Nivolumab and Ipilimumab and Radiation Therapy in MSS and MSI High Colorectal and Pancreatic Cancer

Inclusion Criteria: * Participants must have histologically or cytologically confirmed adenocarcinoma of colorectal or pancreatic origin * Age \>18 years. * Eastern Cooperative Oncology Group (ECOG) performance status ≤1 * Life expectancy of greater than 3 months * Participants must have normal organ and marrow function as defined in Table 1, all screening labs should be performed within 14 days of protocol registration. Table 1 Adequate Organ Function Laboratory Values System Laboratory Value * Hematological * Absolute neutrophil count (ANC) ≥1500 /mcL * White blood count (WBC) ≥2000 /mcL * Platelets ≥100,000 / mcL * Hemoglobin ≥9 g/dL * Renal * Serum creatinine OR Measured or calculated creatinine clearance (GFR can also be used in place of creatinine or CrCl) ≤ Serum creatinine ≤ 1.5 x ULN or creatinine clearance (CrCl) ≥ 40 mL/min (if using the Cockcroft-Gault formula below): * Female CrCl = (140 - age in years) x weight in kg x 0.85 72 x serum creatinine in mg/dL * Male CrCl = (140 - age in years) x weight in kg x 1.00 72 x serum creatinine in mg/dL * Hepatic * Serum total bilirubin ≤ 1.5 X ULN (upper limit of normal) (subjects with Gilbert Syndrome can have a total bilirubin \<3 mg/dL * aspartate aminotransferase (AST) serum glutamic oxaloacetic transaminase (SGOT) and Alanine Aminotransferase ALT (SGPT) ≤ 3 X ULN OR ≤ 5 X ULN for subjects with liver metastases * Coagulation * International Normalized Ratio (INR) or Prothrombin Time (PT) * …