Recurrence monitoring using ctDNA in patients with metastatic colorectal cancer: COSMOS-CRC-03 and AURORA studies

International treatment guidelines recommend tumor resection for patients with oligometastatic colorectal cancer (CRC). Despite this, recurrence occurs in ∼60% of patients post-surgery, indicating that the role and optimal type of perioperative systemic therapy has not been fully defined. In the COSMOS-oligo trials, comprising two studies, we are evaluating the potential role of circulating tumor DNA (ctDNA) analysis in clinical decision making and exploring adjuvant therapy strategies for patients with resectable metastatic CRC. The COSMOS-CRC-03 study aims to evaluate the prognostic value of post-operative minimal residual disease as detected by ctDNA and to explore the role of ctDNA in detecting disease recurrence. We plan to assess the predictive accuracy of ctDNA results for recurrence using blood collected 28 days post-surgery. We will additionally explore whether regular post-operative ctDNA test can detect recurrence earlier than standard imaging. Post-operative adjuvant therapy will not be administered to ctDNA-negative patients. The complementary AURORA trial is a randomized phase II study designed to test whether post-operative mFOLFOXIRI plus bevacizumab is superior to standard mFOLFOX6 for patients with metastatic CRC when the ctDNA status is positive after curative-intent surgery for patients enrolled in the COSMOS-CRC-03 study. Both studies will only include patients with resectable distant metastases of CRC. We designed these studies to stratify patients based on the results of a ctDNA assay and to determine the optimal treatment for patients at the highest risk for recurrence.