An early experiment using adult stem cells to treat heart attack patients has allayed concerns over the treatment's safety and, surprisingly, yielded some data suggesting that stem cells might help repair an injured heart.
on Sunday reported positive safety and efficacy data from a phase I study of its adult stem cell therapy, Provacel, in patients with heart disease.
In the 53-patient, double-blind, placebo-controlled study, heart attack patients given an intravenous infusion of Provacel reported lower adverse events such as abnormal heart rhythms compared with patients given a placebo.
Phase I studies are typically the proving ground for an experimental drug's safety, but in this case, the heart function of Provacel patients also appeared to improve more than that of placebo patients.
"In a phase I study, our top-line hypothesis is safety, but what we found when we looked for safety measure is that Provacel-treated patients also came up better than placebo, hinting at the drug's efficacy and showing that Provacel seems to be providing a clinical benefit for patients," said Dr. Joshua Hare, a cardiologist at the Miller School of Medicine at the University of Miami and the lead investigator of the Provacel study.
Hare presented his findings Sunday at the American College of Cardiology annual meeting in New Orleans.
Osiris Therapeutics is developing new therapies based on mesenchymal stem cells (MSCs), a form of adult stem cell that is capable of differentiating into tissues that provide rigidity or stability in the body -- bone, cartilage, fat, tendon or muscle.
The company's lead product is Prochymal, an intravenous infusion
containing MSCs being developed for graft-vs.-host disease and Crohn's disease in phase III studies. Another Osiris stem cell drug in its pipeline, Chrondrogen, recently failed a study in patients with damaged knee cartilage.
Provacel is being developed for heart-related diseases through a partnership between Osiris and
. Sunday's presentation was the first study of Provacel conducted in patients.
The phase I study enrolled 53 patients hospitalized with their first heart attack. Thirty-four patients were randomized to receive an intravenous infusion of Provacel, split between three different doses. The remaining 19 patients received a sham infusion. Patients were followed for six months after treatment.
The hypothesis behind Provacel is that adult stem cells can migrate to the injured areas of the heart and regenerate into healthy cardiac tissue, reversing the damage done by heart disease.
On the safety side, 9% of patients in the Provacel group reported the occurrence of cardiac arrhythmia over the six-month observation period, compared with 37% of placebo patients reporting a cardiac arrhythmia. The difference between the two groups was statistically significant, with a p value of 0.025.
There were no patient deaths in the study and fewer adverse events reported by Provacel patients compared with placebo patients. Provacel patients also reported fewer re-hospitalizations and longer average time to hospitalization vs. placebo, although these results were not statistically significant.
"Going into this study, there was a lot of consternation about the approach we were taking and concerns about safety," said Hare. "I think these results prove that Provacel is safe."
From an efficacy perspective, 42% of Provacel-treated patients reported an improvement in their overall condition compared with 11% of placebo patients. This global assessment of patient well-being was determined by treating physicians in the study. The results were statistically significant.
On more objectively measured tests of efficacy, Provacel also performed better than placebo, but not enough to reach the level of statistical significance.
Provacel patients had an 18% improvement in left ventricular ejection fraction (LVEF), a measurement of strength in the heart's main pumping chamber. But placebo patients showed an 11% improvement in LVEF, and the difference between the two groups was not statistically significant.
One big surprise in the study, says Hare, was that Provacel seemed to cause improved lung function, which suggests the drug might be used to treat pulmonary diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis.
Overall, Hare believes these Provacel data justify more advanced and larger studies to determine better whether adult stem cells do have a future as a heart-repairing therapy. Such studies would ultimately enroll large numbers of patients and require Provacel to show that it can reduce mortality, prevent or delay further heart attacks or stroke, or help patients avoid further re-vascularization procedures.
Osiris CEO Randy Mills says the company's next steps will be further analyze these results and consult with partner Boston Scientific on phase II Provacel studies. Independent of Boston Scientific, Osiris will also begin looking at stating Provacel studies in lung diseases.
Osiris shares closed Friday up 3.4%, or 59 cents, to $17.90.
Adam Feuerstein writes regularly for RealMoney.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;
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