Study to Assess the Safety and Tolerability of Repeated Doses of an Investigational New Drug in Patients With Cancer and Cachexia.

This 12-week open-label study will explore how PF-06946860 is tolerated, the effects of the study drug, the best dose for treatment and how participants with non-small cell lung, pancreatic or colorectal cancer and cachexia feel after receiving repeated subcutaneous dosing. During the 12-week treatment period, study drug will be administered subcutaneously every 3 weeks for a total of 5 doses. There is a 12-week follow-up period following the last dose of study drug. Additional assessments include: * body weight measurements * blood pressure and heart rate measurements * Lumbar Skeletal Muscle Index (LSMI) by CT scan * Blood samples: * to evaluate safety, * to measure the amount of the study drug in the blood, * to evaluate if the study drug causes an immune response, * to examine the effects of the study drug on levels of a specific cytokine, * and for exploratory samples for bio banking. * Measure the impact of the study drug on appetite, nausea, vomiting, fatigue, physical function, and health-related quality of life with questionnaires. * Measure the impact of study drug on physical activity using wearable digital sensors. * To evaluate the effect of study drug on ability to complete anti-tumor treatment and survival in participants with cancer and cachexia. * To evaluate tumor size.