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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). It consists of a humanized anti-CD33 monoclonal antibody covalently linked to the cytotoxic agent calicheamicin.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients aged 1 month and older (in combination with chemotherapy).
* Relapsed or refractory CD33-positive AML in adults and pediatric patients aged 2 years and older (as a single agent).
## Adult Dosing
Standard dosing is dependent on disease setting and regimen (protocol-specific):
* **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:** 9 mg/m² as a single dose on day 1. If recovery of peripheral blood counts is inadequate, a second dose of 9 mg/m² may be administered after 14 days.
## Pediatric Dosing
Dosing for patients <18 years is based on body surface area (BSA):
* **Newly Diagnosed AML:** 3 mg/m² (maximum 4.5 mg) on days 1, 4, and 7.
* **Relapsed/Refractory AML:** 3 mg/m² on days 1, 4, and 7.
* *Note: Dosing is weight-based (0.1 mg/kg) for patients with a BSA <0.6 m².*
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with severe hepatic impairment (Total Bilirubin >2x ULN, or AST/ALT >2.5x ULN).
* **Hepatotoxicity:** If signs of hepatotoxicity (specifically VOD/SOS) occur, discontinue treatment.
* **Infusion Reactions:** Interrupt or discontinue infusion based on severity.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any of its components.
* Severe hepatic impairment.
## Adverse Effects
* **Hepatotoxicity:** Potential for veno-occlusive disease (VOD) / sinusoidal obstruction syndrome (SOS), particularly with post-HSCT transplantation.
* **Myelosuppression:** Grade 3-4 neutropenia, thrombocytopenia, and anemia.
* **Infusion-Related Reactions:** Chills, fever, hypotension, and dyspnea.
* **Infections:** High risk of opportunistic infections due to prolonged myelosuppression.
* **Hemorrhage:** Incidents related to severe thrombocytopenia.
## Key Drug Interactions
* **Hepatotoxic Agents:** Risk of VOD/SOS is significantly increased when Mylotarg is followed by or precedes hematopoietic stem cell transplantation (HSCT) or when combined with other hepatotoxic medications.
* **Live Vaccines:** Avoid concomitant administration; risk of systemic infection.
## Monitoring
* **Liver Function:** Baseline and periodic monitoring of ALT, AST, total bilirubin, and alkaline phosphatase. Monitor closely for signs/symptoms of hepatotoxicity, including weight gain, hepatomegaly, and ascites.
* **CBC with differential:** Perform frequently until count recovery.
* **Infusion Monitoring:** Monitor patient during and for at least 1 hour after the completion of the infusion.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics 1 hour prior to each dose to mitigate infusion reactions.
* **Handling:** Must be protected from light during storage and reconstitution. Do not use if particles are present.
* **VOD Risk:** The risk of VOD/SOS is substantially increased in patients undergoing HSCT after Mylotarg administration. A delay of at least 2 weeks between the last dose and HSCT is recommended.
* **Documentation:** Mylotarg is high-alert medication; ensure verification of BSA and correct dose calculation, as dosing regimens vary significantly between clinical trials and real-world institutional protocols.
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*Disclaimer: This information is for educational purposes only. Always verify current prescribing information, institutional guidelines, and clinical protocols before administering any medication.*
