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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 convalently linked to the cytotoxic agent calicheamicin, which induces DNA double-strand breaks, leading to cell cycle arrest and apoptosis.
## Primary Indications
* Treatment of newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults.
* Treatment of relapsed or refractory CD33-positive AML in adults and pediatric patients aged 2 years and older.
## Adult Dosing
Induction (Newly Diagnosed): 3 mg/m² (up to a max of one 4.5 mg vial per dose) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
Relapsed/Refractory: 3 mg/m² (up to a max of 4.5 mg) on days 1, 4, and 7.
## Pediatric Dosing
Relapsed/Refractory: 3 mg/m² (up to a max of 4.5 mg) on days 1, 4, and 7. Safety and efficacy not established in patients <2 years.
## Dose Adjustments
* Hepatic Impairment: No adjustment for mild impairment (bilirubin ≤ULN and AST/ALT <2x ULN). Use with caution in moderate to severe impairment; avoid if total bilirubin >2x ULN.
* Renal Impairment: No specific dosage adjustment required.
* Infusion-related reactions: Interrupt or discontinue infusion based on severity.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any of its components.
* History of veno-occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS) related to previous therapy.
## Adverse Effects
* Hepatotoxicity: Including VOD/SOS, elevated LFTs.
* Myelosuppression: Profound neutropenia, thrombocytopenia, anemia.
* Infusion-related reactions: Fever, chills, hypotension, dyspnea.
* Infection: High risk due to prolonged myelosuppression.
* Hemorrhage: Secondary to thrombocytopenia.
## Key Drug Interactions
* QT-Prolonging Agents: Potential additive risk of QT prolongation; monitor ECGs if co-administered.
* Strong CYP3A4 inhibitors/inducers: Gemtuzumab is not a CYP substrate, however, monitor closely due to the high toxicity profile of the drug.
## Monitoring
* Liver Function Tests: Including ALT, AST, total bilirubin, and alkaline phosphatase (prior to each dose and after treatment).
* CBC with differential: For duration of therapy to monitor for cytopenias.
* Signs/Symptoms of VOD/SOS: Weight gain, hepatomegaly, ascites, bilirubin elevation.
## Clinical Pearls
* Premedication: Administer corticosteroids, antihistamines, and antipyretics 1 hour prior to infusion to reduce the risk of reaction.
* Stability: The product is light-sensitive; protect from light during reconstitution and infusion.
* VOD Risk: The risk of VOD/SOS is significantly increased if the patient undergoes hematopoietic stem cell transplantation (HSCT) following administration.
* Dosing precision: Do not exceed 4.5 mg per dose regardless of BSA to minimize toxicity.
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*Disclaimer: This information is for educational purposes only. Clinical practice guidelines and drug information evolve; always consult the most current FDA-approved prescribing information, institutional protocols, and official package inserts before prescribing or administering medication.*
