Neuralstem has announced top line data from the phase II trial of NSI-566 spinal cord-derived neural stem cells under development for the treatment of amyotrophic lateral sclerosis (ALS). The study met primary safety endpoints–the maximum tolerated dose of 16 million transplanted cells and the surgery was well tolerated.
Secondary efficacy endpoints at nine months post-surgery indicate a 47% response rate to the stem cell treatment, as measured by either near-zero slope of decline or positive slope of ALSFRS score in seven out of 15 patients and by either a near-zero decline, or positive strengthening, of grip strength in seven out of 15 patients. Grip strength is an indicator of direct muscle strength of the lower arm. ALSFRS is a standard clinical test used to evaluate the functional status of ALS patients. The average ALSFRS score for responders at nine months after treatment was 37. Non-responders scored an average of 14. These scores represent 93%, versus 35%, of the baseline score retained, respectively, by the responders versus non-responders at nine months, which is a statistically significant difference. As measured by an average slope of decline of ALSFRS, responders’ disease progression was -0.007 point per day, while non-responders’ disease progression was -0.1 per day, which was again statistically significant. Lung function as measured by Seated Vital Capacity shows that responder patients remained within 94% of their starting scores, versus 71% for non-responder patients. The trial met its primary safety endpoints. Both the surgery and cells were well-tolerated, with one patient experiencing a surgical serious adverse event.
“In this study, cervical intervention was both safe and well-tolerated with up to eight million cells in 20 bilateral injections,” says Karl Johe, Neuralstem chief scientific officer. “The study also demonstrated biological activity of the cells and stabilisation of disease progression in a subset of patients. As in the first trial, there were both responders and non-responders within the same cohort, from patients whose general pre-surgical presentation is fairly similar. However, we believe that through the individual muscle group measurements, we may now be able to differentiate the responders from the non-responders.
“Our therapy involves transplanting NSI-566 cells directly into specific segments of the cord where the cells integrate into the host motor neurons. The cells surround, protect and nurture the patient’s remaining motor neurons in those various cord segments. The approximate strength of those remaining motor neuron pools can be measured indirectly through muscle testing of the appropriate areas, such as in the grip strength tests. We believe these types of endpoints, measuring muscle strength, will allow us to effectively predict patients that will respond to treatment, adding a sensitive measure of the therapeutic effects after treatment. Testing this hypothesis will be one of the primary goals of our next trial.” The full data is being compiled into a manuscript for publication.
“We believe the top-line data are encouraging,” says Eva Feldman director of the A Alfred Taubman Medical Research Institute and director of Research of the ALS Clinic at the University of Michigan Health System, and an unpaid consultant to Neuralstem. “We were able to dose up to 16 million cells in 40 injections, which we believe to be the maximum tolerated dose. As in the first trial, the top-line data show disease stabilisation in a subgroup of patients. Perhaps equally as important, we believe the top-line data may support a method of differentiating responders from non-responders, which we believe will support our efforts as we move into the next, larger controlled trial expected to begin this summer.”
“The top-line data look very positive and encouraging. If this proportion of patients doing well after treatment can be corroborated in future therapeutic trials, it will be better than any response seen in any previous ALS trials,” says site principal investigator, Jonathan D Glass, director of the Emory ALS Center. “Elucidating which factors define a patient who may have a therapeutic response to the stem cell treatment will be the next key challenge. We are hopeful that a set of predictive algorithms can be established to help pre-select the responders in our future trials.”
The open-label, dose-escalating trial treated 15 ambulatory patients, divided into five dosing cohorts, at three centres, Emory University Hospital in Atlanta, Georgia, the ALS Clinic at the University of Michigan Health System, in Ann Arbor, Michigan, and Massachusetts General Hospital in Boston, Massachusetts, all USA, and under the direction of principal investigator (PI), Eva Feldman. Dosing increased from one million to eight million cells in the cervical region of the spinal cord. The final trial cohort also received an additional eight million cells in the lumbar region of the spinal cord.
The company anticipates commencing a later-stage, multicentre trial of NSI-566 for treatment of ALS in 2015. Neuralstem has received orphan designation by the FDA for NSI-566 in ALS.