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# Mylotarg (gemtuzumab ozogamicin)
## Overview
Mylotarg is an antibody-drug conjugate that targets CD33, a protein found on the surface of acute myeloid leukemia (AML) cells. It delivers a cytotoxic agent (calicheamicin) directly to the cancer cells.
## Primary Indications
* Treatment of newly diagnosed CD33-positive acute myeloid leukemia (AML) in adult patients.
* Treatment of relapsed or refractory CD33-positive AML in adult patients.
## Adult Dosing
**Newly Diagnosed AML:**
* **Induction:** 3 mg/m² on day 1, 4, and 7. If achieving remission, a second induction course may be considered (dose and schedule to be determined by the treating physician, often similar to the first).
* **Consolidation:** 3 mg/m² on day 1 of each cycle for up to 4 cycles. Cycles are typically given every 2 to 4 weeks.
**Relapsed or Refractory AML:**
* 6 mg/m² on day 1.
* If not achieving remission, a second dose of 3 mg/m² may be administered on day 4.
Maximum cumulative dose is 33 mg/m².
## Pediatric Dosing
The safety and efficacy of Mylotarg have not been established in pediatric patients.
## Dose Adjustments
* **Hepatic Impairment:** Use with caution. No specific dose adjustment is recommended, but consider risk of increased toxicity.
* **Renal Impairment:** Use with caution. No specific dose adjustment is recommended, but consider risk of increased toxicity.
* **Hematologic Toxicity:** Dose interruptions or delays may be necessary based on the degree of myelosuppression. Resumption is typically considered when neutrophils are ≥ 1.0 x 10⁹/L and platelets are ≥ 50 x 10⁹/L.
* **Non-hematologic Toxicity:** Dose reductions or interruptions may be necessary for Grade 3 or 4 non-hematologic toxicities.
## Contraindications
* None listed for Mylotarg itself, but patient-specific contraindications due to comorbidities should be considered.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, stomatitis, mucositis, rash, fever, headache, fatigue, cough, upper respiratory tract infections, pneumonia, neutropenia, thrombocytopenia, anemia, elevated liver enzymes (AST, ALT, alkaline phosphatase), elevated bilirubin.
* **Serious:** Veno-occlusive liver disease (VOD)/sinusoidal obstruction syndrome (SOS), bleeding events (including severe hemorrhage), severe infusion reactions, sepsis, tumor lysis syndrome, myelodysplastic syndrome (MDS) and secondary AML.
## Key Drug Interactions
* **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 unclear.
* **Other Myelosuppressive Agents:** Mylotarg is myelosuppressive and should be used cautiously with other agents that cause bone marrow suppression.
## Monitoring
* **Complete Blood Count (CBC) with differential and platelet count:** Frequently, especially during and after treatment, to monitor for myelosuppression and bleeding risk.
* **Liver Function Tests (LFTs):** Including AST, ALT, bilirubin, and alkaline phosphatase, regularly to monitor for hepatotoxicity.
* **Signs and Symptoms of VOD/SOS:** Monitor for jaundice, ascites, hepatomegaly, splenomegaly, and abdominal pain.
* **Infusion Reactions:** Monitor vital signs during and after infusion.
* **Bleeding Events:** Monitor for signs of bleeding.
## Clinical Pearls
* Premedication with corticosteroids (e.g., dexamethasone) and antihistamines may be considered to reduce infusion reaction severity.
* Patient education regarding signs and symptoms of VOD/SOS, bleeding, and infection is crucial.
* Consider prophylactic antibiotics, antivirals, and antifungals in patients at high risk for infection.
* Hydration and antiemetics are important for managing gastrointestinal side effects.
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*Disclaimer: This information is intended for clinical use and does not replace professional medical judgment. Always consult the most current prescribing information and local institutional protocols before making any treatment decisions.*
