Different Dosing Schedule May Revive Withdrawn Drug

A drug removed from the market last year may have a second chance after researchers tweaked the dose for older patients with acute myeloid leukemia (AML). Mylotarg (gemtuzumab ozogamicin), given accelerated approval in 2000 for relapsed AML, was withdrawn by the manufacturer when later confirmation studies showed the drug did not improve survival and also increased the risk of a rare, but deadly liver complication.

A French group tested the drug in a phase 3 trial using a modified dosing regimen that was easier on patients, reducing side effects and significantly improving event-free and overall survival. Newly diagnosed patients aged 50 to 70 years who received standard chemotherapy with Mylotarg lived longer than patients on chemotherapy alone (19.2 months versus 34 months). “With the lower dose, we have less toxicity and more efficacy,” says Sylvie Castaigne, MD, lead investigator of the study. This study included fewer deaths from liver complications than previous studies, but patients also experienced low but manageable platelet counts.

Several ongoing trials with Mylotarg may show the drug still has a place in AML treatment. The drug’s maker, Pfizer, is awaiting additional study results before determining whether to resubmit the drug for FDA approval. “At this point, we are trying to better understand the data out there in hopes that they indeed look as good as we would like them to look,” says Mark Shapiro, MD, PhD, a senior director of global medical affairs with the drug company. “Pfizer is definitely interested, the issue is what can we do with this data.”

Because the drug was withdrawn, it typically would be unavailable to patients in the U.S. unless they are participating in a clinical trial.