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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 calicheamicin, a potent cytotoxic agent 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 dose of 10 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 10 mg) on days 1, 4, and 7 as a single agent.
* *Note: Dosing is based on body surface area (BSA).*
## Pediatric Dosing
* **Newly Diagnosed AML:**
* BSA ≥ 0.6 m²: 3 mg/m² (max 10 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:** 3 mg/m² (up to a maximum dose of 10 mg) on days 1, 4, and 7.
## Dose Adjustments
* **Hepatic Impairment:** No specific adjustment for mild impairment. Avoid use in patients with moderate to severe hepatic impairment (Total Bilirubin > 2x ULN, AST/ALT > 2.5x ULN).
* **Renal Impairment:** No formal dosage adjustments are provided for renal impairment.
* **Discontinuation:** Permanently discontinue if severe hepatotoxicity or Veno-Occlusive Disease (VOD)/Sinusoidal Obstruction Syndrome (SOS) occurs.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any of its components.
* Previous severe or life-threatening infusion-related reactions.
## Adverse Effects
* **Hepatotoxicity:** High risk of VOD/SOS, particularly post-hematopoietic stem cell transplant (HSCT).
* **Hematologic:** Severe, prolonged thrombocytopenia, neutropenia, and anemia.
* **Infusion Reactions:** Fever, chills, hypotension, and dyspnea (premedication with corticosteroids, antihistamines, and acetaminophen is mandatory).
* **Infection:** Increased risk due to profound myelosuppression.
* **Tumor Lysis Syndrome:** Risk associated with rapid blast reduction.
## Key Drug Interactions
* **Hepatotoxic Agents:** Avoid concomitant use with other drugs known to cause liver injury or VOD to mitigate the risk of severe hepatotoxicity.
* **CYP450/Transporters:** Gemtuzumab ozogamicin is not a substrate of CYP450 enzymes; clinically significant pharmacokinetic interactions are limited.
## Monitoring
* **Liver Function:** Baseline and regular monitoring of bilirubin, AST, ALT, and alkaline phosphatase.
* **CBC:** Frequent monitoring of blood counts for prolonged cytopenias.
* **Signs of VOD/SOS:** Monitor for weight gain, hepatomegaly, and ascites.
* **Infection:** Vigilant screening for signs of bacterial, fungal, or viral infections.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, an antihistamine (e.g., diphenhydramine), and acetaminophen 1 hour prior to infusion.
* **VOD/SOS Risk:** The risk of VOD is significantly increased in patients undergoing HSCT after Mylotarg treatment. Consider a minimum washout period between Mylotarg and subsequent HSCT if possible.
* **Administration:** Infuse over 2 hours; protect the diluted solution from light.
* *Note: Protocols regarding exact timing of transplant relative to Mylotarg therapy may vary by institution.*
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**Educational Disclaimer:** This summary is for informational purposes only and does not replace professional clinical judgment. Prescribing information, institutional guidelines, and drug labeling are subject to change. Always verify the most recent FDA-approved prescribing information and your institution's specific clinical protocols before administration.
