The primary and secondary objectives of the study:~PRIMARY OBJECTIVES:~I. To evaluate and compare 6 month circulating tumor deoxyribonucleic acid (ctDNA) clearance rate in study patients with detectable ctDNA prior to randomization to targeted BRAF therapy versus usual care after standard adjuvant chemotherapy. (Phase II) II. To evaluate and compare 6 month ctDNA recurrence-free survival (ctDNA-RFS) rate in study patients with undetectable ctDNA prior to randomization to targeted BRAF therapy versus usual care after standard adjuvant chemotherapy. (Phase II) III. To evaluate and compare disease-free survival (DFS) (measured from randomization) in patients with resected stage III or high-risk (pT4) stage II mismatch repair protein (MMR) proficient BRAF V600E colon cancer treated with targeted BRAF therapy versus usual care after standard adjuvant chemotherapy. (Phase III)~SECONDARY OBJECTIVES:~I. To evaluate and compare overall survival (OS) between the two treatment arms.~II. To evaluate and compare the toxicity profile between the two treatment arms.~III. To evaluate and compare the alternative DFS endpoint (measured from date of primary tumor resection) between the two treatment arms.~IV. To evaluate and compare DFS in the subset of patients with detectable ctDNA prior to randomization between the two treatment arms.~EXPLORATORY OBJECTIVE:~I. To evaluate and compare patient-reported outcomes for symptoms of rash, diarrhea, and fatigue according to Patient Reported Outcomes Version of Common Terminology Criteria for Adverse Events (PRO-CTCAE) between the two treatment arms.~OUTLINE: Patients are randomized to 1 of 2 arms.~ARM I: Patients receive encorafenib orally (PO) and cetuximab intravenously (IV) on study. Patients also undergo collection of blood samples throughout the study and computed tomography (CT) or magnetic resonance imaging (MRI) during screening and follow-up.~ARM II: Patients undergo observation per usual care on study. Patients also undergo collection of blood samples throughout the study and CT or MRI during screening and follow-up.
This phase II/III trial compares treatment with encorafenib and cetuximab to usual care (patient observation) for reducing the chance of cancer recurrence after standard surgery and chemotherapy in patients with BRAF-mutated stage IIB-III colon cancer. Encorafenib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Cetuximab is in a class of medications called monoclonal antibodies. It binds to a protein called EGFR, which is found on some types of tumor cells. This may help keep tumor cells from growing. Giving encorafenib and cetuximab after standard surgery and chemotherapy may be more effective at reducing the chance of cancer recurrence compared to the usual patient observation.