FDA Approves Leukine for Acute Radiation Syndrome

There’s now a new medical countermeasure (MCM) available in the United States in the event of radiological or nuclear emergency.

The FDA announced on 29 March it has approved use of Leukine (sargramostim) to increase survival in adult and pediatric patients acutely exposed to myelosuppressive doses of radiation (Hematopoietic Syndrome of Acute Radiation Syndrome, or H-ARS).

Myelosuppression occurs when radiation damages the bone marrow. Suppression of the bone marrow blocks the production of blood cells. Leukine can help patients with H-ARS by facilitating recovery of bone marrow cells that develop into white blood cells that help fight off infections.

Leukine is the third FDA-approved MCM that is indicated to increase survival in patients exposed to myelosuppressive doses of radiation. It was approved by FDA based on efficacy studies in animals (under the Animal Rule), as efficacy studies in humans could not be ethically conducted. This is the third product from a similar pharmacological class approved for the same indication. The others are Neupogen and Neulasta, both approved in 2015.

See also: Bloomberg Podcast: Bob Mulroy, CEO of Partner Therapeutics, and former CEO of Merrimack, on FDA approval of their first drug, Leukine, for acute radiation syndrome (ARS), and why the government is interested (6 minutes): Why This Drug Company is Benefiting from Nuclear War Fears.

Leukine was originally approved in 1991 and was originally indicated to shorten time to neutrophil recovery and to reduce the incidence of severe and life-threatening infections following induction chemotherapy in adult patients 55 years and older with acute myeloid leukemia (AML), and subsequently approved for several oncology-related indications.

Data presented at the 2016 annual meeting of the American Society of Hematology, demonstrated Leukine’s ability to increase survival in non-human primates exposed to myelosuppressive doses of radiation without supportive whole blood transfusions or individualized antibiotics. Leukine was shown to increase survival when administered up to 48 hours after total body irradiation exposure at doses expected to be fatal to 50% of those exposed subjects under conditions of minimal supportive care.

A supplemental biologics licensing application (sBLA) was filed in September of 2017 with the FDA requesting approval of Leukine for the treatment of H-ARS.  In December, the application was granted Priority Review with a PDUFA date of March 29, 2018.

Boston-based cancer company Partner Therapeutics, Inc. (PTx) acquired the global rights to develop, manufacture, and commercialize Leukine from Sanofi in early 2018.

Sources: FDA, Partner Therapeutics, adapted.

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