Photo by Bill Branson
Vials of drug
The US Food and Drug Administration (FDA) has approved use of gemtuzumab ozogamicin (GO, Mylotarg), a treatment that was initially approved by the agency in 2000 but later pulled from the US market.
GO is an antibody-drug conjugate that consists of the cytotoxic agent calicheamicin attached to a monoclonal antibody targeting CD33.
GO is now approved to treat adults with newly diagnosed, CD33-positive acute myeloid leukemia (AML) and patients age 2 and older with CD33-positive, relapsed or refractory AML.
GO can be given alone or in combination with daunorubicin and cytarabine.
The prescribing information for GO includes a boxed warning detailing the risk of hepatotoxicity, including veno-occlusive disease or sinusoidal obstruction syndrome, associated with GO.
GO originates from a collaboration between Pfizer and Celltech, now UCB. Pfizer has sole responsibility for all manufacturing, clinical development, and commercialization activities for this molecule.
Market withdrawal and subsequent trials
GO was originally approved under the FDA’s accelerated approval program in 2000 for use as a single agent in patients with CD33-positive AML who had experienced their first relapse and were 60 years of age or older.
In 2010, Pfizer voluntarily withdrew GO from the US market due to the results of a confirmatory phase 3 trial, SWOG S0106.
This trial showed there was no clinical benefit for patients who received GO plus daunorubicin and cytarabine over patients who received only daunorubicin and cytarabine.
In addition, the rate of fatal, treatment-related toxicity was significantly higher in the GO arm of the study.
Because of the unmet need for effective treatments in AML, investigators expressed an interest in evaluating different doses and schedules of GO.
These independent investigators, with Pfizer’s support, conducted clinical trials that yielded more information on the efficacy and safety of GO.
The trials—ALFA-0701, AML-19, and MyloFrance-1—supported the new approval of GO. Updated data from these trials are included in the prescribing information, which is available for download at www.mylotarg.com.
