First Patient Dosed in Clinical Trial for Usher Syndrome Type 2

According to a story from, ProQR Therapeutics N.V. recently announced that it has begun dosing patients in its Phase 1/2 clinical trial. This trial is testing the company’s investigational product candidate QR-421a, which is being tested as a treatment for Usher syndrome type 2, a genetic disorder that can cause deafness and blindness. ProQR is dedicated to the development of transformative RNA-based therapies for serious rare genetic diseases.

About Usher Syndrome

Usher syndrome is the leading cause of deafblindness (the state of being both blind and deaf); however, the disorder is still generally rare. The syndrome is currently uncurable and there are three different types. There are a total of 11 different genes that, if mutated, can cause the disorder. Usher syndrome type 2 is characterized by milder hearing impairment and delayed onset of vision decline. It is linked to mutations of the DFNB31, USH2A, and GPR98 genes. This type may be more common than previously thought and many patients may be undiagnosed. Vision loss is linked to retinitis pigmentosa, in which the retinal cells degenerate over time, and hearing loss is due to defects of the inner ear. There is no known treatment that can stop the progression of symptoms; gene therapy may be the most effective avenue for research. The rate of disease progression can vary drastically from person to person. To learn more about Usher syndrome, click here.

About QR-421a

ProQR is also interested in testing QR-421a in patients with retinitis pigmentosa that is not linked to Usher syndrome. The RNA based drug is intended to treat Usher syndrome type 2 that is linked USH2A mutations that affect Exon 13. This gene normally codes for a protein called Usherin that is deficient in patients with this mutation. QR-421a utilizes an exon-skipping method (which has also been tested in certain therapies for Duchenne muscular dystrophy) with the goal of restoring the function of the Usherin protein.

The trial will include a total of 18 adult patients that have type 2 Usher syndrome. The trial will be conducted at a total of seven sites in Europe and North America. Preliminary data from the trial is expected to become available later this year.

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