This clinical trial is for men and women who have metastatic (stage 4) colorectal cancer (CRC).
   
The purpose of this study is to test the safety and tolerability of ATP128 in double combination with another compound called BI 754091 and in triple combination with BI 754091 and a compound called VSV-GP128. This study is designed to find out what effects ATP128 has on the colorectal cancer. This study will also look at how the cancer responds to the study drug regimen and will look at the side effects of the study drug regimen.

ATP128 is a therapeutic vaccine intended to stimulate the immune system to fight against cancer. It is administered subcutaneously into the skin.

VSV-GP128 is a modified, harmless virus designed to be used as a therapeutic viral vaccine to enhance the anti-tumor effect of ATP128 on the immune system. It is administered via an intravenous injection.

BI 754091 is an anti-PD-1 (also called checkpoint inhibitor) monoclonal antibody that works to stimulate the immune system to fight against cancer. It is also given via an intravenous injection.
   
ATP128, VSV-GP128, and BI 754091 are investigational drugs which means that these drugs have not been approved by the United States Food and Drug Administration (FDA).
   
The group each participant is in will be determined by the study team. Group 1 will receive ATP128 plus BI 754091 and Group 2 will receive ATP128 plus BI 754091 and VSV-GP128.

If the participant is enrolled in Group 1 or 2 and they have surgery to treat their cancer, participation is expected to last up to 13.5 months. If the participants are enrolled in Group 1 or 2 without surgery, participation is expected to last up to 10 months or to a maximum of 18 months if they are benefiting from the BI 754091 regimen.