4BASEBIO PLC

Director's Dealing • Sep 30, 2025

National Storage Mechanism | Additional information

4basebio Plc - Director Dealing

PR Newswire

LONDON, United Kingdom, September 30

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

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 Dr. Heikki Lanckriet, CEO	+44 (0) 1223 967 943
Nominated Adviser        Cairn Financial Advisers LLP Jo Turner / Sandy Jamieson / Ed Downes	+44 (0) 20 7213 0880
Joint Broker RBC Capital Markets Kathryn Deegan / Matthew Coakes	+44 (0) 20 7653 4000
Joint Broker Cavendish Capital Markets Limited Geoff Nash / Nigel Birks	+44 (0) 20 7220 0500

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

1Details of the persons discharging managerial responsibilities / person closely associateda)Name

Heikki Lanckriet

2Reason for the notificationa)Position/StatusChief Executive Officerb)Initial notification/ AmendmentInitial notification3Details of the issuer, emission allowance market participant, auction platform, auctioneer or auction monitora)Name4basebio plcb)LEI213800E2DX9EAIUNCB304Details 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 conducteda)Description of the financial instrument, type of instrument Identification codeOrdinary Shares

ISIN: GB00BMCLYF79b)Nature of the transactionAcquisition of ordinary sharesc)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 -       Aggregated volume -       Aggregated Price2,000 749pe)Date of transaction29 September 2025f)Place of transactionLondon Stock Exchange

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