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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Gemtuzumab ozogamicin is an antibody-drug conjugate that targets CD33, a protein found on the surface of myeloid leukemia cells. It delivers a cytotoxic agent (calicheamicin) directly to CD33-positive cells, leading to cell death.
## Primary Indications
* Relapsed or refractory acute myeloid leukemia (AML) in adults.
* Newly diagnosed AML in adults who are 75 years of age or older and unfit for intensive induction chemotherapy.
## Adult Dosing
* **For newly diagnosed AML in patients unfit for intensive chemotherapy:**
* First cycle: 3 mg/m² on days 1, 4, and 7.
* Second cycle (if CR is achieved): 3 mg/m² on days 1 and 4.
* Third cycle (if CR is achieved): 3 mg/m² on day 1.
* **For relapsed or refractory AML:**
* Administer 6 mg/m² on day 1. If hematologic recovery is not observed, a second dose of 6 mg/m² can be administered on day 4.
* Alternatively, two doses of 3 mg/m² can be given on days 1 and 4, followed by a third dose of 3 mg/m² on day 7 if hematologic recovery is not observed after the first two doses.
* **Maximum cumulative dose:** 34.6 mg/m² over the patient's lifetime.
## Pediatric Dosing
The safety and efficacy of gemtuzumab ozogamicin have not been established in pediatric patients.
## Dose Adjustments
* **Hepatotoxicity:** If AST > 3 times the upper limit of normal (ULN) or total bilirubin > 2 times ULN, withhold gemtuzumab ozogamicin until AST ≤ 3 times ULN and total bilirubin ≤ 2 times ULN.
* **Infusion Reactions:** If a Grade 2 or 3 infusion reaction occurs, slow the infusion rate. If a Grade 4 infusion reaction occurs, discontinue gemtuzumab ozogamicin.
* **Hemorrhage:** If severe or life-threatening hemorrhage occurs, discontinue gemtuzumab ozogamicin.
## Contraindications
* None specific, but caution is advised in patients with pre-existing hepatic impairment.
## Adverse Effects
* **Common:** Febrile neutropenia, thrombocytopenia, nausea, vomiting, diarrhea, mucositis, elevated liver enzymes (AST, ALT, bilirubin), headache, fatigue, rash, neutropenia, anemia, hypokalemia, hypophosphatemia.
* **Serious:** Hepatotoxicity (including VOD/SOS), severe infusion reactions, tumor lysis syndrome, severe myelosuppression, hemorrhage.
## Key Drug Interactions
* **Hepatotoxic agents:** Concomitant use with other drugs known to cause hepatotoxicity may increase the risk of severe liver injury. Monitor liver function closely.
* **Myelosuppressive agents:** Gemtuzumab ozogamicin itself causes myelosuppression. The additive effects with other myelosuppressive agents may increase the risk of severe cytopenias.
## Monitoring
* **Liver Function Tests (LFTs):** Baseline and regularly during treatment (e.g., twice weekly for the first two cycles, then weekly or as clinically indicated).
* **Complete Blood Count (CBC) with differential and platelet count:** Baseline and regularly during treatment (e.g., twice weekly for the first two cycles, then weekly or as clinically indicated).
* **Signs and symptoms of infusion reactions:** Monitor closely during and after infusion.
* **Signs and symptoms of VOD/SOS:** Monitor for jaundice, ascites, hepatomegaly, splenomegaly, abdominal pain, and weight gain.
* **Signs and symptoms of hemorrhage:** Monitor for bleeding, bruising, petechiae.
## Clinical Pearls
* Consider prophylactic use of antiemetics, antidiarrheals, and agents to manage mucositis.
* Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a serious and potentially fatal adverse event. Risk factors include prior stem cell transplant, pre-existing liver disease, and higher doses of gemtuzumab ozogamicin.
* The maximum cumulative dose should not be exceeded due to increased risk of hepatotoxicity.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the official prescribing information and current clinical guidelines for the most up-to-date and comprehensive drug information.
