Cemiplimab With or Without Fianlimab to Treat Older Patients With Localized or Locally Advanced MSI-H Colorectal Cancer

Eligibility Criteria

• * Age ≥70 years.
• * Eastern Cooperative Oncology Group (ECOG) performance status 0 -2
• * Have histologically proven localized or locally advanced mismatch repair deficient (dMMR) or microsatellite unstable (MSI-H) colorectal cancer.
• * Must not have received any prior systemic treatment or radiation.
• * Must be agreeable to endoscopic, and CT surveillance for a total of 24 months.
• * Patient's acceptance to have a tumor biopsy.
• * Patients must have adequate organ and marrow function defined by study-specified laboratory tests and procedures.
• * For both Women and Men, must use acceptable form of birth control while on study.
• * Ability to understand and willingness to sign a written informed consent document.
• * Have received an investigational agent or used an investigational device within 28 days of the first dose of study drug.
• * Have expected to require any other form of systemic or localized antineoplastic therapy while on study.
• * Have had surgery within 28 days of dosing of investigational agent, excluding minor procedures (dental work, skin biopsy, etc.).
• * History of prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA4, or anti-Lag-3 antibodies for any reason in the 5 years proceeding their colorectal cancer diagnosis.
• * Currently using any chronic systemic steroids.
• * History of severe hypersensitivity reaction to any monoclonal antibody.
• * Uncontrolled intercurrent illness including, but not limited to, uncontrolled infection, symptomatic congestive heart failure, unstable angina, cardiac arrhythmia, metastatic cancer, or psychiatric illness/social situations that would limit compliance with study requirements.
• * Active autoimmune disease.
• * Any tissue or organ allograft, regardless of need for immunosuppression, including corneal allograft.
• * Patient is on supplemental home oxygen.
• * Has clinically significant heart disease.
• * Conditions, including alcohol or drug dependence, intercurrent illness, or lack of sufficient peripheral venous access, that would affect the patient's ability to comply with study visits and procedures
• * Unwilling or unable to follow the study schedule for any reason