The US Food and Drug Administration (FDA) has granted breakthrough therapy designation (BTD) to NPI-001 tablets, an investigational therapy developed by Nacuity Pharmaceuticals, for the treatment of patients with retinitis pigmentosa (RP). NPI-001 is a proprietary formulation of N-acetylcysteine amide designed to counter oxidative stress, a central mechanism in retinal cell damage.

The designation follows earlier fast track and orphan drug designations awarded to NPI-001. Breakthrough status is reserved for drugs that target serious conditions and show preliminary evidence of substantial improvement over existing therapies. It provides sponsors with closer FDA guidance and organizational support to expedite development.

Nacuity recently reported positive results from its phase 1/2 SLO RP clinical trial of NPI-001 in patients with RP associated with Usher syndrome. The randomized, placebo-controlled study enrolled 49 patients across 4 sites in Australia and followed them for 2 years. Treatment with NPI-001 slowed photoreceptor loss by more than 50% compared with placebo, with differences evident as early as 6 months. Although retinal sensitivity did not reach statistical significance at 24 months, investigators observed a favorable trend toward slower decline, and effects on ellipsoid zone area and retinal sensitivity were highly correlated. NPI-001 was well tolerated at a daily dose of 500 mg, with more than 80% compliance. The company said a confirmatory trial is planned for 2026.

In a press release, Nacuity said the breakthrough therapy designation marks a significant step in advancing NPI-001 toward late-stage development. RP