ProQR Therapeutics announced that investigational drug QRX-421 for Usher syndrome has received orphan drug designation (ODD) from the FDA and EMA. This marks the third drug candidate in the company’s ophthalmology pipeline and the fourth drug in the broader pipeline to receive ODD from the FDA and EMA. QR-421 is a first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of Usher syndrome due to mutations in exon 13 of the USH2A gene. Usher syndrome is the leading cause of combined deafness and blindness. 

ODD in the U.S. and European Union provides a special status for investigational drugs being developed for rare diseases. The ODD programs offer development program tax benefits and a waiver of the NDA application user fee, as well as market exclusivity for up to seven years in the U.S. and 10 years in the European Union following market approval.

“We are pleased to have ODD designation for both our programs targeting Usher syndrome in the U.S. and EU, representing yet another important milestone for our company and highlighting the unmet need for patients in this disease,” said David M. Rodman, M.D., Chief Development Strategy Officer of ProQR. “At ProQR, we are focused on designing accelerated development strategies that capitalize on our oligonucleotide approach to potentially bring our novel medicines to patients quicker and receiving ODD designations for these is an important step towards this goal.”

ProQR’s ophthalmology pipeline includes the following:

• QR-110 for Leber’s congenital amaurosis 10 (LCA 10) due to the p.Cys998X mutation, which received IND and CTA clearance and is in clinical development (PQ-110-001 Phase 1/2 safety and efficacy study). QR-110 was also granted Fast Track designation by the FDA and ODD designation by the FDA and EMA.
• QRX-421 for Usher syndrome type 2 due to exon 13 mutations in the USH2A gene, for which a clinical candidate has been selected and is ready for IND enabling development studies.
• QRX-411 for Usher syndrome type 2 due to the PE-40 mutation in the USH2A gene, for which a clinical candidate has been selected and is ready for IND enabling development studies. QRX-411 also received ODD designation by the FDA and EMA.
• QRX-1011 for Stargardt’s disease due to c.5461-10T>C mutations in the ABCA4 gene, which is in optimization phase.
• QRX-504 for Fuchs endothelial corneal dystrophy (FECD), for which a clinical candidate has been selected and is ready for IND enabling development studies.

QRX-421 is a first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of Usher syndrome due to mutations in exon 13 of the USH2A gene. Mutations in this exon can cause loss of functional USH2A protein that causes the disease. QRX-421 is designed to exclude exon 13 from the mRNA (exon skipping) and produce truncated but functional USH2A protein, thereby modifying the underlying disease.

Usher syndrome is the leading cause of combined deafness and blindness. Patients with this syndrome generally progress to a stage in which they have very limited central vision and moderate to severe deafness. To date, there are no treatments approved or products in clinical development that treat the vision loss associated with Usher syndrome type 2. Usher syndrome type 2 is one of the most common forms of Usher syndrome and is caused by mutations in the USH2A gene.