US regulators have approved the first targeted therapy for patients with relapsed or refractory acute myeloid leukemia carrying a certain genetic mutation.

Agios Pharmaceuticals’ Tibsovo (ivosidenib) is the first drug in the isocitrate dehydrogenase-1 (IDH1) inhibitor class of medicines to win a green light, and has been approved with a companion diagnostic able to detect specific mutations in the IDH1 gene in patients with the disease.

“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, 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.

“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.”

The drug works by decreasing abnormal production of the oncometabolite 2-hydroxyglutarate (2-HG), leading to differentiation of malignant cells.

Clinical data, at a median follow-up of 8.3 months post treatment, showed that 32.8 percent of patients experienced a complete response or complete remission with partial haematologic recovery.

Also, of the 110 patients who required transfusions of blood or platelets due to AML at the start of the study, 37 percent went at least 56 days without requiring a transfusion after treatment with Tibsovo.

“AML patients who relapse or are refractory to available therapies have few, if any, treatment options,” said Hagop Kantarjian, professor and chair of the Department of Leukemia at The University of Texas MD Anderson Cancer Center.

“The clinical study demonstrated that Tibsovo has the potential to deliver strong, durable responses as a single agent and can help patients achieve and maintain transfusion independence.”

The National Cancer Institute at the National Institutes of Health estimates that around 19,520 people will be diagnosed with AML this year in the US and that approximately 10,670 patients will die from the disease. Around 6-10 percent of AML patients have an IDH1 mutation.