This single arm study is designed to evaluate the safety and tolerability of a personalized treatment in adults with metastatic colorectal cancer by first analyzing the expression of tumor-associated antigens and then treating the patients with a personalized live, attenuated, double-deleted Listeria monocytogenes (pLADD)-based immunotherapy. pLADD is based on the attenuated form of Listeria monocytogenes that has been genetically modified to reduce its ability to cause disease, while maintaining its ability to stimulate a potent immune response. pLADD is manufactured using patient-specific antigens and is therefore individualized to each patient.