Mylotarg (gemtuzumab ozogamicin)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Acute Myeloid Leukemia (AML)
Mylotarg is a chemotherapy agent approved for the treatment of
CD33 positive acute myeloid leukemia (AML) in first relapse. It is
indicated in patients who are 60 years old or older and who are not
considered candidates for other cytotoxic chemotherapy.
The recommended dose of Mylotarg is 9 mg/m2,
administered as a 2-hour IV infusion.
In three trials with Mylotarg, 142 subjects were evaluated in a
treatment regimen of two 9mg/m2 doses separated by 14 days and a
28-day follow-up after the last dose. In the first two studies, the
subects were 18 years of age or older, and the third study included
subjects 60 years of age or older. All subjects had CD33 positive
AML in first relapse. The primary endpoint of the studies was the
rate of complete remission (CR), defined using the following
criteria: 1. leukemic blasts absent from the peripheral blood; 2.
5% or fewer blasts in the bone marrow; 3. Hgb greater than or equal
to 9 g/dL, platelates greater than or equal to 100,000/µL, ANC
greater than or equal to 1,500/µL; 4. red cell and
A second response category, CRp, was also evaluated. CRp is
defined using the same criteria as CR, excluding platelate recovery
greater than or equal to 100,000/µL. This category was added,
because Mylotarg seems to delay platelet recovery in some
Results showed that the overall response rate for the three
studies was 30%, with 16% of subjects achieving CR and 13%
achieving CRp. For both categories, the median time to remission
was 60 days.
Of the subjects acheiving CR or CRp, the median months of
relapse-free survival was 6.8. Six subjects had a relapse-free
survival of >12 months. Median duration of overall survival for
the 142 subjects was 5.9 months.
The following infusion-related adverse events were experienced
by two percent or more of patients receiving Mylotarg during
Fewer infusion-related adverse events were experienced by
patients during the second dose.
Mechanism of Action
Gemtuzumab ozogamicin binds to the CD33 antigen. This antigen is
expressed on the surface of leukemic blasts in more than 80% of
patients with acute myeloid leukemia. Binding of the anti-CD33
antibody portion of Mylotarg with the CD33 antigen results in the
formation of a complex that is internalized. Upon internalization,
the calicheamicin derivative is released inside the lysosomes of
the myeloid cell. The released calicheamicin derivative binds to
DNA in the minor groove resulting in DNA double strand breaks and
cell death. [From the FDA approved product-label.]