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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a targeted therapy, an antibody-drug conjugate, that targets CD33, a protein found on the surface of myeloid leukemia cells. It delivers a cytotoxic agent directly to these cells.
## Primary Indications
* Treatment of adults and pediatric patients aged 1 month and older with newly diagnosed acute myeloid leukemia (AML) in combination with chemotherapy.
* Treatment of adults and pediatric patients aged 1 month and older with relapsed or refractory AML.
## Adult Dosing
* **Newly diagnosed AML (in combination with chemotherapy):** 3 mg/m² intravenously on day 4, 11, and 18 of induction and consolidation cycles. Maximum of 6 cycles for induction and consolidation combined.
* **Relapsed or refractory AML:** 6 mg/m² intravenously on day 1 of the first cycle, and 3 mg/m² intravenously on day 4 of the first cycle, and day 1 of the second cycle. Maximum of 2 cycles.
## Pediatric Dosing
* **Newly diagnosed AML (in combination with chemotherapy):** 1.5 mg/m² intravenously on day 4, 11, and 18 of induction and consolidation cycles. Maximum of 6 cycles for induction and consolidation combined.
* **Relapsed or refractory AML:** 3 mg/m² intravenously on day 1 of the first cycle, and 1.5 mg/m² intravenously on day 4 of the first cycle, and day 1 of the second cycle. Maximum of 2 cycles.
*Note: Pediatric dosing is based on BSA and may vary based on specific protocols. Always refer to institutional guidelines or pediatric oncology expertise for precise dosing, especially in patients with extreme body sizes.*
## Dose Adjustments
* **Hepatotoxicity:** Dose interruptions or discontinuation may be necessary based on the severity of liver enzyme elevations and bilirubin levels. Consult prescribing information for specific guidance on management of hepatotoxicity.
* **Thrombocytopenia:** Dose adjustments are generally not recommended for treatment-induced thrombocytopenia beyond standard supportive care. However, severe thrombocytopenia may warrant delays or dose reductions in some regimens. Always consult the full prescribing information and institutional protocols.
* **Infusion Reactions:** Interrupt infusion if severe reactions occur. Doses may be resumed at a slower rate once symptoms resolve.
## Contraindications
* None specifically listed for Mylotarg itself, but its use in combination with certain chemotherapy agents may have specific contraindications.
## Adverse Effects
* **Common:** Thrombocytopenia (very common), febrile neutropenia, nausea, vomiting, diarrhea, mucositis, headache, pyrexia, fatigue, rash, elevated liver enzymes (ALT, AST).
* **Serious:** Hepatotoxicity (including VOD/SOS), severe infusion reactions, myelosuppression, bleeding events, tumor lysis syndrome.
* Dose-dependent increase in VOD/SOS risk with repeated dosing.
## Key Drug Interactions
* **Strong CYP3A4 Inhibitors/Inducers:** Gemtuzumab ozogamicin is metabolized by the drug conjugate, inotuzumab ozogamicin. While gemtuzumab ozogamicin itself is not metabolized by CYP enzymes, it is theoretically possible that drugs affecting drug transporters could influence gemtuzumab ozogamicin levels. Clinical significance is not well established.
* **Other Chemotherapeutic Agents:** Increased risk of myelosuppression and other toxicities when combined with other myelosuppressive agents.
## Monitoring
* **Complete Blood Count (CBC) with differential and platelet count:** Frequently monitor for myelosuppression.
* **Liver Function Tests (LFTs):** Monitor bilirubin, AST, ALT, and alkaline phosphatase regularly, especially for potential hepatotoxicity. Assess for signs and symptoms of VOD/SOS.
* **Renal Function Tests:** Monitor for changes in renal function.
* **Infusion Reaction Signs/Symptoms:** Observe patients closely during and after infusion.
## Clinical Pearls
* **VOD/SOS Risk:** The risk of veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a significant concern, particularly with repeated dosing. Early recognition and management are crucial.
* **Premedication:** Standard premedications for infusion reactions (e.g., acetaminophen, diphenhydramine) are often recommended, though not explicitly stated in all prescribing information. Consult institutional protocols.
* **Handling:** Mylotarg is a hazardous drug. Follow appropriate handling precautions for preparation and administration.
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*This information is intended for healthcare professionals and does not substitute for a thorough review of the current prescribing information and institutional protocols. Always verify current drug information with the manufacturer's prescribing information and relevant guidelines before making clinical decisions.*
