This study is being conducted to examine the safety of the investigational drug, Xilonix(™), in addition to standard doses of Onivyde® (nanoliposomal irinotecan) and 5- fluorouracil (5FU)/folinic acid (leucovorin) for pancreatic cancer patients with cachexia. Cachexia is a syndrome that includes involuntary weight loss and physical deterioration that can contribute to poor outcomes of cancer treatment. In other studies, Xilonix has increased lean body mass in advanced cancer patients. This increase could lead to improved weight maintenance and quality of life.