Investigational RNA therapy QR-421a for USH2A mediated retinitis pigmentosa & Usher syndrome

QR-421a is an investigational RNA therapy that aims to stop vision loss in people with retinitis pigmentosa (RP) and Usher syndrome due to mutation(s) in a specific part of the USH2A gene, called exon 13.

QR-421a

Disease: USH2A mediated retinitis pigmentosa and Usher syndrome

QR-421a is an RNA therapy that aims to stop vision loss in retinitis pigmentosa (RP) and Usher syndrome type 2 due to mutations in exon 13 of the USH2A gene.

How does QR-421a work?

QR-421a aims to stop vision loss in people with Usher syndrome and retinitis pigmentosa due to mutation(s) in exon 13 of the USH2A gene. Mutations in exon 13 are a common cause of these conditions. The mutations cause a mistake in the USH2A RNA and therefore the cell cannot use the RNA to produce a working USH2A protein that is essential for vision.

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.

Genetic testing

To know what mutation is causing RP or Usher, genetic testing is necessary. Genetic testing is the only way to receive an accurate diagnosis and will help find out if there are treatments or clinical trials available.

Learn about genetic testing

QR-421a clinical trials

Stellar is a Phase 1/2 clinical trial of QR-421a, that is testing whether it is safe and leads to better vision. Results from the trial were positive with QR-421a showing a concordant benefit in multiple measures of vision. QR-421a was also observed to be well tolerated. In parallel to completing this Phase 1/2 trial we are planning to start Phase 2/3 clinical trials for this program.

Learn more about clinical trials and why you should consider participating.

Stellar study - Phase 1/2 clinical trial

Ongoing, not recruiting

Stellar is an international clinical trial of QR-421a in adults with Usher syndrome and retinitis pigmentosa (RP) due to mutation(s) in exon 13 of the USH2A gene. In total 20 participants received a single intravitreal (into the eye) injection or underwent a sham-procedure (simulated intravitreal procedure but no study medicine administered).

Clinical trial results

Results from Stellar suggested the single injection with QR-421a was well tolerated with no serious adverse events reported. The Stellar study also showed benefit in the treated eye in comparison to the untreated eye across multiple eye tests. We have seen this benefit across all participants in the Stellar study.

Based on these positive findings we will finish the Stellar trial and at the same time plan to start two final stage Phase 2/3 clinical studies.

More about Stellar