Quizartinib (formerly AC220) is a once-daily, orally-administered, potent and selective inhibitor of two receptor tyrosine kinases, FLT3 and KIT. Quizartinib is currently in a Phase 2 clinical study in the relapsed/refractory AML patient population with internal tandem duplication (ITD positive) activating mutations of the FLT3 kinase (FLT3-ITD positive). These mutations are present in approximately 30% of all AML patients and drive a particularly aggressive and deadly form of this disease. Quizartinib has been granted Orphan Drug designation by regulatory authorities in the United States and European Union, and in 2010 received Fast Track designation in the United States for the treatment of FLT3-ITD positive patients with relapsed/refractory AML. Quizartinib is being developed in concert with a companion diagnostic to identify FLT3-ITD positive patients.

Quizartinib is distinguished from earlier or first-generation FLT3 inhibitors by a combination of potency, selectivity and favorable pharmacokinetic properties that allow for once-daily dosing and activity as a single agent. Based on our preclinical studies and clinical trials conducted to date, we believe that the properties of quizartinib offer a number of potential advantages over both currently available therapies and those in development. These include:

  • Targeted Activity. Quizartinib specifically inhibits two potentially cancer-causing kinase targets, FLT3 and KIT.
  • Potency and Selectivity. Based on published data of approved drugs and drug candidates in both preclinical and clinical settings, we believe quizartinib is the most potent and selective FLT3 inhibitor. We believe these characteristics will enable quizartinib to demonstrate a high degree of efficacy with reduced off-target toxicities.
  • Activity as Monotherapy. Quizartinib has shown promise as monotherapy in relapsed/refractory AML patients. While other agents showed some ability to clear leukemia from the circulating blood, quizartinib has shown significant ability to clear leukemic cells from the bone marrow, where the disease originates.
  • Convenient to Dose. We believe quizartinib's potency and selectivity for inhibiting FLT3 and KIT signaling and its long half-life will allow for once-daily oral dosing. We believe that continuous and sustained inhibition of FLT3 is required for optimal single-agent activity in AML.