1. What it is
- Radiopharmaceutical (alpha-particle emitter).
- Mimics calcium → selectively targets areas of increased bone turnover (bone metastases).
- Emits high-energy alpha particles → localized double-strand DNA breaks in adjacent tumor cells.
- Minimal penetration (~<100 µm), so less damage to surrounding marrow compared to beta emitters.
2. Indications
- Metastatic castration-resistant prostate cancer (mCRPC) with:
- Symptomatic bone metastases, and
- No visceral metastases (e.g., no liver/lung mets).
- Shown in ALSYMPCA trial to improve overall survival and delay skeletal-related events (fractures, spinal cord compression).
3. Dosing
- 55 kBq/kg IV injection every 4 weeks × 6 doses.
- Administered in a nuclear medicine setting (special handling required).
4. Toxicities / Safety
- Dose-limiting toxicity (DLT):
- Myelosuppression → anemia, neutropenia, thrombocytopenia.
- Other adverse effects:
- Nausea, diarrhea, fatigue.
- Bone pain flare (sometimes after first dose).
- Precautions:
- Not recommended in patients with visceral metastases or poor marrow reserve.
- Use caution with prior extensive chemotherapy or radiation.
- Avoid concurrent abiraterone + prednisone (ERA-223 trial → ↑ fractures & mortality).
5. Monitoring
- Before each dose:
- CBC (absolute neutrophils ≥1.5 × 10⁹/L, platelets ≥100 × 10⁹/L, Hb ≥10 g/dL).
- During therapy:
- Monitor for cytopenias, infection, bleeding.
- Assess pain response and quality of life.
6. Oncology Pharmacist Role
- Verify appropriate patient selection (bone-only metastases, mCRPC, symptomatic).
- Review concurrent medications (avoid with abiraterone + prednisone).
- Counsel patients on:
- Safety around excreta (small amount of radioactivity in stool/urine).
- Expected side effects (fatigue, diarrhea, cytopenias).
- Collaborate with oncology team on supportive care (growth factors, transfusion if needed).
In summary:
Radium-223 is an alpha-emitting radiopharmaceutical used in mCRPC with symptomatic bone mets (no visceral disease). It improves survival and reduces skeletal complications, but requires careful monitoring for myelosuppression and should not be combined with abiraterone/prednisone.
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