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FDA approves new targeted therapy drug Tibsovo as leukemia treatment




Last week, Tibsovo (ivosidenib), a new targeted therapy for the treatment of certain adult patients with relapsed or refractory acute myeloid leukemia (AML) with a specific genetic mutation, was approved by the US Food and Drug Administration. 

Richard Pazdur, MD, 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, said the approval “fills an unmet need” for patients with leukemia who also have the isocitrate dehydrogenase-1 (IDH1) mutation. 

AML is among the less common forms of cancer, with around 20,000 new diagnoses expected annually, according to figures from the Centers for Disease Control and Prevention. This rapidly progressing cancer of the bone marrow causes an increase in abnormal white blood cell levels in the bone marrow and bloodstream.  Between six and ten percent to AML patients have the IDH1 enzyme, which blocks the normal blood cell differentiation. 

Tibsovo is the first IDH1 inhibitor to gain approval in the US. If an FDA-approved test identifies the IDH1 mutation in a patient’s blood or bone marrow, they may be eligible for treatment with Tibsovo. It works by decreasing the abnormal production of the oncometabolite 2-hydroxyglutarate (2-HG), which blocks the differentiation of leukemia cells. 

News of the FDA’s approval of Tibsovo was welcomed by the Leukemia & Lymphoma Society, with its president and CEO Louis J DeGennaro commenting: “For too long, AML has been treated as a one-size-fits-all disease, so it is encouraging to see these new treatments added to the armamentarium for AML patients.”

“Today’s approval is further proof that we are headed in the right direction with a precision medicine approach to conquering this difficult cancer,” he added. 

A number of drugs are approved to treat AML including pyrimidine analogs, such as Cytarabine (cytarabine) and vinca alkaloids and analogs, for example, Vincasar Pfs (vincristine). However, unlike Tibsovo, these drugs are not specifically targeted therapies for patients who have AML with the IDH1 mutation. 

The drug was granted Fast Track, Priority Review, and Orphan Drug designations by the FDA. Orphan Drug designation incentivizes and encourages pharmaceutical companies to develop medication for rare diseases or those that affect less than 200,000 people in the United States. 

Safety and efficacy of the targeted therapy were shown in a single-arm trial of 174 adults with relapsed or refractory AML with the IDH1 mutation. “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,” Pazdur stated.