysis (82%). Of the 92 currently available results, 5 (5 %) had detectable ctDNA. The median time from surgery to blood collection was 15 days (IQR 11-19), with a median turnaround time from surgery to ctDNA result of 47 days (IQR 39-54). Conclusion: Multicenter postoperative tumor-informed ctDNA testing for MRD is operationally and technically feasible within the clinically relevant 8-12 week window to start ACT. The observed ctDNA detection rate is in accordance with expectations and the study design. Upon study finalization, the results will be used for health technology assessment to demonstrate the putative clinical utility of ctDNA-guided ACT in stage II colon cancer. Citation Format: Ingrid Franken, Suzanna Schraa, Karlijn van Rooijen, Dave van der Kruijssen, Carmen Rubio-Alarcón, Steven Ketelaars, Sietske van Nassau, Teunise Snetselaar, Bregje Adriaans, Jillian Phallen, Sam Angiuoli, Amy Greer, Ellen Verner, Veerle Coupé, Helena Verkooijen, Miranda van Dongen, Linda Bosch, Mirthe Lanfermeijer, Daan van den Broek, Gerrit Meijer, Victor Velculescu, Mark Sausen, Miriam Koopman, Remond Fijneman, Geraldine Vink, on behalf of the PLCRC-MEDOCC group. MEDOCC-CrEATE trial: Feasibility of measuring circulating tumor DNA after surgery to guide adjuvant chemotherapy in stage II colon cancer patients abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5022.