Key Findings from AX-0810 Phase 1 Trial

The initial safety data from the first cohort of healthy volunteers indicate a strong safety profile, with no serious adverse events reported over the four-week dosing period. These outcomes are closely aligned with ProQR's non-clinical data, supporting the continuation of treatment.

• No safety signals were detected after 4 weeks of dosing.
• Pharmacokinetics observed were consistent with non-clinical findings.
• Enrollment and dosing in healthy volunteers are ongoing.
• Target engagement data expected in H1 2026.

Expert Insights on the Road Ahead

“The initial human data from AX-0810 mark an important early milestone for ProQR, providing safety and pharmacokinetic observations in healthy volunteers,” stated Dr. Cristina Lopez Lopez, Chief Medical Officer of ProQR. “These data support continued dosing and position us well for the upcoming target engagement readout in the first half of 2026.”

Daniel A. de Boer, Founder and CEO of ProQR, added, “We have made significant progress with our pipeline in 2025, with the selection of Development Candidates for AX-2402 for Rett syndrome and AX-2911 for metabolic-associated steatohepatitis (MASH). This is further enhanced by ongoing collaboration with Eli Lilly, which has resulted in $4.5 million in milestones achieved during the year."

Insights into Development Candidates AX-2402 and AX-2911

ProQR's developmental focus is not limited to AX-0810; the company has selected AX-2402 and AX-2911 as candidates for further development. Both programs showcase the versatility of the Axiomer platform.

AX-2402 for Rett Syndrome

AX-2402 targets the MECP2 gene variant R270X, with a robust preclinical profile prompting plans for a first-in-human trial in 2027. Early data indicate significant functional improvements in mouse models, supported by funding of up to $9.2 million from the Rett Syndrome Research Trust (RSRT).

AX-2911 for MASH

AX-2911 targets the PNPLA3 I148M mutation, associated with metabolic liver disease. Preliminary results show over 80% reduction in hepatic fat content in relevant mouse models, suggesting AX-2911 as a promising disease-modifying option for MASH.

Strategic Collaboration and Financial Outlook

ProQR's collaboration with Eli Lilly has not only provided external validation for the Axiomer platform but also yielded significant financial support. The collaboration achieved $4.5 million in milestones in 2025, enhancing the company's financial position and extending its runway into mid-2027.

Looking ahead, ProQR aims to:

• Report target engagement data from the AX-0810 Phase 1 trial in healthy volunteers in H1 2026.
• Initiate a patient cohort in the AX-0810 trial following healthy volunteer dosing.
• Advance AX-2402 toward a first-in-human trial planned for 2027.
• Continue to disclose preclinical data to highlight the potential of the Axiomer platform.

About AX-0810

AX-0810 is ProQR's first-in-class investigational RNA editing oligonucleotide designed to modulate NTCP function. It aims to address cholestatic diseases characterized by toxic bile acid accumulation in the liver. As the leading candidate from ProQR's Axiomer™ RNA editing pipeline, AX-0810 represents a significant step toward potentially disease-modifying therapeutics for patients.

About Axiomer™

ProQR Therapeutics is at the forefront of RNA-based therapeutics with its pioneering Axiomer™ RNA editing technology. This innovative approach seeks to deliver transformative treatments for a variety of genetic diseases, leveraging the body's natural editing mechanisms.