Synthetic opDNA® utilised in Phase I/II US clinical trials

27 October 2025

4basebio PLC

("4basebio" or the "Company")

Synthetic opDNA® utilised in Phase I/II US clinical trials

Global pharma partner initiates mRNA therapy trial using 4basebio’s opDNA® template, marking a key milestone in synthetic DNA adoption for advanced genetic medicines

Cambridge, UK, 27 October 2025 - 4basebio PLC (AIM: 4BB), an innovation-led provider of novel synthetic DNA products announces that, following Investigational New Drug (IND) approval from the FDA, a global Tier 1 pharmaceutical partner has begun dosing patients with an mRNA product developed using 4basebio’s proprietary opDNA® template. The Company signed the supply agreement with the partner in April 2024. Specific details of the clinical trial are not able to be disclosed at this time due to innovator confidentiality.

The opDNA® template, one of four application-specific DNA templates developed by 4basebio, supports mRNA invitro transcription (IVT) processes and offers significant cost, purity and timeline advantages against the incumbent plasmid DNA.

These clinical achievements follows 4basebio receiving the GMP certification from the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) of its late-phase manufacturing facility in April 2025. These accomplishments underscore 4basebio’s role as a trusted partner to the global biopharma industry, delivering high-quality synthetic DNA to power next-generation therapies.

Synthetic DNA represents a fundamental shift for the life sciences sector. Unlike traditional plasmid DNA, which is constrained by lengthy manufacturing timelines and contamination risks, 4basebio’s proprietary technology platform enables faster, scalable, and cell-free production of DNA templates. This technology advancement not only accelerates the development timelines for cell & gene therapies and vaccines but also offers superior safety and consistency, two critical factors for clinical success.

By removing bottlenecks in DNA supply, 4basebio enables researchers and drug development innovator companies to bring transformative therapies to patients more quickly and more safely, with the potential to change lives across infectious disease, oncology, and rare genetic disorders.

Dr. Heikki Lanckriet, 4basebio CEO, commented , “We are delighted to have supported this leading pharmaceutical innovator in their recent IND filing and start of their patient dosing trials. This represents another major regulatory milestone for 4basebio and a clear signal of growing industry adoption of synthetic DNA in the use of cell and gene therapies and vaccines.

“We are excited to see increasing momentum as a growing number of client programs advance into the clinic .”

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014 as amended by regulation 11 of the Market Abuse (Amendment) (EU Exit) Regulations 2019/310.

For further enquiries, please contact:

4basebio PLC	+44 (0)12 2396 7943
Dr. Heikki Lanckriet, CEO
Cairn Financial Advisers LLP (Nominated Adviser )	+44 (0)20 7213 0880
Jo Turner / Sandy Jamieson / Ed Downes
Cavendish Capital Markets Limited ( Joint Broker)	+44 (0)20 7220 0500
Geoff Nash / Nigel Birks
RBC Capital Markets (Joint Broker)	+44 (0) 20 7653 4000
Kathryn Deegan / Matthew Coakes

Notes to Editors

About 4basebio

4basebio (AIM: 4BB) is an innovation driven life biotechnology company focused on accelerating the development of advanced therapy medicinal products (ATMPs) through its high-performance synthetic DNA products and non-viral, cell targeting nucleic acid delivery platform. The Company’s objective is to become a market leader in the manufacture and supply of high-quality synthetic DNA products for research, therapeutic and pharmacological use as well as development of target specific non-viral vectors for the efficient delivery of payloads in patients.