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# Mylotarg (Gemtuzumab Ozogamicin)
## Overview
Gemtuzumab ozogamicin is a CD33-directed antibody-drug conjugate (ADC). It consists of a humanized anti-CD33 monoclonal antibody covalently linked to the cytotoxic agent calicheamicin, which causes DNA double-strand breaks leading to apoptosis.
## Primary Indications
- Newly diagnosed CD33-positive acute myeloid leukemia (AML).
- Relapsed or refractory CD33-positive AML.
## Adult Dosing
*Dosing depends heavily on the specific treatment phase and patient population (refer to institutional protocols).*
- **Newly Diagnosed AML (Combination Therapy):** 3 mg/m² (up to a max of 4.5 mg per dose) on Days 1, 4, and 7 in combination with daunorubicin and cytarabine.
- **Newly Diagnosed AML (Monotherapy):** 6 mg/m² on Day 1 and 3 mg/m² on Day 8 of induction.
- **Relapsed/Refractory AML:** 3 mg/m² (up to a max of 4.5 mg per dose) on Days 1, 4, and 7.
## Pediatric Dosing
- **Children ≥2 years:** Dosing is typically based on body surface area (BSA). Similar to adult regimens, 3 mg/m² (up to a max of 4.5 mg/dose) is commonly utilized in induction/consolidation combination protocols. **Consult institutional pediatric oncology protocols for precise weight-based or BSA-based dosing as these vary significantly by study protocol.**
## Dose Adjustments
- **Hepatic Impairment:** Avoid in patients with severe hepatic impairment (Total Bilirubin >2x ULN). Dosage adjustments for mild to moderate impairment are not clearly defined; exercise extreme caution.
- **Liver Toxicity:** Withhold dose for severe hepatotoxicity or signs of VOD/SOS until resolution.
## Contraindications
- Known hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
- History of veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS).
## Adverse Effects
- **Hepatotoxicity:** High risk of VOD/SOS, particularly in patients undergoing hematopoietic stem cell transplantation (HSCT) post-therapy.
- **Myelosuppression:** Profound neutropenia, thrombocytopenia, and anemia.
- **Infusion-Related Reactions:** Fever, chills, hypotension, and dyspnea (pre-medicate with antihistamines, acetaminophen, and corticosteroids).
- **Infection:** Opportunistic infections due to prolonged myelosuppression.
## Key Drug Interactions
- **Live Vaccines:** Avoid live virus vaccines during therapy due to immunosuppression.
- **Hepatotoxic Agents:** Use with extreme caution alongside other drugs known to cause liver injury or VOD to mitigate the risk of SOS.
## Monitoring
- **Liver Function:** Baseline and frequent monitoring of ALT, AST, alkaline phosphatase, and total bilirubin.
- **Hematology:** Daily CBC with differential during induction/consolidation phase.
- **Infection:** Monitor for signs/symptoms of infection; implement prophylactic anti-infectives per institution policy.
- **VOD/SOS:** Monitor for sudden weight gain, abdominal pain, hepatomegaly, or ascites.
## Clinical Pearls
- **VOD/SOS Risk:** The risk is significantly increased if the interval between Mylotarg and HSCT is short or if the patient received prior transplantation. A gap of at least 2 weeks post-Mylotarg is generally suggested before pursuing HSCT.
- **Infusion:** Administer as a 2-hour IV infusion. Ensure the specialized light-protected tubing is used during preparation and administration to prevent degradation.
- **Pre-medication:** Mandatory pre-medication for infusion reactions (e.g., diphenhydramine, acetaminophen, and dexamethasone) is essential.
***
**Educational Disclaimer:** This information is for educational purposes only. Drug information is subject to frequent updates. Always verify current prescribing information, institutional protocols, and FDA labeling before prescribing or administering medication.
