Igos (Arsenic Trioxide)

Igos (arsenic trioxide) is used within the acute promyelocytic leukemia (APL) therapeutic pathway to achieve disease control.

• Acute promyelocytic leukemia (newly diagnosed): induces remission by promoting differentiation of leukemic cells.
• Acute promyelocytic leukemia (relapsed or refractory): provides disease control when standard therapy has failed.
• High‑risk acute promyelocytic leukemia: contributes to differentiation therapy as part of combination regimens.

• Arsenic trioxide binds to the PML‑RARA oncoprotein, triggering its degradation and thereby releasing the transcriptional block that prevents promyelocyte maturation. This degradation induces apoptosis and partial differentiation of leukemic cells, restoring normal hematopoietic development and reducing the leukemic burden in acute promyelocytic leukemia.

Arsenic trioxide may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Fatigue: generalized tiredness during therapy.
• Fever: transient elevations in body temperature.
• Headache: mild to moderate intensity.
• Constipation: reduced bowel movements.
• Mild QT interval prolongation: detectable on ECG monitoring.

Serious or Rare Side Effects

• Differentiation syndrome: potentially life‑threatening inflammatory response.
• Severe QT prolongation: risk of torsades de pointes arrhythmia.
• Hepatic toxicity: elevated liver enzymes or hepatic dysfunction.
• Renal failure: impaired kidney function requiring monitoring.
• Severe infection: opportunistic infections due to immunosuppression.
• Leukocytosis: rapid rise in white blood cell count.

When using Igos, clinicians should observe specific safety measures to minimize risk.

• Cardiac monitoring: perform baseline and periodic ECGs to detect QT prolongation.
• Electrolyte management: correct potassium and magnesium deficits before infusion.
• Hepatic function: assess liver enzymes and adjust therapy if significant impairment exists.
• Pregnancy considerations: avoid use in pregnant women unless benefits outweigh potential risks.
• Differentiation syndrome vigilance: monitor for fever, weight gain, respiratory distress, and intervene promptly.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Arsenic trioxide can interact with other medicines, altering safety or efficacy.

Major Interactions (Avoid)

• QT‑prolonging agents (e.g., quinidine, sotalol): increase risk of dangerous arrhythmias.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): may raise arsenic levels.
• Azole antifungals: potentiate toxicity through metabolic inhibition.

Moderate Interactions (Monitor Closely)

• All‑trans retinoic acid (ATRA): heightened risk of differentiation syndrome; monitor closely.
• Diuretics: may exacerbate electrolyte disturbances; check serum potassium and magnesium.
• Electrolyte supplements: adjust dosing to avoid over‑correction of potassium/magnesium.