Additional Study Information: The purpose of this study is to test the safety of a study drug called AMG 232 given with radiation in patients with soft tissue sarcoma (STS) prior to surgery. The AMG 232 is investigational. It has been tested in other cancers but not yet in sarcoma. AMG 232 has not been tested using the dosing schedule in this study and it has not been tested with radiation therapy. This study tests increasing frequency of AMG 232 doses (2-5 per week) to determine the maximum safe dose, if any, that can be used in combination with radiation therapy. The dose that you receive will depend on when you begin to participate in this study. There will be between 12 to 46 people taking part in this study.