Celyad Oncology : Report of the Statutory Auditor on the Consolidated Annual Account 2023 ENG

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CELYAD ONCOLOGY SA

Statutory auditor's report to the general meeting

for the year ended 31 December 2023 (Consolidated financial statements)

Free translation

BDO Bedrijfsrevisoren BV / BTW BE 0431.088.289 / RPR Brussel

BDO Réviseurs d'Entreprises SRL / TVA BE 0431.088.289 / RPM Bruxelles

BDO Bedrijfsrevisoren - BDO Réviseurs d'Entreprises BV/SRL, a company under Belgian law in the form of a private limited liability company, is a member of BDO International Limited, a UK company limited by guarantee, and forms part of the international BDO network of independent member firms.

BDO is the brand name for the BDO network and for each of the BDO Member Firms.

T : [phone]	Uitbreidingstraat 72/1
F : [phone]	B-2600 Antwerpen
www.bdo.be

Free translation

STATUTORY AUDITOR'S REPORT TO THE GENERAL MEETING OF CELYAD ONCOLOGY SA FOR THE YEAR ENDED 31 DECEMBER 2023 (CONSOLIDATED FINANCIAL STATEMENTS)

In the context of the statutory audit of the consolidated financial statements of

Celyad Oncology SA ('the Company') and its subsidiaries (together referred to as 'the Group'), we hereby present our statutory auditor's report. It includes our report of the consolidated financial statements and the other legal and regulatory requirements. This report is an integrated whole and is indivisible.

We have been appointed as statutory auditor by the general meeting of 5 May 2023, following the proposal formulated by the administrative body upon recommendation of the Audit Committee. Our statutory auditor's mandate expires on the date of the General Meeting deliberating on the financial statements closed on 31 December 2025. We have performed the statutory audit of the consolidated financial statements of the Group for the first year.

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 2023, 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 to the consolidated financial statements, including a summary of significant accounting policies and other explanatory information, and which is characterised by a consolidated statement of financial position total of

16.282 (000) EUR and for which the consolidated statement of profit or loss shows a loss for the year of

8.426 (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 2023, as well as of its consolidated financial performance and its

consolidated cash flows for the year then ended, in accordance with International Financial Reporting Standards (IFRS) 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.

BDO Bedrijfsrevisoren BV / BTW BE 0431.088.289 / RPR Brussel

BDO Réviseurs d'Entreprises SRL / TVA BE 0431.088.289 / RPM Bruxelles

BDO Bedrijfsrevisoren - BDO Réviseurs d'Entreprises BV/SRL, a company under Belgian law in the form of a private limited liability company, is a member of BDO International Limited, a UK company limited by guarantee, and forms part of the international BDO network of independent member firms.

BDO is the brand name for the BDO network and for each of the BDO Member Firms.

Key audit matters

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.

Financial funding

Description of the Matter

As described in the note 5.2.1 "going concern" to the consolidated financial statements, the Company has disclosed that based on its current scope of activities, the Group estimates that its treasury position as of 31 December 2023 is sufficient to cover its cash requirements at least until May 2025, so that there is no material uncertainty on the Company's ability to continue as a going concern. This area was important to our audit given the significant estimates included in management forecasts and the sensitivity to the expected cash burn schedule, based on the expectations about future financial resources needed to run the activities on a going concern basis.

Procedures performed

Our audit procedures included, amongst others:

• We obtained the business plan and the cash forecast for the year 2024 and 2025 and reviewed it for consistency and mathematical accuracy;
• We made some retrospective analysis about the forecast's reliability;
• We challenged the reasonableness of the assumptions underlying this budget and cash forecast,

especially the structure of costs to be assumed over 2024, the cut-off of costs on an annual basis as well as the revenue expectations;

• We verified the effective availability of the cash and short- term receivables with external relevant supporting documents;
• Within our subsequent procedures, we have checked the actual cash position at the end of the first quarter 2024 against the budgeted cash position;
• We verified the adequacy and completeness of the disclosures as included in the notes 5.2.1 and 5.4
  "going concern" of the consolidated financial statements.

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 International Financial Reporting Standards (IFRS) 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.

Celyad Oncology SA:
Statutory auditor's report to the general meeting of the company on the consolidated financial statements for the year ended 31 December 2023	3.

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 policies 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;

Celyad Oncology SA:
Statutory auditor's report to the general meeting of the company on the consolidated financial statements for the year ended 31 December 2023	4.

• 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 (version revised 2020) 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, as well as 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

Celyad Oncology SA:
Statutory auditor's report to the general meeting of the company on the consolidated financial statements for the year ended 31 December 2023	5.

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 1.15 of the activity report,
• 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 terms 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 standard on auditing the conformity of financial statements with the European Single Electronic Format (hereinafter "ESEF"), we also audited the conformity of the ESEF format with the regulatory technical standards established by Commission Delegated Regulation (EU) 2019/815 of 17 December 2018 (hereinafter: "Delegated Regulation").

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

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

Based on our work, we believe that the format and the mark-up of information in the official version of the digital consolidated financial statements included in the annual financial report of Celyad Oncology as at 31 December 2023 comply in all material aspects with the ESEF requirements under the Delegated Regulation.

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 2024

BDO Réviseurs d'Entreprises SRL

Statutory auditor

Represented by Christophe Pelzer* Auditor

*Acting for a company

Celyad Oncology SA:
Statutory auditor's report to the general meeting of the company on the consolidated financial statements for the year ended 31 December 2023	6.