Nacuity’s Antioxidative Therapy NACA Performs Encouragingly in Phase 1/2 Clinical Trial

Nacuity Pharmaceuticals reported positive results for the SLO-RP Phase 1/2 clinical trial in Australia for NPI-001, an oral small molecule known as N-acetylcysteine amide or NACA, which is designed to mitigate oxidative stress, thereby slowing retinal degeneration and vision loss in people with retinitis pigmentosa (RP) and Usher syndrome. Researchers believe NPI-001 can be effective regardless of the mutated gene causing disease. The randomized, placebo-controlled clinical trial enrolled 49 people with Usher syndrome and followed them for two years. The emerging treatment was safe and well tolerated in the trial. The company is planning a confirmatory clinical trial in 2026 in the US and Australia. Details for the confirmatory trial are forthcoming.

In the SLO-RP trial, photoreceptor loss for patients receiving NPI-001 was slowed by 50 percent when compared to those receiving placebo. Photoreceptor loss was assessed by measuring the Ellipsoid Zone (EZ) Area, the area of viable photoreceptors captured using optical coherence tomography (OCT) imaging technology. OCT is used by retinal specialists to assess retinal health and structural changes.

Also in the clinical trial, loss of retinal sensitivity was slowed by nearly 30 percent for patients receiving NPI-001 when compared to retinal sensitivity for those receiving the placebo. Retinal sensitivity was captured using microperimetry, which measures light sensitivity at several points (loci) in the retina. The slowing of retinal sensitivity loss was not statistically significant but correlated with slowing of photoreceptor loss.

 The RD Fund, the Foundation’s venture philanthropy arm, is an original investor in Nacuity.

“These results are promising, and we’re excited by NACA’s potential to slow photoreceptor loss for a broad range of people with RP and Usher syndrome, regardless of their mutated gene,” said Rusty Kelley, PhD, managing director of the RD Fund. “We look forward to the forthcoming clinical trial for hopefully confirming NACA’s efficacy.”

NACA is a modified form of N-acetylcysteine (NAC), a powerful antioxidant approved by the US Food & Drug Administration in 1963 for acetaminophen overdose and other uses. NACA was designed by Nacuity to be more potent and bioavailable to the retina than NAC.

Research has shown that loss of rod photoreceptors in conditions like RP increases damaging oxidative stress in the retina thereby accelerating loss of cone photoreceptors. Rods provide peripheral and night vision. Cones provide the ability to perceive details, colors, and objects in lighted settings.