Pfizer to Withdraw Leukemia Drug From Market

Pfizer Inc. has decided to withdraw <"">Mylotarg (gemtuzumab ozogamicin) from the market. According to a notice on the U.S. Food & Drug Administration’s (FDA) Web site, Pfizer took the action at the agency’s request after a recent clinical trial raised new concerns about the product’s safety and the drug failed to demonstrate clinical benefit to patients enrolled in trials.

Mylotarg is a treatment for patients with acute myeloid leukemia (AML), a bone marrow cancer. Specifically, it was approved to treat patients ages 60 years and older with recurrent AML who were not considered candidates for other chemotherapy. There are no other medicines approved for treating relapsed AML.

Mylotarg was approved in May 2000 under the FDA’s accelerated approval program to help bring treatments for serious diseases to patients more quickly. The program requires drug maker to conduct clinical trials after approval to confirm a drug’s benefit.

According to the FDA, such a trial was begun by Wyeth (now Pfizer) in 2004. The study was designed to determine whether adding Mylotarg to standard chemotherapy demonstrated an improvement in clinical benefit (survival time) to AML patients. The trial was stopped early when no improvement in clinical benefit was observed, and after a greater number of deaths occurred in the group of patients who received Mylotarg compared with those receiving chemotherapy alone. The fatality rate was 5.7 percent for Mylotarg patients, compared with 1.4 percent without the drug.

At initial approval, Mylotarg was associated with a serious liver condition called veno-occlusive disease, which can be fatal. This rate has increased in the postmarket setting, the FDA said.

As a result of the withdrawal, Mylotarg will not be commercially available to new patients. Patients who are currently receiving the drug may complete their therapy following consultation with their health care professional. Health care professionals should inform all patients receiving Mylotarg of the product’s potential safety risks.

Mylotarg will be withdrawn October 15, but Pfizer recommends that no new patients be prescribed it in the meantime.

Following the withdrawal, any future use of Mylotarg in the United States will require submission of an investigational new drug application to FDA.

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