Astellas has filed its experimental Acute Myeloid Leukaemia (AML) therapy gilteritinib with US regulators, seeking approval for its use to treat FLT3 mutation-positive (FLT3mut+) relapsed or refractory forms of the blood cancer.

The drug, discovered by Astellas and developed with partner Kotobuki, already holds orphan status in the US and EU, indicating that regulators believe it has the potential to be of significant benefit to patients with the rare condition.

Gilteritinib is an investigational compound that has shown inhibitory activity against both internal tandem duplication (ITD) and tyrosine kinase domain (TKD), FLT3 mutations that are seen in around one-third of patients with AML, Astellas said.

The drug has also been submitted for approval in Japan, also on the back of data from the the Phase III ADMIRAL trial, an open-label, multicenter, randomised study of gilteritinib versus salvage chemotherapy in adult patients with FLT3 mutations who are refractory to or have relapsed after first-line AML therapy.

The co-primary endpoints of the trial are OS (Overall Survival) and CR (complete remission) / CRh (CR with partial hematological recovery) rate and the study is still ongoing.