Evaluation of the Safety and Efficacy of Mifamurtide Versus Standard Treatment With Sorafenib in Patients With High-risk Osteosarcoma

The DRAGONFLY study includes: 1. Perform molecular and immunohistochemical studies from tumor tissue from biopsy orarchival material. 2. Perform molecular tests from blood ‐ ctDNA analysis (liquid biopsy). 3. Assess the stage of progression by performing standard tests to evaluate the extentof the disease and the capacity of the various organs 4. In patients classified in the high‐risk group, modification of therapy. Patientswill be randomly assigned in proportions (1:1) to the experimental (M) and standard(S) groups.The M (experimental) group will receive immunotherapy ‐ mifamurtide along withstandard conventional chemotherapy, and the S (standard) group will receive standardconventional treatment containing sorafenib. 5. Correlate the results of the obtained genetic tests with clinical data (preliminaryassessment of the impact of mutations on the clinical picture, course of treatmentand prognosis). 6. Comparison of the usefulness of molecular/immunohistochemical profile assessment asa prognostic factor with other recognized prognostic factors. 7. Conduct a reanalysis of patients according to the intention‐to‐treat (ITT)principle.