FDA Approves Tibsovo, First IDH1 Inhibitor for Acute Myeloid Leukemia

The Food and Drug Administration (FDA) approved Tibsovo (ivosidenib) for the treatment of adult patients with relapsed or refractory acute myeloid leukemia (AML) who have an IDH1 gene mutation.

The drug, which is an IDH1 inhibitor, is the first of its kind to be approved, and will be used with an FDA-approved diagnostic tool called the RealTimeIDH1 Assay that detects mutations in the IDH1 gene, which was also granted FDA approval today.

Tibsovo works by decreasing the body’s abnormal production of the oncometabolite 2-hydroxyglutarate (2-HG) which will eventually restore the ability of cancerous cells to differentiate. Its efficacy was proved in a single-arm trial that included 174 patients with relapsed or refractory AML with the IDH1 mutation.

After a median follow-up of 8.3 months, nearly a third of patients (32.8 percent) experienced complete remission or complete remission with partial recovery of blood counts after treatment that lasted a median 8.2 months. At the start of the study, 110 patients required a blood or platelet transfusion, and of that group, 37 percent went 56 days or longer without requiring a transfusion after they started treatment with Tibsovo.

“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, M.D., 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, in a 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.”

The common side effects that patients experienced included: fatigue, increase in white blood cells, joint pain, diarrhea, shortness of breath, swelling of the arms or legs, nausea, pain or sores in the mouth/throat, irregular heartbeat (QT prolongation), rash, fever, cough and constipation. It is recommended that women who are currently breastfeeding do not take Tibsovo, as it could cause harm to newborns.

QT prolongation is also listed among more serious complications that may happen while a patient is taking Tibsovo. Patients should undergo electrocardiogram during treatment to monitor their hearts. Guillain-Barré syndrome, a rare neurological disorder, may also occur, making it important that patients and their health care teams monitor for issues that arise within their nervous systems.

The drug’s Medication Guide explains differentiation syndrome, a side effect that could be fatal if it is not treated. Symptoms include: fever, difficulty breathing, acute respiratory distress, lung inflammation, fluid around the heart or lungs, rapid weight gain, swelling and organ dysfunction. If these signs arise, it is recommended that the patient be treated with corticosteroids and closely monitored.