Usher syndrome is a genetic disorder that presents recessive inheritance and is characterized by hearing loss and retinitis pigmentosa, traits that may be total or partial. The prevalence of this disease is 1: 30,000 individuals considering the three types of USHER identified, the most common being type II (60% of cases), caused mostly by the USH2A gene.
There was no treatment available for this type of genetic disease, however, the biotech company ProQR has developed a novel therapeutic strategy with QR-421a STELLAR, at present in clinical phase 1/2. This therapy is based on the use of “antisense” oligonucleotides that promote the deletion (deletion) of exon 13 of the mRNA and prevent the pathogenic mutations localized in this exon to severely affect the functionality of the protein encoded by this gene. Given that many pathogenic changes are concentrated in this region of the gene (exon 13), this therapy could be applied to more than 16,000 patients.
On March 11 (2019) ProQR announced the administration of the first dose of the drug QR-421a STELLAR to the first of eighteen adults enclosed in this trail. The patient has received a single dose of treatment by intravitreal injection into one eye. The purpose of this phase of the clinical study is to determine the absence of side effects and characterize the appropriate doses of the drug. In the medium and long term, the objectives are to stop the progression of the disease and reverse the loss of vision.