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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 conjugated to the cytotoxic agent calicheamicin, an enediyne antitumor antibiotic that induces double-strand DNA breaks.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients aged 1 month and older.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients aged 2 years and older.
## Adult Dosing
* **Newly Diagnosed AML:** 3 mg/m² (up to a maximum of one 4.5 mg vial) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Relapsed/Refractory AML:** 9 mg/m² as a single dose. If a second course is required, 3 mg/m² on day 1.
## Pediatric Dosing
* **Newly Diagnosed AML:**
* BSA ≥ 0.6 m²: 3 mg/m² (max 4.5 mg) on days 1, 4, and 7.
* BSA < 0.6 m²: 0.1 mg/kg on days 1, 4, and 7.
* **Relapsed/Refractory AML:** 3 mg/m² on days 1, 4, and 7.
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with total bilirubin > 2x ULN, or AST/ALT > 2.5x ULN.
* **Toxicity:** If severe infusion-related reactions occur, interrupt or discontinue based on severity. Hold doses for severe hepatotoxicity (e.g., suspected VOD/SOS).
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin.
* Severe hepatic impairment.
## Adverse Effects
* **Hepatotoxicity:** Including veno-occlusive disease (VOD) / sinusoidal obstruction syndrome (SOS). Increased risk with prior or subsequent hematopoietic stem cell transplant (HSCT).
* **Myelosuppression:** Grade 3 or higher neutropenia, thrombocytopenia, and anemia.
* **Infusion-related reactions:** Chills, fever, tachycardia, hypotension.
* **Infection:** Increased susceptibility due to prolonged neutropenia.
## Key Drug Interactions
* **Hepatotoxic agents:** Use with extreme caution as they may increase the risk of VOD/SOS.
* **Myelosuppressive agents:** Concurrent use will exacerbate cytopenias; typically integrated into clinical protocols.
## Monitoring
* **Hepatic Function:** Monitor ALT, AST, total bilirubin, and alkaline phosphatase prior to and during treatment. Monitor for signs of VOD/SOS (weight gain, hepatomegaly, ascites).
* **Hematology:** CBC with differential frequently during the induction and consolidation phases; monitor for prolonged cytopenias.
* **Infusion:** Monitor vital signs throughout and for at least 1 hour post-infusion.
## Clinical Pearls
* **Premedication:** Administer antihistamines, acetaminophen, and corticosteroids prior to each dose to prevent infusion-related symptoms.
* **VOD Risk:** The risk of VOD is significantly higher in patients undergoing HSCT. If possible, avoid hepatotoxic conditioning regimens.
* **Handling:** Must be protected from light. Reconstituted and diluted solutions must be infused immediately (or stored under strictly controlled conditions if necessary per institutional policy).
* **Uncertainty:** Dosing protocols vary significantly between cooperative groups (e.g., COG vs. adult oncology protocols). Always verify the exact schedule against the current institutional oncology order set or clinical trial protocol.
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*Disclaimer: This information is for educational purposes and does not substitute for professional clinical judgment. Always verify prescribing information against the current FDA label and institution-specific protocols before administration.*
