Preventive & Therapeutic Radiation Vaccine Candidate Works on Mice

An Israel-based regenerative medicine company presented positive results on July 31, 2019, from a series of clinical studies regarding the PLX-R18 cell therapy vaccine.

PLX-R18 cells release a combination of therapeutic proteins in response to a damaged or poorly functioning hematopoietic system. 

The studies were designed to evaluate PLX-R18 as a potential prophylactic countermeasure against acute radiation syndrome (ARS) administered ‘prior’ to radiation exposure.

These animal studies demonstrate that PLX-R18, administered 24 hours ‘before’ radiation exposure, and again 72 hours ‘after’ exposure, resulted in a significant increase in survival rates.

The survival rates increase from 4 percent to 74 percent in the treated group. 

In addition, the data show an increase in recovery of blood lineages and a favorable safety profile. 

Furthermore, histopathological analysis and hematopoietic progenitor clonogenic assay of tissues collected show a significant increase in bone marrow cell numbers and improved regenerative capability into all blood lineages. 

These animal studies were conducted by the U.S. Department of Defense’s (DoD) Armed Forces Radiobiology Research Institute at the Uniformed Services University of the Health Sciences. 

Yaky Yanay, President and Chief Executive Officer of Pluristem, said in a press release, “It is Pluristem’s goal to provide the different federal agencies access to PLX-R18 so it may be used as a countermeasure both before and after radiation exposure in order to minimize hematological and other organ damage.”

In addition to the DoD study, PLX-R18 is also being evaluated by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, as a treatment ‘following’ radiation exposure (ARS). 

Data from these NIAID studies demonstrated a significant increase in survival rates and enhanced neutrophil and lymphocyte recovery in radiation subjects.

ARS results from exposure to high levels of radiation, as in the case of a nuclear accident or attack.

ARS examples are the survivors of the Hiroshima and Nagasaki atomic bombs and the firefighters that first responded after the Chernobyl Nuclear Power Plant event in 1986, says the Centers for Disease Control and Prevention (CDC).

ARS may cause severe or fatal systemic effects such as injuries that hinder the bone marrow’s ability to produce blood cells and platelets, as well as other organs and systems within the body, increasing patients’ susceptibility to life-threatening hemorrhage, infection, and anemia.

Furthermore, ARS usually will be accompanied by some skin damage. It is also possible to receive a damaging dose to the skin without symptoms of ARS, especially with acute exposures to beta radiation or X-rays.

Sometimes this occurs when radioactive materials contaminate a patient’s skin or clothes.

When the basal cell layer of the skin is damaged by radiation, inflammation, erythema, and dry or moist desquamation can occur, says the CDC.

According to the company, PLacental eXpanded (PLX) cells are placenta-derived, mesenchymal-like adherent stromal cells that are designed to be administered to patients without the need for tissue or genetic matching.

These cells release soluble biomolecules, such as cytokines, chemokines and growth factors, which act in a paracrine or endocrine manner to facilitate healing of damaged tissue by stimulating the body’s own regenerative mechanisms.

Pluristem Therapeutics Pluristem Therapeutics Inc. is a leading regenerative medicine company developing novel placenta-based cell therapy products.