To assess the safety, tolerability, and maximum tolerated/ recommended dose of ganetespib when administered in combination with sirolimus in patients with refractory sarcomas or unresectable or metastatic sporadic or neurofibromatosis type 1 (NF1) associated MPNST. Toxicities observed during the first cycle will be used to define the MTD/Recommended dose. Toxicity will be graded using the NCI Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. DLT will be defined as any of the following events that are possibly, probably, or definitely attributable to ganetespib or sirolimus. The DLT observation period for the purposes of dose escalation will be the first cycle of therapy.

10 patients were enrolled in Phase 1 of the study to determine MTD/RD. Three patients were enrolled in the first dose level. Six patients were enrolled at dose level 2. 1 patient was inevaluable.

Assessed using the World Health Organization (WHO) criteria. Tumor assessments will be obtained every 2 cycles. Clinical benefit is defined as stable disease, Partial Response (PR), Complete Response (CR). For patients who experience progression by WHO but in the opinion of the treating investigator are deriving benefit from therapy and have not otherwise met off treatment or off study criteria, may continue on treatment as long as patient has not met progression by RECIST 1.1.

10 patients were enrolled in Phase 1 and 10 patients were enrolled in Phase 2 of the study. Overall number of patients enrolled was 20.

To describe the plasma pharmacokinetic profile of ganetespib and sirolimus when administered in combination therapy.

10 patients were enrolled in Phase 1 of the study. Three patients were enrolled in the first dose level. Six patients were enrolled at dose level 2. 1 patient was inevaluable.

To explore changes in pharmacodynamic parameters in peripheral blood mononuclear cells performed on day 1 prior to ganetespib and sirolimus administration, and on day 15, 6 hours post drug administration. Hsp inhibition (Hsp70), mTOR inhibition (phospho-S6 and Akt Phosphorylation), UPR activation (EIF2alpha phosphorylation) will be explored. Western blot analyses were performed for phospho (p)-Akt, p-eIF2α, p-S6, and Hsp70. The absorbance of each phosphoprotein lane was recorded and protein levels were determined after normalizing for levels of corresponding total protein.

11 subjects provided consent and had adequate specimens for analysis.

To assess patient-reported pain severity and the impact of pain on daily activities before and during treatment with ganetespib and sirolimus. The Numerical Rating Scale-11 (NRS-11) will be used to assess pain severity. The NRS-11 is a self-report segmented 11-point numeric scale that assesses pain severity. It consists of a horizontal line with 0 representing "no pain" at the right end of the line and 10 representing "worst pain you can imagine" at the left end.The Brief Pain Inventory is a 7-item self-report questionnaire that measures the extent to which pain interferes with daily functioning. Patients are asked to indicate how much pain interfered with various activities in the past week, with scores ranging from 0 (does not interfere) to 10 (completely interferes). A total score is obtained by taking the mean of the scores for all 7 items; thus, the total pain interference score can range from 0 to 10.

Thirteen subjects in phase 1 and phase 2 cohorts combined had MPNST and completed the pain evaluations. 4/13 subjects completed both baseline and pre-cycle 3 evaluations for pain.

To evaluate the utility of three-dimensional MRI (3D-MRI) analysis in comparison to 1-dimensional and 2-dimensional measurements as a method to more sensitively monitor response.

The 3D-MRI were not measurable with current modalities. Due to their nature and incomplete imaging, volumetric analysis was not feasible.

To describe the plasma pharmacokinetic profile of ganetespib in terms of half life.

10 patients were enrolled in Phase 1 of the study. 1 patient was inevaluable.

A conventional 3+3 dose escalation design was used for phase 1. All patients in phase 2 were treated with the recommended dose.

1 patient was inevaluable in Phase 1 of study. The recommended dose of ganetespib was determined to be 200 mg/m2 intravenously on days 1, 8, 15 with sirolimus 4mg orally once daily with a cycle 1 day 1 loading dose of 12mg. All patients in phase 2 were treated with the recommended dose.