Israel’s Pluristem Therapeutics has reported positive results from a recently completed trial that was designed to evaluate PLX-R18 cells to treat bone marrow damaged by exposure to high levels of radiation, such as can occur after a nuclear disaster.
Conducted by the US National Institutes of Health (NIH), the trial showed that injection of PLX-R18 cells into muscle, compared to a placebo, improved the recovery of white blood cell, red blood cell and platelet levels in animals exposed to high levels of radiation.
Data from the trial also suggested that the treatment may potentially be able to shorten time to recovery.
In the trial, 256 mice were randomised to be injected intramuscularly with PLX-R18 or placebo after total body irradiation, or PLX-R18 or placebo after sham irradiation.
High levels of radiation can destroy the body’s ability to produce white blood cell, red blood cell and platelet levels and regaining that capacity is a key factor in surviving the haematologic component of acute radiation syndrome (ARS).
ARS is a condition caused by high-dose irradiation that can involve severe, sometimes lethal damage to the bone marrow as well as other physiologic systems and organs.
The trial is designed to investigate the mechanism of action behind the significant improvement in survival in irradiated mice treated with PLX-R18 that was showed in the NIH’s first efficacy study.
Pluristem chairman and CEO Zami Aberman said: "Our PLX-R18 cell product was developed and targeted to become a strong candidate for government procurement programmes designed to protect the population in the case of exposure to dangerous levels of radiation.
"PLX-R18 cells are an off-the-shelf cell therapy product with a long shelf life. They do not require matching before use and can be administered through intramuscular injection. These features are important to facilitate rapid initiation of treatment on a large scale.
"The study results also support Pluristem’s unique approach of injecting cells intramuscularly to enable the cells to remain in the body long enough to respond to signals from damaged tissues and adapt their therapeutic secretion profiles accordingly."
Results from the current trial show that intramuscular administration exerts a systemic healing effect on bone marrow, lending further support to the concept that the company’s cells work systemically via secretion of therapeutic proteins, even though the cells themselves remain in the muscle into which they were initially injected.
The company said that additional animal trials are needed before to US Food and Drug Administration (FDA) approval of PLX-R18 for use in ARS and no human trials would be needed as product development is conducted under the FDA’s Animal Rule.
PLX-R18 cells are being developed by Pluristem for other potential indications including improvement of engraftment of transplanted haematopoietic stem cells for the treatment of bone marrow deficiency.
The company is carrying out trials for this indication at Case Western University and Hadassah Medical Center.
Data from the NIH trials in ARS are expected to benefit the company’s development of its haematology programme.