Alpharadin, a 223Ra-based alpha-particle-emitting pharmaceutical for the treatment of bone metastases in patients with cancer.

Bone metastases occur in many patients with different forms of solid malignant tumors, particularly in advanced stages of prostate and breast cancer, and are commonly associated with increased morbidity and mortality. The resulting bone pain interferes with quality of life and thus requires effective treatment. However, various non-radiotherapeutic modalities such as analgesics, hormone therapy, orchidectomy, cytostatic and cytotoxic drugs, bisphosphonates and surgery are not universally effective. External-beam radiotherapy is suitable only for well-defined localized bone metastases, and extended field radiation is often accompanied by serious side effects. Therefore, systemic radionuclide therapy must be considered as a valuable and effective method of treatment in patients with widespread skeletal metastases. The alpha-emitter 223Ra-based Alpharadin is a new radiopharmaceutical under development by Algeta ASA in collaboration with Bayer Schering Pharma AG. Early clinical data demonstrated a significant decrease in bone-alkaline phosphatase levels following therapy with Alpharadin compared with placebo. Median time to PSA progression, median survival and pain relief were also superior to placebo, and no dose-limiting hematological toxicity was observed. A phase III trial for Alpharadin was ongoing at the time of publication.