Celyad Presents Update on r/r AML and MDS Program at 61st ASH Annual Meeting

Regulatory News:

Celyad (Euronext Brussels and Paris, and Nasdaq: CYAD), a clinical-stage biopharmaceutical company focused on the development of CAR-T cell therapies, today announced updates to the company’s autologous NKG2D-based CAR-T development program for the treatment of relapsed/refractory (r/r) acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) at the American Society of Hematology (ASH) 61^st Annual Meeting, which is being held from December 7-10, 2019 in Orlando, Florida.

Filippo Petti, CEO of Celyad, commented, “Over the past few months we have worked diligently to transition our proprietary OptimAb manufacturing process to become the cornerstone of our autologous CAR-T program for the treatment of relapsed/refractory acute myeloid leukemia and myelodysplastic syndromes. We are encouraged by the body of data generated to date by our lead autologous candidate CYAD-01 for the treatment of AML and MDS, especially given its tolerability profile and anti-leukemic activity.”

“We are excited to further evaluate our NKG2D-based CAR-T approach using our OptimAb manufacturing process, which generates a higher frequency of less differentiated CAR-T cells that exhibit enhanced anti-tumor activity in preclinical studies. Overall, we believe the process gives us the best opportunity for success across both autologous product candidates, CYAD-01 and CYAD-02. Along with our ongoing DEPLETHINK trial, the key next steps for our broad r/r AML and MDS program include the expansion of the THINK trial and initiation of the CYCLE-1 trial as we look to establish NKG2D as an important target for the treatment of difficult-to-treat malignancies”, continued Mr. Petti.

CYAD-01 THINK Phase 1 Trial

• Sixteen patients have been enrolled to date in the trial evaluating CYAD-01 administered as a multiple injection with a biweekly schedule and an additional nine patients have been enrolled in the dose dense (weekly) schedule in the dose escalation segment of the trial

• CYAD-01 without preconditioning chemotherapy was generally reported to be well-tolerated, with 11 out of 25 patients experiencing grade 3/4 treatment-related adverse events (AEs). Cytokine release syndrome (CRS) occurred in 13 patients, with four grade 3 and two grade 4 events, which showed rapid resolution following the appropriate treatment, including tocilizumab. Two dose-limiting toxicities were reported at dose level 3 (3 billion cells per infusion), including one CRS grade 4 (biweekly) and one CRS grade 3 (dose dense schedule). No treatment-related neurotoxicity AEs were reported
• Overall, eight patients out of 15 evaluable patients treated with CYAD-01 produced with the prior manufacturing process demonstrated anti-leukemic activity. Five out of the eight patients exhibited an objective response. In addition, one patient is exhibiting disease stabilization of over three months
• Patients treated within the CYAD-01 dose-dense (weekly) schedule cohorts of the trial did not demonstrate an improvement in clinical outcome as compared to patients treated with the biweekly dosing schedule. However, patients enrolled in the dose-dense schedule cohorts appeared to have greater bone marrow blasts infiltration and to be more pancytopenic at baseline compared to patients enrolled in the biweekly dose escalation segment of the trial
• Most of the anti-leukemic activity observed in the trial, except for the two patients who bridged to an allogeneic human stem cell transplant, experienced a short durability of response
• To date, anti-leukemic activity appears predominantly observed in patients initially diagnosed with non-adverse (ELN 2017, AML) or non-very high (IPSS-R, MDS) risk stratification categories. Additional patients are needed in the trial to better assess the observation

• Company plans to progress to the expansion segment of the THINK trial to further evaluate CYAD-01 produced with the OptimAb manufacturing process. Enrollment in the expansion segment of the trial is expected to begin in first quarter 2020 with preliminary data anticipated by the end of first half 2020

CYAD-01 DEPLETHINK Phase 1 Trial