Minimal Residual Disease-Directed Adjuvant Therapy for Patients With Early-Stage Colon Cancer: CIRCULATE-US.

Background: The ability to detect circulating tumor DNA (ctDNA), a novel surrogate for minimal residual disease (MRD) for patients with solid tumors, has significantly evolved over the past decade. Several studies have shown that ctDNA may provide clinical insight into the biological dynamics of MRD. The CIRCULATE-US (NRG-GI008; NCT05174169) trial will aim to address the role of ctDNA for risk stratification to intensify and deintensify adjuvant chemotherapy for patients with early-stage colon cancer.

Methods: CIRCULATE-US, a prospective phase 2/3 randomized trial, is investigating the molecular dynamics and prognostic role of ctDNA (evaluated by Natera's Signatera assay) for patients with resected colon cancer. Patients with negative postoperative ctDNA will be enrolled in cohort A and randomized to receive either immediate treatment with 5-fluorouracil and folinic acid or capecitabine plus oxaliplatin (FOLFOX6 or CAPEOX; Arm 1) or serial ctDNA surveillance with delayed adjuvant therapy (Arm 2). Patients randomized to Arm 2 with subsequent positive ctDNA results will be enrolled in cohort B for a second randomization to receive either FOLFOX6/CAPEOX (Arm 3) or 5-fluorouracil, folinic acid, oxaliplatin, and irinotecan (FOLFIRINOX; Arm 4) for 6 months. Patients with positive postoperative ctDNA results will be directly enrolled in cohort B and randomized to receive either FOLFOX6/CAPEOX (Arm 3) or FOLFIRINOX (Arm 4). Patients with stage II or stage IIIC colon cancer with positive ctDNA results (tested as standard of care with commercial testing) will be eligible for enrollment in cohort B. The primary end point for cohort A is time to positive ctDNA status for phase 2 and disease-free survival for phase 3 with a noninferiority design. The primary end point for cohort B is disease-free survival for both phase 2 and phase 3 with a superiority design.

Discussion: CIRCULATE-US will aim to understand postoperative ctDNA dynamics in early-stage colon cancer and will investigate escalation and de-escalation approaches by using ctDNA status as a surrogate for MRD status.