CLYYF Celyad SA (CE)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the Month of September 2022

Commission File Number: 001-37452

CELYAD ONCOLOGY SA

(Translation of registrant’s name into English)

Rue Edouard Belin 2

1435 Mont-Saint-Guibert, Belgium

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F  ☒                Form 40-F    ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

Celyad Oncology SA

On September 20, 2022, Celyad Oncology SA (the “Company”) issued a press release announcing its entry into a transaction whereby Cellistic will acquire the Company’s Good Manufacturing Practice grade cell therapy manufacturing capability, including the existing facility and all related personnel. A copy of the Company’s press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

The information contained in this Current Report on Form 6-K, including Exhibit 99.1, except for the quotes of Michel Lussier and Stefan Braam contained in Exhibit 99.1, is hereby incorporated by reference into the Company’s Registration Statements on Forms F-3 (File No. 333-248464) and S-8 (File No. 333-220737).

EXHIBITS