Phase II Study of Regorafenib as Maintenance Therapy

Inclusion Criteria: * Age ≥18 years * Histologically proven soft tissue sarcoma including leiomyosarcoma, synovial sarcoma and other sarcomas * Patients in partial response or stable disease after 6 cycles of doxorubicin-based first-line chemotherapy for metastatic/locally advanced soft tissue sarcoma * Metastatic/locally advanced disease not amenable to surgical resection with curative intent * Eastern Cooperative Oncology Group (ECOG) Performance Status =0 or 1 * Measurable disease, defined as at least 1 unidimensionally measurable lesion on a CT scan as defined by RECIST 1.1. * Available tumor tissue for translational research program * Adequate bone marrow, renal, and hepatic function, as evidenced by the following within 7 days of study treatment initiation: * Absolute neutrophil count (ANC) ≥1,500/mm3 * Platelets ≥100,000/mm3 * Hemoglobin ≥9.0 g/dL * Serum creatinine ≤1.5 x upper limit of normal (ULN) * Glomerular filtration rate (GFR) ≥30 ml/min/1.73m2 * AST and ALT ≤2.5 x ULN ( ≤5.0 × ULN for patients with liver involvement of their cancer) * Bilirubin ≤1.5 X ULN * Alkaline phosphatase ≤2.5 x ULN (≤5 x ULN with liver involvement of their cancer) * Lipase ≤1.5 x ULN * Spot urine must not show 1+ or more protein in urine or the patient will require a repeat urine analysis. If repeat urinanalysis shows 1+ protein or more, a 24-hour urine collection will be required and must show total protein excretion \<1000 mg/24 hours * INR/PTT ≤1.5 x ULN (Patients who are therapeuti…