NurExone Biologic Inc. recently announced new preclinical results showing that its lead candidate ExoPTEN produces a reproducible, dose-dependent therapeutic effect in an eye model of glaucoma.

The study was conducted in collaboration with Prof. Ygal Rotenstreich team at the Goldschleger Eye Institute at Sheba Medical Center, one of the world’s leading hospitals. It demonstrated that ExoPTEN’s biological activity increases with higher dosing levels in animals with optic nerve injury, resulting in consistent and measurable recovery of visual function. The findings show that ExoPTEN’s regenerative effect is reproducible, quantifiable, and scales with dose.

“Reproducibility is the key challenge in science, and now we have a first validation of the results,” said Prof. Michael Belkin, Professor Emeritus of Ophthalmology at Tel Aviv University and Scientific Advisor to NurExone. “These results confirm that ExoPTEN has the potential impact of a true therapeutic, producing reproducible repair of damaged optic nerves in small animals, advancing our ability to address vision loss in patients with optic nerve damage, such as glaucoma and related conditions.”

Dr. Tali Kizhner, Director of Research and Development at NurExone, added: “We are seeing a clear, dose-dependent effect of ExoPTEN in the eye, with stronger functional recovery at higher doses. It highlights the one-two punch of our platform: exosomes that reach and protect neural tissue, and the siRNA cargo that switches on the regenerative response. This dose-response data marks an essential step toward future clinical trials and brings us closer to translating this therapy to patients.”

This dose-response study, the third independent investigation of ExoPTEN’s activity in optic nerve injury, complements the previously announced results from June 2024 and December 2024, which showed structural preservation and survival of retinal ganglion cells.

The optic nerve crush (ONC) model used in these experiments mimics the nerve damage that occurs in glaucoma, one of the leading causes of irreversible blindness. The researchers led by Prof. Rotenstreich, tested low and high doses of ExoPTEN delivered by extrachoroidal injection directly to the eye.

Functional measurements of retinal activity using scotopic threshold response electroretinography (STR-ERG) showed that both ExoPTEN doses improved visual signal strength in animals with optic nerve injury, with the high-dose group achieving response amplitudes comparable to those of uninjured eyes. This result demonstrates substantial functional recovery and provides clear evidence of a dose-dependent therapeutic effect that aligns with ExoPTEN’s proposed biological mechanism.

“This collaboration opens a new treatment avenue for blinding glaucoma and other ophthalmological indications,” commented Prof. Rotenstreich.

Figure 1. Dose-dependent restoration of retinal response following ExoPTEN treatment in the ONC model.

The figure depicts scotopic threshold response (STR) amplitudes measured by electroretinography (ERG) in rats subjected to optic nerve crush (ONC) and treated with exosome-based formulations. The y-axis shows STR amplitude (µV), representing retinal ganglion cell function, while the x-axis displays experimental groups. Eyes with ONC were treated with low-dose or high-dose ExoPTEN (exosomes loaded with PTEN siRNA). Additional groups included eyes treated with naïve exosomes and uninjured eyes to establish baseline retinal response. In this model, visual responses are considered detectable when retinal signal amplitudes exceed about 5 µV; signals below that level indicate no measurable retinal activity.

Each bar shows the mean STR amplitude ± standard error of the mean (SEM). Both ExoPTEN dose groups exhibited recovery of retinal electrical response relative to the expected ONC-induced decline, with the high-dose group achieving STR amplitudes comparable to those of uninjured eyes.

Figure 1 shows the amplitude of Electroretinogram (ERG) measurements of dark-adapted (scotopic) threshold retinal response (STR, in microvolts, µV) at 0.00062 cd/m^2. In each rat, one eye was left intact as a healthy control (“no ONC”, light grey). The second eye had ONC and was treated according to group – treatment with PBS (vehicle, Saline, dark grey), with naïve exosomes (Exosomes, blue) or with ExoPTEN (ExoPTEN, orange). Naïve exosomes and ExoPTEN were given in low (4E+8 particles, light blue and orange) or high dose (4E+9 particles, dark blue or orange). Each treatment was given twice – right after the ONC surgery and 1 week after it.

A true response to light was considered any amplitude above 5µV. As can be seen, normal (no ONC) eyes (n=13) showed a clear response to the light in this low light intensity, while Saline-treated eyes show no response (n=6). In Exosome treated eyes, no eyes (n=2) responded to the light in low dose treatment, and only 1 of 2 high dose receiving eyes responded. In ExoPTEN-treated eyes, all eyes responded to the light, with a clear dose response shown by the higher, normal values, response of the high dose receiving eyes (n=2) compared to the lower dose receiving eyes (n=2).

NurExone Biologic Inc. is a TSXV, OTCQB, and Frankfurt-listed biotech company focused on developing regenerative exosome-based therapies for central nervous system injuries. Its lead product, ExoPTEN, has demonstrated strong preclinical data supporting clinical potential in treating acute spinal cord and optic nerve injury, both multi-billion-dollar markets. Regulatory milestones, including obtaining the Orphan Drug Designation, facilitates the roadmap towards clinical trials in the U.S. and Europe. Commercially, the Company is expected to offer solutions to companies interested in quality exosomes and minimally invasive targeted delivery systems for other indications. NurExone has established Exo-Top Inc., a U.S. subsidiary, to anchor its North American activity and growth strategy. For more information, visit www.nurexone.com.