• circVec boosts AAV potency by up to 40x in the eye and heart indicating significant potential in these two areas; testing in other tissues is ongoing
• New circVec 3.2 design achieves 3x increased expression level vs. previous circVec generations specifically in AAV gene therapy vectors
• circVec may enable >10-fold or more viral dose reduction, addressing key safety concerns and costs challenges of current AAV gene therapy
• First half year report demonstrates continued cost control and financial runway until end of 2025

Oslo, Norway, 28 August 2025 – Circio Holding ASA (OSE: CRNA), a biotechnology company developing powerful circular RNA technology for next generation nucleic acid medicine, today announces it is presenting strengthened in vivo data for its circVec-AAV expression system. The data demonstrates up to 40 times advantage vs. conventional mRNA-based AAVs in multiple settings. Circio management will provide an overview of the new circVec results, as well as a summary of the first half year 2025 financial report, in a live webcast at 10:00am CEST, today, Thursday 28 August 2025.

In the presentation, Circio´s CTO Dr. Thomas B Hansen will showcase the latest circVec generation 3.2. This novel circVec design significantly enhances gene expression from AAV vectors in vivo. The encouraging circVec-AAV heart data presented in May 2025 has now been validated in a larger in vivo repeat experiment and further augmented by circVec 3.2, which delivers up to 40 times protein expression level advantage vs. conventional mRNA-AAV. Circio is now incorporating and testing circVec 3.2 in its portfolio of AAV vectors.

In parallel, Circio is characterizing the performance of circVec-AAVs in several other tissues, and has identified the eye as an organ showing 15 times expression advantage compared to benchmark AAVs. Following successful pilot experiments, broader in vivo testing is currently ongoing. Circio expects to report this data during the second half of 2025.

“Circio has now completed substantial characterization, engineering and optimization of its circVec expression system for gene therapy. These results make it evident that circular RNA-based expression has the potential to substantially improve the therapeutic potency of AAV vectors in a tissue-specific manner. This creates multiple distinct development opportunities for the circVec platform,” said Dr. Thomas B Hansen, CTO of Circio. “A major challenge of conventional mRNA-based AAV gene therapy is the need for extremely high dose levels. This can cause severe toxicity in patients and drives up manufacturing cost and complexity. Our current data package suggests that switching to circVec-based expression may enable 10-fold, or more, dose reduction, which would be a major breakthrough for the AAV gene therapy field.”

During the first half of 2025 Circio has continued to implement tight cost controls with a lean organizational set-up, strictly prioritizing R&D activities that can deliver near-term technology validation and business development opportunities. The extension of the financing commitment by Atlas Capital Markets secures funding until the end of 2025. The company is exploring multiple alternatives to secure new capital, strengthen the shareholder base and thereby minimize the reliance on the convertible bond facility.

“The technical achievements of Circio´s research team continue to impress, especially given our lean, cost-efficient set-up,” said Dr. Lubor Gaal, CFO of Circio. “Importantly, the latest circVec-AAV in vivo results confirm that the robust circVec advantage applies broadly. The data package now includes several tissues, additional AAV capsids and multiple genetic promoters driving expression. These results broaden and strengthen Circio’s data package, and derisks the technology for potential partners and investors. Our aim is to leverage these new data to establish R&D collaborations with AAV expert companies and validate the performance of the circVec platform in their systems. We already have ongoing dialogues and aim to enter multiple such partnerships during 2025-26.

Presenters:
CEO Dr. Erik Digman Wiklund
CFO Dr. Lubor Gaal
CTO Dr. Thomas Birkballe Hansen

Time: 10:00 CEST on 28 August 2025

click here to access the Teams webcast
Meeting ID: 352 997 264 281
Passcode: dj23Wc6o

Participate by phone:
+47 21402155
Phone conference ID: 591397143#

Questions can be submitted in advance by email to Erik D Wiklund: erik.wiklund@circio.com or directly in the live webcast

A recording of the webcast will be made available on the Circio webpage

Reporting material attached to this press release:

• Circio first half year report 2025

• Circio 1H25 Webcast presentation

The report and presentation are also available at www.circio.com