RecruitingPhase 2Drug trialA Study of Gefitinib, Trametinib, Disulfiram, and Sunitinib in Addition to Standard Chemotherapy in People With OsteosarcomaThe researchers are doing this study to find out whether adding gefitinib, trametinib, disulfiram, and sunitinib to standard chemotherapy is a more effective treatment approach for people with osteosarcoma than standard chemotherapy on its own. The researchers will also look at the safety of adding these drugs to standard chemotherapy. The researchers will also use the additional research biopsies from Cohort 1 participants to learn more about how osteosarcoma survives during chemotherapy.