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  1. Designating an Orphan Product: Drugs and Biological Products

Clinical Superiority Findings

In accordance with section 527(e)(2) of the FD&C Act (21 U.S.C. 360cc(e)(2)), FDA will publish a summary of the clinical superiority findings when a drug is granted exclusive approval or licensure on the basis of a demonstration of clinical superiority. This page will only include the clinical superiority findings for those drugs approved on or after August 18, 2017, the date that the FDA Reauthorization Act of 2017 added section 527(e)(2) to the FD&C Act. “Clinical superiority,” is used here only within the meaning of that term under FDA’s regulations at 21 CFR Part 316 and section 527(c) of the FD&C Act. For the definition of “same drug,” see 21 CFR 316.3(b)(14).

Approval Date 09/01/2017
NDA/BLA BLA 761060
Sponsor Wyeth Pharmaceuticals, Inc., a Pfizer Company
Drug Mylotarg (gemtuzumab ozogamicin)
Orphan Designation Treatment of acute myeloid leukemia
Approved Indication
  1. Treatment of newly-diagnosed CD33-positive acute myeloid leukemia in adults, and
  2. Treatment of relapsed or refractory CD33-positive acute myeloid leukemia in adults and in pediatric patients 2 years and older
Summary of Clinical Superiority Findings

Mylotarg (gemtuzumab ozogamicin) received accelerated approval in 2000, under NDA 21174, for treatment of patients with CD33 positive acute myeloid leukemia in first relapse who are 60 years of age or older and who are not considered candidates for other cytotoxic chemotherapy. Post-approval studies identified safety concerns including veno-occlusive disease, myelosuppression, infusion-related reactions, and early deaths. As a result, FDA requested that Wyeth voluntarily withdraw approval of Mylotarg from the market and Wyeth complied.

The new approval for Mylotarg is for a lower dose and different schedule than the previous approval. In a cross-study analysis of clinical outcomes for patients with relapsed or refractory acute myeloid leukemia treated with single-agent Mylotarg, in comparison to the regimens using the previously approved regimen, patients treated with the new dosing regimen had less early mortality, less hepatotoxicity, less veno-occlusive disease, more rapid platelet recovery and less hemorrhage. Therefore, the sponsor has demonstrated that the newly approved dosing regimen is safer than the previously approved dosing regimen, and thus clinically superior for the purposes of orphan-drug exclusivity. 21 CFR 316.3(b)(3), 316.34(c).