The U.S. Department of Defense’s (DOD) Armed Forces Radiobiology Research Institute (AFRRI) is to undertake a pilot study in nonhuman primates (NHP) evaluating Pluristem Therapeutics’ PLX-R18 as a treatment for acute radiation syndrome (ARS) prior to and within the first 24 hours of radiation exposure. The AFRRI is part of the Uniformed Services University of Health Sciences (USUHS).
Pluristem’s PLX-R18 is an off-the-shelf placental expanded (PLX) cell therapy product generated from placenta-derived mesenchymal-like adherent stromal cells. The cells are designed to release a combination of therapeutic proteins to help treat bone marrow that has been damaged due to ARS, or as a result of cancer, cancer therapy, or immune-mediated bone marrow failure.
Last month, Pluristem reported positive data from an ongoing Phase II-equivalent NHP trial carried out by the National Institute of Allergy and Infectious Diseases (NIAID), which also investigated PLX-R18 cells as a treatment for ARS. The results confirmed that therapy increased survival rates in irradiated NHP animals.
The NIAID study is evaluating PLX-R18 administration 24 hours after radiation exposure. The prospective AFRRI study will evaluate therapy given prior to or within the first 24 hours of radiation exposure, which Pluristem points out is a timeframe that will be more relevant to the needs of the U.S. armed forces. Data from the two parallel studies will, in addition, provide a broader understanding of the potential therapeutic effects of PLX-R18 used as a countermeasure for ARS.
The new trial will also be carried out in accordance with FDA’s Animal Rule pathway, which is followed when human efficacy trials are not feasible, in this case due to the ethics of exposing humans to nuclear radiation. Product approval via the Animal Rule pathway can be granted following large animal efficacy studies and human safety data.
“We are pleased to see increased interest from U.S. governmental agencies in our PLX-R18 cell therapy,” noted Zami Aberman, chairman and co-CEO of Pluristem. “In view of the therapeutic effects of our product and the current geopolitical situation, governments can potentially shield their citizens from the dire health effects arising from exposure to nuclear radiation, saving many lives in the process, which is our ultimate goal.”
Pluristem’s first PLX product, PLX-PAD, is designed for treating tissues damaged by ischemia, trauma, or inflammation, by secreting therapeutic proteins that trigger tissue repair, reduce inflammation, and modulate the immune system. The product is undergoing an international Phase III study for treating critical limb ischemia. The study, which will enroll 250 patients, is supported by an $8 million grant from the European Union’s Horizon 2020 program. PLX-PAD is also undergoing Phase II development for treating intermittent claudication and is separately being evaluated for additional orthopedic indications, pulmonary arterial hypertension, and pre-eclampsia.
Pluristem has separately been granted FDA clearance to start a Phase I clinical trial evaluating PLX-R18 in patients with incomplete bone marrow recovery following hematopoietic cell transplantation.