The oral FLT3/AXL inhibitor gilteritinib was approved by the FDA for the treatment of adult patients with FLT3-mutated, relapsed or refractory AML. The FDA also expanded the indication for the LeukoStrat CDx FLT3 Mutation Assay, a companion diagnostic to detect the FLT3 mutation.
“[Mutations in the FLT3 gene] are associated with a particularly aggressive form of the disease and a higher risk of relapse,” said Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “[Gilteritinib] is the first drug to be approved that can be used alone in treating patients with AML with a FLT3 mutation who have relapsed or who don’t respond to initial treatment.”
The agency’s decision was based on interim results from the phase III ADMIRAL trial of 138 patients with relapsed or refractory AML and a confirmed FLT3 mutation. . After a median follow-up of 4.6 months (range = 2.8-15.8 months), 29 gilteritinib-treated patients achieved CR or CR with partial hematologic recovery, for a CR rate of 21 percent. Of the 106 patients who required red blood cell or platelet transfusions at the start of treatment with gilteritinib, 31 percent became transfusion-free for at least 56 days.
The most common AEs included myalgia/arthralgia, fatigue, and liver transaminase elevation. The approval also advises health-care providers to monitor patients for posterior reversible encephalopathy syndrome, prolonged QT interval, and pancreatitis. Instances of differentiation syndrome were rare, according to the approval letter, but were observed in gilteritinib-treated participants.
Gilteritinib was approved through the FDA’s fast-track and priority-review pathways, and it also received orphan-drug designation.
Source: FDA news release, November 28, 2018.