Circio presents new and differentiating circVec data and corporate update in live webcast

· Significant advantage of circVec confirmed in vivo for therapeuticallyrelevant AAV variants and DNA formats · Distinct expression biology positions circular RNA expression systems as anovel alternative for diseases where current approaches are less suitable · Early data shows 10-fold increase in potency for circVec AAV in heart,opening development opportunities in cardiac genetic disease

Oslo, Norway 28 May 2025 - Circio Holding ASA (OSE: CRNA), a biotechnologycompany developing powerful circular RNA technology for next generationnucleicacid medicine, announces it is hosting a live update webcast at 10:00am CETtoday Wednesday 28 May 2025. In the webcast, Circio management will presentnovel in vivo data for its circular RNA expression technology. This databroadens the therapeutic development and partnership opportunities of thecircVec platform.

In the presentation, Circio´s CTO Dr. Thomas B Hansen will showcase the latestcircVec DNA gene and cell therapy in vivo data. circVec continues to performsubstantially better than equivalent mRNA vectors in multiple settings. Inaddition to increased and prolonged protein expression, a distinct tissueexpression pattern is emerging, pointing to development opportunities inspecific disease areas.

"It is becoming evident that circular RNA-based expression has a completelydifferent biology compared to mRNA vectors. This creates a unique set ofopportunities for Circio´s circVec platform," said Dr. Thomas B Hansen, CTO ofCircio. "Interestingly, the increased and prolonged expression level is morepronounced in certain tissues, and absent in others, which gives us cleartargets to proceed with. Muscle, heart and spleen have emerged as sites wherecircVec is particularly advantageous. As a result, we have identified severalpotential development opportunities in muscle and cardiac genetic disease,whichare not well served by conventional approaches."

Substantial progress has been made on circVec-AAV gene therapy development.Micehave been monitored for up to six months following one systemicadministration,showing a 50% increase in total expression level vs. mRNA-AAV. Importantly,postmortem ex vivo tissue and organ analysis after six months reveal a uniquesignaldistribution. Circio is in the process of exploring these observations infurther detail, and early data indicate 10-fold increased potency for circVec-AAVs designed for specific expression in heart.

"The heart AAV data indicating up to a 10-fold increase in potency for circVecis precisely what we have been working towards achieving," said Dr. Erik DWiklund, CEO of Circio. "Our latest data package points to a strong advantagefor circVec in tissue-specific AAV gene therapy and DNA-format in vivo celltherapy. Following broad interest at the recent ASGCT 2025 conference, Circioisin the process of discussing the latest results with experts in these fieldsandaim to continue development both in house and through partnerships. This willallow us to generate external validation of the circVec technology andaccelerate platform development towards defining Circio´s first therapeuticcandidates."

In the webcast, CEO Dr Erik D Wiklund will also provide a corporate update,anddiscuss the upcoming annual general meeting on 5 June 2025.

Presenters:CEO Dr. Erik Digman WiklundCTO Dr. Thomas Birkballe Hansen

Time: 10:00 CEST on 28 May 2025

Click here to access Teamswebcast (https://teams.microsoft.com/meet/3919530790393?p=D2tS9HOrDxAFf5WhLj)Meeting ID: 391 953 079 039 3Passcode: PB2gk7wt

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 Circiowebpage (http://www.circio.com/)

For further information, please contact:Erik Digman Wiklund, CEOPhone: +47 413 33 536Email: erik.wiklund@circio.com

Neil Hunter - Hunter PRPhone:+44 7821 255568 (Email: neiljameshunter@gmail.com

This information is considered to be inside information pursuant to the EUMarket Abuse Regulation (MAR) and is subject to the disclosure requirementspursuant to MAR article 17 and section 5-12 of the Norwegian SecuritiesTradingAct.

This stock exchange announcement was published by Erik Digman Wiklund, CEO, onbehalf of the Company, at the time and date stated above in this announcement.

About Circio

Building circular RNA expression systems for enhanced gene and cell therapies

Circio Holding ASA is a biotechnology company developing powerful circular RNAvector expression technology for next generation nucleic acid medicine.

Circio has established a unique circular RNA (circRNA) vector expressionplatform for novel DNA, RNA and viral therapeutics. The proprietary circVectechnology is based on a modular genetic cassette design for efficientbiogenesis of multifunctional circRNA inside cells, which can be deployed inmultiple therapeutic settings, including genetic medicine, cell therapy andchronic disease. The circVec platform has demonstrated up to 15-fold enhancedand more significantly more durable protein expression vs. classic mRNA vectorsystems and has the potential to become a new gold-standard platformtechnologyfor nucleic acid and viral therapeutics in the future. The circRNA R&Dactivities are being conducted by the wholly owned subsidiary Circio AB basedatthe Karolinska Institute in Stockholm, Sweden.

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