Histologically confirmed metastatic colorectal cancer, not amenable to curative resection Histologically or cytologically confirmed GI malignancy for which mFOLFOX is considered an appropriate treatment (e.g., gastric cancer [GC], colorectal carcinoma, pancreatic adenocarcinoma) Measurable, histologically/cytologically confirmed metastatic colorectal cancer (mCRC). Pathologically documented diagnosis of colorectal adenocarcinoma. Histologically confirmed unresectable metastatic colorectal adenocarcinoma Histologically confirmed colorectal adenocarcinoma Patients must have histologically or cytologically confirmed metastatic colorectal cancer. Have histologically confirmed, locally advanced unresectable or metastatic (stage IV) colorectal adenocarcinoma For patients with metastatic colorectal cancer:\r\n* Stage IV histologically-proven colorectal adenocarcinoma\r\n* Liver metastasis confirmed to be surgically resectable, with surgery evaluation and planned resection; may have minimal extrahepatic disease that is determined to be resectable\r\n* Tumor must be confirmed to be microsatellite stable (MSS); if not already reported at a Clinical Laboratory Improvement Act (CLIA)-certified laboratory, we will be able to perform this at Emory University\r\n* No prior immunotherapy\r\n* No cancer chemotherapy treatment weeks prior to day of treatment Histologically confirmed diagnosis of colorectal adenocarcinoma Patients must have histologically and or cytologically confirmed metastatic colorectal cancer Participants must have histologically or cytologically confirmed adenocarcinoma of colorectal or pancreatic origin Histologically confirmed colorectal cancer Have a diagnosis of histologically confirmed metastatic colorectal cancer to the liver (no other sites of metastatic disease)\r\n* Histologic confirmation of a colorectal primary tumor is acceptable if accompanied by radiographic evidence of metastatic disease Patients with histologically confirmed KRAS positive metastatic colorectal cancer Histologically or cytologically confirmed metastatic colorectal adenocarcinoma (colon, rectal, colorectal, appendiceal cancer) or small bowel that is not resectable Patients must have a histologically documented peritoneal carcinomatosis from either colorectal or appendiceal adenocarcinoma Histologically or cytologically confirmed colorectal adenocarcinoma. Histologically or cytologically confirmed colorectal adenocarcinoma Histologically confirmed unresectable metastatic colorectal adenocarcinoma Histologically or cytologically confirmed colorectal adenocarcinoma, with metastatic disease documented on diagnostic imaging studies Histologically confirmed stage IV colorectal adenocarcinoma without any prior systemic treatment Patients must have histologically or cytologically confirmed peritoneal surface malignancies from primary colorectal and appendiceal tumors Locally confirmed dMMR or MSI-H stage IV colorectal carcinoma Histologically confirmed recurrent or metastatic colorectal cancer Histologically proven colorectal adenocarcinoma Patients with histologically confirmed metastatic colorectal cancer, who have received and/or progressed on a prior oxaliplatin-based chemotherapy regimen Histologically and/or cytologically confirmed and radiographically evaluable refractory metastatic colorectal adenocarcinoma for which regorafenib would be considered a therapeutic option Cohort A: patients with histologically proven metastatic or locally advanced MSI colorectal adenocarcinoma Cohort B: patients with histologically proven metastatic or locally advanced microsatellite stable (MSS) colorectal adenocarcinoma A histologically or cytologically confirmed colorectal cancer that is metastatic, unresectable, or recurrent. Patients must have histologically confirmed adenocarcinoma of colorectal origin that is metastatic or locally advanced and unresectable History of histologically confirmed colorectal adenocarcinoma metastatic to the liver with no clinical or radiographic evidence of extrahepatic disease; confirmation of diagnosis must be performed by the enrolling institution Histologically confirmed, chemo-refractory, locally advanced, recurrent or metastatic gastric (including GE junction), colorectal, or pancreatic adenocarcinoma. Histologically or cytologically confirmed diagnosis of metastatic colorectal cancer with a product related mutation in Ras (GV, GC, GD, GR, QL, QR, QH) Patients with histologically proven, unresectable, evaluable metastatic colorectal cancer, by RECIST criteria Histologically confirmed colorectal cancer with at least one measurable metastatic lesion by RECIST v ., that is considered unresectable at baseline Histologically confirmed colorectal cancer Histologically or cytologically confirmed refractory colorectal cancer Histologically or cytologically confirmed colorectal adenocarcinoma Patients must have histologically confirmed, radiologically measurable metastatic or locally advanced unresectable colorectal adenocarcinoma that is amenable to image-guided biopsy; disease in previously radiated regions may not be considered measurable unless there has been demonstrated progression in the lesion Histologically/cytologically proven colorectal carcinoma Histologically confirmed peritoneal carcinomatosis from appendiceal, colorectal, ovarian, or primary mesothelioma, with no systemic metastases Patients must have histologically or cytologically confirmed colorectal or pancreatic carcinoma Histologically confirmed diagnosis of colorectal adenocarcinoma