- Have been treated in the metastatic setting with 0 to 2 prior systemic regimens for mSTS (Systemic treatment regimens given in the neoadjuvant setting and maintenance therapies will not be considered as regimens in the metastatic setting for the purposes of this protocol. Prior anthracycline-based regimen is allowable but not required. Subjects with extra-skeletal small round blue cell sarcomas, including rhabdomyosarcomas, must have exhausted or be intolerant of standard first line anthracycline-based chemotherapy.)