Mylotarg: The Journey to FDA Reapproval and Broad International Approval

Mylotarg (gemtuzumab ozogamicin) was the first cytotoxic antibody-drug conjugate approved by the FDA. After its approval, it was withdrawn from the US market in 2010 although it continued to be marketed in Japan. As new clinical data were amassed, an effort to have it reapproved by the FDA and approved in other major markets was initiated. The efforts to bring the Chemistry, Manufacturing, and Controls portion of the regulatory filings up to contemporary standards while still maintaining the original product profile provide an interesting journey through the advances in chemistry, analysis, and regulatory science since the late twentieth century.