Key takeaways
- NVG-291 is a peptide that targets the PTPsigma receptor, a molecular brake that normally stops nerve fibers from growing through scar tissue after injury to the brain or spinal cord.
- By easing that brake, the goal is to let damaged nerve connections grow past the scar and reconnect, something the central nervous system does poorly on its own.
- The published evidence is preclinical, drawn largely from rodent studies. In those models, PTPsigma-targeting strategies improved axon outgrowth, remyelination, and functional recovery after CNS injury.
- Human research has now begun. A Phase 1 safety study in healthy adults and a Phase 1b/2a study (CONNECT) in people with spinal cord injury have both completed.
- This is an active line of research. The strongest data remain in animal models, so it is best understood as an emerging field rather than an established outcome in people.
What is NVG-291
NVG-291 is a peptide being studied for its potential to help repair the central nervous system, meaning the brain and spinal cord. It is designed to interact with a specific receptor called PTPsigma (PTPσ), which sits on the surface of nerve cells. The approach grew out of laboratory work on a parent molecule known as the intracellular sigma peptide, or ISP, and is being developed by NervGen Pharma.
The science here is still early. The strongest published evidence comes from preclinical studies in animals, and the first human trials have only recently finished.
How it works
After an injury to the brain or spinal cord, the body lays down scar tissue rich in molecules called chondroitin sulfate proteoglycans, or CSPGs. These molecules act as a kind of biochemical roadblock. They bind to the PTPsigma receptor on nerve fibers and signal them to stop growing, which is one reason damaged nerve connections in the central nervous system tend not to regenerate well on their own.
NVG-291 is designed to modulate PTPsigma so that this inhibitory signal is reduced. Easing that brake may give nerve fibers a better chance to grow past the scar and re-establish connections.
What the research shows
Most of the published evidence is preclinical, meaning it comes from laboratory and animal studies. Modulating PTPsigma enhanced axon outgrowth by relieving CSPG-driven inhibition in a 2018 study in the Journal of Neuroscience, which also identified the mechanism: the receptor modulation triggered secretion of an enzyme, cathepsin B, that helped digest the inhibitory scar molecules. A 2019 paper in Molecular and Cellular Neuroscience reported that the parent ISP strategy improved remyelination and functional recovery in mice with experimental demyelination, with better visual pathway conduction and visual acuity.
Inhibiting PTPsigma also promoted functional recovery in a rodent model of preterm brain injury, according to a 2023 study in Experimental Neurology, improving motor and cognitive outcomes, myelination, and the inflammatory response. Taken together, these studies form a consistent picture across several models of CNS injury: targeting PTPsigma helps nerve fibers grow past scar tissue and recover function.
The human work has now started. A Phase 1 safety study (NCT05308953) tested single and multiple ascending doses of NVG-291 in healthy adults and enrolled 74 subjects; it was designed to characterize safety, tolerability, and how the drug behaves in the body, and it has finished. Building on that, the CONNECT study (NCT05965700), a Phase 1b/2a trial run at the Shirley Ryan AbilityLab in Chicago, evaluated NVG-291 in people with spinal cord injury across both chronic and subacute groups. Its primary measure was electrophysiological, tracking the strength of corticospinal signals to target muscles, alongside walking speed, hand dexterity, and motor scores. That trial has wrapped as well, with results not yet published.
What it is being explored for
Because of how it works, NVG-291 is being investigated for central nervous system injury and repair, with spinal cord injury as the lead human indication. The animal research also points to remyelination, the rebuilding of the protective sheath around nerve fibers, as a relevant effect, which is why related strategies have been studied in models of demyelination. Across this work, the outcome of interest is functional recovery: the return of movement, sensation, and connectivity that injury takes away.
This remains an emerging research field. The animal data are consistent and the first human trials have finished, but published human outcomes are still pending. The CONNECT readout is the next signal worth watching: whether the corticospinal and functional measures in people with spinal cord injury move the way the rodent recovery data suggest they might.
The evidence
Selected references, each verified against primary sources (PubMed and ClinicalTrials.gov). Explore the full, filterable research library on our Science page.
This article is for educational purposes only and is not medical advice, a diagnosis, or a treatment recommendation. NVG-291 is discussed in the context of the published research; inclusion of a study does not imply a guaranteed outcome. Many of these compounds are investigational and not approved for the uses described in all jurisdictions. Any treatment decision should be made with a qualified physician. Individual results vary.