FDA Approves Tibsovo for IDH1 Mutated Myelodysplastic Syndromes

The FDA has approved Servier’s Tibsovo (ivosidenib) to treat patients with isocitrate dehydrogenase 1 (IDH1)-mutated relapsed or refractory myelodysplastic syndromes (MDS). This is the fifth indication for Tibsovo across IDH1-mutated cancers.

Myelodysplastic syndromes are disorders in which stem cells do not mature into healthy blood cells. In the United States, about 16,000 new cases of MDS are reported each year, and one-third of these patients will eventually progress to acute myeloid leukemia (AML). About 3.6% of MDS patients have an IDH1 mutation, which has been associated with worse overall outcomes.

Tibsovo is currently approved in the United States as a monotherapy to treat adults with IDH1-mutant relapsed or refractory AML and as a monotherapy or in combination with azacitidine for adults with newly diagnosed IDH1-mutant AML who are 75 years old or older. It is also approved to treat adults with bile duct cancer. It has a list price of $31,687 for a supply of 60 tablets, according to Drugs.com.

“The novel use of targeted therapy across IDH-mutated cancers has become a powerful therapeutic option for patients within this molecularly defined subset,” Amir Fathi, M.D., hematologist, medical oncologist, and expert in myeloid malignancies, said in a press release. “This new indication in IDH1-mutated relapsed or refractory myelodysplastic syndromes reinforces the importance of mutational testing to inform treatment decisions and potentially improve patient outcomes.”

The newest FDA approval is supported by data from 18 patients enrolled in a phase 1, open-label study in IDH1-mutated relapsed or refractory MDS patients. In the trial, 38.9% of patients treated with Tibsovo achieved a complete remission and 83.3% achieved an objective response. The median time to complete response was 1.9 months (with a range of 1 month to 5.6 months). The median overall survival was 35.7 months (with a range 3.7 months to 88.7 months).

Additionally, of the nine patients who were transfusion dependent with red blood cells or platelets, 66.7% became independent of transfusions during any ≥56-day post-baseline period.

Overall, treatment-related adverse events were consistent with the known safety profile of Tibsovo. This includes diarrhea, constipation, nausea, joint pain, fatigue, cough, muscle aches and rash. Tibsovo may also cause a condition which can lead to abnormal heart rhythms called QTc prolongation.

The FDA also approved the Abbott RealTime IDH1 Assay as a companion diagnostic device to select patients for Tibsovo. The Abbott RealTime IDH1 Assay was also previously approved as a companion diagnostic to identify AML patients with an IDH1 mutation for treatment with Tibsovo or Rezlidhia (olutasidenib).