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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is an antibody-drug conjugate consisting of a humanized anti-CD33 monoclonal antibody linked to the cytotoxic agent calicheamicin. It targets CD33-expressing cells, primarily myeloid blasts.
## Primary Indications
* Newly diagnosed acute myeloid leukemia (AML) in adult patients who are 75 years of age or older.
* Relapsed or refractory AML in adult patients.
## Adult Dosing
* **Newly Diagnosed AML (in combination with daunorubicin and cytarabine):**
* Day 1: 3 mg/m² IV infusion
* Day 4: 3 mg/m² IV infusion
* Day 7: 2 mg/m² IV infusion
* Maximum cumulative dose: 9 mg/m² over the first cycle.
* **Relapsed or Refractory AML:**
* First cycle: 6 mg/m² IV infusion on day 1. If tolerated, a second cycle can be administered on day 4 at 3 mg/m², and day 7 at 3 mg/m².
* Maximum cumulative dose: 9 mg/m².
*Note: Dosing for combination therapy may vary based on local protocol and specific treatment regimens.*
## Pediatric Dosing
The safety and efficacy of Mylotarg in pediatric patients have not been established.
## Dose Adjustments
* **Hepatotoxicity:** Discontinue or delay Mylotarg if AST or ALT >3 times the upper limit of normal (ULN), or bilirubin >2 times ULN.
* **Thrombocytopenia:** Dose interruption may be necessary. Mylotarg should not be administered if platelet count < 50,000/mm³.
* **Overlapping Toxicities:** If toxicities from concomitant chemotherapy overlap, delay Mylotarg administration until recovery.
## Contraindications
* None specifically listed, but caution is advised in patients with severe hepatic impairment.
## Adverse Effects
* **Common:** Febrile neutropenia, thrombocytopenia, nausea, vomiting, diarrhea, mucositis, rash, headache, increased AST/ALT, increased bilirubin, peripheral neuropathy.
* **Serious:** Hepatotoxicity (including VOD/SOS), severe myelosuppression, infusion-related reactions, tumor lysis syndrome.
## Key Drug Interactions
* **Chemotherapy Agents:** Increased risk of myelosuppression and hepatotoxicity when used in combination with other myelosuppressive or hepatotoxic agents (e.g., daunorubicin, cytarabine).
* **CYP3A4 Substrates:** Gemtuzumab ozogamicin is a substrate of CYP3A4. Concomitant use of strong CYP3A4 inhibitors or inducers may alter gemtuzumab ozogamicin exposure, though clinical significance is uncertain.
## Monitoring
* Complete blood counts (CBC) with differential and platelets (prior to each dose and as clinically indicated).
* Liver function tests (LFTs), including AST, ALT, and bilirubin (prior to each dose and as clinically indicated).
* Signs and symptoms of hepatotoxicity (e.g., jaundice, abdominal pain, ascites).
* Signs and symptoms of infusion-related reactions.
* Signs and symptoms of tumor lysis syndrome.
## Clinical Pearls
* Mylotarg carries a boxed warning for hepatotoxicity, including Veno-Occulsive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS), which can be fatal. Monitor liver function closely.
* Administer prophylactic anti-emetics, anti-diarrheals, and anti-infectives as per institutional guidelines.
* Consider prehydration and slow infusion rates to minimize infusion-related reactions.
* Due to the risk of severe thrombocytopenia and bleeding, monitor platelet counts closely and manage appropriately.
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**Disclaimer:** This information is intended for educational purposes and is not a substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider for any health concerns or before making any decisions related to your health or treatment.
