Development of PLX-R18, a promising and novel countermeasure for radiation-associated injuries.

PLX-R18 is a novel cell-based product of ex vivo expanded adherent human-placenta-derived stromal cells. After intramuscular administration, these living cells are capable of secreting various cytokines that produce a therapeutic benefit. The endogenously secreted cytokines facilitate the recovery of hematopoietic progenitor cells and regenerate multiple blood lineage cells. Preclinical studies have demonstrated that PLX-R18 cells can prevent and also mitigate hematopoietic acute radiation syndrome in experimental animal models. This agent has an open US Food and Drug Administration investigational drug status for hematopoietic system-associated ARS (H-ARS). A phase I study using patients with bone marrow failure demonstrated the safety of the agent while promoting hematopoietic regeneration in humans.