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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Gemtuzumab ozogamicin is an antibody-drug conjugate (ADC) consisting of a CD33-directed monoclonal antibody linked to the cytotoxic agent calicheamicin. It is designed to target and deliver chemotherapy directly to CD33-positive leukemic cells.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients aged ≥1 month.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients aged ≥2 years.
## Adult Dosing
Variable based on treatment setting and combination therapy:
* **Newly Diagnosed AML (Combination Therapy):** 3 mg/m² (up to a max of one 4.5 mg vial) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Newly Diagnosed AML (Monotherapy):** 6 mg/m² on day 1; 3 mg/m² on day 8.
* **Relapsed/Refractory AML:** 3 mg/m² on days 1, 4, and 7.
* *Note: Dosing must be adjusted based on Body Surface Area (BSA).*
## Pediatric Dosing
* **Newly Diagnosed AML (Combination Therapy):**
* BSA ≥0.6 m²: 3 mg/m² (max 4.5 mg) on days 1, 4, and 7.
* BSA <0.6 m²: 0.1 mg/kg on days 1, 4, and 7.
* **Relapsed/Refractory AML:** Consult institutional protocol; dosing typically follows weight-based or BSA-based regimens similar to the adult schedule adjusted for size.
## Dose Adjustments
* **Hepatic Impairment:** Reduce dose for patients with total bilirubin >2x ULN or AST/ALT >2.5x ULN.
* **Hepatotoxicity:** Hold dosing if evidence of Venocclusive Disease (VOD)/Sinusoidal Obstruction Syndrome (SOS) or significant liver enzyme elevation occurs. Permanently discontinue if severe hepatotoxicity persists.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any of its components.
* History of VOD/SOS.
## Adverse Effects
* **Severe/Fatal:** Hepatotoxicity (including VOD/SOS), infusion-related reactions (hypotension, bronchospasm, dyspnea), myelosuppression, and severe hemorrhage.
* **Common:** Infection, nausea, stomatitis, pyrexia, constipation, and fatigue.
## Key Drug Interactions
* **Hepatotoxic Agents:** Use with caution; may increase the risk of VOD/SOS.
* **Myelosuppressive Agents:** Concurrent use may potentiate neutropenia and thrombocytopenia.
## Monitoring
* **Liver Function:** Baseline and regular monitoring of bilirubin, ALT, AST, and alkaline phosphatase.
* **Hematology:** CBC with differential frequently to monitor for prolonged myelosuppression.
* **Infusion:** Monitor closely for signs/symptoms of hypersensitivity (pre-medication with acetaminophen, diphenhydramine, and corticosteroids is required).
* **Clinical:** Watch for signs of VOD/SOS (e.g., rapid weight gain, RUQ pain, ascites, jaundice).
## Clinical Pearls
* **VOD Risk:** The risk of VOD is significantly increased in patients undergoing hematopoietic stem cell transplantation (HSCT) after Mylotarg therapy, particularly when used as a conditioning regimen or at high doses.
* **Handling:** Product is light-sensitive; reconstituted vials must be protected from light.
* **Pre-medication:** Mandatory premedication protocol is required to mitigate infusion-related reactions.
* **Dosing Constraints:** Max dose for any given administration is 4.5 mg to minimize toxicity.
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**Educational Disclaimer:** This information is for educational purposes only. Drug protocols, indications, and dosing must be verified against the most current FDA-approved labeling, institutional guidelines, and clinical consultation.
