Pfizer resubmits US and EU application for withdrawn ADC Mylotarg

By Dan Stanton

- Last updated on GMT

Image: iStock/scyther5
Image: iStock/scyther5

Related tags Leukemia

Pfizer has resubmitted its antibody-drug conjugate Mylotarg (gemtuzumab ozogamicin) for regulatory review almost seven years after withdrawing it from the market.

The acute myeloid leukemia (AML) drug was the first antibody-drug conjugate (ADC) to be launched in the US after the Food and Drug Administration (FDA) approved the product through an accelerated review in May 2000.

However, ten years later, Pfizer voluntarily withdrew Mylotarg after results from a post-approval clinical trial raised concerns about the product’s safety and efficacy.

But Pfizer confirmed this week the FDA accepted to review a re-submission of a Biologics License Application (BLA) for the ADC, based on additional data from a Phase III randomised, open-label study.

The ALFA-0701 study “evaluated the addition of Mylotarg to standard induction chemotherapy using an alternative fractionated dosing schedule in 280 adult, de novo, AML patients aged 50-70 years old, as well as a meta-analysis of patient-level data from over 3,000 patients in five randomized Phase III studies (including ALFA-0701) spanning 10 years of research,”​ Pfizer said.

The firm expects a decision by the FDA in September. Meanwhile, Pfizer resubmitted its application for review by the European Medicines Agency (EMA) last month​, based on the same study.


Mylotarg is a chemotherapy agent composed of a recombinant humanized IgG4, kappa antibody conjugated with a cytotoxic antitumor antibiotic, calicheamicin, isolated from fermentation of a bacterium, Micromonospora echinospora subsp. calichensis.

The antibody portion of Mylotarg binds specifically to the CD33 antigen, a sialic acid-dependent adhesion protein found on the surface of leukemic blasts and immature.

The product was developed through a collaboration between Wyeth and Celltech (now UCB), but Pfizer – which acquired Wyeth for $68bn in 2009​ – now has sole responsibility for the manufacturing and development of the molecule.

Since Mylotarg’s withdrawal, there are only two ADCs available in the US and Europe: Takeda/Seattle Genetics’ Adcetris ((brentuximab vedotin), and Roche’s Kadcyla (trastuzumab emtansine).

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