First-in-class targeted drug approved for acute myeloid leukemia

Ivosidenib (Tibsovo, Agios Pharma) is the first drug approved for acute myeloid leukemia (AML) patients with a specific genetic mutation.

FDA approved the drug for patients with relapsed or refractory AML late last week. The first drug in its class (IDH1 inhibitors), Tibsovo is used with a FDA-approved companion diagnostic used to detect specific mutations in the IDH1 gene in patients with AML.

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Between 6% and 10% of AML patients have the IDH1 mutation.

“Tibsovo is a targeted therapy that fills an unmet need for patients with relapsed or refractory AML who have an IDH1 mutation,” said Richard Pazdur, MD, director of 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, in an FDA statement. “The use of Tibsovo is associated with a complete remission in some patients and a reduction in the need for both red cell and platelet transfusions.”

FDA approved a companion diagnostic test, the RealTime IDH1 Assay (Abbot Laboratories), which can be used to detect the mutation.

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The efficacy of Tibsovo was studied in a single-arm trial of 174 adult patients with relapsed or refractory AML with an IDH1 mutation. With a median follow-up of 8.3 months, 32.8% of patients experienced a complete remission or complete remission with partial hematologic recovery that lasted a median 8.2 months.
Of the 110 patients who required transfusions of blood or platelets due to AML at the start of the study, 37% went at least 56 days without requiring a transfusion after treatment with Tibsovo.

The prescribing information for Tibsovo includes a boxed warning that an adverse reaction known as differentiation syndrome can occur and can be fatal if not treated.

Other serious warnings include a QT prolongation, which can be life-threatening. Electrical activity of the heart should be tested with an electrocardiogram during treatment. Guillain-Barré syndrome, a rare neurological disorder in which the body's immune system mistakenly attacks part of its peripheral nervous system, has happened in people treated with Tibsovo, so patients should be monitored for nervous system problems, FDA said.

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