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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). It delivers the cytotoxic agent calicheamicin to CD33-expressing leukemia cells.
## 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 in adults and pediatric patients aged 2 years and older.
## Adult Dosing
Consult local institutional protocols/clinical trials, as dosing varies by regimen.
* **Newly diagnosed AML (Combination):** 3 mg/m² (up to a maximum dose of 4.5 mg) on days 1, 4, and 7 of the induction cycle.
* **Newly diagnosed AML (Monotherapy):** 6 mg/m² on day 1 and 3 mg/m² on day 8.
* **Relapsed or Refractory AML:** 3 mg/m² on days 1, 4, and 7.
## Pediatric Dosing
* **Newly diagnosed AML (1 month and older):** 3 mg/m² (up to a maximum dose of 4.5 mg) on days 1, 4, and 7.
* **Relapsed or Refractory AML (2 years and older):** 3 mg/m² on days 1, 4, and 7.
* *Note:* Weight-based dosing is sometimes utilized in younger/smaller patients; strictly adhere to institutional guidelines.
## Dose Adjustments
* **Hepatic Impairment:** No formal dosage adjustments for mild impairment. Avoid in moderate or severe hepatic impairment (Total Bilirubin > 2x ULN).
* **Renal Impairment:** No adjustment required.
* **Infusion Reactions:** Interrupt or discontinue infusion based on severity.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any component of the product.
* History of veno-occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS).
## Adverse Effects
* **Hepatotoxicity:** Including fatal VOD/SOS.
* **Infusion-related reactions:** Hypotension, bronchospasm, chills, fever.
* **Myelosuppression:** Severe neutropenia, thrombocytopenia, and anemia.
* **Infection:** Risk of opportunistic infections due to prolonged cytopenias.
* **Hemorrhage:** Consistent with thrombocytopenia.
## Key Drug Interactions
* **Strong CYP3A4 inhibitors/inducers:** Monitor closely for increased toxicity or decreased efficacy, though pharmacokinetics of the conjugated calicheamicin are not significantly altered by CYP3A4.
* **QT-prolonging agents:** Caution advised due to potential for cumulative toxicity.
## Monitoring
* **Liver Function:** Baseline and prior to each dose (ALT, AST, Total Bilirubin, Alkaline Phosphatase).
* **CBC:** Monitor regularly for degree and duration of cytopenias.
* **VOD/SOS:** Monitor for sudden weight gain, hepatomegaly, ascites, and elevated bilirubin.
* **Cardiac:** Monitor ECG for QT prolongation if indicated.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics 1 hour prior to infusion to attenuate infusion reactions.
* **Extravasation:** Ensure proper venous access; the drug is a vesicant.
* **Handling:** Must be protected from light during preparation and administration.
* **VOD Risk:** The risk of VOD/SOS is significantly increased if the patient undergoes hematopoietic stem cell transplantation (HSCT) post-Mylotarg, particularly with the use of hepatotoxic conditioning regimens.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice guidelines are subject to change based on emerging data. Always verify the most current prescribing information (package insert) and internal institutional protocols before administering cytotoxic chemotherapy.
