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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is an antibody-drug conjugate (ADC) consisting of a humanized anti-CD33 monoclonal antibody linked to a cytotoxic agent, calicheamicin. It targets CD33-expressing myeloid cells.
## Primary Indications
* Treatment of newly diagnosed adult patients with acute myeloid leukemia (AML) in morphologic remission who have not undergone hematopoietic stem cell transplantation.
* Treatment of adult patients with relapsed or refractory AML with ≥30% blasts and myeloid surface marker CD33 expression.
## Adult Dosing
* **Newly Diagnosed AML (in combination with standard chemotherapy):**
* **Induction:** 3 mg/kg on day 4 of each cycle of daunorubicin/cytarabine chemotherapy.
* **Consolidation:** 3 mg/kg on day 4 of each consolidation chemotherapy cycle.
* **Relapsed or Refractory AML:**
* **First Course:** 6 mg/kg as a single dose.
* **Second Course (if indicated):** 3 mg/kg as a single dose, administered approximately 14 to 21 days after the first course. Do not administer if the patient experienced severe (Grade 3 or 4) liver toxicity during the first course.
* **Maximum single dose:** 6 mg/kg.
## Pediatric Dosing
Dosing in pediatric patients is not established.
## Dose Adjustments
* **Hepatic Impairment:**
* **Total Bilirubin 1.5 to 3 times ULN:** Reduce dose to 3 mg/kg (first course) or 1.5 mg/kg (second course).
* **Total Bilirubin >3 times ULN:** Mylotarg is contraindicated.
* **Veno-occlusive Disease (VOD)/Sinusoidal Obstruction Syndrome (SOS):** Discontinue Mylotarg.
## Contraindications
* Severe hepatic impairment (total bilirubin >3 times ULN).
## Adverse Effects
Common adverse effects include:
* **Hematologic:** Febrile neutropenia, thrombocytopenia, anemia, neutropenia, leukopenia.
* **Hepatic:** Increased AST, increased ALT, hyperbilirubinemia, VOD/SOS.
* **Gastrointestinal:** Nausea, vomiting, diarrhea, stomatitis, constipation.
* **Infections:** Pneumonia, sepsis.
* **Other:** Fatigue, headache, pyrexia, rash, hypokalemia.
**Serious adverse effects include:** Hepatotoxicity (including VOD/SOS), myelosuppression, bleeding events, infusion-related reactions, and embryo-fetal toxicity.
## Key Drug Interactions
* **Warfarin:** Increased risk of bleeding. Monitor INR closely.
* **Other Myelosuppressive Agents:** Increased risk of myelosuppression.
## Monitoring
* Complete blood counts with differential and platelet count regularly.
* Liver function tests (AST, ALT, bilirubin) before and during treatment.
* Signs and symptoms of bleeding.
* Signs and symptoms of infusion-related reactions.
* Pregnancy status in females of reproductive potential.
## Clinical Pearls
* Mylotarg carries a boxed warning for hepatotoxicity, particularly VOD/SOS, which can be fatal. Risk factors include prior stem cell transplantation, prior liver radiation, and high bilirubin levels.
* Mylotarg can cause severe myelosuppression, requiring close monitoring and supportive care.
* Women of reproductive potential and men should use effective contraception during and for at least 6 months after the last dose.
* Administer Mylotarg as a 2-hour IV infusion.
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*This information is intended for healthcare professionals. Always consult the current Prescribing Information and local institutional protocols for definitive guidance.*
