Positive results of QR-421a Phase 1/2 Clinical Trial for Usher Syndrome and non-syndromic Retinitis Pigmentosa

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.

Stellar study
The Stellar study is a first-in-human clinical trial of the medicine QR-421a. The Phase 1/2 study includes adults that experience different levels of vision loss due to mutation(s) in exon 13 of the USH2A gene. This trial aims to study the safetly profile and efficacy of QR-421a.

QR-421a is an investigational RNA therapy designed to skip exon 13 in the RNA with the aim to stop vision loss.

A total of 20 clinical trial participants took part in the Stellar study. The trial design consisted of four study groups of which three groups received QR-421a at three different dose levels. A fourth group received sham treatment, where an intravitreal injection is mimicked but no injection or study drug is given. For each participant one eye was treated with a single injection of QR-421a or sham, and the fellow untreated eye was a control.

Summary

QR-421a was observed to be 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).

Next steps
Based on the safety profile and early evidence of efficacy observed to date, ProQR plans to conduct two final stage/pivotal Phase 2/3 clinical trials.

The two-final stage/pivotal Phase 2/3 clinical trials, named: Sirius and Celeste, will study two different patient populations.
The Sirius study is a Phase 2/3 trial that will focus on advanced clinical trial participants with BCVA of equal or worse than 20/40. The preliminary design for Sirius is a doublemasked, randomized, controlled, 24-month, multiple-dose study.
In parallel to Sirius, the Celeste study is a Phase 2/3 trial focusing on early-moderate clinical trial participants with BCVA of better than 20/40. The preliminary design for Celeste is a double-masked, randomized, controlled, 24-month, multiple-dose study.

This study is based on the research and findings of Dr. Erwin van Wijk at the Radboudumc

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