Regulatory press release

Circio presents data that further strengthens and broadens its circVec circular RNA expression platform

New circVec 4.0 construct boosts gene expression level by 50% on top of highly efficient generation 3 design
Validation and enhancement of circVec-AAV in heart, showing higher yield, improved tissue selectivity and reduced toxicity
circVec-AAV advantage in brain shown for the first time, opening new opportunity to address major unmet medical needs in CNS disease
The recently announced R&D agreement with a big pharma demonstrates Circio´s position as the leader in circular RNA gene expression technology
Flexible access to capital available through 1Q 2026

Oslo, Norway, 24 November 2025 – Circio Holding ASA (OSE: CRNA), a biotechnology company developing novel circular RNA expression technology for gene and cell therapy, today announces it is presenting additional and substantially strengthened in vivo data for its circVec-AAV expression platform. The latest results validate and expand on the previously presented 40 times advantage compared to conventional mRNA-based AAVs in heart. Circio management will provide an overview of the new circVec results, as well as a business development and finance update, in a live webcast at 10:00am CET, today, Monday 24 November 2025.

In the presentation, Circio´s CTO Dr. Thomas B Hansen will showcase the latest circVec generation 4 design. This new circVec construct incorporates a novel genetic element that provides a 50% boost over circVec generation 3, which was already performing at a very high level compared to conventional mRNA-based expression systems.

The strong circVec-AAV heart data first presented in May 2025 has been validated and expanded, adding 50% further improvement with circVec 4.0. Live in vivo tracking and ex vivo tissue analyses demonstrate that heart-specific circVec-AAV consistently achieves around 40-fold increased gene expression, improved tissue specificity and reduced toxicity.

These results clearly demonstrate the potential of the circVec platform to improve conventional AAV vectors. As such, the circVec technology addresses major caveats of the current gold-standard approach and offers a solution to make AAV gene therapy safer and more commercially viable.

In parallel, Circio is testing circVec performance in several other tissues. Seven-fold increased activity in the eye for locally delivered circVec-AAV was presented in 3Q 2025. These important findings are now being further explored in ongoing in vivo experiments. Today, Circio presents emerging AAV in vivo data showing 4-fold increased expression in the brain, which opens central nervous system (CNS) indications as a novel circVec development opportunity. Gene therapy for diseases of the eye and CNS represent areas of increasing biopharma activity, as evidenced by several recent strategic transactions by major pharma companies.

“Circio has been undertaking broad characterization, engineering and optimization of the circVec AAV platform. As a result, we now have an in vivo data package that confirms enhanced expression, better target selectivity and reduced toxicity compared to conventional AAVs,” said Dr. Thomas B Hansen, CTO of Circio. “These results clearly demonstrate the significant potential of circVec to make heart disease gene therapies more effective and safer for patients. Early data suggests that the circVec advantages also apply for AAVs delivered locally to the eye and CNS, and we are currently exploring these findings in a set of ongoing in vivo experiments. In addition, we are continuing to enhance the underlying circVec technology platform with novel design features. We are expanding our science team in Stockholm to advance these opportunities, and look forward to an exciting 2026 with many important R&D milestones.”

During 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. Four funding tranches of NOK 4 million remain available from the financing commitment extension by Atlas, which provides flexible access to capital through Q1 2026. Based on the recent strong data and BD activity, Circio is exploring multiple alternatives to secure additional financing to enable further expansion and acceleration of its R&D operations.

“The technical achievements of Circio´s research team continue to impress, especially given our lean, cost-efficient set-up,” said Dr. Erik Digman Wiklund, CEO of Circio. “These achievements have now led to Circio entering its first agreement with a major pharmaceutical company. This provides important validation of our circVec technology and opens novel therapeutic and commercial possibilities for the future. We are expanding the circVec platform with both gene and cell therapy programs, which we anticipate will create several opportunities for additional partnerships.”

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

Time: 10:00 CET on 24 November 2025

Click here to access Teams webcast
Meeting ID: 366 918 860 415 63
Passcode: Kn2Pq9pM

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

About Circio
Building circular RNA expression systems for enhanced gene and cell therapies

Circio Holding ASA is a biotechnology company developing novel circular RNA expression technology for gene and cell therapy.

Circio has established a unique circular RNA (circRNA) vector expression technology for next generation RNA, DNA and viral therapeutics. The proprietary circVec platform is based on a modular genetic construct designed for efficient biogenesis of multifunctional circRNA inside target cells. The circVec platform has applications in multiple therapeutic settings, including genetic medicine, cell therapy and chronic disease. It has demonstrated 75-fold increased RNA half-life and up to 40-fold enhanced protein expression vs. conventional mRNA-based viral and non-viral vector systems, with the potential to become a new gold-standard gene expression technology. The circVec R&D activities are being conducted by the wholly owned subsidiary Circio AB in Stockholm, Sweden.

In parallel, Circio is continuing to develop its legacy immuno-oncology program, TG01, through cost-efficient external academic and industry collaborations. TG01 targets RAS-mutated cancers and is being tested in two clinical trials in Norway and the USA. TG01 is a therapeutic peptide vaccine adjuvanted by STIMULON QS-21 licensed from Agenus Inc.