NSI-566 is an experimental stem cell-based therapy that Seneca Biopharma (previously known as Neuralstem) is developing as a potential treatment for amyotrophic lateral sclerosis (ALS).

The company also is investigating NSI-566 as a potential treatment for chronic spinal cord injury and to restore motor deficits after an ischemic stroke or traumatic brain injury.

The U.S. Food and Drug Administration (FDA) granted NSI-566 orphan drug designation for the treatment of ALS in August 2018.

How does NSI-566 work?

NSI-566 is a human spinal cord-derived neural stem cell line (HSSC), which originates from the spinal cord of an eight-week-old aborted fetus.

When injected into the spinal cord, these fetal stem cells differentiate into the kind of neurons that exist in the adult body. They surround and support the impaired motor neurons in ALS by integrating into the neural network and forming connections (synapses) with the patient’s own neurons. They also secrete neurotrophic factors or proteins that promote the growth and survival of motor neurons.

Researchers think that through these mechanisms, NSI-566 may decrease motor neuron loss in ALS patients and improve motor function.

NSI-566 in clinical trials

A review study analyzed long-term follow-up results from Phase 1 (NCT01348451) and Phase 2 (NCT01730716) clinical trials of NSI-566 transplants. The authors published their findings in the journal Annals of Clinical and Translational Neurology in March 2018.

The Phase 1 study assessed the safety of HSSC injection into the spine of ALS patients. The Phase 2 study assessed the safety of escalating doses of the treatment. Both studies confirmed the safety of HSSC transplants.

In the follow-up analysis of these two studies, researchers compared the clinical outcome and survival of ALS patients for up to three years with data from previous ALS clinical trials.

They obtained the previous data from the PRO-ACT database and the ceftriaxone (brand name Rocephin) trial. The PRO-ACT database contains results from 23 Phase 2 and Phase 3 ALS clinical trials. The ceftriaxone trial assessed the safety and effectiveness of ceftriaxone (an antibiotic) in the treatment of ALS.

Measurements that the researchers included in the analysis were ALSFRS-R and ALS/SURV. ALSFRS-R is an ALS functional rating scale that is based on a questionnaire. ALS/SURV is a composite statistical analysis that combines survival and functional outcomes.

Researchers compared data from 21 Phase 1/2 clinical trial participants to data from 1,108 people from the PRO-ACT database. They also compared data from 20 Phase 1/2 clinical trial participants to data from 177 people from the ceftriaxone trial.

The results showed that after 24 months, the ALSFRS-R and ALS/SURV scores were significantly higher in people who received NSI-566 transplants  than in both comparison groups. Survival did not differ significantly between groups.

Next steps for NSI-566

Seneca met with the FDA in March 2020 to discuss future clinical development plans for NSI-566. The company is hoping to finalize the design of a Phase 3 trial soon.


Last updated: April 10, 2020.


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