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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Gemtuzumab ozogamicin is an antibody-drug conjugate that targets CD33, a protein found on the surface of myeloid leukemia cells. It delivers the cytotoxic agent ozogamicin directly to these cells.
## Primary Indications
* Relapsed or refractory acute myeloid leukemia (AML) in adults.
* Newly diagnosed CD33-positive AML in adults in combination with chemotherapy.
## Adult Dosing
**Newly Diagnosed CD33-Positive AML (in combination with chemotherapy):**
* Dosing varies based on the specific chemotherapy regimen. Typically, it is administered on days 4, 7, and 10 of induction cycles or on days 6, 9, and 12 of consolidation cycles.
* **Example Regimen:** 3 mg/m² on days 4, 7, and 10 of induction, and 3 mg/m² on days 6, 9, and 12 of consolidation.
* **Maximum Dose per Administration:** 4.5 mg/m². The total dose per cycle should not exceed 9 mg/m².
**Relapsed or Refractory CD33-Positive AML:**
* **First Relapse:** 3 mg/m² on day 1, 4, and 7 of the first cycle. If the patient does not experience unacceptable toxicity, a second cycle may be given on the same schedule, but the total dose per cycle must not exceed 4.5 mg/m².
* **Subsequent Relapses:** 3 mg/m² on day 1. If the patient does not experience unacceptable toxicity, a second cycle may be given on day 1, but the total dose per cycle must not exceed 4.5 mg/m².
* **Maximum Dose per Administration:** 4.5 mg/m². The total dose per cycle should not exceed 9 mg/m².
Specific dosing and scheduling may depend on local institutional protocols and the patient's overall treatment plan.
## Pediatric Dosing
The safety and efficacy of gemtuzumab ozogamicin have not been established in pediatric patients.
## Dose Adjustments
* **Hepatotoxicity:** Dose interruptions and reductions may be necessary based on the severity of transaminase elevations or bilirubin increase.
* **Myelosuppression:** Dose interruptions may be necessary. Consider prophylactic growth factors.
* **Infusion Reactions:** Slow infusion rate, or interrupt and resume at a slower rate. Discontinue if severe.
## Contraindications
* Hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
## Adverse Effects
**Common:**
* Hepatotoxicity (including veno-occlusive disease/sinusoidal obstruction syndrome, hyperbilirubinemia, elevated AST/ALT)
* Thrombocytopenia
* Neutropenia
* Febrile neutropenia
* Anemia
* Leukopenia
* Nausea
* Vomiting
* Diarrhea
* Fatigue
* Fever
* Peripheral neuropathy
* Bleeding events (including intracranial hemorrhage)
* Infusion-related reactions (fever, chills, rash, dyspnea)
## Key Drug Interactions
* **Hepatotoxic Agents:** Concomitant use with other drugs known to cause hepatotoxicity may increase the risk of liver injury. Closely monitor liver function.
## Monitoring
* **Liver Function Tests:** Baseline and regularly throughout treatment (e.g., daily for the first week, then weekly, or as clinically indicated). Monitor for signs and symptoms of VOD/SOS.
* **Complete Blood Counts (CBC) with Differential and Platelet Count:** Regularly throughout treatment, with particular attention to nadirs.
* **Signs and Symptoms of Infusion Reactions:** Monitor during and after infusion.
* **Signs and Symptoms of Bleeding:** Monitor closely, especially in patients with thrombocytopenia.
## Clinical Pearls
* Gemtuzumab ozogamicin carries a significant risk of hepatotoxicity, particularly VOD/SOS, which can be fatal. Close monitoring of liver function is paramount.
* Infusion reactions are common and can be managed by slowing the infusion rate or premedication.
* Prophylactic administration of G-CSF is recommended.
* Due to the risk of myelosuppression, careful monitoring of CBCs is essential.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making clinical decisions.
