Sorafenib in Relapsed High Grade Osteosarcoma

Inclusion Criteria: * histologically documented and not surgically resectable or metastatic high-grade osteosarcoma which progressed after first or second line treatments for relapsing disease. * measurable disease as defined by having at least one lesion that can be accurately measured by means of CT or MRI. * ECOG PS of 0, 1 and an estimated life expectancy of at least 3 months. ECOG P.S. 2 is acceptable provided that it depends solely on orthopedic problems * Age ≥15 years. * Adequate bone marrow, liver and renal function * Written informed consent Exclusion Criteria: * Dementia or significantly altered mental status that would prohibit the understanding or rendering of informed consent and compliance with the requirements of this protocol. * Coexisting malignancies, except for basal or epithelial cell carcinoma of the skin or other solid tumors curatively treated with no evidence of disease for ≥3 years. * History of cardiac disease: congestive heart failure \>NYHA class 2; active CAD (MI more than 6 months prior to study entry is allowed); cardiac arrhythmias requiring anti-arrhythmic therapy (beta blockers or digoxin are permitted) or uncontrolled hypertension. * History of HIV infection or chronic hepatitis B or C. * Active clinically serious infections (\> grade 2 NCI-CTC version 3.0) * Symptomatic metastatic brain or meningeal tumors (unless the patient is \> 6 months from definitive therapy, has a negative imaging study within 4 weeks of study entry and is clinically stable with respect to the tumor at the time of study entry) * Patients with seizure disorders requiring medication (such as steroids or anti-epileptics) * Pregnant or breast-feeding patients. Women of childbearing potential must have a negative pregnancy test performed within 7 days of the start of treatment. Both men and women enrolled in this trial must use adequate barrier birth control measures during the course of the trial and two weeks after the completion of trial. * Patients with evidence or history of bleeding diathesis * Patients undergoing renal dialysis * Patients unable to swallow oral medications