By Kamal Choudhury and Christy Santhosh

(Reuters) -The U.S. Food and Drug Administration on Thursday approved Kura Oncology and Japanese ​partner Kyowa Kirin's once-daily pill, Komzifti, to treat a ‌rare form of blood cancer that has returned or stopped responding to treatment.

The drug is approved for acute ‌myeloid leukemia patients with an NPM1 mutation, a genetic change found in about 30% of cases.

Acute myeloid leukemia is an aggressive cancer of the blood and bone marrow.

Kura said the drug will be available within the next few business days at a price of $48,⁠500 for a one-month supply.

With ‌the approval, Kura's drug now competes with Syndax Pharmaceuticals' Revuforj, which was approved for the same indication by the ‍FDA last month.

Komzifti’s approval comes with a boxed warning for differentiation syndrome and an additional warning for QTc interval prolongation, a delay in the heart’s electrical recovery after a beat, ​and potential harm to unborn babies.

A boxed warning is the U.S. ‌Food and Drug Administration’s strongest alert for serious or life-threatening risks and appears prominently on a drug’s label to warn doctors and patients.

Revuforj carries a boxed warning for QTc interval prolongation, giving Kura “a significant competitive advantage,” according to Wedbush analysts.

Kura's Chief Medical Officer Mollie Leoni said the risk of QTc prolongation ⁠with Komzifti is low, adding it is ​“extraordinarily unlikely” to lead to a boxed ​warning.

The company said it is in dialogue with the FDA about potential steps post-approval that could help refine the labeling.

Under the terms of ‍its collaboration with Kyowa,⁠ Kura is responsible for manufacturing Komzifti and will lead commercialization in the United States, while Kyowa handles commercial strategy and development outside the U.S.

Analysts, ⁠on average, expect Komzifti to have annual sales of $1.32 billion by 2031, according to ‌LSEG data.

(Reporting by Kamal Choudhury and Christy Santhosh in Bengaluru;‌ Editing by Shailesh Kuber and Tasim Zahid)