Neuralstem ($CUR) unveiled positive top-line safety results for its in-development ALS therapy, but some murky efficacy data led investors to question the future of the stem cell treatment, sending the biotech's shares down as much as 25%.
The company's candidate, NSI-566, is an injection of human spinal cord stem cells designed to fight the muscle-wasting effects of amyotrophic lateral sclerosis, or ALS. In a 15-patient, open-label Phase II trial, the treatment met its primary safety goal, Neuralstem said, as the maximum dose, 16 million transplanted cells, was well tolerated.
However, on the efficacy side, just 7 of those 15 patients responded to NSI-566, with "response" defined as a near-zero decline or improvement in motor function and grip strength. And Neuralstem, in a bit of clinical data tautology, noted that the responder group charted a statistically significant improvement in motor function compared to the nonresponders. That is to say, at 9 months, NSI-566 worked on the patients on whom it worked.
Investors were less than thrilled with those efficacy results, sending the biotech's shares as low as $2.97 apiece on Thursday morning. Neuralstem's stock price eventually settled to around 3.15, down about 15%.
Moving forward, the big hurdle for Neuralstem will be figuring out how to determine which ALS patients will respond to NSI-566 before enrolling a clinical trial. The company believes that a battery of muscle strength tests may light the way to predicting treatment response, and its investigators say they're still on track to begin a controlled, multicenter trial of NSI-566 this summer.
"Elucidating which factors define a patient who may have a therapeutic response to the stem cell treatment will be the next key challenge," said Jonathan Glass, NSI-655 investigator and director of the Emory ALS Center, in a Neuralstem statement. "We are hopeful that a set of predictive algorithms can be established to help pre-select the responders in our future trials."
- read the statement