US regulators have issued a green light for Celgene and Agios’ Idhifa, the first and only targeted treatment for adult patients with relapsed/refractory acute myeloid leukaemia and an isocitrate dehydrogenase-2 mutation.

Acute myeloid leukaemia (AML) is a rapidly progressing cancer that forms in the bone marrow and results in an increased number of abnormal white blood cells in the bloodstream and bone marrow. The disease has many genetic mutations, which can make it difficult to treat, and patients who become relapsed or refractory to initial therapy have a particularly poor prognosis.

Idhifa (enasidenib) is an isocitrate dehydrogenase-2 inhibitor that works by blocking several enzymes that promote cell growth.

According to Celgene, the drug’s approval marks “a major breakthrough” in the treatment the disease at it offers the first-ever targeted treatment option to patients with the IDH2 mutation whose first-line therapy was not successful, while Richard Pazdur, director of the FDA’s Oncology Center of Excellence, also said that the drug “fulfills an unmet need for patients”.

Clearance was issued on the back of data from a Phase I/II trial showing that treatment with IDHIFA had clinically meaningful efficacy, with patients achieving a combined complete response or complete response with partial haematologic improvement (CR/CRh) rate of 23 percent.

For patients who achieved a CR/CRh, the median time to first response was 1.9 months and the median time to best response of CR/CRh was 3.7 months.

“AML is a complex, heterogeneous disease, which is particularly difficult to treat in the relapsed or refractory setting,” said Martin Tallman, hematologic oncologist and chief, Leukaemia Service at Memorial Sloan Kettering Cancer Center. “IDH2 mutations inhibit the normal maturation of myeloid cells, so having a treatment that targets this mechanism is promising for patients and encouraging to us as physicians who have it as our goal to provide options for every patient.”