Novel therapeutic agents for osteosarcoma.

Osteosarcoma is the most common malignant primary bone tumor in childhood. Despite multiagent chemotherapy and aggressive surgical resection, 30% of patients with localized disease and 80% of patients with metastatic disease at diagnosis will relapse. Survival for these patients has remained unchanged over the past 20 years. A number of novel agents in various stages of development hold promise for improving therapy for patients with osteosarcoma. This article will focus on novel therapeutic approaches, including agents targeting signal-transduction pathways, inhibitors of the tumor microenvironment and immunomodulatory agents, as well as overcoming resistance mechanisms and the use of novel delivery mechanisms.