PRIMARY OBJECTIVES:~I. To investigate whether treatment with gemcitabine (gemcitabine hydrochloride) plus pazopanib (pazopanib hydrochloride) improves the median progression-free survival (PFS) of patients with metastatic soft tissue sarcoma when compared to gemcitabine plus placebo.~SECONDARY OBJECTIVES:~I. To assess overall response in this population to gemcitabine plus pazopanib compared to gemcitabine plus placebo.~II. To assess overall survival (OS) in this population to gemcitabine plus pazopanib compared to gemcitabine plus placebo.~III. To investigate differences in treatment response in different histologic subgroups (liposarcoma vs. all other eligible soft tissue sarcoma subtypes).~IV. To evaluate the safety and tolerability of the combination of gemcitabine plus pazopanib.~V. To assess the progression-free survival and overall response in patients treated with single agent pazopanib following administration of gemcitabine in the cross-over portion of this study.~VI. To collect specimens for an exploratory analysis of potential biomarkers that predict response in patients receiving combination therapy with gemcitabine plus pazopanib.~OUTLINE: Patients are randomized to 1 of 2 treatment arms.~ARM I: Patients receive gemcitabine hydrochloride intravenously (IV) over 30 minutes on days 1 and 8 and pazopanib hydrochloride orally (PO) on days 1-21. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity.~ARM II: Patients receive gemcitabine hydrochloride IV over 30 minutes on days 1 and 8 and placebo PO on days 1-21. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity. Patients who experience disease progression may receive single-agent pazopanib hydrochloride PO daily. Cycles repeat every 21 days in the absence of disease progression or unacceptable toxicity.~After the completion of study treatment, patients are followed up every 3 months.
This randomized phase II trial studies how well gemcitabine hydrochloride works with or without pazopanib hydrochloride in treating patients with refractory soft tissue sarcoma. Drugs used in chemotherapy, such as gemcitabine hydrochloride, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Pazopanib hydrochloride may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Pazopanib hydrochloride may also stop the growth of tumor cells by blocking blood flow to the tumor. It is not yet known whether gemcitabine hydrochloride is more effective with or without pazopanib hydrochloride in treating patients with soft tissue sarcoma.