The US Food and Drug Administration (FDA) granted approval to gemtuzumab ozogamicin (Mylotarg) for the treatment of relapsed or refractory CD-33 positive acute myeloid leukemia (AML) in patients ages 2 years and older and newly diagnosed CD-33 positive AML in adult patients.1

Gemtuzumab ozogamicin is an antibody-drug conjugate (ADC) comprised of a monoclonal antibody that targets CD33 and the cytotoxic agent calicheamicin. It is the only AML therapy to target CD33, an antigen that is expressed in up to 90% of patients with AML.

The FDA based its approval on multiple clinical trials.

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In the phase 3 ALFA-0701 trial, researchers randomly assigned 271 patients with newly diagnosed AML to receive gemtuzumab with chemotherapy or chemotherapy alone. Patients who received gemtuzumab achieved a significantly prolonged event-free survival of 17.3 months compared with 9.5 months in patients receiving chemotherapy alone (hazard ratio [HR], 0.56; 95% CI, 0.42-0.76).2

In the phase 3 AML-19 study, patients who could not tolerate other AML therapies were randomized to receive gemtuzumab monotherapy or best supportive care. Patients who received gemtuzumab achieved a significantly improved median overall survival (OS) of 4.9 months compared with 3.6 months for patients receiving best supportive care (HR, 0.69; 95% CI, 0.53-0.90; P =.005).

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The single-arm, phase 2 MyloFrance-1 study enrolled 57 patients with AML in first relapse to gemtuzumab. Fifteen (26%; 95% CI, 16%-40%) patients achieved complete remission and had an 11.6 month median relapse-free survival (RFS).

Commonly reported adverse events for gemtuzumab ozogamicin include fever, nausea, infection, vomiting, bleeding, thrombocytopenia, stomatitis, constipation, rash, headache, elevated liver function test results, and neutropenia.

Gemtuzumab ozogamicin also received orphan drug designation, which is granted to therapies intended to prevent, diagnose, or treat conditions that affect fewer than 200,000 people in the United States.


1. FDA approves Mylotarg for treatment of acute myeloid leukemia [news release]. Silver Spring, MD: US Food and Drug Administration; September 1, 2017. Accessed September 17, 2017.

2. Pfizer receives FDA approval for Mylotarg (gemtuzumab ozogamicin) [news release]. New York, NY: Pfizer Inc; September 1, 2017. Accessed September 17, 2017.