FDA grants breakthrough therapy designation to Nacuity’s NPI-001 for retinitis pigmentosa

The US Food and Drug Administration (FDA) has granted Nacuity Pharmaceuticals’ N-acetylcysteine amide tablets (NPI-001) a breakthrough therapy designation.

NPI-001 is Nacuity’s investigational therapy for the treatment of patients with retinitis pigmentosa (RP). It is a GMP-grade formulation of N-acetylcysteine amide developed to target oxidative stress. According to the company, preclinical results show that NPI-001 “boosts glutathione to stop chemically aggressive oxygen molecules from damaging retinal cells.”

G. Michael Wall, PhD, senior vice president and chief scientific officer of Nacuity Pharmaceuticals, commented on the FDA’s decision in a press release from the company.¹

“Breakthrough Therapy Designation represents [an] objective assessment by the FDA that early clinical evidence supports the potential of NPI-001 tablets to deliver substantial treatment effects for patients with retinitis pigmentosa, a serious blinding disease. This recognition represents a key value-creating milestone for Nacuity and underscores our commitment to efficiently advancing NPI-001 toward late-stage development,” said Wall.

The company noted a benefit of breakthrough therapy designation is that it makes it eligible for “intensive guidance on efficient drug development and organizational commitment from the FDA.”

RP affects an estimated 1.5 million people globally. The disease progressively damages the retina, leading to the breakdown of photoreceptor cells responsible for sight. This typically starts with night blindness and advances to the loss of peripheral, color, and central vision.²

A randomized, placebo-controlled, double-masked, multicenter, phase 1/2 clinical trial of NPI-001 tablets in patients with RP (NCT04355689) showed that NPI-001 slowed photoreceptor loss by more than 50% over 2 years and that following daily dosing, loss of photoreceptors was significantly lower than with placebo.³

The trial enrolled 49 patients and was conducted at 4 clinical sites across Australia. Patients were administered oral NPI-001 or placebo tablets twice a day and followed over 2 years.³

The company noted that while retinal sensitivity did not reach statistical significance at 24 months, patients demonstrated nearly 30% slower loss of visual function than those receiving placebo.³

Jami Kern, PhD, senior vice president and chief clinical officer at Nacuity, commented on the trial results, saying, “Available treatment for RP benefits only a small fraction of patients experiencing progressive vision loss. These findings reinforce NPI-001’s promise as a differentiated and much-needed therapy for the broader RP community still awaiting treatment options.”³

At the beginning of 2025, the FDA granted a fast track designation to NPI-001 and an orphan drug designation for the treatment of RP, which provides 7 years of US FDA regulatory exclusivity for the product upon regulatory approval.⁴

References

1. Nacuity Pharmaceuticals granted US FDA breakthrough therapy designation for NPI-001 (N-acetylcysteine amide) tablets for the treatment of retinitis pigmentosa. News release. Nacuity Pharmaceuticals, Inc. October 2, 2025. Accessed October 3, 2025. https://www.nacuity.com/news/nacuity-pharmaceuticals-granted-u-s-fda-breakthrough-therapy-designation-for-npi-001-n-acetylcysteine-amide-tablets-for-the-treatment-of-retinitis-pigmentosa/

2. Hutton D. AAO 2024: New gene therapy shows promise for treatment of retinitis pigmentosa. Ophthalmology Times. October 20, 2024. Accessed October 3, 2025. https://www.ophthalmologytimes.com/view/aao-2024-new-gene-therapy-shows-promise-for-treatment-of-retinitis-pigmentosa

3. Nacuity Pharmaceuticals announces positive data from clinical trial evaluating NPI-001 to treat retinitis pigmentosa associated with Usher syndrome. News release. Nacuity Pharmaceuticals, Inc. September 11, 2025. Accessed October 3, 2025. https://www.nacuity.com/news/nacuity-pharmaceuticals-announces-positive-data-from-clinical-trial-evaluating-npi-001-to-treat-retinitis-pigmentosa-associated-with-usher-syndrome/

4. Joy J. FDA grants fast track designation to N-acetylcysteine amide tablets from Nacuity Pharmaceuticals. Ophthalmology Times. January 23, 2025. Accessed October 3, 2025. https://www.ophthalmologytimes.com/view/fda-grants-fast-track-designation-to-n-acetylcysteine-amide-tablets-from-nacuity-pharmaceuticals