This study is for patients with metastatic pancreatic cancer (cancer that has spread to other parts of the body). The purpose of this study is to determine whether molecularly tailored therapy can improve the effectiveness of standard chemotherapy combinations for patients with metastatic pancreatic cancer. A series of special tests will be performed on a sample of tumor, and based on the results subjects will be assigned to one of seven chemotherapy treatments, with each being the combination of two standard chemotherapies. Each of these combinations has been safely used in patients with pancreatic or other types of cancer. The purpose of this study is to to determine the ability to personalize therapy in this manner, and to determine how many patients a larger study would need. A second purpose is not to determine if one doublet is better than another. Rather, this second purpose is to show that for all patients enrolled in this protocol who have been assigned a doublet based on their tumor's molecular analysis (molecular tailoring), treatment response will be better than would be expected compared to patients who have been treated in the past with no molecular tailoring.