Xofigo
Castration-resistant prostate cancer (CRPC) with symptomatic bone metastases and no known visceral metastatic disease.
55 kBq (1.49 microcuries) per kg body weight IV at 4-week intervals for 6 doses
Administer by slow IV injection over 1 minute
Pre-treatment labs: ANC ≥1,500, platelets ≥100,000, hemoglobin ≥10 g/dL
Safety interval: Before first dose and before each subsequent dose, obtain CBC to verify counts
Injection: 1,100 kBq/mL (27 microcuries/mL) in single-dose vial
Pregnancy.
- Myelosuppression: Thrombocytopenia (12% Grade 3-4), neutropenia (5% Grade 3-4), anemia (6% Grade 3-4). Monitor CBC every 4 weeks. D/C if counts don't recover within 6-8 weeks.
- Bone Fractures: Increased risk of fractures (pathological and non-pathological). Consider use of bone-protective agents.
- Do NOT use with abiraterone + prednisone: ERA-223 trial showed increased fractures and deaths with combination.
- Radiation Safety: Administer only in authorized settings. Minimize radiation exposure to patient contacts and healthcare workers.
- Secondary Malignancies: Myelodysplastic syndrome and acute leukemia reported.
Nausea (36%), diarrhea (25%), vomiting (19%), peripheral edema (13%), thrombocytopenia (12%), anemia (11%), bone pain (10%), fatigue (10%)
Consult the complete prescribing information for a comprehensive list of adverse reactions and their frequencies.
Radium-223 is an alpha-emitting radioactive isotope that mimics calcium and is selectively taken up by bone, specifically areas of increased osteoblastic activity (bone metastases). It forms complexes with hydroxyapatite in the bone matrix. Once incorporated, radium-223 emits alpha particles (high linear energy transfer, range <100 µm/10 cell diameters) that induce double-strand DNA breaks in surrounding tumor cells, causing cytotoxic effects confined to the immediate microenvironment with minimal damage to surrounding normal tissue.
After IV injection, radium-223 rapidly clears from blood (15-minute distribution phase). Primarily distributes to bone and is excreted through the gut. Physical half-life: 11.4 days. No hepatic metabolism (inorganic compound). Approximately 63% excreted in feces, 5% in urine within 7 days.
Clinical efficacy and safety data supporting the approval are available in the full prescribing information and from the clinical trials listed below.
- ALSYMPCA — Radium-223 vs. placebo in mCRPC with bone metastases. Phase III, n=921.