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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). It delivers the cytotoxic agent calicheamicin to CD33-expressing leukemia cells.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients ≥1 month.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients ≥2 years.
## Adult Dosing
* **Newly Diagnosed AML (Combination Therapy):** 3 mg/m² (up to a max of 4.5 mg) on days 1, 4, and 7.
* **Relapsed or Refractory AML (Monotherapy):** 9 mg/m² as a single dose.
* *Note:* Always verify the specific treatment regimen (regimen-dependent dosing varies widely).
## Pediatric Dosing
* **Newly Diagnosed AML (≥1 Month):** 3 mg/m² (up to a max of 4.5 mg) on days 1, 4, and 7 in combination with chemotherapy. For patients with a body surface area (BSA) <0.6 m², the dose is 0.1 mg/kg.
* **Relapsed/Refractory (≥2 Years):** 3 mg/m² (max 4.5 mg) on days 1, 4, and 7.
## Dose Adjustments
* **Hepatic Impairment:** Not recommended in patients with severe hepatic impairment (Total Bilirubin >2x ULN).
* **Renal Impairment:** No specific dosage adjustment recommended for mild to moderate impairment.
* **Toxicity-based:** Withhold for severe infusion reactions, severe hepatotoxicity (e.g., VOD/SOS), or persistent severe neutropenia (consult current package insert for specific threshold criteria).
## Contraindications
* Hypersensitivity to gemtuzumab ozogamicin or any component of the product.
* History of veno-occlusive disease (VOD) or sinusoidal obstruction syndrome (SOS).
## Adverse Effects
* **Hepatotoxicity:** Including VOD/SOS (life-threatening, risk elevated post-HSCT).
* **Hematologic:** Severe neutropenia, thrombocytopenia, and anemia.
* **Infusion-related reactions:** Fever, chills, hypotension, and dyspnea.
* **Infection:** Risk of myelosuppression-related infections (bacterial, fungal, viral).
* **Hemorrhage:** Due to severe thrombocytopenia.
## Key Drug Interactions
* **Hepatotoxic Agents:** Avoid concomitant use with other drugs known to cause liver injury or VOD (e.g., certain azoles, high-dose cyclophosphamide post-transplantation).
* **Live Vaccines:** Avoid due to immunosuppression.
## Monitoring
* **Baseline/Frequent:** LFTs (bilirubin, ALT, AST, alkaline phosphatase), CBC with differential, electrolytes.
* **Clinical:** Signs and symptoms of VOD (unexplained weight gain, abdominal pain, hepatomegaly, ascites), infusion reaction symptoms, and bleeding/infection signs.
## Clinical Pearls
* **VOD Risk:** The risk of VOD is significantly increased in patients undergoing hematopoietic stem cell transplantation (HSCT) after Mylotarg administration.
* **Pre-medication:** Administer corticosteroids, antihistamines, and antipyretics 1 hour prior to each dose to attenuate infusion reactions.
* **Preparation:** This is a hazardous drug. Prepare in a vertical laminar flow hood using closed systems. Protect from light during reconstitution and infusion.
* **Dosing Uncertainty:** Dosing is highly protocol-specific. Always reference the institutional protocol or the specific clinical trial regimen if using in combination therapy.
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*Disclaimer: This information is for educational purposes for healthcare professionals. Clinical practice guidelines and drug labeling evolve. Always verify current prescribing information, institutional protocols, and FDA labeling before administration.*
