A Phase 2/3, Randomized, Open-Label Study of Maintenance GRT-C901/GRT-R902, a Neoantigen Vaccine, in Combination with Immune Checkpoint Blockade for Patients with Metastatic Colorectal Cancer

The purpose of this research study is to learn more about an experimental personalized vaccine that has 2 components called GRT-C901 and GRT-R902. We will learn more about the effects of this vaccine on your cancer when used together with approved medications that activate the immune system, Ipilimumab (Yervoy) and Atezolizumab (Tecentriq), in combination with a Fluoropyrimidine and Bevacizumab (Avastin). All have been approved by the United States Food and Drug Administration (FDA) including several Fluoropyrimidines (Capecitabine (Xeloda), FUDR (Floxuridine), and 5-Fluorouracil [several brands available]). The vaccine (GRT-C901 and GRT-R902) study treatment is investigational, which means that it has not been approved by any regulatory authorities, including the FDA. The vaccine is specific to you and your tumor and cannot be used to treat any other patients. The combination of the vaccine with Ipilimumab and Atezolizumab are called the "study treatment" in this consent form. This study will test the activity and safety of GRT-C901 and GRT-R902 plus Ipilimumab and Atezolizumab in addition to a Fluoropyrimidine and Bevacizumab. The study treatment is being tested to see if it is safe and if it can help your immune system control your cancer. The immune system is the part of the body that fights infection. Sometimes, the immune system can also recognize cancer cells as foreign and destroy them. This study may lead to the development of a personalized anti-cancer vaccine that is specifically designed for each patient's tumor and that teaches their immune system to recognize and possibly destroy their own tumor cells. Your participation in this study is divided into 2 parts, Vaccine Production Stage and Study Treatment Stage. You have already signed an informed consent form for the first part of this study (the Vaccine Production Stage), during which the study sponsor determined that a vaccine could be made for you. This informed consent form describes the second part of the study (Study Treatment Stage) where you may receive study treatment. If you sign this informed consent, your doctor will determine if you are eligible for the Study Treatment Stage. If you were randomized to the vaccine arm during the Vaccine Production Stage, you will then receive the vaccine that was made for you in addition to your routine therapy. If you were randomized to the control arm, you will continue to receive your routine therapy. The study will be conducted in 2 parts: the first part is Phase 2 and the second part is Phase 3. Once enrollment numbers are met for Phase 2, participants will begin enrolling into Phase 3. Based on the safety information from Phase 2, Phase 3 will test whether the study treatment continues to be safe and whether it can slow down or stop a tumor from growing. A bigger group of patients will participate in Phase 3. We don't know if this study will help you. Your condition may get better, but it could stay the same or even get worse. We hope the information from this study will help us develop a better treatment for colorectal cancer in the future.