STS are uncommon tumors of the connective tissues. The OS of patients with advanced sarcomas has improved in the last 20 years, but remains under 2 years. Drug discovery for this disease has been complicated by the fact that there are many different subtypes that comprise STS. In fact, emerging data suggest that each of these subtypes may represent a different entity, with a unique molecular profile and responsiveness to therapy. Testing of new agents and determining predictors for response in this heterogeneous disease is therefore of utmost importance.