Report of the Statutory Auditor on the Consolidated Annual Account 2024 ENG

REPORT ON THE CONSOLIDATED FINANCIAL STATEMENTS

Unqualified opinion

We have performed the statutory audit of the Group's consolidated financial statements, which comprise the consolidated statement of financial position as at 31 December 2024, and the consolidated statement of profit or loss and other comprehensive income, the consolidated statement of changes in equity and the consolidated statement of cash flows for the year then ended, and notes, comprising material accounting policy information and other explanatory information, and which is characterised by a consolidated statement of financial position total of 9.928.000 EUR and for which the consolidated statement of profit or loss shows a loss for the year of 5.828.000 EUR.

In our opinion, the consolidated financial statements give a true and fair view of the Group's net equity and financial position as at 31 December 2024, as well as of its consolidated financial performance and its consolidated cash flows for the year then ended, in accordance with the IFRS

Accounting Standards as adopted by the European Union and with the legal and regulatory requirements applicable in Belgium.

Basis for unqualified opinion

We conducted our audit in accordance with International Standards on Auditing (ISA) as applicable in Belgium.

Our responsibilities under those standards are further described in the 'Statutory auditor's responsibilities for the audit of the consolidated financial statements' section in this report.

We have complied with all the ethical requirements that are relevant to the audit of consolidated financial statements in Belgium, including those concerning independence.

We have obtained from the administrative body and company officials the explanations and information necessary for performing our audit.

We believe that the audit evidence we have obtained is sufficient and appropriate to provide a basis for our opinion.

Material uncertainty related to going concern

We draw attention to Note 5.2.1 of the Group's consolidated financial statements which describes the events and conditions indicating a material uncertainty exists that may cast significant doubt on the Company's ability to continue as a going concern. Our opinion is not modified in respect of this matter.

Key audit matter

Key audit matters are those matters that, in our professional judgment, were of most significance in our audit of the consolidated financial statements of the current year. These matters were addressed in the context of our audit of the consolidated financial statements as a whole, and in forming our opinion thereon, and we do not provide a separate opinion on these matters.

We refer for this point to the foregoing paragraph, which mentions a material uncertainty regarding the going concern. In this context, we determine that there is no matter requiring a description as a key audit matter.

Responsibilities of the administrative body for the drafting of the consolidated financial statements

The administrative body is responsible for the preparation of consolidated financial statements that give a true and fair view in accordance with the IFRS Accounting Standards as adopted by the European Union and with the legal and regulatory provisions applicable in Belgium, and for such internal control as the administrative body determines is necessary to enable the preparation of consolidated financial statements that are free from material misstatements, whether due to fraud or error.

In preparing the consolidated financial statements, the administrative body is responsible for assessing the Group's ability to continue as a going concern, disclosing, as applicable, matters related to going concern and using the going concern basis of accounting unless the administrative body either intends to liquidate the Group or to cease operations, or has no realistic alternative but to do so.

Statutory auditor's responsibilities for the audit of the consolidated financial statements

Our objectives are to obtain reasonable assurance about whether the consolidated financial statements as a whole are free from material misstatement, whether due to fraud or error, and to issue a statutory auditor's report that includes our opinion. Reasonable assurance is a high level of assurance, but it is not a guarantee that an audit conducted in accordance with ISAs will always detect a material misstatement when it exists. Misstatements can arise from fraud or error and are considered material if, individually or in the aggregate, they could reasonably be expected to influence the economic decisions of users taken on the basis of these consolidated financial statements.

When executing our audit, we respect the legal, regulatory and normative framework applicable for the audit of the consolidated financial statements in Belgium. However, a statutory audit does not guarantee the future viability of the Group, neither the efficiency and effectiveness of the management of the Group by the administrative body. Our responsibilities regarding the continuity assumption applied by the administrative body are described below.

As part of an audit in accordance with ISAs, we exercise professional judgment

and maintain professional skepticism throughout the audit. We also:

• Identify and assess the risks of material misstatement of the consolidated financial statements, whether due to fraud or error, design and perform audit procedures responsive to those risks, and obtain audit evidence that is sufficient and appropriate to provide a basis for our opinion. The risk of not detecting a material misstatement resulting from fraud is higher than for one resulting from error, as fraud may involve collusion, forgery, intentional omissions, misrepresentations, or the override of internal control;
• Obtain an understanding of internal control relevant to the audit in order to design audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the
  Group's internal control;
• Evaluate the appropriateness of accounting policy information used and the reasonableness of accounting estimates and related disclosures made by the administrative body;
• Conclude on the appropriateness of the administrative body's use of the going concern basis of accounting and, based on the audit evidence obtained, whether a material uncertainty exists related to events or conditions that may cast significant doubt on the Group's ability to continue as a going concern. If we conclude that a material uncertainty exists, we are required to draw attention in our statutory auditor's report to the related disclosures in the consolidated financial statements or, if such disclosures are inadequate, to modify our opinion. Our conclusions are based on the audit evidence obtained up to the date of our statutory auditor's report. However, future events or

conditions may cause the Group to cease to continue as a going concern;

• Evaluate the overall presentation, structure and content of the consolidated financial statements and whether the consolidated financial statements represent the underlying transactions and events in a manner that achieves fair presentation;
• Obtain sufficient appropriate audit evidence regarding the financial information of the entities or business activities within the Group to express an opinion on the consolidated financial statements. We are responsible for the management, the supervision and the performance of the Group audit. We assume full responsibility for the auditor's opinion.

We communicate with the Audit Committee regarding, among other matters, the planned scope and timing of the audit and significant audit findings, including any significant deficiencies in internal control identified during the audit.

We also provide the Audit Committee with a statement that we respected the relevant ethical requirements relating to independence, and we communicate with them about all relationships and other issues which may influence our independence, and, if applicable, about the related measures to guarantee our independence.

From the matters communicated with the Audit Committee, we determine those matters that were of most significance in the audit of the consolidated financial statements of the current year, and are therefore the key audit matters. We describe these matters in our statutory auditor's report, unless law or regulation precludes public disclosure about the matter.

OTHER LEGAL AND REGULATORY REQUIREMENTS

Responsibilities of the administrative body

The administrative body is responsible for the preparation and the contents of the director's report on the consolidated financial statements and for the other information included in the annual report on the consolidated financial statements

Responsibilities of the statutory auditor

In the context of our mission and in accordance with the Belgian standard (draft version 2025) which is complementary to the International Standards on Auditing (ISA) as applicable in Belgium, it is our responsibility to verify, in all material aspects, the director's report on the consolidated financial statements and the other information included in the annual report on the consolidated financial statements, and to report on these elements.

Aspects relating to the director's report on the consolidated financial statements and to the other information included in the annual report on the consolidated financial statements

In our opinion, after having performed specific procedures in relation to the director's report, this director's report is consistent with the consolidated financial statements for the same financial year, and it is prepared in accordance with article 3:32 of the Code of companies and associations.

In the context of our audit of the consolidated financial statements, we are also responsible for considering, in particular based on the knowledge we have obtained during the audit, whether the director's report on the consolidated

financial statements and the other information included in the annual report on the consolidated financial statements, namely:

• the chapters 1.8 to 1.13 of the activity report;
• the chapter 2.7 about the remuneration report;

contain a material misstatement, i.e. information which is inadequately disclosed or otherwise misleading. Based on the procedures we have performed, there are no material misstatements we have to report to you.

Statement concerning independence

• Our audit firm and our network did not provide services which are incompatible with the statutory audit of the consolidated financial statements and our audit firm remained independent of the Group during the term of our mandate.
• The fees related to additional services which are compatible with the statutory audit as referred to in article 3:65 of the Code of companies and associations were duly itemised and valued in the notes to the consolidated financial statements.

European Single Electronic Format (ESEF)

In accordance with the Draft standard of the Institute of Réviseurs d'Entreprises concerning the audit of conformity of the annual report with the European Single Electronic Format (hereinafter "ESEF"), we also audited the conformity of the ESEF format with the regulatory technical standards established by the European Delegated Regulation 2019/815 of

17 December 2018 (hereinafter: "Delegated Regulation") and with the royal decree of 14 November, 2007, concerning the obligations of issuers of

financial instruments that are admitted to trade on a regulated market.

The administrative body is responsible for preparing an annual report in accordance with ESEF requirements, including the consolidated financial statements in the form of an electronic file in ESEF format (hereinafter "digital consolidated financial statements").

It is our responsibility to obtain sufficient and appropriate supporting information to conclude that the format of the annual report and mark-up language XBRL of the digital consolidated financial statements comply in all material aspects with the ESEF requirements under the Delegated Regulation and with the royal decree of 14 November, 2007.

Based on our work, we believe the digital format of the annual report and the tagging of information in the official version of the consolidated financial statements included in the annual report of Celyad Oncology SA as of 31 December 2024, and which will be available in the Belgian official mechanism for the storage of regulated information (STORI) of the FSMA, are in all material respects in accordance with the ESEF requirements pursuant to the Delegated Regulation and the royal decree of November 14, 2007.

Other statements

• This report is in compliance with the contents of our additional report to the Audit Committee as referred to in article 11 of regulation (EU) No 537/2014.

Battice, 4 April 2025

BDO Réviseurs d'Entreprises SRL Statutory auditor

Represented by Christophe Pelzer* Auditor

*Acting for a company