A cellular therapeutic company known as Stem Cells, Incorporated has been carrying out a Phase I/II clinical trial that was specifically designed to assess both safety and preliminary efficacy of their proprietary HuCNS-SC cells as a treatment for chronic spinal cord injury. Recently, Dr. Armin Curt, the principal investigator of this clinical trial, presented a summary of the safety and preliminary efficacy data from this Phase I/II study at the 4th Joint International Spinal Cord Society (ISCoS) and American Spinal Injury Association (ASIA) meeting which was held in Montreal, Canada.
Spinal cord injury patients are classified by a system that was developed by the American Spinal Injury Association (ASIA) and uses grades A through E on the American Spinal Injury Association Impairment Scale (AIS) to indicate the severity of the spinal cord injury. AIS Grade A injuries consist of a loss of all spinal cord function (sensation and movement) below the level of injury is lost. This is known as a complete injury. All the other AIS grades are considered incomplete. Patients with Grade B injuries have some sensation below the level of injury, but there is no movement below the injury.. In patients with AIS Grade C injuries, there is both sensation and movement, but most of the muscles below the injury cannot function against resistance and that includes gravity. Those with AIS Grade D spinal cord injuries have some sensation and movement, but more than half of the muscles below the injury can function against resistance. Finally those with AIS Grade E injuries have both normal sensation and movement, but there may be other signs of injury, for example, pain.
For this trial, Stem Cell Inc enrolled 12 subjects who had suffered from a severe spinal cord injury at the thoracic or chest level (T2-T11); seven AIS A and 5 AIS B patients.. In order to qualify for this study, all patients had to be classified as either AIS A or B and a minimum of 3 months from injury.
The trial involved internationally prominent medical centers for spinal cord injury and rehabilitation, and associated principal investigators; Dr. Armin Curt at the University of Zurich and Balgrist University Hospital, Dr. Steve Casha at the University of Calgary, and Dr. Michael Fehlings at the University of Toronto.
All subjects in this trial received HuCNS-SC cells by means of direct transplantation into the spinal cord and they were also treated, temporarily, with immunosuppressive drugs to prevent the immune system from rejecting the implanted cells. Patients were regularly evaluated for safety of the treatment protocol, and to determine if patients showed any change in neurological function. To determine this, patients were given a standard battery of movement and sensory tests before the surgery and at routine intervals after the procedure. Thus all patients were simultaneously enrolled in a safety evaluation and separate evaluation that tested the efficacy of the procedure as well.
In the safety analyses of these subjects, all the data demonstrated that the surgical transplantation technique and cell dose were safe and well tolerated by all patients. HuCNS-SC cells were injected directly into the spinal cord both above and below the level of injury and none of the patients in sequential examinations over the course of twelve months showed any abnormal changes in spinal cord function associated with the transplantation technique. Additionally, there were no adverse events that could be attributed to the HuCNS-SC cells.
Analyses of the functional data after twelve-months revealed sustained improvements in sensory function that emerged consistently around three months after transplantation and persisted until the end of the study. These gains in sensory function involved multiple sensory pathways and were observed more frequently in the patients with less severe spinal cord injuries. Three of the seven AIS A patients and four of the five AIS B patients showed signs of positive sensory gains. Two patients in the study progressed from AIS A, to the lesser degree of injury grade, AIS B.
“It has been a privilege to be a part of the first study to test the potential of neural stem cell transplantation in thoracic spinal cord injury,” said Dr. Armin Curt, Professor and Chairman of the Spinal Cord Injury Center at Balgrist University Hospital, University of Zurich. “The gains we have detected indicate that areas of sensory function have returned in more than half the patients. Such gains are unlikely to have occurred spontaneously given the average time from injury. This patient population represents a form of spinal cord injury that has historically defied responses to experimental therapies, and the measurable gains we have found strongly argue for a biological result of the transplanted cells. These gains are exciting evidence that we are on the right track for developing this approach for spinal cord injury. This early outcome in thoracic injury firmly supports testing in cervical spinal cord injury.”
Stephen Huhn, M.D., FACS, FAAP, Vice President, Clinical Research and CMO at StemCells, Inc., said, “This research program has the potential to revolutionize the therapeutic paradigm for spinal cord injury patients. The clinical gains observed in this first study are a great beginning. We found evidence of sensory gains in multiple segments of the injured thoracic spinal cord across multiple patients. Our primary focus in this study for spinal cord injury was to evaluate safety and also to look for even small signs of an effect that went beyond the possibility of spontaneous recovery. We are obviously very pleased that the pattern of sensory gains observed in this study are both durable and meaningful, and indicate that the transplantation has impacted the function of damaged neural pathways in the cord. The Company’s development program has now advanced to a Phase II controlled study in cervical spinal cord injury where the corollary of sensory improvements in thoracic spinal cord injury could well be improved motor function in the upper extremities of patients with cervical spinal cord injuries.”