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# Mylod (Mylotarg / Gemtuzumab ozogamicin)
## Overview
Gemtuzumab ozogamicin is a CD33-directed antibody-drug conjugate (ADC) consisting of a monoclonal antibody linked to the cytotoxic agent calicheamicin. It is designed to target CD33-expressing leukemia cells to induce DNA double-strand breaks and apoptosis.
## Primary Indications
CD33-positive acute myeloid leukemia (AML):
* Newly diagnosed de novo 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 (Combination Therapy):** 3 mg/m² (up to a maximum of one 4.5 mg vial) on Days 1, 4, and 7 of the induction cycle.
* **Relapsed/Refractory AML (Monotherapy):** 9 mg/m² as a single dose on Day 1. If response is inadequate, a second dose of 9 mg/m² may be administered 14 days later.
* *Note:* Dose reduction or modified schedules are often required during consolidation phases; follow institutional protocols.
## Pediatric Dosing
* **Patients < 13 kg:** Dose is based on weight (0.1 mg/kg or 0.3 mg/kg, depending on the regimen).
* **Patients ≥ 13 kg:** Dose is based on BSA (mg/m²), identical to adult dosing protocols (3 mg/m² or 9 mg/m² respectively).
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with severe hepatic impairment (total bilirubin > 2x ULN). Use caution in mild-to-moderate impairment.
* **Veno-occlusive disease (VOD):** Discontinue permanently if VOD/SOS occurs.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
* Patients with documented, ongoing severe hepatic impairment (as noted above).
## Adverse Effects
* **Hepatotoxicity:** Including fatal veno-occlusive disease (VOD/sinusoidal obstruction syndrome).
* **Infusion-related reactions:** Hypotension, bronchospasm, and dyspnea.
* **Hematologic:** Severe prolonged neutropenia, thrombocytopenia, and anemia.
* **Infections:** High risk of opportunistic infections due to profound immunosuppression.
* **Hemorrhage:** Increased risk, particularly with high blast counts (> 30,000/mcL).
## Key Drug Interactions
* **Hepatotoxic agents:** Use with extreme caution as they may increase the risk of VOD.
* **Live vaccines:** Avoid administration; may increase risk of disseminated infection in immunosuppressed patients.
* **Strong CYP3A inhibitors/inducers:** Monitor closely for altered efficacy or toxicity.
## Monitoring
* **Liver Function Tests:** Monitor ALT, AST, total bilirubin, and alkaline phosphatase prior to each dose and frequently during treatment.
* **CBC with Differential:** Monitor blood counts frequently throughout therapy.
* **Infusion monitoring:** Observe for signs of infusion-related reaction for at least 1 hour post-infusion.
* **Signs of VOD:** Assess body weight, hepatomegaly, and ascites daily.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics prior to infusion to attenuate infusion reactions.
* **Tumor Lysis Syndrome (TLS):** Prophylactic hydration and antihyperuricemic agents are mandatory, especially in patients with high peripheral blast counts.
* **Administering:** The product is sensitive to light. Protect the diluted solution from light and administer immediately.
* **Specific Toxicity:** The association with VOD is significantly higher in patients undergoing subsequent hematopoietic stem cell transplantation (HSCT).
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**Educational Disclaimer:** This information is for educational purposes only. Always consult the latest FDA-approved prescribing information, the current hospital formulary, and official institutional treatment protocols before prescribing or administering medication.
