French Assessment of MRD by Liquid Biopsies in Colorectal With Liver Metastasis Patients (FRENCH.MRD.CRLM)

FRECNH.MRD.CRLM is a part of WP3 of the overarching GUIDE.MRD project. Each study chair has a local clinical trial protocol where patients are recruited. After the end of recruitment, samples will be analyzed under the GUIDE.MRD consortium.

The overall aim of GUIDE.MRD is to investigate the clinical utility of ctDNA analysis to predict and guide the choice of multi-modal therapies prospectively. The fundamental steps towards this aim are assessment and benchmarking of the many available ctDNA diagnostics to identify the best-suited tests for clinical application. Clinical samples will be used to benchmark ctDNA diagnostics and assess their true clinical performance. The samples should reflect clinical situations where the ctDNA diagnostics are particularly useful, such as post-operatively, post-adjuvant, during chemotherapy, and longitudinally during post-treatment surveillance. In these situations, ctDNA diagnostics could be used to either monitor treatment response (in case of MRD after surgery) or to identify relapse at an early time point. Based on ctDNA information, medical treatment could be changed, or radiology could be used to reveal the location of residual disease.

The rationale for the observational clinical study FRENCH.MRD.CRLM is to prospectively collect the clinical samples needed to enable assessment of the performance of ctDNA diagnostics in the setting of colorectal cancer (CRC). There are two main scenarios where ctDNA diagnostic is useful in CRC:

Metastatic CRC with isolated liver metastases. Metastatic CRC with liver metastases is a unique tumor type in that surgical resection or complete ablation of the metastases, is the standard of care. In virtually all other tumor types, resection of liver metastases is considered only within clinical trials or in exceptional clinical circumstances. In contrast, resection, or ablation of colorectal cancer liver metastases (CRLM) are routinely performed with curative intention, and the overall 5-year survival is around 50%. Most relapses present within three years after operative intervention. The clinical benefit of adjuvant chemotherapy is currently a matter of debate, due to limited data from randomized controlled trials and recent results that indicate inferior overall survival (OS) in patients who received adjuvant therapy (JCOG0603). Based on these and earlier data (EORTC Trial 40983) that failed to show an OS benefit of adjuvant therapy after CRLM resection, it can be assumed that most patients are treated unnecessarily with chemotherapy, and those patients that could receive targeted agents are missed. No histological or clinical markers are available to guide decisions on adjuvant treatment. In this setting, ctDNA could be valuable to guide decisions on adjuvant chemotherapy (yes/no), the addition of biologicals such as anti-VEGF and anti-EGFR agents, targeted therapies in the case of BRAF mutations, or the presence of microsatellite instability (MSI), for example.

PRIMARY OBJECTIVES Primary objective 1 (P1) To confirm that ctDNA analysis performed immediately after CRLM treatment can identify patients with a high risk of recurrence.

Specifically, the investigators want to determine the association between 3-year disease-free survival (DFS) and ctDNA detection status immediately after

1. Curative intended surgery and,
2. Postoperative chemotherapy.

SECONDARY OBJECTIVES Secondary objective 1 (S1) To technically assess, compare, and rank existing commercial ctDNA diagnostics after intended curative CRLM treatment (pre-operative chemotherapy, surgery or radiofrequency ablation +/- postoperative chemotherapy) to identify the best method at each time point, with no impact on diagnosis or treatment of patients enrolled in the study.

Secondary objective 2 (S2) To assess the effect of standard-of-care adjuvant chemotherapy on the level of ctDNA. Especially, for patients with ctDNA detected after surgery, the investigators will measure and compare the ctDNA levels in plasma samples drawn before and after adjuvant chemotherapy. Further, the change in ctDNA level will be correlated to the oncological outcomes (time to clinical recurrence, disease-free survival, and overall survival).

Secondary objective 3 (S3) To investigate if time to Molecular recurrence determined using serial ctDNA analyses in longitudinally collected plasma samples is shorter than time to Clinical recurrence using standard-of-care radiological imaging.

Secondary objective 4 (S4) To investigate the correlation between ctDNA analysis results and findings on CT scans. ctDNA analysis will be restricted to blood sampling times that are coinciding with standard-of-care CT scans during standard-ofcare surveillance. If ctDNA analysis can predict the outcome of the CT scan, the potential is that ctDNA analysis in the future can guide when to perform CT scans.

Secondary objective 5 (S5) To investigate the prognostic power of ctDNA at the time point of indeterminate CT scans.