Phase I/II Study of the Combination Immunotherapy Regimen: SX-682, TriAdeno Vaccine, Retifanlimab and IL-15 Agonist N-803 (STAR15) for Metastatic Colorectal Cancer (mCRC)

Background: Each year, more than 32,000 people in the United States are diagnosed with colorectal cancer that has returned or progressed after treatment and spread to other organs. This is called metastatic colorectal cancer (mCRC). Most people with mCRC survive only about 2 years. Objective: To test the ability of a combination of up to 4 experimental anti-cancer drugs treat mCRC. The names of these drugs are retifanlimab, TriAdeno vaccine, N-803, and SX-682. They are described below. Eligibility: Adults aged 18 years or older with mCRC. Participants must have Design: Participants will be screened. This includes having a physical exam, blood tests, urine tests, and imaging tests. If signed on to the study, participants will have 2 tumor biopsies. One when starting the study and once about 8 weeks after bring on the study. Participants will receive $500 for each biopsy. Participants will be treated with either 3 or 4 drugs and will receive a detailed calendar explaining when each drug is given. Retifanlimab is given every 4 weeks through an IV (an IV is tube attached to a needle inserted into a vein in the arm). N-803 is injected under the skin on the abdomen every 4 weeks. TriAdeno vaccine is injected under the skin of the upper arm or thigh once a month for 3 doses and then once every 3 months. Some participants will also receive a 4th drug. SX-682 is a pill taken by mouth. Participants will take this drug 2 times a day at home for about 3 weeks of each month. Study treatment will continue up to 2 years. Follow-up phone calls/emails may continue for 3 more years.