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FDA Approves Radiation Medical Countermeasure

Acute Radiation Syndrome | Animal Rule Approval | Radiation Emergency Preparedness | Contacts

This page is no longer updated. For new updates, see: Radiological and Nuclear Emergency Preparedness Information from FDA

FDA approves Neupogen for treatment of patients with radiation-induced myelosuppression following a radiological/nuclear incident

On March 30, 2015, FDA approved use of Neupogen (filgrastim) to treat 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 internal organs, including bone marrow. Suppression of the bone marrow blocks the production of blood cells. Neupogen can help patients with H-ARS by facilitating recovery of bone marrow cells that develop into white blood cells, including neutrophils, that help fight off infections.

Neupogen is the first FDA-approved medical countermeasure to increase survival in patients exposed to myelosuppressive doses of radiation. It was approved by FDA based on studies in animals (under the Animal Rule), as studies in humans could not be ethically conducted.

Originally approved in 1991 to treat cancer patients receiving myelosuppressive chemotherapy, and subsequently approved for several oncology-related indications and severe chronic neutropenia, Neupogen is manufactured by Amgen, Inc., based in Thousand Oaks, CA. It was developed for the H-ARS indication with support and collaboration from the National Institute of Allergy and Infectious Diseases, Radiation Nuclear Countermeasures Program (NIAID RNCP). The FDA approval was based on the animal models and data from the adequate and well-controlled animal efficacy studies sponsored by NIAID RNCP.

The most commonly reported side effects associated with Neupogen injection are fever, pain, rash, cough, shortness of breath, headache, and bleeding from the nose.

Acute Radiation Syndrome

Acute Radiation Syndrome is an acute illness caused by irradiation of the entire body (or most of the body) by a high dose of penetrating radiation in a short period of time, usually a matter of minutes.

Patients exposed to high doses of radiation will not be able to produce sufficient numbers of new white blood cells, red blood cells, and platelets, a condition called myelosuppression. Two major clinical manifestations of radiation bone marrow injury are neutropenia (abnormally low level of neutrophils, a type of white blood cell) and thrombocytopenia (abnormally low level of platelets) that directly impact the survival of victims exposed to radiation. Severe neutropenia increases the risk of sepsis and death due to infections, while thrombocytopenia increases the risk of hemorrhage and death due to bleeding.

Until patients' bone marrow recovers and creates enough new blood cells—a slow process—these patients are at a high risk of death from infection and bleeding. Neupogen can effectively reduce the duration and severity of neutropenia and increase survival. (More, from CDC)

Animal Rule Approval

This indication was approved under FDA’s Animal Rule, which allows efficacy findings from adequate and well-controlled animal studies to support FDA approval when it is not feasible or ethical to conduct efficacy trials in humans.

The results of efficacy studies in research animals provided sufficient evidence that Neupogen is reasonably likely to benefit humans with H-ARS.

In addition, orphan drug designation was granted for this indication, and this supplemental application received priority review.

Radiation Emergency Preparedness

Although Neupogen was approved in 2015, in 2013, the Biomedical Advanced Research and Development Authority (BARDA) purchased Neupogen under Project BioShield for the U.S. Strategic National Stockpile to support the nation’s preparedness against a possible radiological or nuclear emergency.  Because this new indication of Neupogen was not approved yet, such use to treat ARS patients was considered investigational and would have required an Emergency Use Authorization from FDA.

With the approval of Neupogen for the treatment of humans acutely exposed to myelosuppressive doses of radiation, the U.S. population is better prepared for a possible radiological or nuclear emergency.


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