ICYMI: Quoin's QRX003 Receives FDA Orphan Drug Status for Netherton Syndrome

Last week, the US Food and Drug Administration (FDA) granted Orphan Drug Designation (ODD) to QRX003, the lead product candidate of Quoin Pharmaceuticals.¹ The therapy, which previously received Orphan Drug Designation by the European Medicines Agency (EMA) in May and Rare Pediatric Disease (RPD) Designation in June, is a novel therapy for Netherton Syndrome.²

With this designation, the company receives several benefits, including tax credits for qualified clinical testing, waiver or partial payment of FDA application fees, and 7 years of market exclusivity upon approval. If approved, QRX003 would be the first approved treatment for Netherton Syndrome.

“Receiving Orphan Drug Designation from the FDA is yet another important milestone in our mission to bring QRX003 to patients suffering with Netherton Syndrome,” Michael Myers, PhD, CEO of Quoin Pharmaceuticals, said in a statement. “Together with the EMA designation granted earlier in the year, this latest recognition by the FDA could potentially help facilitate the pathway of QRX003 to approval in the US whilst providing significant data protection to the product, if approved. Quoin remains steadfastly committed to completing the clinical development of QRX003 with a high degree of urgency on behalf of patients and families living with this devastating disease.”¹

Netherton Syndrome is a severe, autosomal recessive genetic skin disorder caused by mutations in the SPINK5 gene. This results in a deficiency of LEKTI, a serine protease inhibitor, leading to unregulated kallikrein activity and subsequent skin barrier dysfunction, excessive desquamation, chronic inflammation, and debilitating pruritus.

QRX003 is a topical lotion containing a broad-spectrum serine protease inhibitor. Designed to inhibit the kallikrein proteases implicated in NS pathology, QRX003 aims to restore skin barrier integrity and mitigate key symptoms. In earlier clinical data, QRX003 demonstrated encouraging therapeutic activity, including rapid and sustained skin healing, resolution of pruritus, and elimination of night-time sleep disturbances.

In an open-label, 12-week study, clinical improvements observed during treatment were substantial.³ At the end of 12 weeks, the subject's Modified Ichthyosis Area of Severity Index (M-IASI) score improved from 18 at baseline to 3, and Worst Itch Numeric Rating Scale (WINRS) dropped from 7 to 2. The Investigator’s Global Assessment (IGA) also improved from “moderate” to “almost clear.” However, 4 weeks after treatment discontinuation, all clinical endpoints returned to baseline levels, indicating complete loss of therapeutic benefit. For example, the M-IASI score reverted to 18, and IGA returned to “moderate.”

Furthermore, the 4% formulation of QRX003 is currently being evaluated in 2 late-stage whole-body pivotal clinical trials, recruiting 24 to 30 patients across 6 US and up to 6 international sites. Enrollment in both of these studies is expected to be completed in the first quarter of 2026, with top-line data and NDA submission anticipated later in the year.

“These data provide the clearest clinical evidence to date that the active ingredient in QRX003 is a competitive broad-spectrum serine protease inhibitor. The rapid reversal of benefit upon discontinuation highlights the critical need for chronic whole-body treatment. We remain committed to completing development expeditiously to make QRX003 widely available to the Netherton community upon approval,” Myers said earlier this year.

References

1. Quoin Pharmaceuticals Announces U.S. FDA Grants Orphan Drug Designation for QRX003 in Netherton Syndrome. News release. Quoin Pharmaceuticals. Published October 21, 2025. Accessed October 27, 2025. https://investors.quoinpharma.com/news-releases/news-release-details/quoin-pharmaceuticals-announces-us-fda-grants-orphan-drug

2. Quoin Pharmaceuticals Announces FDA Grants Rare Pediatric Disease Designation for QRX003 in Netherton Syndrome. News release. Global Newswire. June 24, 2025. Accessed October 27, 2025. https://www.globenewswire.com/news-release/2025/06/24/3104239/0/en/Quoin-Pharmaceuticals-Announces-FDA-Grants-Rare-Pediatric-Disease-Designation-for-QRX003-in-Netherton-Syndrome.html

3. Quoin Pharmaceuticals announces further clinical evidence of QRX003 effectiveness in Netherton Syndrome. News release. Quoin Pharmaceuticals. Published January 23, 2024. Accessed October 27, 2025. https://investors.quoinpharma.com/news-releases/news-release-details/quoin-pharmaceuticals-announces-further-clinical-evidence-qrx003