The US Food and Drug Administration (FDA) granted orphan drug designation to gilteritinib for the treatment of acute myeloid leukemia (AML).1

Gilteritinib is an inhibitor of FLT3, a mutated gene commonly found in AML, and AXL, which plays a role in activating FLT3. Gilteritinib has shown inhibitory effects against FLT3 internal tandem duplication (ITD) and tyrosine kinase domain (TKD), 2 frequently occurring FLT3 mutations found in patients with AML.

The FDA based its approval on data from a number of currently underway phase 3 trials, including the ADMIRAL trial ( Identifier: NCT02421939) for relapsed/refractory FLT3-positive AML.

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Data from a previous phase 1/2 trial showed that patients with FLT3+ AML treated with gilteritinib reported a 53% overall response rate (ORR) regardless of prior therapy, and patients who were treated with tyrosine kinase inhibitors prior to the study saw an ORR of 48%. The median overall survival was around 31 weeks.2

Nearly 21,000 patients were diagnosed with AML in 2016, and over 50% of cases resulted in death. Orphan drug designation is granted to therapies intended to prevent, diagnose, or treat conditions that affect fewer than 200,000 people in the US.


  1. U.S. FDA grants orphan-drug designation to Astellas for development of FLT3 inhibitor gilteritinib in acute myeloid leukemia [news release]. Tokyo, Japan: PRNewswire; July 20, 2017. Accessed July 20, 2017.
  2. Astellas announces updated data from the phase ½ chrysalis trial for gilteritinib (ASP2215) in patients with relapsed or refractory acute myeloid leukemia [news release]. Northbrook, IL: PRNewswire; December 6, 2015. Accessed July 20, 2017.