Osteosarcoma is the most common primary malignant condition of the bone in children, adolescents, and young adults. We have reached a therapeutic plateau with standard chemotherapy.1 Patients with relapsed disease have a dismal prognosis. There have been no new therapies for osteosarcoma approved by the US Food and Drug Administration (FDA) in the last 3 decades.
Radium 223 dichloride (223RaCl2) is an alpha-emitting radiopharmaceutical and calcimimetic that has intrinsic bone-targeting properties.2 It recently received FDA approval for prostate cancer with bone metastases.2,3 Preclinical studies in mice with human osteosarcoma xenografts and in dogs with osteosarcoma have shown that 223RaCl2 is a potentially low-toxicity, high-efficacy targeted agent for osteosarcoma, which is an osteoblastic bone-forming tumor.4 Knowing this, we hypothesized that 223RaCl2 could be safely administered to patients with osteosarcoma and that early response or resistance signals could be assessed by quantitative or qualitative correlative imaging studies.