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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate. It consists of a humanized anti-CD33 monoclonal antibody covalently linked to the cytotoxic agent calicheamicin.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients ≥1 month.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients ≥2 years.
## Adult Dosing
* **Newly Diagnosed AML:** 3 mg/m² (up to a maximum of one 4.5 mg vial per dose) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Relapsed/Refractory AML (Monotherapy):** 9 mg/m² as a single dose on day 1. If no disease progression or excessive toxicity, a second dose of 3 mg/m² may be administered on day 8.
## Pediatric Dosing
* **Newly Diagnosed AML:** 3 mg/m² (maximum 4.5 mg/dose) on days 1, 4, and 7 in combination with chemotherapy. For patients with a body surface area (BSA) <0.6 m², dose at 0.1 mg/kg.
* **Relapsed/Refractory AML:** 3 mg/m² (maximum 4.5 mg/dose) on days 1, 4, and 7. For patients with BSA <0.6 m², dose at 0.1 mg/kg.
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with severe hepatic impairment (Total Bilirubin >2x ULN or AST/ALT >5x ULN). Use caution in patients with baseline bilirubin abnormalities.
* **Toxicity:** Hold doses for severe infusion-related reactions, severe mucositis, or persistent hematologic toxicity.
## Contraindications
* Known severe hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
## Adverse Effects
* **Hepatotoxicity:** Including veno-occlusive disease (VOD)/sinusoidal obstruction syndrome (SOS).
* **Myelosuppression:** Severe neutropenia, thrombocytopenia, and anemia.
* **Infusion-related reactions:** Hypotension, dyspnea, and fever.
* **Infection:** High risk of opportunistic infections due to immunosuppression.
* **Tumor Lysis Syndrome (TLS).**
## Key Drug Interactions
* **Strong CYP3A inhibitors/inducers:** Monitor closely for changes in efficacy or toxicity; though calicheamicin metabolism is not purely CYP-dependent, caution is advised.
* **Anticoagulants/Antiplatelets:** Increased risk of hemorrhage due to thrombocytopenia.
## Monitoring
* **Liver Function:** Baseline and prior to each dose (Bilirubin, ALT, AST, ALP). Monitor for rising bilirubin or signs of VOD/SOS post-transplant.
* **CBC:** Frequent monitoring for myelosuppression.
* **Electrolytes/Renal Function:** Monitor for Tumor Lysis Syndrome.
* **Infusion:** Monitor site-of-care for infusion-related reactions.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics 1 hour prior to infusion to attenuate infusion-related reactions.
* **VOD Risk:** High risk in patients post-hematopoietic stem cell transplant (HSCT). Delay planned transplant for at least 2 weeks after final dose.
* **Preparation:** Must be reconstituted and diluted using aseptic technique; protect from light during preparation.
* **Dosing protocol:** Always verify specific institution-based AML treatment protocols, as variations exist regarding combinations and cycle schedules.
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*Disclaimer: This information is for educational purposes only. Clinical practice guidelines and FDA-approved labeling can change. Always verify the most current prescribing information and institutional protocols prior to drug administration.*
