Celyad Oncology SA — Audit Report / Information 2016

Apr 4, 2017

CELYAD SA

Statutory auditor's report to the general
shareholders' meeting on the consolidated
accounts for the year ended 31 December 2016

4 April 2017

Free Translation

STATUTORY AUDITOR'S REPORT TO THE GENERAL SHAREHOLDERS' MEETING ON THE CONSOLIDATED ACCOUNTS FOR THE YEAR ENDED 31 DECEMBER 2016

In accordance with the legal requirements, we report to you on the performance of our mandate of statutory auditor. This report includes our opinion on the consolidated accounts, as well as the required additional statement. The consolidated accounts comprise the consolidated statement of financial position as at 31 December 2016 and the consolidated statements of comprehensive loss, changes in equity and cash flows for the year then ended, and notes, comprising a summary of significant accounting policies and other explanatory information.

Report on the consolidated accounts - Unqualified opinion

We have audited the consolidated accounts of Celyad SA ("the Company") and its subsidiaries (jointly "the Group") for the year ended 31 December 2016, prepared in accordance with International Financial Reporting Standards as adopted by the European Union, and with the legal and regulatory requirements applicable in Belgium. The total of the consolidated statement of financial position amounts to 000' EUR 138.806 and the consolidated statement of comprehensive loss shows a loss for the year of 000' EUR 23.436.

Board of directors' responsibility for the preparation of the consolidated accounts

The board of directors is responsible for the preparation and fair presentation of these consolidated accounts in accordance with International Financial Reporting Standards as adopted by the European Union, and with the legal and regulatory requirements applicable in Belgium, and for such internal control as the board of directors determines, is necessary to enable the preparation of consolidated accounts that are free from material misstatement, whether due to fraud or error.

Statutory auditor's responsibility

Our responsibility is to express an opinion on these consolidated accounts based on our audit. We conducted our audit in accordance with International Standards on Auditing (ISAs) as endorsed in Belgium. Those standards require that we comply with ethical requirements and plan and perform the audit to obtain reasonable assurance about whether the consolidated accounts are free from material misstatement.

An audit involves performing procedures to obtain audit evidence about the amounts and disclosures in the consolidated accounts. The procedures selected depend on the statutory auditor's judgment, including the assessment of the risks of material misstatement of the consolidated accounts, whether due to fraud or error. In making those risk assessments, the statutory auditor considers internal control relevant to the Group's preparation and fair presentation of the consolidated accounts 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. An audit also includes evaluating the appropriateness of accounting policies used and the reasonableness of accounting estimates made by the board of directors, as well as evaluating the overall presentation of the consolidated accounts.

PwC Bedrijfsrevisoren cyba, burgerlijke vennootschap met handelsvorm - PwC Reviseurs d'Entreprises scrl. société civile à forme commerciale - Financial Assurance Services Maatschappelijke zetel/Siège social: Woluwe Garden, Woluwedal 18, B-1932 Sint-Stevens-Woluwe Vestigingseenheid/Unité d'établissement: Rue Visé-Voie, 81 ABC-4000 Liège $T: +32(0)$ 4 220 62 11, F: $+32(0)$ 4 220 62 99, www.pwc.com BTW/TVA BE 0429.501.944 / RPR Brussel - RPM Bruxelles / ING BE43 3101 3811 9501 - BIC BBRUBEBB / BELFIUS BE92 0689 0408 8123 - BIC GKCC BEBB

We have obtained from the board of directors and the company's 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.

Unqualified Opinion

In our opinion, the consolidated accounts give a true and fair view of the Group's net equity and consolidated financial position as at 31 December 2016 and of its consolidated financial performance and its consolidated cash flows for the year then ended in accordance with International Financial Reporting Standards as adopted by the European Union, and with the legal and regulatory requirements applicable in Belgium.

Report on other legal and regulatory requirements

The board of directors is responsible for the preparation and the content of the directors' report on the consolidated accounts.

In the context of our mandate and in accordance with the Belgian standard which is complementary to the International Standards on Auditing (ISAs) as applicable in Belgium, our responsibility is to verify, in all material respects, compliance with certain legal and regulatory requirements. On this basis, we provide the following additional statement which does not impact our opinion on the consolidated financial statements:

The directors' report on the consolidated accounts includes the information required by law, is consistent with the consolidated accounts and does not present any material inconsistencies with the information that we became aware of during the performance of our mandate.

Liège, 4 April 2017