RecruitingPhase 1Drug trialLosartan + Sunitinib in Treatment of OsteosarcomaThis study is a Phase 1/1b clinical trial that aims to determine the Maximally Tolerated Dose of Losartan and Sunitinib Combination Therapy. Patients will first be accrued to the Dose Escalation phase of the study, using a 3+3 design. Medication dosages will increase until a maximally tolerated dose is found. Patients will then be accrued to the Dose Expansion phase of the trial, where efficacy of pre-determined dose will be preliminarily assessed.