Pluristem Therapeutics (PSTI) reports positive topline Phase I results in innovative hematology program, which is first to study PLX-R18 in humans

Pluristem Therapeutics Inc. (Nasdaq: PSTI) (TASE: PSTI), a leading regenerative medicine company, today reported positive topline results in its first study to evaluate the safety and exploratory efficacy of PLX-R18 in humans. The company’s Phase I, open-label, dose-escalation study is evaluating the safety and exploratory efficacy of intramuscular injections of PLX-R18 in subjects with incomplete hematopoietic recovery following Hematopoietic Cell Transplantation (HCT).

Pluristem CEO and President, Yaky Yanay, said, "The promising topline results demonstrate insight into how PLX cells may provide a more effective therapeutic benefit than current technologies. We believe that PLX-R18 affects the regeneration activity of the hematopoietic cells. By supporting blood cell lineage’s recovery, this approach could be used to address a variety of hematological deficiencies. We intend to push forward the clinical development of PLX-R18 with the goal of establishing it as the new standard of care in the field."

Poor graft function is a life-threatening complication for patients undergoing HCT. Current standard-of-care treatments do not develop satisfactory blood counts in some or all blood cell lineages. Consequently, patients are vulnerable to bleeding and recurrent infections, and require repeated costly transfusions of blood products, which only provide a short-term effect. Pluristem's PLX-R18 aims to improve the standard of care by stimulating the regenerative potential of the bone marrow. This potentially enhances the production of all three blood cell lineages, differentiating it from other products which target only one of the three blood cell lineages.

The study enrolled 21 patients in the U.S. and Israel, who were at least three months after the HCT procedure (median: 236 days), and had low blood counts in at least one blood cell lineage. They were assigned to one of three treatment arms: 1 million cells/kg, 2 million cells/kg or 4 million cells/kg. Each patient received two treatments of the assigned dose.

The results demonstrate that PLX-R18 has the potential to stimulate the implanted hematopoietic cells to realize their therapeutic potential and generate improved blood counts over the long term in all three blood cell lineages at once – a meaningful advantage over other existing and proposed treatments.

Available data1 at six-month follow-up demonstrates:

• PLX-R18 was well-tolerated with a favorable safety profile.
• Statistically significant improvement from baseline counts was observed in all cohorts for hemoglobin and platelet counts (p<0.05). The patients in the high dose arm (4 million cells/kg) exhibited statistically significant improvements in all three blood cells lineages (p<0.01).
• Approximately 60% of patients exhibited improvements in all three blood cell lineages: hemoglobin, neutrophil and platelet counts, that are above the initial criteria for inclusion in the study.
• 13 patients were transfusion dependent at baseline. Six of those became transfusion independent at six-month follow up. No patients who were transfusion independent at baseline became transfusion dependent.

The study supports previous preclinical results, conducted via the U.S. Food and Drug Administration’s (FDA) Animal Rule in collaboration with the U.S. National Institutes of Health (NIH), in which PLX-R18 was found effective in treating bone marrow failure from Acute Radiation Syndrome (ARS).

PLX-R18 is the first product candidate manufactured using Pluristem’s proprietary serum-free media on its 3D bioreactor system.

The company will conduct an analyst and investor call on May 3, 2021, at 10am EDT, for registration: https://Veidan.activetrail.biz/pluristem

___________________1 Data from the six-month follow-up is available for 14 of the 21 treated patients: one patient was terminated early, three patients missed the 6-month visit and three died prior to the 6-month visit (two fatal events in the 2 million cell dose, and one fatal event in the 4 million cell dose). All fatal events in the study were considered unrelated to the study treatment. Mortality rates were in line with publicly available information (references: Gao et al 2020, Halahleh et al 2021, Tang et al 2018, Sun et al. 2015, Zhao et al 2019)

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