News from ProQR

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April 20, 2021

News from ProQR

Retinitis Pigmentosa and Usher Syndrome – ProQR has announced positive results of their Usher syndrome and retinitis pigmentosa clinical study Stellar, which has met all its stated objectives. This marks a crucial milestone in their ongoing inherited retinal disease research.

ProQR has published positive results from its Phase 1/2 Stellar trial of QR-421a, an investigational RNA therapy for the treatment of Usher syndrome and retinitis pigmentosa (RP) due to mutation(s) in exon 13 of the USH2A gene. QR-421a aims to stop vision loss or restore vision in people with a mutation in a specific part of the USH2A gene, called exon 13. QR-421a works by binding to the mutated USH2A RNA and exclude exon 13 from the RNA. This approach is known as exon skipping. The cells in the retina can then produce a slightly shorter but functional USH2A protein. With only one injection of QR-421a, the Stellar study showed benefit in the treated eye in comparison to the untreated eye across multiple eye tests. This benefit was seen across all participants in the study, which included patients  with both advanced vision loss as well as early to moderate vision loss.

This trial studied the safety and efficacy of RNA therapy designed to skip exon 13 in the RNA with the aim to stop vision loss. A total of 20 participants took part in the Stellar study. Results showed that QR-421a was well tolerated with no serious adverse events reported.  QR-421a also demonstrated benefit in multiple measures of vision, including best corrected visual activity (BCVA), static perimetry, and retinal imaging (OCT).

ProQR will now proceed to an open label extension study, named the Helia trial.  

Professor Robert Koenekoop, from the Montreal Children’s Hospital and McGill University in Canada stated:

“The safety profile and efficacy findings for QR-421a are very encouraging. Usher syndrome and non-syndromic retinitis pigmentosa due to USH2A exon 13 mutations are devastating retinal diseases representing a high unmet medical need, as there are no approved therapies to treat the severe vision loss associated with these diseases”.


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