4basebio Plc - Director Dealing

                
                          30 September 2025

4basebio PLC

("4basebio" or the "Company")

Director Dealing

Cambridge, UK, 30 September 2025 - 4basebio PLC (AIM: 4BB), an innovation-led
provider of novel synthetic DNA products and a non-viral, thermostable nucleic
acid delivery platform, announces that it was informed by Dr. Heikki Lanckriet,
CEO of the Company, that on 29 September 2025 he made the following purchase in
ordinary shares in the capital of the Company through the market.

Further details are set out in the Notification of Dealing Form below.

Director    Number     Purchase    Shareholding   Shareholding
  / PCA       of        Price       Following       Following
           Ordinary  (Aggregated)  Acquisition   Acquisition as
            Shares       (p)                     a Percentage of
           Acquired                               Issued Share
                                                     Capital
 Heikki     2,000        749        1,119,688         7.21%
Lanckriet

The 2,000 additional shares purchased represent approximately 0.01 per cent. of
the Company's issued share capital. The issued share capital of the Company
comprises 15,538,518 ordinary shares.

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                            [phone]

Dr. Heikki Lanckriet, CEO
Nominated Adviser                       [phone]

Cairn Financial Advisers LLP

Jo Turner / Sandy Jamieson / Ed Downes
Joint Broker                            [phone]

RBC Capital Markets

Kathryn Deegan / Matthew Coakes
Joint Broker                            [phone]

Cavendish Capital Markets Limited

Geoff Nash / Nigel Birks

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.

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.

Notification and public disclosure of transactions by persons discharging
managerial responsibilities and persons closely associated with them

1   Details of the persons discharging
    managerial responsibilities / person
    closely associated
a)  Name                             Heikki Lanckriet
2   Reason for the notification
a)  Position/Status                  Chief Executive Officer
b)  Initial notification/ Amendment  Initial notification
3   Details of the issuer, emission
    allowance market participant, auction
    platform, auctioneer or auction
    monitor
a)  Name                             4basebio plc
b)  LEI                              213800E2DX9EAIUNCB30
4   Details of the transaction(s): section
    to be repeated for (i) each type of
    instrument; (ii) each type of
    transaction; (iii) each date; and (iv)
    each place where transactions have
    been conducted
a)  Description of the               Ordinary Shares
    financialinstrument, type        ISIN: GB00BMCLYF79
    ofinstrumentIdentification code
b)  Nature of the transaction        Acquisition of ordinary shares
c)  Price(s) and volume(s)
                                     Date        Price(s)  Volume(s)
                                     29/09/2025  750p      1,000
                                     29/09/2025  748p      1,000
d)  Aggregated information           2,000749p
    -      Aggregated volume
    -      Aggregated Price
e)  Date of transaction              29 September 2025
f)  Place of transaction             London Stock Exchange


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