FDA to Speed Up Review of Tibsovo for IDH1-Mutant MDS

The U.S. Food and Drug Administration (FDA) granted a priority review for a supplemental new drug application to Tibsovo (ivosidenib tablets) for the treatment of patients IDH1-mutant relapsed or refractory myelodysplastic syndrome (MDS), according to a press release from Sevier, the manufacturer of the drug.

The FDA grants priority reviews to drugs that show promise in filling an unmet treatment need. In doing so, the agency agrees to expedite the development and potential FDA approval of the drug. According to Sevier, if Tibsovo is approved, it would be a first-in-class targeted treatment option for this patient population.

“While the novel use of targeted IDH inhibition has been proven across a number of difficult-to-treat cancers, there continues to be a significant unmet need for MDS patients within this molecularly defined subset, especially for those who experience disease progression,” said Dr. Amir Fathi, program director, Center for Leukemia at Massachusetts General Hospital and Associate Professor of Medicine at Harvard Medical School. “Today’s filing acceptance provides further support for the potential efficacy and acceptable safety profile of Tibsovo in relapsed or refractory MDS and reinforces the importance of mutational testing in this patient population.”

READ MORE: MDS Diagnoses Need an Expert Opinion

The priority review is based on findings from a group of 18 patients enrolled a phase 1 trial evaluating Tibsovo in IDH1-mutant relapsed or refractory MDS. Results showed that 38.9% of patients experienced a complete response, meaning that they had no signs of cancer after being treated. The average time to complete response was 1.87 months. At the time of the most recent data collection, the average duration of complete response has not been reached, meaning that most patients did not experience relapse, so an average time could not be calculated.

The objective response rate, which is the percentage of patients whose disease shrinks or disappears, was 83.3%. Average overall survival (time from treatment until death of any cause) was 35.7 months and ranged from 3.7 to 88.7 months.

Of note, at the start of the trial, nine patients (50%) were reliant on transfusions for red blood cells or platelets. After treatment with Tibsovo, six of these patients became independent of transfusions for any 56-day period after the start of the trial.

Tibsovo is currently approved for certain subsets of patients with acute myeloid leukemia and for patients with previously treated IDH1-mutated cholangiocarcinoma, which is a cancer of the bile ducts. The drug works by inhibiting IDH1, thereby promoting myeloblasts (immature blood cells in the bone marrow that eventually grow into a type of white blood cell) to mature properly rather than into cancerous cells.

Treatment-related side effects observed on the trial were consistent with the known toxicity profile of the drug, and there were no new side effects that were observed in the study.

“This filing acceptance and Priority Review for Tibsovo in patients with relapsed or refractory myelodysplastic syndromes underscores our continued work to advance therapeutic progress across IDH mutated cancers, and if approved in this setting, will bring the first and only targeted therapy to patients living with a significant unmet need,” Dr. Susan Pandya, vice president of clinical development and head of Cancer Metabolism Global Development Oncology and Immuno-Oncology at Sevier, said in the release.

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