Durvalumab and Tremelimumab in Treating Patients With Microsatellite Stable Metastatic Colorectal Cancer to the Liver

PRIMARY OBJECTIVES: I. Establish the safety of durvalumab and tremelimumab following radioembolization with selective internal radiation (SIR)-Spheres in patients with microsatellite stable (MSS) metastatic colorectal cancer to the liver. II. Determine the hepatic response rate of SIR-Spheres followed by durvalumab and tremelimumab in patients with MSS metastatic colorectal cancer to the liver. SECONDARY OBJECTIVES: I. Estimate the progression free survival (PFS) and overall survival (OS) of the overall treated population. II. Describe the overall response rate of the treated population. III. Describe the extra-hepatic response in the treated population (abscopal responses). TERTIARY OBJECTIVES: I. Describe intra-tumor immune alterations following SIR-Spheres, and following durvalumab plus tremelimumab in comparison to baseline through serial hepatic metastases biopsies. II. Describe the immune alterations in the blood following SIR-Spheres and following durvalumab plus tremelimumab. OUTLINE: Patients receive durvalumab intravenously (IV) over 60 minutes and tremelimumab IV over 60 minutes on day 1. Treatment repeats every 4 weeks for up to 4 courses in the absence of disease progression or unacceptable toxicity. Beginning at week 17, patients receive durvalumab IV over 60 minutes on day 1. Treatment repeats every 4 weeks for up to 9 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically.