Study of Perioperative Dostarlimab in Participants With Untreated T4N0 or Stage III dMMR/MSI-H Resectable Colon Cancer

Inclusion Criteria:

• Has untreated pathologically confirmed colon adenocarcinoma

• Has resectable colon adenocarcinoma defined as clinically T4N0 or Stage III

• Has radiologically evaluable disease

• Has a tumor demonstrating the presence of either dMMR status or MSI-H

Exclusion Criteria:

• Has distant metastatic disease.

• Has received prior medical therapy (chemotherapy, immunotherapy, biologic, ortargeted therapy), radiation therapy or surgery for management of the currentdiagnosis of colon cancer

• Has a tumor that, in the investigator's judgment is causing symptomatic bowelobstruction or otherwise requires urgent/emergent surgery at the time of screening.Participants with a history of colonic obstruction are eligible after obstruction isrelieved by a diverting stoma (defunctioning ileostomy or colostomy). Patients witha history of colonic obstruction in the context of current colon cancer diagnosisand treated with colonic stents are not eligible.

• Has undergone any major surgical procedure, open biopsy, or experienced significanttraumatic injury within 28 days prior to randomization

• Has any history of interstitial lung disease or pneumonitis and/or history ofradiation induced enteritis.

• Has cirrhosis or current unstable liver or biliary disease per investigatorassessment defined by the presence of ascites, encephalopathy, coagulopathy,hypoalbuminemia, esophageal/gastric varices, or persistent jaundice

• Has a history of allogenic stem cell transplantation or organ transplantation

• Is receiving any other anticancer or experimental therapy. No other experimentaltherapies (including but not limited to chemotherapy, radiation, hormonal treatment,antibody therapy, immunotherapy, gene therapy, vaccine therapy, or otherexperimental drugs) of any kind are permitted while the participant is receivingstudy intervention

• Is pregnant, breastfeeding, or expecting to conceive children within the projectedduration of the study

• Has a history of severe allergic and/or anaphylactic reactions to chimeric, human orhumanized antibodies, fusion proteins, or known allergies to dostarlimab, or itsexcipients, or any components of FOLFOX or CAPEOX