Cabazitaxel

Class & MOA

  • Class: Taxane, microtubule‐stabilizing agent.
  • Mechanism: Binds β‐tubulin → inhibits microtubule depolymerization → cell cycle arrest at G₂/M phase → apoptosis.
  • Designed to overcome resistance to other taxanes (e.g., P‐gp–mediated efflux).

Indication

Dose & Administration

  • Standard dose: 25 mg/m² IV over 1 hour every 3 weeks + prednisone.
  • Alternative: 20 mg/m² for patients at higher toxicity risk.
  • Premedication (30 min before infusion):
    • Dexamethasone 8 mg IV or PO.
    • H₁‐antagonist (e.g., diphenhydramine or loratadine).
    • H₂‐antagonist (e.g., ranitidine or famotidine).
  • Use non‐PVC infusion containers/sets due to leaching risk.

Toxicities

  • Hematologic: Neutropenia (grade 3–4 up to 80%), febrile neutropenia (~7–8%).
  • GI: Diarrhea (can be severe), nausea, vomiting.
  • Hypersensitivity reactions: Flushing, rash, bronchospasm, hypotension.
  • Neuropathy: Less than paclitaxel but still possible.
  • Fatigue, asthenia, hematuria possible.

Management & Monitoring

  • CBC weekly during cycle 1, then before each cycle.
  • G‐CSF: consider prophylaxis in high‐risk patients (e.g., elderly, poor marrow reserve).
  • Hydration and antidiarrheal agents for GI toxicity.
  • If grade 4 neutropenia >1 week or febrile neutropenia: hold dose, treat, then resume at 20 mg/m².
  • Permanently discontinue for severe hypersensitivity or persistent severe toxicity.

Drug Interactions

  • Metabolism: CYP3A4 substrate → avoid strong inhibitors (e.g., ketoconazole, clarithromycin) or inducers (e.g., rifampin, carbamazepine).
  • Avoid concomitant live vaccines.

Special Populations

  • Hepatic impairment: Avoid if AST/ALT ≥1.5× ULN and bilirubin ≥ULN.
  • Renal impairment: Minimal renal excretion; no adjustment unless severe.
  • Elderly (≥65 y): Higher risk of neutropenia and diarrhea—close monitoring.
  • Pregnancy: Contraindicated; may cause fetal harm.

Practice Pearls

  • Always check baseline CBC and LFTs before each cycle.
  • Educate patients on early signs of infection and dehydration.
  • Consider primary G‐CSF prophylaxis for elderly or high‐risk patients.
  • Monitor for delayed diarrhea—may require loperamide regimen.

Key Takeaway:

Cabazitaxel is a second‐line taxane for mCRPC post‐docetaxel with high efficacy but significant hematologic and GI toxicity risks—requires vigilant monitoring, premedication, and often growth factor support.