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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). It consists of a monoclonal antibody monoclonal antibody (gemtuzumab) linked to a cytotoxic agent (calicheamicin). It is associated with a high risk of hepatotoxicity, including veno-occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS).
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients aged 2 years and older.
## Adult Dosing
Consult institutional protocol as dosing varies by regimen.
* **Newly Diagnosed AML:** 3 mg/m² (up to a maximum dose of 4.5 mg) on Days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Relapsed/Refractory AML:** 3 mg/m² (up to a maximum dose of 4.5 mg) on Days 1, 4, and 7 as a single agent.
## Pediatric Dosing
**Pediatric Patients (≥ 2 years):**
* 3 mg/m² (up to a maximum dose of 4.5 mg) on Days 1, 4, and 7.
* For patients with body surface area (BSA) < 0.6 m², dose is 0.1 mg/kg on Days 1, 4, and 7.
## Dose Adjustments
* **Hepatotoxicity:** If total bilirubin > 2x ULN, or AST/ALT > 5x ULN prior to a scheduled dose, withhold treatment until recovery. Delay dose if infusion-related reaction occurs.
* **VOD/SOS:** Discontinue permanently if VOD/SOS occurs.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
* Active severe hepatic disease.
## Adverse Effects
* **Black Box Warning:** Hepatotoxicity, including fatal SOS/VOD.
* **Hematologic:** Myelosuppression (prolonged neutropenia, thrombocytopenia, anemia).
* **Infections:** Significant risk of opportunistic infections.
* **Infusion-related:** Fever, chills, hypotension, hypoxia, and dyspnea.
* **Other:** Hemorrhage, elevated LFTs.
## Key Drug Interactions
* Avoid administration with strong CYP3A4 inhibitors or inducers, though clinical data on ADC metabolism interactions is limited compared to small molecules.
* Avoid concurrent use of hepatotoxic agents.
* Live vaccines: Avoid due to immunosuppression.
## Monitoring
* **Hepatic Function:** Monitor ALT, AST, total bilirubin, and alkaline phosphatase prior to each dose and throughout treatment. Monitor closely for signs of SOS/VOD (weight gain, hepatomegaly, ascites).
* **Hematology:** CBC with differential should be monitored frequently during treatment and recovery periods.
* **Infusion:** Monitor vital signs during and for at least 1 hour after infusion.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and acetaminophen 30 minutes prior to infusion to mitigate infusion-related reactions.
* **Preparation:** Must be reconstituted and diluted under aseptic conditions, avoiding exposure to light. The final concentration must be 0.075 mg/mL to 0.234 mg/mL.
* **Hydration:** Ensure adequate hydration to prevent tumor lysis syndrome.
* **Shelf Life:** Administer immediately after preparation; once-diluted infusions should not be stored longer than 6 hours at room temperature.
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*Disclaimer: This information is for educational purposes only and does not establish a standard of care. Dosing protocols may vary significantly based on specific clinical trial settings or institutional guidelines. Always verify the most current prescribing information in the official FDA-approved package insert or local drug database before prescribing or administering medication.*
