NPI-001 shows more than 50% reduction in photoreceptor loss caused by RP associated with USH over two years

NPI-001 was well tolerated, with no persistent drug-related adverse events

Results were leveraged to design confirmatory trial planned for 2026

Nacuity Pharmaceuticals, Inc. (Nacuity), a clinical-stage biopharmaceutical company focused on innovative treatment of ocular diseases involving oxidative stress,  announced positive, new results from the SLO-RP Phase 1/2 clinical trial evaluating NPI-001 tablets to treat patients with retinitis pigmentosa (RP) associated with Usher syndrome (USH).

“These results provide important clinical validation of NPI-001’s potential to slow photoreceptor loss in RP associated with USH,” said Halden Conner, Chairman, CEO and Co-Founder of Nacuity. “The trial directly informed the design of a confirmatory study, which we plan to initiate in 2026. This marks a pivotal step in advancing NPI-001 toward approval for this underserved patient population.”

The SLO-RP core trial is a randomized, placebo-controlled, multicenter trial designed to evaluate the safety, tolerability and efficacy of NPI-001 tablets versus placebo in patients with vision loss due to RP-associated USH. The trial, conducted at four clinical sites in Australia, enrolled 49 patients who were administered oral NPI-001 or placebo tablets twice a day and followed over two years. Ellipsoid Zone (EZ) Area (SD-OCT), an indication of photoreceptor health, was measured by masked experts at a central reading center. Retinal sensitivity was assessed by MAIA microperimetry, a measure of functional vision. The database lock for this trial was completed in June 2025.

Key highlights of the data are as follows:

• NPI-001 slowed photoreceptor loss by more than 50% over two years
• Following daily dosing of NPI-001, loss of photoreceptors was significantly lower than with placebo, starting at 6 months and continuing throughout the 24-month study
• Retinal sensitivity did not reach statistical significance at 24 months, but a favorable trend was observed in participants treated with NPI-001, who demonstrated nearly 30% slower loss of visual function compared to those receiving placebo
• Effects on EZ area and retinal sensitivity were highly correlated
• NPI-001 was safe and well-tolerated at dose levels of 500mg/day, with over 80% compliance with planned dosing
  
  

“Available treatment for RP benefits only a small fraction of patients experiencing progressive vision loss,” said Jami Kern, Ph.D., Senior Vice President and Chief Clinical Officer of Nacuity. “These findings reinforce NPI-001’s promise as a differentiated and much-needed therapy for the broader RP community still awaiting treatment options.”

“NPI-001 is the only small molecule drug for which a measurable treatment effect has ever been objectively demonstrated for RP. These results constitute initial Proof of Concept for the treatment of RP with NPI-001 tablets and provide support for further studies of this drug as a gene-agnostic treatment,” said Mark Pennesi, MD, Ph.D., Director of Ophthalmic Genetics at the Retina Foundation of the Southwest, Dallas, Texas.

Nacuity has partnered with the Foundation Fighting Blindness on various initiatives related to the development of NPI-001, including trial design, awareness and education and strategic guidance. The Foundation has also provided funding through its venture arm, the Retinal Degeneration Fund (RD Fund).

“On behalf of the community affected by RP, we are encouraged by the data showing EZ Area preservation and eager to seek confirmation of these results in a registrational trial,” said Rusty Kelly, Ph.D., Managing Director of the RD Fund.