StemCells reports positive top-line results of thoracic spinal cord injury Phase I/II trial

The summary will be presented today at 10:15 a.m. EDT at the 4th Joint International Spinal Cord Society (ISCoS) and American Spinal Injury Association (ASIA) meeting being held in Montreal, Canada. The abstract was selected as one of the top six platform submissions for the conference.

The international, open-label, Phase I/II trial evaluated both safety and preliminary efficacy of StemCells, Inc.’s proprietary HuCNS-SC human neural stem cells as a treatment for chronic spinal cord injury. The trial enrolled twelve patients who had suffered injury to the thoracic cord and were in the early chronic stage of recovery.

The severity of spinal cord trauma is classified by the ASIA Impairment Scale (AIS) according to the degree of sensory and motor loss. Patients classified as AIS A, the most severe injury, have lost both sensory and motor function below the level of injury.

AIS B patients are considered less severely injured because, although they also have no motor function below the level of injury, some limited sensory function is maintained. The protocol was specifically designed to test safety and preliminary efficacy across this spectrum of injury severity, and ultimately the trial transplanted seven AIS A and five AIS B patients.

The analysis of the study 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 cord both above and below the level of injury and sequential examinations of the patients over the course of twelve months showed no abnormal changes in spinal cord function associated with the transplantation technique. There were no adverse events attributed to the HuCNS-SC cells.

In addition to safety, analysis of the twelve-month data revealed sustained improvements in sensory function that emerged consistently around three months after transplantation and persisted until the end of the study.

The patterns of sensory gains were confirmed to involve multiple sensory pathways and were observed more frequently in the patients with less severe injury; three of the seven AIS A patients and four of the five AIS B patients showed signs of positive sensory gains confirming the previously released interim results. In addition, two patients progressed during the study from the most severe classification, 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."

The Company’s Phase I/II clinical trial was designed to assess both safety and preliminary efficacy of HuCNS-SC cells as a treatment for chronic spinal cord injury.

The Company enrolled 12 subjects with thoracic T2-T11 level (chest-level) neurological injuries classified as either AIS A or B according to the ASIA Impairment Scale (AIS) who were a minimum of 3 months from injury. Both AIS A and B are considered to have complete loss of motor function below the level of injury, but AIS B subjects have some degree of preserved sensory function below the level of injury.

The trial involved three world-leading 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 who enrolled in the trial received HuCNS-SC cells through direct transplantation into the spinal cord and underwent temporary treatment with immunosuppressive drugs. Evaluations were performed regularly throughout the post-transplant period in order to monitor and assess the safety of the HuCNS-SC cells, the surgery and the immunosuppression, as well as to measure any change in neurological function.

Preliminary efficacy was evaluated based on defined clinical endpoints using established spinal cord injury scales assessing changes in sensory and motor function. Patients were enrolled in a separate observational study after completing the twelve-month Phase I/II trial.

Enrollment included seven AIS A and 5 AIS B patients. The study showed a favorable safety, feasibility and tolerability profile with no adverse events associated to the HuCNS-SC cells.

Twelve months after transplantation of the HuCNS-SC cells, data showed gains in sensory function in three of the seven AIS A patients and four of the five AIS B patients. In addition, two patients progressed from the most severe classification, AIS A, to a lesser degree of injury grade, AIS B.

In follow-up to the thoracic study, the Company has initiated a Phase II trial designed to measure efficacy in cervical spinal cord injury. The Phase II trial, also called the Pathway study, is a controlled study and was initiated in late 2014.