Celyad Oncology Presents Preliminary Data from Phase 1 IMMUNICY-1 Trial of shRNA-based Allogeneic CAR T Candidate CYAD-211 in Relapsed/Refractory Multiple Myeloma at the European Hematology Association Virtual Congress - Seite 2

Of the six patients dosed at the first two dose levels (30×10⁶ and 100×10⁶ cells per infusion):

• No dose limiting toxicity (DLT), Graft-versus Host disease (GvHD) or CAR T-cell-related encephalopathy syndrome (CRES) were observed in the first two dose cohorts.
• One cytokine release syndrome (CRS) Grade 1 (fever) requiring hospitalization occurred 10 days post CYAD-211 administration in patient 1 (dose level 1) who achieved a partial response (PR).
• One patient experienced an anemia adverse event (Grade 3) and neutropenia (Grade 4) possibly related to CYAD-211.

Clinical activity:

Of the five evaluable patients at the first two dose levels (30×10⁶ and 100×10⁶ cells per infusion):

• Two patients achieved a PR. Both patients were ‘triple-therapy exposed’ (previously treated with an immunomodulator (IMiD), a proteasome inhibitor and an anti-CD38 antibody).
• The three additional patients had stable disease (SD).

Cell kinetics:

• CYAD-211 cells were detected by PCR-based methods in all six patients from dose cohorts 1 and 2.
• Cell engraftment was seen in all three patients at dose level 2 at a similar magnitude. In addition, preliminary data suggest that all patients in dose level 2 showed deep lymphodepletion. Across dose level 1, the depth of lymphodepletion appears to correlate with the degree of observed systemic CAR T engraftment.

Next steps:

• Enrollment in dose cohort 3 (300×10⁶ cells per infusion) is ongoing.
• Additional clinical data from the dose escalation trial are expected during second half 2021.
• shRNA technology platform to be highlighted at upcoming virtual R&D Day in Q3 2021.

Conference Call and Webcast Details

Celyad Oncology will host a conference call to discuss the update from EHA on Friday, June 11, 2021 at 2 p.m. CET / 8 a.m. ET. The conference call can be accessed through the following numbers:

United States: #1 877-407-9208
International: #1 201-493-6784

The conference call will be webcast live and can be accessed here. The event will also be archived and available on the “Events ” section of the company’s website. Please visit the website several minutes prior to the start of the broadcast to ensure adequate time for registration to the webcast.

About CYAD-211

CYAD-211 is an investigational, shRNA-based allogeneic CAR T candidate for the treatment of r/r MM. CYAD-211 is engineered to co-express an anti-BCMA targeting chimeric antigen receptor and a single shRNA to knockdown the CD3ζ component of the T cell receptor complex.