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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). The cytotoxic agent, calicheamicin, is released upon internalization into the CD33-positive cell, leading to DNA double-strand breaks and cell death.
## Primary Indications
Treatment of newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients aged 1 month and older; treatment of relapsed or refractory CD33-positive AML.
## Adult Dosing
* **Newly Diagnosed AML:** 3 mg/m² (up to a maximum dose of 4.5 mg per single dose) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Relapsed/Refractory AML:** 9 mg/m² as a single agent on day 1. If no response after the first dose, a second dose of 9 mg/m² may be administered after 14 days. If progression occurs after the first dose, do not administer the second.
## Pediatric Dosing
* **Newly Diagnosed AML (≥1 month):**
* BSA ≥0.6 m²: 3 mg/m² (max 4.5 mg/dose) on days 1, 4, and 7.
* BSA <0.6 m²: 0.1 mg/kg on days 1, 4, and 7.
* **Relapsed/Refractory AML:** Dosing is often extrapolated from adult data or institutional protocol. Pediatric dosing strategies vary significantly by protocol; consult institutional oncology guidelines.
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with total bilirubin >2x ULN or AST/ALT >2.5x ULN.
* **Toxicity:** Treatment may require delay or discontinuation based on infusion-related reactions, severe myelosuppression, or hepatotoxicity. No specific renal adjustment is required.
## Contraindications
Hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
## Adverse Effects
* **Black Box Warning:** Hepatotoxicity, including life-threatening and fatal hepatic veno-occlusive disease (VOD/sinusoidal obstruction syndrome).
* **Common:** Myelosuppression (leukopenia, neutropenia, thrombocytopenia, anemia), infection, hemorrhage, mucositis, nausea, and infusion-related reactions.
## Key Drug Interactions
* **Hepatotoxic Agents:** Use with caution; may increase risk of VOD. Consider monitoring liver function more frequently.
* **Live Vaccines:** Avoid live virus vaccines during therapy; immunosuppression may diminish vaccine efficacy and increase risk of disseminated infection.
## Monitoring
* **Liver Function:** Baseline and prior to each dose: bilirubin, ALT, AST, and alkaline phosphatase. Monitor for signs of VOD (weight gain, hepatomegaly, ascites).
* **Complete Blood Count:** Monitor frequently for myelosuppression, specifically neutrophil and platelet counts.
* **Infusion:** Monitor vital signs throughout and for at least 1 hour post-infusion for hypersensitivity or cytokine release symptoms.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and acetaminophen prior to each dose to mitigate infusion-related reactions.
* **Handling:** Mylotarg is a cytotoxic drug; handle according to institutional hazardous drug protocols. Ensure reconstitution is performed under strict aseptic conditions.
* **VOD Risk:** The risk of VOD is significantly higher in patients undergoing hematopoietic stem cell transplantation (HSCT) post-therapy. Ensure careful timing of transplant sequences.
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*Disclaimer: This information is for educational purposes only. Mylotarg dosing and protocols are highly complex and subject to change based on evolving clinical data, patient-specific factors, and institutional oncology guidelines. Always verify current prescribing information and confirm doses against the full FDA label or your institution's approved clinical trial/treatment protocol prior to administration.*
