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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is a humanized anti-CD33 monoclonal antibody linked to a cytotoxic agent, ozogamicin. It is designed to target CD33-expressing cells, primarily acute myeloid leukemia (AML) blasts.
## Primary Indications
* Relapsed or refractory CD33-positive acute myeloid leukemia (AML) in adults.
* Newly diagnosed CD33-positive AML in adults in combination with chemotherapy.
## Adult Dosing
The dosing regimen can vary significantly based on whether Mylotarg is used as monotherapy or in combination with chemotherapy, and the specific treatment phase (induction, consolidation).
**Monotherapy (for relapsed/refractory AML):**
* **Day 1:** 3 mg/m² intravenously (IV) infused over 2-2.5 hours.
* **Day 4:** 3 mg/m² IV infused over 2-2.5 hours.
* **Day 7:** 3 mg/m² IV infused over 2-2.5 hours.
* A maximum of two cycles is recommended. If no remission is achieved after the first cycle, further treatment may not be beneficial. The second cycle should be administered if peripheral blood counts have recovered from the first cycle.
**Combination Therapy (for newly diagnosed AML):**
* **Induction:** 3 mg/m² IV infused over 2-2.5 hours on days 1, 4, and 7 of the first induction cycle, and on days 1, 4, and 7 of the second induction cycle if needed.
* **Consolidation:** 3 mg/m² IV infused over 2-2.5 hours as a single dose on day 1 of each consolidation cycle.
Specific protocols may dictate the number and timing of consolidation cycles. Always refer to the specific institutional protocol.
## Pediatric Dosing
Mylotarg is **not established** in pediatric patients. Its use in this population is generally not recommended outside of clinical trials.
## Dose Adjustments
Dose adjustments are primarily based on the occurrence of adverse events, particularly liver toxicity (Hepatotoxicity) and Bleeding events.
* **Hepatotoxicity (Veno-occlusive disease/Sinusoidal obstruction syndrome - VOD/SOS):** Permanent discontinuation is recommended if severe or life-threatening VOD/SOS occurs. If mild to moderate VOD/SOS occurs, interrupt or delay treatment and consider dose reduction for subsequent doses/cycles.
* **Bleeding:** In case of severe or life-threatening bleeding, permanent discontinuation is recommended. For less severe bleeding events, management of symptoms and consideration of dose interruption or reduction may be appropriate depending on clinical judgment.
Specific dose reduction guidelines are not universally standardized and should be guided by clinical assessment and institutional protocols.
## Contraindications
* Hypersensitivity to gemtuzumab ozogamicin or any excipients.
## Adverse Effects
**Black Box Warnings:**
* **Hepatotoxicity:** Including VOD/SOS, potentially fatal, has occurred in patients treated with Mylotarg, particularly those who have undergone stem cell transplantation or have pre-existing liver abnormalities. Monitor liver function tests frequently.
* **Bleeding:** Severe and fatal hemorrhagic events, including intracranial, gastrointestinal, and pulmonary hemorrhage, have occurred. Monitor for signs and symptoms of bleeding.
**Common Adverse Effects (≥20%):**
* **General:** Fever, headache, fatigue, edema peripheral.
* **Gastrointestinal:** Nausea, vomiting, diarrhea, constipation, stomatitis, abdominal pain.
* **Hematologic:** Thrombocytopenia, anemia, neutropenia, febrile neutropenia, leukopenia.
* **Hepatic:** Elevated AST, ALT, bilirubin.
* **Infections:** Pneumonia, sepsis, febrile neutropenia.
* **Musculoskeletal:** Arthralgia, back pain.
* **Skin:** Rash, pruritus.
## Key Drug Interactions
* **Myelosuppressive Agents:** Concurrent use with other myelosuppressive chemotherapy can potentiate myelosuppression. Monitor blood counts closely.
There is limited data on other significant drug interactions. Caution is advised with drugs affecting liver enzymes or increasing bleeding risk.
## Monitoring
* **Hematologic Parameters:** Complete blood counts (CBC) with differential and platelet count frequently, especially before and after each dose.
* **Liver Function Tests:** AST, ALT, alkaline phosphatase, and bilirubin levels before and regularly during treatment.
* **Renal Function Tests:** Serum creatinine.
* **Signs of Bleeding:** Monitor for any signs or symptoms of hemorrhage.
* **Signs of Infusion Reactions:** Monitor during and after infusion.
* **Signs of VOD/SOS:** Monitor for jaundice, hepatomegaly, ascites, and thrombocytopenia.
## Clinical Pearls
* Premedication with corticosteroids, antihistamines, and antipyretics may help reduce infusion-related reactions.
* Mylotarg administration requires meticulous attention to infusion rates to mitigate infusion-related reactions.
* Consider potential for cross-reactivity with other anti-CD33 therapies if applicable.
* Close monitoring for hepatotoxicity and bleeding is critical due to the potential for severe and life-threatening events.
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**Disclaimer:** This information is intended as a concise reference for healthcare professionals. It is **crucial** to consult the most current official prescribing information and relevant institutional protocols for complete and up-to-date guidance. Always verify dosing, administration, and safety monitoring requirements before administering Mylotarg.
