Gemtuzumab Ozogamicin [Mylotarg]: Market Withdrawal

June 21, 2010 –  FDA notified healthcare professionals that results from 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.

Background:

Gemtuzumab Ozogamicin [Mylotarg], indicated for treatment of acute myeloid leukemia (AML), a bone marrow cancer, was approved in May 2000 under the FDA’s accelerated approval program. A confirmatory, post approval clinical trial was begun by Wyeth (now Pfizer) in 2004. The trial was designed to determine whether adding Gemtuzumab Ozogamicin [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 Gemtuzumab Ozogamicin [Mylotarg] compared with those receiving chemotherapy alone.

Recommendation:

Gemtuzumab Ozogamicin [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 Gemtuzumab Ozogamicin [Mylotarg] of the product’s potential safety risks. Any future use of Gemtuzumab Ozogamicin [Mylotarg] in the United States will require submission of an investigational new drug application to the FDA.

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Reduced Effect from Clopidogrel [Plavix] in “Poor Metabolizer” Patients

Through a new boxed warning, the FDA is alerting healthcare professionals about a subgroup of patients who cannot effectively metabolize the anti-platelet drug Clopidogrel [Plavix].

These patients, called “poor metabolizers,” have little or no activity of the liver enzyme CYP2C19, which converts Clopidogrel [Plavix] to its active form, so they may not experience the full anti-clotting benefits of the drug.

Practitioners should know that tests are available to identify genetic differences in CYP2C19 function and thus identify poor metabolizers. They should consider using other anti-platelet medication or an alternative dosing strategy for these patients. And although raising the dose of Clopidogrel [Plavix] in poor metabolizers can increase anti-platelet response, an appropriate dose regimen has not been established in a clinical trial.

Please find additional information here:

The Original Article

FDA MedWatch Safety Alert. Plavix (clopidogrel): Reduced effectiveness in patients who are poor metabolizers of the drug. March 12, 2010.

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