RaCl2 DE IN MEN WITH CASTRATION-RESISTANT PROSTATE CANCER

VThe majority of patients with late stage castrationresistant prostate cancer (CRPC) develop bone metastases that often result in significant bone pain. Therapeutic palliation strategies can delay or prevent skeletal complications and may prolong survival. An alpha-particle based therapy, radium-223 dichloride (RaCl2), has been developed that delivers highly localized effects in target areas and likely reduces toxicity to adjacent healthy tissue, particularly bone marrow. Radiation safety aspects were evaluated for a single comprehensive cancer center clinical phase 1, open-label, single ascending-dose study for three cohorts at 50, 100, or 200 kBq kg body weight. Ten patients received administrations, and six patients completed the study with 1 y follow-up. Dose rates from patients administered Ra dichloride were typically less than 2 mSv h MBq on contact and averaged 0.02 mSv hMBq at 1 m immediately following administration. Removal was primarily by fecal excretion, and whole body effective half-lives were highly dependent upon fecal compartment transfer, ranging from 2.5Y11.4 d. Radium-223 is safe and straightforward to administer using conventional nuclear medicine equipment. For this clinical study, few radiation protection limitations were recommended post-therapy based on facility evaluations. Specific precautions are dependent on local regulatory authority guidance. Subsequent studies have demonstrated significantly improved overall survival and very low toxicity, suggesting that 223Ra may provide a new standard of care for patients with CRPC and bone metastases. Health Phys. 106(4):494Y504; 2014