News items Genetic patch 'inhibits' blindness in patients with Usher syndrome

14 April 2021

This week (March 24th) Leiden-based biotech company ProQR Therapeutics presented the positive results of the Stellar trial, a clinical phase I/II study testing the safety and efficacy of the molecule QR-421a in 14 patients. The promising result was achieved with an agent that in its earliest phase was developed by researchers at Radboudumc.

"QR-421a is a genetic patch that allows a specific part of the USH2A gene to be covered," says Dr. Erwin van Wijk, in response to the news. "Some patients with Usher syndrome have a mistake, a mutation in that part of the gene. These hereditary errors cause people to eventually lose both their sight and their hearing. By covering the mistake with this patch, you should be able to prevent these problems. Regular, but somewhat smaller proteins will then be produced again. The expectation is that these proteins will function well enough to inhibit the deterioration of vision."

From licence to Leiden

The treatment method (exon skipping) from which ProQR's QR-421a molecule originated was developed years ago, within Van Wijk's research group. Van Wijk is part of the Hearing & Genes group that is part of the Department of ENT at Radboudumc. The specific method that was developed and patented here was licensed to ProQR. They then further developed it, in collaboration with Radboudumc, into the product that has now been tested.

Further applications

In a press release, the company has now shared that the molecule was well tolerated at all doses tested, no serious side effects were seen, and vision improved somewhat in everyone. Given these positive results, they plan to start follow-up studies at the end of this year.

Van Wijk's research group is already working on the development of a possible treatment for another type of Usher syndrome, namely Usher syndrome type 2C (article in Dutch) (USH2C) using minigenes. The principle of the genetic patch is now also being investigated, albeit with a different approach, as a possible therapy for other disorders, such as for DFNA9 (article in Dutch).


Read more about the Usher syndrom (in Dutch)

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Pieter Lomans


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