HAIFA, Israel (Reuters) - Pluristem Therapeutics Inc, a developer of placenta-based stem cell products, said the U.S. Food and Drug Administration has cleared the emergency use of its therapy to treat acute radiation exposure in a nuclear event.

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Pluristem said it will start preparations to keep an emergency stock of PLX-R18 on hand for use in such events.

Full approval of the drug will depend on the results of a Phase III clinical trial. Pluristem said on Monday it is in discussions with the FDA and several U.S. agencies to clear the path for such a large final-stage study.

The U.S. National Institutes of Health’s National Institute of Allergy and Infectious Diseases sponsored and completed a mid-stage study of PLX-R18 in the treatment of acute radiation syndrome (ARS) in animals via the FDA’s “animal rule pathway” as ARS cannot be tested in humans. PLX-R18 will be provided up to 96 hours following radiation exposure.

It is also being studied by the U.S. Department of Defense to support the armed forces as a treatment prior to, or within the first 24 hours of radiation exposure.

“We are increasing the survival rate following high-level radiation exposure,” Arik Eisenkraft, Pluristem’s director of homeland defense projects, told Reuters. “We see improvement in all three blood lineages - red cells, white cells and platelets.”

PLX-R18 is injected into the muscle twice, a week apart.

It is designed to treat bone marrow that is unable to produce enough blood cells due to a variety of causes, including ARS and certain cancers or cancer treatments.

“We think that the everyday use of the compound will be for bone marrow failure of any cause,” Eisenkraft said.

Pluristem said its cells can be administered to patients without the need for tissue matching. One placenta makes 20,000 treatments.

Pluristem is conducting advanced Phase III trials in the United States and Europe of another product, PLX-PAD, to treat patients with the end-stage of peripheral artery disease, to prevent the need for amputation.

“In Europe, we are hoping to open data at the end of 2019 and in the U.S. a year later,” co-CEO Zami Aberman said.

That treatment has also been approved for a Phase III trial, to begin in the next few months, in patients with the most common form of hip fracture, in which the cells are injected during surgery, he said.