“First-in-class” treatment for vision loss in Usher syndrome takes a step towards clinical testing

Posted on: Thursday 6 December 2018

A potentially transformative new treatment for vision loss in Usher syndrome type 2 has been given the go-ahead for initial clinical testing in a small number of adults living with the condition.

Dutch biotechnology company ProQR Therapeutics announced this week that the U.S. Food and Drug Administration has approved its Investigational New Drug (IND) application for the new therapeutic molecule, known as QR-421a. This comes hot on the heels of the IND approval for a gene editing treatment for Leber Congenital Amaurosis, which we reported earlier.

Usher syndrome is the leading cause of combined vision and hearing loss, with a significant proportion of cases being associated with faults in the USH2A gene. USH2A provides the instructions for building a protein called usherin, which is thought to play an essential role in the development and support of cells in the retina and inner ear. Mutations in the gene result in a lack of functional usherin.

QR-421a targets and effectively ‘silences’ the faulty section of the USH2A gene in RNA, the intermediary molecule that is used by cells to translate the genetic code from DNA into a completed protein. This results in a shortened but nonetheless functional usherin molecule, thereby potentially modifying the progression of retinal degeneration. QR-421a is the first treatment of its type and, if it is successful, will pave the way for similar therapies to target other genes.

ProQR now plans to start enrolling approximately 18 adults with USH2A-associated sight loss into an early stage clinical trial, which will be known as the STELLAR trial. It will be conducted at expert sites in the USA and Europe and will investigate the safety and tolerability of gradually escalating doses of QR-421a, along with assessments of any beneficial effects on visual function and retinal structure. Each trial participant will be given one injection of QR-421a into one eye, with the other eye acting as a comparison. This treatment is aimed at the eye only and will not impact on any hearing loss. There are currently no plans for a UK centre for this trial.

For further updates on the progress of this treatment through the clinical trials process, keep an eye on the Research News section of our website.