Osteogenic Sarcoma: Systemic Chemotherapy Options for Localized Disease

Treatment for osteosarcoma, the most common malignant tumor of bone in children and adolescents, has not changed in decades. Treatment is multimodal, employing neoadjuvant chemotherapy followed by aggressive and complete surgical resection to achieve negative margins and a prolonged course of adjuvant chemotherapy. The primary tumor is usually successfully managed via surgery, but micrometastases are likely present in most patients at diagnosis. Death is the result of tumor recurrence in the lungs or more rarely in other bones despite aggressive treatment regimens and is likely attributable to innate resistance to chemotherapy. Better therapies are desperately needed. The three most active agents-high-dose methotrexate, doxorubicin, and cisplatin-commonly referred to as "MAP," form the backbone of therapy. After 2 cycles of MAP, surgical resection is performed of all sites of disease if possible. Histologic response following neoadjuvant chemotherapy is prognostic in non-metastatic osteosarcoma, but augmentation of adjuvant therapy for poor responders with additional agents (ifosfamide, etoposide) has not improved outcome. Inclusion of immunotherapy into treatment regimens is promising. Specifically, liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE), a macrophage and monocyte activator, improved 10-year overall survival for patients with localized disease, with a similar pattern of response in patients with metastatic disease. L-MTP-PE (mifamurtide) is approved and in widespread use in Europe and elsewhere but has not been approved for use by the Federal Drug Administration in the USA. Identifying novel targeted therapies to improve outcomes for patients with osteosarcoma remains an area of active research.