4basebio PLC

("4basebio" or the "Company")

4basebio Launches Enzymatic ssDNA Platform

    --         Overcomes critical manufacturing and performance bottlenecks
        associated with traditional chemical synthesis, providing faster and
        more reliable ssDNA manufacturing to aid commercial scale up
    --         4basebio team to present at ASGCT Annual Meeting 2026 in Boston,
        MA

CAMBRIDGE, UK – 11 May 2026 – 4basebio PLC (AIM: 4BB), a specialist in synthetic DNA manufacturing and nucleic acids for next-generation therapeutics, announces the commercial launch of its high-capacity single-stranded DNA (ssDNA) product line to accelerate the development of safer, more precise genetic therapies by enabling targeted gene editing, advanced cell engineering, and innovative nucleic acid-based medicines.

Built on a proprietary enzymatic manufacturing process, the platform provides biopharma with high-purity, long-form ends protected ssDNA templates, designed to overcome critical manufacturing and performance bottlenecks associated with traditional chemical synthesis in CRISPR-based gene editing, enabling large-scale, clinically viable therapeutics.

With the growth of gene editing and with a particular need for complex "knock-in" applications, the demand for longer, purer and safer DNA templates has increased exponentially. 4basebio’s ssDNA offering enables the production of constructs up to 10,000 nucleotides with protected ends, ensuring stability, reduced immunogenicity and a cleaner path to clinical manufacturing.

The technical advantages of the platform will be showcased at the upcoming American Society of Gene & Cell Therapy (ASGCT) Annual Meeting in Boston, MA.Amine Bouchareb, Director of Molecular Biology and Gene Editing at 4basebio, will deliver a presentation titled "An enzymatic ssDNA platform addresses manufacturing and performance bottlenecks in non-viral CRISPR gene editing" on 14 May at 9:00 AM EDT.

“The launch of our ssDNA platform marks a pivotal milestone in our mission to provide the foundational tools for genomic medicine and personalized therapies,” said Amy Walker, CEO of 4basebio. “By replacing legacy chemical synthesis with our scalable, cell-free enzymatic approach, we are empowering our partners to design therapies without the traditional constraints of length or sequence complexity. We are not just providing DNA; we are enhancing the reliability and safety profile required for life-changing therapeutics.”

“For too long, researchers have been forced to choose between the high toxicity of double-stranded DNA or the severe length limitations of chemically synthesized oligonucleotides,” said Amine Bouchareb. “Our enzymatic platform eliminates this compromise.

“At ASGCT, I look forward to presenting data that demonstrates how our long-form ssDNA constructs significantly enhance Homology Directed Repair (HDR) gene editing efficiency while maintaining superior cell viability in sensitive primary cell types. This technology is the bridge between discovery-phase editing and large-scale clinical success.”

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 Amy Walker, CEO

    Cairn Financial Advisers LLP (Nominated Adviser )
                                                          +44 (0)20 7213 0880
Jo Turner / Sandy Jamieson / Ed DownesCavendish Capital Markets Limited (Joint Broker)      +44 (0)20 7220 0500
Geoff Nash / Nigel BirksRBC Capital Markets (Joint Broker)                    +44 (0)20 7653 4000
Kathryn Deegan / Matthew CoakesICR Healthcare (Media and Investor Relations)         +44 (0)203 707 5700
Mary-Jane Elliott / Jessica Hodgson

About 4basebio

4basebio (AIM: 4BB) is a Cambridge-based biotechnology company pioneering the use of synthetic DNA to enable next-generation therapeutics and vaccines. Through its proprietary enzymatic DNA synthesis platform, 4basebio produces GMP-grade synthetic DNA and mRNA with superior speed, purity, and scalability, overcoming the limitations of plasmid-based systems. The company offers application-specific DNA constructs tailored to the diverse needs of gene therapies, genome editing, mRNA production, and DNA vaccines, helping partners accelerate proof-of-concept studies and reach clinical milestones more efficiently while maintaining the highest standards of safety and quality.

For more information, visit 4basebio.com .

Forward-looking statements

This announcement may contain certain statements about the future outlook for 4basebio.  Although the directors believe their expectations are based on reasonable assumptions, any statements about future outlook may be influenced by factors that could cause actual outcomes and results to be materially different.