Pluristem BMT Pre-Clinical Success

Pluristem Therapeutics Inc. (NasdaqCM: PSTI) TASE: PSTI) has shown strong positive data from a preclinical study of PLX-R18 cells to improve outcomes of bone marrow transplantation. In the study, conducted in conjunction with Hadassah Medical Center’s Department of Bone Marrow Transplantation and Cancer Immunotherapy, mice with damaged bone marrow who received intramuscular injections of PLX-R18 cells together with a bone marrow transplant had significantly faster recovery of blood cell production compared to those who received a placebo with the bone marrow transplant. A rapid return to normal blood cell counts is critical for people who require a transplant to replace dysfunctional bone marrow because of diseases such as leukemia or other blood cancers. PLX-R18, Pluristem’s second product, is being developed to treat a range of hematologic indications including bone marrow deficiency and complications of bone marrow and umbilical cord blood transplantation.

The objective of the Hadassah trial was to compare the production of blood cells after intramuscular injection with PLX-R18 cells or placebo in the context of transplantation of hematopoietic stem cells obtained from bone marrow. Mice received lethal doses of radiation followed by either a low dose or a high dose of bone marrow cells and either PLX-R18 cells or placebo. Evidence of more rapid recovery was found at the two earliest data collection time points of the study. Nine days after transplantation with a low dose of bone marrow cells and concurrent administration of either PLX-R18 or placebo, those treated with PLX-R18 had statistically significant increases in numbers of platelets and granulocytes as compared to controls; they also had more lymphocytes and total white blood cells, though these increases were not statistically significant. Nine days after transplantation with a high dose of bone marrow cells and concurrent administration of either PLX-R18 or placebo, those treated with PLX-R18 also had statistically significant increases in platelet levels. One week later, at 16 days after a low dose transplantation, those treated with PLX-R18 cells had more platelets than controls, and those treated with PLX-R18 and a high dose of bone marrow had statistically significant increases in platelets, granulocytes and total white blood cells. After a bone marrow transplant patients cannot fight infections or prevent hemorrhage until white blood cell and platelet levels return to normal. The accelerated recovery of platelet and white blood cell levels demonstrated in this study could potentially have important clinical implications.

Alongside the study at Hadassah, a preliminary study was conducted by Hillard M. Lazarus, MD, a Professor of Medicine in the Department of Hematology and Oncology at Case Western Reserve University. The study was part of ongoing research there to test PLX-R18 for use in umbilical cord blood stem cell transplantation. Data in eight mice showed that six weeks after exposure to high doses of radiation, followed by transplantation with human umbilical cord blood cells, three out of four mice who received PLX-R18 cells survived compared to only one out of the four who received a placebo after transplant. At eight weeks after irradiation and transplantation the mice who received PLX-R18 each had a higher percent of hematopoietic cells (CD45+) in their peripheral blood than the surviving control subject. This early finding is encouraging as research continues at Case Western University to study the effects of PLX-R18 on the speed and success of engraftment of umbilical cord blood cells.

“A statistically significant increase in blood counts soon after bone marrow transplant is very meaningful. For the transplant patient, the most critical period for hematopoietic recovery is in the days following the transplant. We were particularly encouraged to see that the administration of PLX-R18 cells resulted in the greatest early improvement when using a lower dose of bone marrow cells. This means we could one day potentially achieve success with lower bone marrow transplant doses, thus addressing both treatment costs and donor availability,” stated Professor Reuven Or, Director of the Department of Bone Marrow Transplantation and Cancer Immunotherapy at Hadassah Medical Center and the study’s Principal Investigator.