4basebio Plc – Director Dealing

11 February 2026

4basebio PLC

(«4basebio» or the «Company»)

Director Dealings

Cambridge, UK,11 February 2026-4basebio PLC(AIM: 4BB), an innovation driven
biotechnology company enabling and accelerating development of advanced therapy
medicinal products (ATMPs) through its high performant GMP-grade synthetic DNA
products, announces that on 10 February 2026 it was informed that certain Non
-executive Directors of the Company made the following purchases 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
Dr. Heikki 3,000 575.82 1,122,688 7.23%
Lanckriet
Mr Hansjörg 1,000 585.00 7,667† 0.05%†
Plaggemars*

* Purchase
was made by
Mr
Plaggemars,
on behalf of
his wife.

† Aggregate
shareholding
of Mr
Plaggemars
and persons
closely
associated
with him.

The 3,000 and 1,000 additional shares purchased represent approximately 0.02 per
cent. and 0.01 per cent. of the Company’s issued share capital, respectively.

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                +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 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 +44 (0)203 707 5700

ICR Healthcare (Media and Investor Relations)

Mary-Jane Elliott / Jessica Hodgson

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 |1)      Dr. Heikki Lanckriet |
| | | |
| | |2)      Mr Hansjörg Plaggemars|
+–+—————-+——————————+
|2 |Reason for the |
| |notification |
+–+—————-+——————————+
|a)|Position/Status |1)      Non-executive Director|
| | | |
| | |2)      Non-executive Director|
+–+—————-+——————————+
|b)|Initial |Initial notification |
| |notification/ | |
| |Amendment | |
+–+—————-+——————————+
|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 |Ordinary Shares |
| |the financial | |
| | |ISIN: GB00BMCLYF79 |
| |instrument, type| |
| |of | |
| | | |
| |instrument | |
| | | |
| |Identification | |
| |code | |
+–+—————-+——————————+
|b)|Nature of the |Acquisition of ordinary shares|
| |transaction | |
+–+—————-+——————————+
|c)|Price(s) and | |
| |volume(s) | Price(s) Volume(s) |
| | |1) 575.82p 3,000 |
| | |2) 585.00p 1,000 |
+–+—————-+——————————+
|d)|Aggregated |1)      3,000 |
| |information | |
| | |2)      1,000 |
| |-Aggregated | |
| |volume |1)      575.82p |
| | | |
| |-Aggregated |2)      585.00p |
| |Price | |
+–+—————-+——————————+
|e)|Date of |10 February 2026 |
| |transaction | |
+–+—————-+——————————+
|f)|Place of |London Stock Exchange |
| |transaction | |
+–+—————-+——————————+

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