Exhibit 99.1

ProQR Announces First Quarter 2026 Operating and Financial Results

LEIDEN, Netherlands & CAMBRIDGE, Mass., May 12, 2026 – ProQR Therapeutics N.V. (Nasdaq: PRQR) (ProQR), a clinical-stage company dedicated to changing lives through transformative RNA therapies based on its proprietary Axiomer™ RNA editing technology platform, today reported its financial and operating results for the quarter ended March 31, 2026, and provided a business update.

“We are on track to deliver multiple clinical readouts within our current runway, including target engagement data for AX-0810 in the second quarter,” said Daniel A. de Boer, Founder and Chief Executive Officer of ProQR. “We have refined our initial development strategy for AX-0810 to prioritize biliary atresia, where we believe we can generate the most meaningful clinical data in this target patient population, while maintaining flexibility to explore additional indications, including PSC, as the program advances. We also continue to advance our platform more broadly to bring RNA editing therapies to patients.”

Recent Progress and Anticipated Upcoming Events

AX-0810 Advancing Toward Target Engagement Data

AX-0810, ProQR’s lead RNA editing program targeting NTCP, remains on track to report target engagement data from healthy volunteers in the second quarter of 2026.

The Company has selected biliary atresia (BA) as the initial indication for Phase 2 development, based on strong biological rationale and high unmet need. As part of this strategy, ProQR plans to conduct an investigator-initiated trial (IIT) in pediatric participants with BA in China instead of the previously planned adult participant PSC cohort in its Phase 1 program. While PSC remains of interest as a potential setting for broader development, the Company is prioritizing a BA-focused IIT to provide a more direct path to early, data generation in the target patient population, prior to initiation of a Phase 2 study. ProQR is working with investigators to initiate the IIT, with initial clinical data targeted for H1 2027.

Pipeline Expansion and Upcoming Catalysts

ProQR continues to expand its pipeline, with multiple programs advancing toward the clinic:

Scientific Conference Presentations

ProQR is presenting multiple presentations at scientific conferences in May, including TIDES USA, the American Society of Gene & Cell Therapy (ASGCT) Annual Meeting, the RNA Society Annual Meeting, and the European Association for the Study of the Liver (EASL) Congress. Collectively, these presentations expand the body of evidence supporting the breadth and versatility of the Company’s Axiomer RNA editing platform including applications across multiple tissues and disease areas.

Advancing the Axiomer™ Platform

ProQR continues to enhance its Axiomer platform through the integration of AI-enabled discovery and high-throughput screening to accelerate the design and optimization of RNA editing therapeutics.

Board Nomination and Annual General Meeting

Dr. Lykke Hinsch Gylvin, Chief Medical Officer and Head of Global Medicine at Boehringer Ingelheim, has been nominated for appointment to the ProQR Board of Directors, subject to shareholder approval at the upcoming Annual General Meeting, scheduled for June 2, 2026. Dr. Hinsch Gylvin is a seasoned pharmaceutical executive with more than 20 years of global leadership experience spanning all phases of drug development in a broad range of therapeutic areas.

Summary of Anticipated Milestones

Financial Highlights

At March 31, 2026, ProQR held cash and cash equivalents of approximately € 81.1 million, compared to € 92.4 million at December 31, 2025.

Net cash used in operating activities during the first quarter ended March 31, 2026 was € 11.1 million, compared to € 15.8 million used for the same period in 2025.

Research and development (R&D) costs for the quarter ended March 31, 2026 were € 11.8 million, compared to € 12.3 million for the same period last year.

General and administrative costs for the quarter ended March 31, 2026 were € 3.9 million, compared to € 3.2 million for the same period in 2025.

Net loss for the quarter ended March 31, 2026 was € 13.4 million, or € 0.13 per diluted share, compared to € 10.1 million, or € 0.10 per diluted share, for the same period in 2025.

For further financial information for the period ended March 31, 2026, please refer to our Q1 financial report filing available on our website, www.proqr.com under Financials and Filings.

About Axiomer™

ProQR is pioneering a next-generation RNA base editing technology called Axiomer™, which could potentially yield a new class of medicines for diverse types of diseases. Axiomer™ “Editing Oligonucleotides”, or EONs, mediate single nucleotide changes to RNA in a highly specific and targeted way using molecular machinery that is present in human cells called ADAR (Adenosine Deaminase Acting on RNA). Axiomer™ EONs are designed to recruit and direct endogenously expressed ADARs to change an Adenosine (A) to an Inosine (I) in the RNA – an Inosine is translated as a Guanosine (G) – correcting an RNA with a disease-causing mutation back to a normal (wild type) RNA, modulating protein expression, or altering a protein so that it will have a new function that helps prevent or treat disease.

About ProQR

ProQR Therapeutics is dedicated to changing lives through the creation of transformative RNA therapies. ProQR is pioneering a next-generation RNA technology called Axiomer™, which uses a cell’s own editing machinery called ADAR to make specific single nucleotide edits in RNA to reverse a mutation or modulate protein expression and could potentially yield a new class of medicines for both rare and prevalent diseases with unmet need. 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 www.proqr.com.

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 “continue,” "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 regarding our business, technology, strategy, preclinical and clinical model data; our initial pipeline targets and the upcoming strategic priorities and milestones related thereto; the continued advancement of our lead development pipeline programs, including ongoing and planned clinical trials; the ongoing Phase 1 clinical study of AX-0810 in NTCP for cholestatic diseases, including the anticipated timing of initial Phase 1 target engagement data from the first cohort of healthy volunteers in the second quarter of 2026; our expectations regarding the safety and therapeutic benefits of AX-0810, including the planned dosing levels and their efficacy; our ability to collaborate with investigators to execute and recruit for an investigator-initiated trial of AX-0810 in China in pediatric participants with biliary atresia and to generate meaningful data therefrom, including the anticipated timing of initial data readout in H1 2027; risks and uncertainties associated with conducting clinical trials in China, including evolving regulatory requirements; our pipeline targets, including the planned Phase 1 clinical trial of AX-0811 for cholestatic diseases; our ability to recruit for and complete a Phase 1 clinical trial for AX-0811, including the anticipated timing of a CTA filing in mid 2026 and initial data readout by year end 2026; the anticipated first-in-human study of AX-0422 targeting IDUA for Hurler syndrome, with a CTA filing expected in early 2027 and anticipated initial clinical data readout in H1 2027; the anticipated investigator-initiated study in China of AX-2911 targeting PNPLA3 for MASH in H1 2027; our expectations regarding clinical updates across multiple programs in 2026 and 2027; the therapeutic potential and development timeline regarding AX-0810, AX-0811, AX-0422, and AX-2911; the anticipated benefits from our partnership with Ginkgo Bioworks; the role and expected contributions of our AI Advisory Board; our participation at upcoming scientific conferences; the continued development and advancement of our Axiomer platform; the therapeutic potential of our Axiomer RNA editing oligonucleotides and product candidates; the timing, progress and results of our preclinical studies and other development and pipeline activities, including the release of data related thereto; our patent estate, including our anticipated strength and our continued investment in it, as well as the timing of our clinical development; the potential of our technologies and product candidates; the collaboration with Lilly and the intended benefits thereof, including timing for data updates, potential milestones, exercise of an option to expand targets and the receipt of an opt-in payment; our ability to selectively form new partnerships and enter into future collaborations; our financial position and cash-runway to fund our operations into mid 2027, and the anticipated changes to our Board composition, including the nomination of Dr. Lykke Hinsch Gylvin, subject to shareholder approval. 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 expressed or implied by 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 most recent annual report filed on Form 20-F. These risks and uncertainties include, among others, the cost, timing and results of preclinical studies and clinical trials and other development activities by us and our collaborative partners whose operations and activities may be slowed or halted due to shortage and pressure on supply chains and logistics in the global market, economic sanctions and international tariffs; the likelihood of our preclinical and clinical programs being initiated and executed on timelines provided and our reliance on our contract research organizations and predictability of timely enrollment of subjects and patients to advance our clinical trials and maintain their own operations; our reliance on contract manufacturers to supply materials for research and development and the risk of supply interruption from a contract manufacturer; the potential for future data to alter initial and preliminary results of early-stage clinical trials; the unpredictability of the duration and results of the regulatory review of applications or clearances that are necessary to initiate and continue to advance and progress our clinical programs; the ability to secure, maintain and realize the intended benefits of collaborations with partners, including the collaboration with Lilly; the possible impairment of, inability to obtain, and costs to obtain intellectual property rights; possible safety or efficacy concerns that could emerge as new data are generated in research and development; general business, operational, financial and accounting risks, and risks related to litigation and disputes with third parties; and risks related to macroeconomic conditions and market volatility resulting from global economic developments, geopolitical events and conflicts, inflationary pressures, fluctuating interest rates, tariffs and potential for significant changes in U.S. policies and regulatory environment. 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 and media contact: Sarah Kiely ProQR Therapeutics N.V. T: +1 617 599 6228 skiely@proqr.com PROQR THERAPEUTICS N.V. Unaudited Condensed Consolidated Statement of Financial Position

or

Investor contact:
Peter Kelleher
LifeSci Advisors
T: +1 617 430 7579
pkelleher@lifesciadvisors.com

PROQR THERAPEUTICS N.V.
Unaudited Condensed Consolidated Statement of Profit or Loss and Other Comprehensive Income

(€ in thousands, except share and per share data)

PROQR THERAPEUTICS N.V.
Unaudited Condensed Consolidated Statement of Changes in Equity

PROQR THERAPEUTICS N.V.
Unaudited Condensed Consolidated Statement of Cash Flows