 In this clinical trial, the investigators hypothesize that treating MRP colon cancer patients with immunostimulating agent poly-ICLC will generate an inflammatory response, increasing epitope recognition and development of tumor reactive T-cells at the tumor site. However, interferon alpha and gamma produced by the poly-ICLC will increase PD-L1 expression and limit new T-cell development. Thus, PD1 blockade will increase the effectiveness of treatment with pembrolizumab. 