Cell therapy: a losing streak
Developed by Osiris, based in Maryland, the drug Prochymal, containing live mesenchymal stem cells from the bone marrow of healthy young donors, has not passed the two final stages of clinical trials. This event is a major setback for cellular medicine, as Prohimal has so far been considered the closest to market stem cell-based drug of all the drugs in this group currently undergoing clinical trials.
According to the results of animal experiments, Prohimal suppresses inflammation and accelerates tissue repair by stimulating the release of molecular cell growth factors.
Stem cells, especially in the form of bone marrow repair transplants, have long been used in medical practice. Osiris does not lose hope that Prohimal will become the first pharmaceutical product of mass production based on stem cells that has received official approval from the US Food and Drug Administration.
However, the failure of two clinical trials makes it much more difficult to achieve this goal. In both studies, Prochimal was tested as a means to treat the graft-versus-host reaction, which develops in cases when the immune cells of the transplanted organ begin to attack the recipient's organs, recognizing them as foreign tissue.
In one of the studies, Prohimal was administered simultaneously with steroid preparations. At the same time, a positive reaction to the combination of Prohymal and steroids was observed in 46% of cases, and to the combination of Prohymal and placebo – in 45%.
In the second study, Prohimal was administered to patients who did not respond to steroid therapy. In this case, the graft-versus-host reaction stopped for at least 28 days in 35% of patients taking Prohimal, whereas in patients of the control group receiving placebo, the same indicator was 30%. Thus, the differences in the results of both studies are not statistically significant.
However, Osiris stated that in the second study, the administration of the drug was associated with a statistically significant level of improvement in the condition of patients in whom the graft-versus-host reaction caused predominant damage to the liver or gastrointestinal tract.
Currently, the drug is also undergoing clinical trials as a treatment for myocardial infarction, chronic obstructive pulmonary diseases and type 1 diabetes. Earlier this year, Osiris stopped conducting the final stages of clinical trials of Prochymal as a treatment for Crohn's disease (a form of inflammatory bowel disease) due to the high level of patient response to placebo.
This failure was soon followed by another significant failure in the field of cellular medicine. Last month, Geron, a California-based company specializing in working with embryonic stem cells, announced that the start of its planned world-first clinical trials using human embryonic stem cells was postponed indefinitely by the U.S. Food and Drug Administration after animal experiments showed that treatment leads to the formation of small cysts in the affected area.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Technology Review: Stem Cell Drug Fails in Testing.
08.10.2009