New Targeted Drug OK'd for Acute Myeloid Leukemia

The FDA approved quizartinib (Vanflyta) for FLT3 internal tandem duplication (ITD)-positive acute myeloid leukemia (AML), the agency announced on Thursday.

Quizartinib is indicated for newly diagnosed patients in combination with standard cytarabine and anthracycline induction and cytarabine consolidation, and as maintenance monotherapy for patients who do not undergo allogeneic hematopoietic stem cell transplantation (HSCT). The FDA noted that quizartinib is not indicated as maintenance monotherapy following allogeneic HSCT, where its efficacy has not been assessed.

Support for approval was based on results from QuANTUM-First, a phase III study of over 500 AML patients with FLT3-ITD positive disease undergoing standard induction and consolidation therapy. Median overall survival doubled for patients randomized to the FLT3 inhibitor rather than placebo from induction through maintenance (31.9 vs 15.1 months, respectively; HR 0.78, 95% CI 0.62-0.98, P=0.032).

And median duration of remission, a secondary outcome, was significantly longer in the quizartinib arm (38.6 vs 12.4 months with placebo).

With the approval, quizartinib becomes the “first and only” FLT3 inhibitor to receive approval specifically for FLT3-ITD positive AML across these three phases of treatment, according to drug developer Daiichi Sankyo.

“The approval of Vanflyta represents a significant advancement for the treatment of patients with newly diagnosed FLT3-ITD-positive AML, which is one of the most aggressive and difficult-to-treat subtypes,” said trial investigator Harry Erba, MD, PhD, of the Duke Cancer Institute in Durham, North Carolina, in a press release from the drugmaker.

“In the QuANTUM-First trial, Vanflyta added to standard chemotherapy and continued as maintenance resulted in longer remission and prolonged overall survival and it will be a much-needed new treatment option that has potential to change the way FLT3-ITD positive AML is treated,” he added.

The companion diagnostic LeukoStrat CDx FLT3 Mutation Assay has also been approved to assess patients’ eligibility for quizartinib.

A boxed warning in the labeling for quizartinib notes the risk for QT prolongation, torsades de pointes, and cardiac arrest, and the drug will be available under a risk evaluation and mitigation strategy (REMS) program due to these risks.

The most common grade 3/4 adverse events (AEs) in QuANTUM-First included febrile neutropenia, hypokalemia, and pneumonia in both groups and neutropenia in the quizartinib group. Serious AEs occurring in at least 5% of patients in the quizartinib arm included febrile neutropenia (11%).

Fatal AEs occurred in 10% of quizartinib-treated patients and included sepsis (5%), fungal infections (0.8%), brain edema (0.8%), and one case each of febrile neutropenia, pneumonia, cerebral infarction, acute respiratory distress syndrome, pulmonary embolism, ventricular dysfunction, and cardiac arrest.

Permanent discontinuation of therapy due to AEs occurred in 20% of patients, while dose interruptions occurred in a third.