Promising results for a first-in-class Usher syndrome IIA therapy

The Dutch biotechnology company ProQR has just presented (March 2021) the first results of a clinical trial, named Stellar, with QR-421a, an antisense oligonucleotide designed to stop vision loss or restore vision in Usher syndrome IIA and non-syndromic retinitis pigmentosa patients due to USH2A exon 13 mutations. The therapeutical approach aims to exclude the exon 13 coding region in the messenger RNA (exon skipping) and, therefore, rescue the function of the USH2A protein.

Participants in the Stellar phase 1/2 clinical trial were administered an intravitreal dose of QR-421a. The treatment was well tolerated and no serious adverse effects were shown. After a single dose of QR-421a, patients showed vision improvement measured by best corrected visual activity (BCVA), static perimetry and retinal imaging (OCT). These benefits were observed in both, early-stage patients and in those with more advanced disease.

Based on the positive results, ProQR announces two pivotal phase 2/3 clinical trials by the end of 2021 to expand and confirm the effectiveness of the treatment, a requested step for its future approval.