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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a CD33-directed antibody-drug conjugate (ADC). It delivers a potent cytotoxic agent (calicheamicin) specifically to CD33-expressing leukemia cells, causing double-stranded DNA breaks and apoptosis.
## Primary Indications
* Newly diagnosed CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients ≥1 month.
* Relapsed or refractory CD33-positive AML in adults and pediatric patients ≥2 years.
## Adult Dosing
* **Newly diagnosed AML:** 3 mg/m² (up to a maximum dose of 4.5 mg) on days 1, 4, and 7 in combination with daunorubicin and cytarabine.
* **Relapsed/Refractory AML:** 3 mg/m² (up to a maximum dose of 4.5 mg) on days 1, 4, and 7 as a single agent.
* **Note:** Dosing is based on body surface area (BSA).
## Pediatric Dosing
* **Patients ≥2 years:** Follow the same weight-based or BSA-based dosing as adults (3 mg/m²; max 4.5 mg).
* **Patients <2 years (Newly Diagnosed):** 0.1 mg/kg on days 1, 4, and 7.
* *Note: Always consult local institutional protocols or specific clinical trial guidelines for pediatric oncology weight-based dosing variants.*
## Dose Adjustments
* **Hepatic Impairment:** Avoid in patients with total bilirubin >2x ULN or AST/ALT >2.5x ULN.
* **Infusion-Related Reactions:** If Grade 2+ reaction occurs, interrupt infusion and treat symptomatically. Resume at reduced rate if resolved. Discontinue for severe or life-threatening reactions.
* **Hematologic Toxicity:** If severe/prolonged cytopenias occur, delay subsequent cycles.
## Contraindications
* Known hypersensitivity to gemtuzumab ozogamicin or any component of the formulation.
* Combination with other hepatotoxic therapies (if possible) due to risk of Veno-Occlusive Disease (VOD)/Sinusoidal Obstruction Syndrome (SOS).
## Adverse Effects
* **Hepatotoxicity:** Including veno-occlusive disease (VOD), jaundice, and elevated transaminases.
* **Hematologic:** Severe neutropenia, thrombocytopenia, and anemia.
* **Infusion-Related Reactions:** Fever, chills, hypotension, and dyspnea.
* **Infections:** Increased risk due to prolonged myelosuppression.
* **Hemorrhage:** Due to severe thrombocytopenia.
## Key Drug Interactions
* **Hepatotoxic Agents:** Risk of additive liver injury and VOD. Use with extreme caution.
* **Live Vaccines:** Avoid due to immunosuppression; delay vaccination until immune recovery.
* **Myelosuppressive Drugs:** Potential for additive hematologic toxicity.
## Monitoring
* **Hepatic:** Monitor ALT, AST, total bilirubin, and alkaline phosphatase prior to each dose. Monitor closely for signs of VOD (weight gain, hepatomegaly, ascites).
* **Hematologic:** Complete blood counts (CBC) frequently during therapy until blood count recovery.
* **Infusion:** Monitor vital signs throughout the 2-hour infusion window.
* **Infection:** Monitor for signs/symptoms of systemic infection.
## Clinical Pearls
* **Premedication:** Always administer corticosteroids, antihistamines, and antipyretics 1 hour prior to infusion to attenuate infusion reactions.
* **VOD Risk:** The risk of VOD is significantly increased in patients undergoing hematopoietic stem cell transplantation (HSCT) post-therapy. Ensure strict adherence to dosing intervals.
* **Handling:** Mylotarg is a hazardous drug; use appropriate chemotherapy handling precautions (cytotoxic).
* **Stability:** Protect from light; use immediately after reconstitution and dilution.
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*Disclaimer: This information is for educational purposes only. Clinical guidelines and protocols change frequently. Always verify specific dosing, safety requirements, and local institutional policies against the most current FDA-approved package insert or recognized clinical resources (e.g., Lexicomp, UpToDate) before prescribing or administering medication.*
