Mylotarg is a monoclonal antibody that was developed to treat older patients with relapsed or refractory acute myeloid leukemia (AML). Although it has been available since 2000, it has been removed from the market for reasons of safety and efficacy.
Drug Profile
- Class: Monoclonal antibody
- Mechanism of action: This drug targeted the CD33 protein expressed on the surface of many leukemic blast cells.
- Treatment type: Targeted treatment
- US approval: 2000 (accelerated), 2010 (withdrawn)
- Synonyms: Mylotarg
- FDA Use-in-Pregnancy Rating: No longer applicable
What it's effective for and why
Gemtuzumab was initially approved for the treatment of relapsed acute myeloid leukemia (AML) under the FDA's accelerated approval program a decade ago. Under this program, a drug is rushed into the market on the belief that its benefits for a needy patient population are so great that they outweigh the potential risks. However, the manufacturer is expected to continue to carry out a large-scale clinical trial to prove the drug's efficacy and safety.
Wyeth began such a confirmatory, post-approval clinical trial in 2004 (SWOG S0106). It combined gemtuzumab with the chemotherapeutic agents daunorubicin and cytosine arabinoside vs. chemotherapy alone in 627 patients younger than 61 years old. Unfortunately the trial was halted early because it was clear that gemtuzumab was providing no benefit.
Consequently, the drug will no longer be available to new patients by October of 2010 as it is being voluntarily withdrawn from the market. Current patients can finish their regimen.
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