Safety Study of IPI-504 in Patients With Gastrointestinal Stromal Tumors (GIST) or Soft Tissue Sarcomas (STS)

Inclusion Criteria: * Pathologically confirmed diagnosis of GIST or STS * Failed prior therapies * ECOG performance status of 0-2 * Ability to adhere to the study visit schedule and all protocol requirements Exclusion Criteria: * Previous treatment with 17-AAG, DMAG, or other known Hsp90 inhibitor * Participation in any investigational drug study or treatment with any other kinase inhibitor therapy within 2 weeks preceding start of treatment * Concurrent radiation therapy is not permitted * Concurrent treatment with any agent that alters CYP3A activity * Concurrent treatment with any agent that may prolong the QTc interval * Myocardial infarction or active ischemic heart disease within 6 months * History of arrhythmia * Baseline QTc \>450 * Grade 3 or greater peripheral neuropathy * Renal insufficiency, serum creatinine \>1.5 x ULN * Platelets \< 100,000 mm3 * AST and / or ALT \> 2.5 x ULN * ANC \<1,500 cells/mm3 * Alkaline phosphatase \> 2.5 x ULN * Amylase and lipase \> 1.5 x ULN * Hemoglobin \< 9.0 g/dL