· Significant advantage of circVec confirmed in vivo for therapeutically
relevant AAV variants and DNA formats
  · Distinct expression biology positions circular RNA expression systems as a
novel 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 biotechnology
company developing powerful circular RNA technology for next generation nucleic
acid medicine, announces it is hosting a live update webcast at 10:00am CET
today Wednesday 28 May 2025. In the webcast, Circio management will present
novel in vivo data for its circular RNA expression technology. This data
broadens the therapeutic development and partnership opportunities of the
circVec platform.

In the presentation, CircioŽs CTO Dr. Thomas B Hansen will showcase the latest
circVec DNA gene and cell therapy in vivo data. circVec continues to perform
substantially better than equivalent mRNA vectors in multiple settings. In
addition to increased and prolonged protein expression, a distinct tissue
expression pattern is emerging, pointing to development opportunities in
specific disease areas.

"It is becoming evident that circular RNA-based expression has a completely
different biology compared to mRNA vectors. This creates a unique set of
opportunities for CircioŽs circVec platform," said Dr. Thomas B Hansen, CTO of
Circio. "Interestingly, the increased and prolonged expression level is more
pronounced in certain tissues, and absent in others, which gives us clear
targets to proceed with. Muscle, heart and spleen have emerged as sites where
circVec is particularly advantageous. As a result, we have identified several
potential development opportunities in muscle and cardiac genetic disease, which
are not well served by conventional approaches."

Substantial progress has been made on circVec-AAV gene therapy development. Mice
have been monitored for up to six months following one systemic administration,
showing a 50% increase in total expression level vs. mRNA-AAV. Importantly, post
mortem ex vivo tissue and organ analysis after six months reveal a unique signal
distribution. Circio is in the process of exploring these observations in
further 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 circVec
is precisely what we have been working towards achieving," said Dr. Erik D
Wiklund, CEO of Circio. "Our latest data package points to a strong advantage
for circVec in tissue-specific AAV gene therapy and DNA-format in vivo cell
therapy. Following broad interest at the recent ASGCT 2025 conference, Circio is
in the process of discussing the latest results with experts in these fields and
aim to continue development both in house and through partnerships. This will
allow us to generate external validation of the circVec technology and
accelerate platform development towards defining CircioŽs first therapeutic
candidates."

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

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

Time: 10:00 CEST on 28 May 2025

Click here to access Teams
webcast (https://teams.microsoft.com/meet/3919530790393?p=D2tS9HOrDxAFf5WhLj)
Meeting ID: 391 953 079 039 3
Passcode: 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 Circio
webpage (http://www.circio.com/)

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

Neil Hunter - Hunter PR
Phone:+44 7821 255568 (http://tel:+447821255568)
Email: neiljameshunter@gmail.com

This information is considered to be inside information pursuant to the EU
Market Abuse Regulation (MAR) and is subject to the disclosure requirements
pursuant to MAR article 17 and section 5-12 of the Norwegian Securities Trading
Act.

This stock exchange announcement was published by Erik Digman Wiklund, CEO, on
behalf 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 RNA
vector expression technology for next generation nucleic acid medicine.

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