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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 cytotoxic agent that causes double-strand DNA breaks, leading to cell cycle arrest and apoptosis.
## Primary Indications
Treatment of newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients 1 month and older. Also indicated for relapsed or refractory CD33-positive AML in adults and pediatric patients 2 years and older.
## Adult Dosing
Standard dosing is highly protocol-dependent.
* **Newly diagnosed AML (combination therapy):** 3 mg/m² (up to a maximum dose of 4.5 mg) on days 1, 4, and 7.
* **Single-agent (relapsed/refractory):** 9 mg/m² on day 1 (often administered as 3 mg/m² on days 1, 4, and 7 in current practice to mitigate toxicity).
* *Note: Always verify doses against the specific institutional clinical trial or local oncology protocol.*
## Pediatric Dosing
* **Patients ≥ 1 month:** 3 mg/m² (up to a maximum of 4.5 mg) on days 1, 4, and 7 in combination with chemotherapy. If BSA is < 0.6 m², dose is 0.1 mg/kg.
* **Patients ≥ 2 years (single agent):** 3 mg/m² (up to 4.5 mg) on days 1, 4, and 7.
* *Note: Dosing is strictly weight/BSA-based; consult local pediatric hematology-oncology protocols.*
## Dose Adjustments
* **Hepatic Impairment:** No specific adjustment for mild impairment; avoid in patients with severe hepatic impairment (bilirubin > 2x ULN).
* **Toxicity:** Hold doses for severe infusion-related reactions, severe myelosuppression (if persistent), or evidence of VOD/SOS. Permanently discontinue if severe hepatic VOD occurs.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any excipients.
* Prior severe hypersensitivity reaction to gemtuzumab ozogamicin.
## Adverse Effects
* **Hepatotoxicity:** High risk of Veno-Occlusive Disease (VOD)/Sinusoidal Obstruction Syndrome (SOS), particularly post-hematopoietic stem cell transplant (HSCT).
* **Myelosuppression:** Profound neutropenia, thrombocytopenia, and anemia.
* **Infusion-related reactions:** Fever, chills, hypotension, and dyspnea.
* **Others:** Infection, hemorrhage, mucositis, and electrolyte imbalances.
## Key Drug Interactions
Use caution when combining with other hepatotoxic agents. Increased risk of prolonged myelosuppression if administered with other myelosuppressive chemotherapeutic agents.
## Monitoring
* **Hepatic function:** ALT, AST, total bilirubin, and alkaline phosphatase prior to each dose.
* **Hematologic:** CBC with differential frequently to monitor for count recovery and post-treatment myelosuppression.
* **VOD/SOS:** Monitor for sudden weight gain, hepatomegaly, ascites, and unexplained jaundice.
* **Infusion:** Vital signs monitored closely during and for at least 1 hour post-infusion.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics prior to each infusion to reduce incidence of infusion-related reactions.
* **VOD Risk:** Avoid administration of Mylotarg within 2 weeks of HSCT if possible. If HSCT is planned, monitor hepatic function aggressively.
* **CD33 Status:** Must confirm CD33-positive status prior to initiation.
* **Handing:** This is a hazardous drug; strictly follow institutional hazardous drug handling/safety protocols.
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*Disclaimer: This information is for educational purposes only. Clinical protocols and prescribing information are subject to change. Always consult the most recent FDA-approved package insert, institutional guidelines, and clinical pharmacy specialists before prescribing or administering any medication.*
