Stage III Colon Cancer

This Phase II/III trial will evaluate the what kind of chemotherapy to recommend to patients based on the presence or absences of circulating tumor DNA (ctDNA) after surgery for colon cancer.

Improving personalized cancer treatments and finding the best strategies to treat each patient relies on using new diagnostic technologies. Currently, for colorectal cancer, the methods used to decide who gets additional post-surgery treatment are suboptimal. Some patients get too much treatment, while others do not get enough. There is a new way to explore if there is any cancer left in a patient's body using circulating tumor DNA (ctDNA) detected in blood samples. This can help decide who needs more treatment after surgery. Even though many tests have been developed, it has yet to be determined which test performs best at relevant time points. The GUIDE.MRD consortium is a group of experts, including scientists, technology, and pharmaceutical companies. The consortium is working on creating a reliable standard for the ctDNA tests, validating their clinical utility, and collecting data to help decide on the best treatment for each patient. FRENCH-MRD-CRC is the French study of the european GUIDE.MRD project.

This research study is comparing two standard of care treatment options based on blood test results for participants who have metastatic colon cancer. The names of the potential treatments involved in this study are: * Active surveillance * FOLFIRI treatment * Nivolumab treatment * Encorafenib/Binimetinib/Cetuximab treatment * Trastuzumab + Pertuzumab

This is a Phase II open-label trial of neoadjuvant immunochemotherapy with Atezolizumab and CAPOX followed by surgery and potentially adjuvant chemotherapy for patients with localized resectable pMMR adenocarcinoma of the colon with a target accrual of 28 patients. The investigators will explore if appropriately timed neoadjuvant CAPOX with anti-PD-L1 mAb (Atezolizumab) can be administered safely and feasibly, and that this combination will lead to improved clinical response associated with enhanced numbers of immune cells in surgically resected colon tumors. Patients will receive 4 cycles of atezolizumab in combination with 4 cycles of CAPOX (atezolizumab will be administered prior to chemotherapy) before standard of care surgical resection. Following surgery, patients still considered to be at high-risk of recurrence (per SOC guidelines) will receive further adjuvant chemotherapy (mFOLFOX6 or CAPOX), based on the discretion of the treating oncologist/investigator. Circulating tumor DNA (ctDNA) dynamic change status will be analyzed through collection of blood samples throughout different stages of the patient's neoadjuvant treatment regimen (baseline, pre-neoadjuvant therapy, mid-neoadjuvant, post-neoadjuvant therapy, and during postoperative period) as a marker of early read on efficacy. The end of the study for each patient enrolled will be at the 6 month postoperative visit. On Study Protocol: Patients will be followed up for an efficacy follow-up phase during the first 6 months after surgery (week 2 \& months 3, 6 visits). All assessments beyond the 6 month visit will be performed under standard of care surveillance office visits. Off Study Protocol: Thereafter they will enter a survival follow-up phase per standard of care protocols. Patients will be seen every 6 months starting at month 12 until month 36. All collection of research-specific assessments including whole blood, stool collection and quality of life questionnaires will be optional beyond the 6 month postop visit (months 12-36).