ProQR to Present Results from Phase 1/2 Trial of QR-421a for Usher Syndrome

LEIDEN, Netherlands & CAMBRIDGE, Mass., March 17, 2021 (GLOBE NEWSWIRE) -- ProQR Therapeutics N.V. (Nasdaq: PRQR) (the “Company”), a company dedicated to changing lives through the creation of transformative RNA therapies for inherited retinal diseases (IRDs), today announced that Company management will present and discuss results from its Phase 1/2 Stellar trial of QR-421a in adults with Usher syndrome and non-syndromic retinitis pigmentosa (nsRP) on March 24, 2021. The data will be announced in a press release and management will host an investor conference call at 8:15 a.m. EDT the same day to discuss the results in detail.

The live and archived webcast of this presentation will be accessible through the Events page of the “Investors and Media” section of the Company’s website,  The dial-in details for the call are +1 631-510-7495 (US), +31 (0)20 714 3545 (NL), conference ID: 8596733. The archived webcast will be available for approximately 30 days following the presentation date.

About the Stellar Phase 1/2 Trial

The Stellar trial is a randomized, single ascending dose, global, multicenter, 24-month study. The study includes a total of 20 patients, of which 14 received a single dose of QR-421a and six received a single sham procedure for masking. The 14 treatment patients enrolled varied in their disease stage and were classified as advanced patients (defined as patients with baseline visual acuity of <70 letters or equivalent to worse than 20/40 on a Snellen chart) or early-moderate patients. Six patients had advanced disease and eight patients had early-moderate disease. Three different dose levels were studied. The population also varied in disease characteristics with both Usher syndrome (n=7) and nsRP (n=7) and genetic background with both homozygous (n= 9) and heterozygous (n=5) subjects for USH2A exon 13 mutations. The majority of the patients were followed for up to 48 weeks, with one patient followed up to 96 weeks.

About Usher Syndrome Type 2a and Non-Syndromic Retinitis Pigmentosa

Usher syndrome is the leading cause of combined deafness and blindness. People with Usher syndrome type 2a are usually born with hearing loss and start to have progressive vision loss during adulthood. The vision loss can also occur without hearing loss in a disease called non-syndromic retinitis pigmentosa. Usher syndrome type 2a and non-syndromic retinitis pigmentosa can be caused by mutations in the USH2A gene. To date, there are no pharmaceutical treatments approved or in clinical development that treat the vision loss associated with mutations in USH2A.

About QR-421a

QR-421a is a first-in-class investigational RNA therapy designed to address the underlying cause of vision loss in Usher syndrome type 2a and non-syndromic retinitis pigmentosa due to mutations in exon 13 of the USH2A gene. QR-421a is designed to restore functional usherin protein by using an exon skipping approach with the aim to stop or reverse vision loss in patients. QR-421a is intended to be administered through intravitreal injections in the eye and has been granted orphan drug designation in the US and the European Union and received fast-track and rare pediatric disease designations from the FDA.

About ProQR

ProQR Therapeutics is dedicated to changing lives through the creation of transformative RNA therapies for the treatment of severe genetic rare diseases such as Leber congenital amaurosis 10, Usher syndrome and retinitis pigmentosa. Based on our unique proprietary RNA repair platform technologies we are growing our pipeline with patients and loved ones in mind.

Learn more about ProQR at

Forward Looking Statements

This press release contains forward-looking statements. All statements other than statements of historical fact are forward-looking statements, which are often indicated by terms such as "anticipate," "believe," "could," "estimate," "expect," "goal," "intend," "look forward to", "may," "plan," "potential," "predict," "project," "should," "will," "would" and similar expressions. Such forward-looking statements include, but are not limited to, statements relating to our announcement of results from our QR-421a clinical trial, and the clinical development and the therapeutic potential of our product candidates, including QR-421a. Forward-looking statements are based on management's beliefs and assumptions and on information available to management only as of the date of this press release. Our actual results could differ materially from those anticipated in these forward-looking statements for many reasons, including, without limitation, the risks, uncertainties and other factors in our filings made with the Securities and Exchange Commission, including certain sections of our annual report filed on Form 20-F. Given these risks, uncertainties and other factors, you should not place undue reliance on these forward-looking statements, and we assume no obligation to update these forward-looking statements, even if new information becomes available in the future, except as required by law.

ProQR Therapeutics N.V.

Investor Contact:
Sarah Kiely
ProQR Therapeutics N.V.
T: +1 617 599 6228
Hans Vitzthum
LifeSci Advisors
T: +1 617 535 7743

Media Contact:
Cherilyn Cecchini, MD
LifeSci Communications
T: +1 646 876 5196

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