Regorafenib, Ipilimumab and Nivolumab for the Treatment of Chemotherapy Resistant Microsatellite Stable Metastatic Colorectal Cancer

PRIMARY OBJECTIVE: I. To determine the recommended dose level of the combination of regorafenib, nivolumab and ipilimumab in patients with advanced metastatic colorectal cancer. SECONDARY OBJECTIVES: I. Assess the objective overall response rate per Response Evaluation Criteria in Solid Tumors (RECIST) version (v)1.1. II. Estimate the duration of response, duration of stable disease (SD), progression free survival (PFS), and overall survival (OS). III. Describe the safety of this regimen as determined by frequency and severity of associated adverse events. EXPLORATORY OBJECTIVES: I. Correlate the presence of colony stimulating factor 1 receptor (CSF1R)+ macrophages, regulatory T cells (Tregs), TILs (tumor infiltrating lymphocytes) and tumor PD-L1, CTLA-4 and PD1 expression (at baseline and post treatment) on tumor biopsies with response rate. II. Characterize the systemic immune alteration through evaluation of mandatory pre and post cycle 1, and cycle 2, and at progression blood draws. OUTLINE: This is a dose-escalation study of regorafenib. Patients receive regorafenib orally (PO) once daily (QD) on days 1-21, nivolumab intravenously (IV) over 30 minutes every 2 weeks (Q2W), and ipilimumab IV over 30 minutes every 6 weeks (Q6W). Cycles repeat every 28 day for up to 2 years in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 and 90 days, then every 3 months for up to 5 years.