The U.S. Food and Drug Administration (FDA) has approved the first targeted treatment for people with acute myeloid leukemia (AML) that has relapsed or is refractory (hasn’t responded to previous treatment) who have an IDH1 mutation: Tibsovo® (ivosidenib). Tibsovo is manufactured by Agios Pharmaceuticals and is an oral tablet taken once daily.1,2
Approval based on research
The FDA’s approval was based on a clinical trial of 174 adults with relapsed or refractory AML. All patients in the trial were given Tibsovo (there was not a comparative or placebo arm). The trial measured the percentage of patients who achieved complete remission (defined as no evidence of disease and full recovery of blood counts after treatment), as well as the percentage of patients with no evidence of disease and partial recovery of blood counts after treatment.1
After an average follow-up of 8.3 months and an average treatment duration of 4.1 months, 24.7% of the patients taking Tibsovo had a complete remission and another 8% had no evidence of disease with partial recovery of blood counts. These remissions lasted an average of 8.2 months. In addition, treatment with Tibsovo reduced the need for blood and platelet transfusions. Of the 110 patients who needed blood or platelet transfusions at the start of the clinical trial, 37% were able to go at least 56 days without needing a transfusion after treatment with Tibsovo.1,2
How Tibsovo works
Cancers begin when mutations occur in the DNA of the cells. AML develops when there are mutations in the myeloid cells, the cells that normally develop into red blood cells, platelets, and white blood cells. Approximately 6% to 10% of people with AML have a mutation on the isocitrate dehydrogenase-1 (IDH1) gene.3 This mutation is involved in the cancer’s ability to replicate quickly.4
Tibsovo is a targeted therapy that specifically works on AML that has IDH1 mutation. This mutation can be detected through an FDA-approved genetic test. By blocking the mutated enzyme that is produced by the IDH1 gene. Tibsovo decreases the number of AML cells in the blood and increases the number of healthy, mature myeloid cells.2
Possible side effects of Tibsovo
Tibsovo comes with a black box warning – the strongest warning from the FDA due to the risk of a potentially serious side effect. Tibsovo may cause differentiation syndrome, a condition that can be fatal if not treated. Differentiation syndrome can cause symptoms such as unexplained fever, difficulty breathing, low blood pressure, rapid weight gain, fluid build-up in the feet or legs (peripheral edema), fluid build-up in the lungs or around the heart, and organ dysfunction or failure. In the clinical trial, 19% of patients treated with Tibsovo experienced differentiation syndrome. Differentiation syndrome can be treated with corticosteroids.2
The most common side effects with Tibsovo are fatigue, a high white blood cell count, joint pain, diarrhea, difficulty breathing, fluid build-up (edema), nausea, mouth ulcers, a change in heart rhythm called QT prolonged, rash, fever, cough, and constipation. These are not all the possible side effects of Tibsovo.2
Important things to know about Tibsovo
There are certain medications which should not be taken at the same time as Tibsovo. Before starting treatment with Tibsovo, patients should discuss with their doctor all medications, supplements, and vitamins they are taking.
Tibsovo should not be used in women who are breastfeeding, as it may cause harm to a breastfeeding infant.2
FDA approves first targeted treatment for patients with relapsed or refractory acute myeloid leukemia who have a certain genetic mutation. U.S. Food & Drug Administration. Available at https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm614115.htm. Accessed 7/23/18.
Tibsovo prescribing information. Available at https://www.tibsovopro.com/pdf/prescribinginformation.pdf. Accessed 7/23/18.
Sagonowsky E. Agios wins FDA nod for targeted AML drug Tibsovo. Fierce Pharma. Available at https://www.fiercepharma.com/pharma/agios-wins-fda-nod-for-targeted-aml-drug-tibsovo. Accessed 7/23/18.
About IDH mutations in cancer. Agios Pharmaceuticals. Available at http://www.agios.com/patients-caregivers/idh-mutations/. Accessed 7/23/18.