Stem cell trial can re-start

US regulators have given the green light for the first human trial of an embryonic stem cell therapy to resume.

Californian biotech firm Geron can now re-start phase I trials of GRNOPC1 for acute spinal injury after running new pre-clinical trials showing the therapy met FDA safety standards.

The FDA had placed a ‘clinical hold’ on the trial in October 2009 after a pre-clinical trial showed a higher frequency of test animals developed cysts at the injury site than had previously been noted in earlier studies.

Geron's president and chief executive Thomas Okarma said: "We are pleased with the FDA's decision to allow our planned clinical trial of GRNOPC1 in spinal cord injury to proceed.

"Our goals for the application of GRNOPC1 in sub-acute spinal cord injury are unchanged - to achieve restoration of spinal cord function by the injection of human embryonic stem cell-derived oligodendrocyte progenitor cells directly into the lesion site of the patient's injured spinal cord.”

The phase I trial of GRNOPC1 that was on hold was testing its safety in patients with "complete" American Spinal Injury Association (ASIA) impairment scale grade A and sub-acute thoracic spinal cord injuries.

Secondary endpoints are set to assess the treatment’s efficacy, using measures such as improved neuromuscular control or sensation in the trunk or lower extremities.

Once safety in this patient population has been established, Geron plans to seek FDA approval to extend the study by increasing the dose of GRNOPC1 and enrolling subjects with complete cervical injuries. The company also plans to expand the trial to include patients with severe incomplete injuries.

Richard Fessler, professor of neurological surgery at the Feinberg School of Medicine at Northwestern University, said: "The neurosurgical community is ready to begin the clinical testing of this new approach to treating devastating spinal cord injury.

"We know that demyelination is central to the pathology of the injury, and its reversal by means of injecting oligodendrocyte progenitor cells would be revolutionary for the field. If found to be safe and effective, the therapy would provide a viable treatment option for thousands of patients who suffer severe spinal cord injuries each year."

Geron is initially developing GRNOPC1 for spinal cord injury, but is also exploring its application for use against neurological diseases, including multiple sclerosis, stroke, Canavan’s disease and Alzheimer’s disease.

Ben Adams