Doxorubicin is a chemotherapy drug used in the standard treatment of soft-tissue sarcoma. Doctors would like to increase the effectiveness of this treatment. In this study, researchers want to see if adding the investigational drug olaratumab to doxorubicin therapy is more effective than doxorubicin alone for treating patients with advanced or metastatic soft-tissue sarcoma.

Olaratumab is an antibody that targets a protein called PDGFR-alpha, which is overproduced in certain sarcomas and can drive cancer metastasis. Patients in this study will be randomly assigned to receive either doxorubicin plus olaratumab or doxorubicin plus a placebo (inactive drug). Both doxorubicin and olaratumab are given intravenously (by vein).