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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is an antibody-drug conjugate consisting of a humanized anti-CD33 monoclonal antibody conjugated to the cytotoxic agent calicheamicin. It targets CD33-expressing cells, primarily myeloid blasts in acute myeloid leukemia (AML).
## Primary Indications
* Treatment of newly diagnosed adult patients with acute myeloid leukemia (AML).
* Treatment of adult patients with relapsed or refractory AML.
## Adult Dosing
**Newly Diagnosed AML:**
* **First cycle:** 3 mg/m² on day 1, 2 mg/m² on day 4, and 2 mg/m² on day 7.
* **Second cycle (if bone marrow blast percentage is ≥5% and patient has not experienced disease progression or unacceptable toxicity):** 3 mg/m² on day 1, 2 mg/m² on day 4, and 2 mg/m² on day 7.
**Relapsed or Refractory AML:**
* **Cycles 1-2:** 3 mg/m² on day 1, 2 mg/m² on day 4, and 2 mg/m² on day 7.
* **Subsequent cycles (if bone marrow blast percentage is ≥5% and patient has not experienced unacceptable toxicity):** 3 mg/m² on day 1 every 2-4 weeks.
**Maximum Dose:** Do not exceed 3 mg/m² per infusion. Total cumulative dose should not exceed 18 mg/m².
## Pediatric Dosing
Dosing for pediatric patients is not established.
## Dose Adjustments
* **Hepatotoxicity:** Discontinue or dose reduce based on severity of AST/ALT elevation or total bilirubin.
* Grade 3/4 AST/ALT elevation: Delay treatment. If resolution to Grade ≤1, resume at a reduced dose (e.g., 2 mg/m²).
* Grade 3/4 bilirubin elevation: Delay treatment. If resolution to Grade ≤1, resume at a reduced dose (e.g., 2 mg/m²).
* **Thrombocytopenia:** Dose modifications are generally not recommended for myelosuppression, but treatment delays may be necessary.
## Contraindications
* None listed.
## Adverse Effects
The most common adverse reactions (incidence >30%) are:
* Infections (including sepsis, pneumonia)
* Thrombocytopenia
* Nausea
* Vomiting
* Mucositis
* Diarrhea
* Constipation
* Headache
* Pyrexia
* Anemia
* Neutropenia
* Febrile neutropenia
* Decreased appetite
* Rash
* Peripheral edema
* Fatigue
* Hepatotoxicity (including veno-occlusive liver disease/sinusoidal obstruction syndrome)
* Bleeding events
**Serious Adverse Reactions:**
* Hepatotoxicity, including VOD/SOS.
* Myelosuppression, including severe thrombocytopenia and neutropenia.
* Infusion-related reactions.
* Embryo-fetal toxicity.
## Key Drug Interactions
* **Warfarin:** Increased risk of bleeding. Monitor INR closely.
* **CYP3A4 substrates:** Gemtuzumab ozogamicin is not an inhibitor or inducer of CYP enzymes. However, concurrent use with potent CYP3A4 inhibitors or inducers may alter exposure of co-administered drugs.
## Monitoring
* Complete blood counts (CBC) with differential and platelet count prior to each dose.
* Liver function tests (LFTs), including bilirubin and transaminases, prior to each dose.
* Monitor for signs and symptoms of infusion-related reactions.
* Monitor for signs and symptoms of hepatotoxicity (VOD/SOS).
* Monitor for bleeding events.
## Clinical Pearls
* Mylotarg carries a black box warning for hepatotoxicity, particularly VOD/SOS, and for myelosuppression.
* Hepatotoxicity may occur in patients receiving other potentially hepatotoxic medications (e.g., chemotherapy, NSAIDs, warfarin).
* Administer prophylactic anti-emetics, anti-diarrheals, and anti-infectives as clinically indicated.
* Female patients of childbearing potential and male patients should use effective contraception during treatment and for a period after the last dose.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines for complete details before making any treatment decisions.*
