Celyad Presents Update on CYAD-01 Hematological Malignancies Clinical Program at 60th ASH Annual Meeting

Celyad (Paris:CYAD) (Brussels:CYAD) (NASDAQ:CYAD) (Euronext Brussels and Paris, and Nasdaq: CYAD), a clinical-stage biopharmaceutical company focused on the development of CAR-T cell-based therapies, today announced updated clinical data for the CYAD-01 program in hematological malignancies presented at the American Society of Hematology (ASH) 60^th Annual Meeting.

THINK Phase 1 Trial Update – Hematological Malignancies

• Results from the dose-escalation trial were accepted as an oral presentation at ASH and presented by Principal Investigator David A. Sallman, M.D., Department of Malignant Hematology at Moffitt Cancer Center (abstracts #902). Interim analysis was reported for ten r/r AML patients across the three dose levels of CYAD-01 without preconditioning.
• Out of eight r/r AML patient evaluable per protocol (at least one cycle of treatment) in the dose escalation segment of the trial:
  • Five patients (62%) showed anti-leukemic activity with three out of eight patients (38%) exhibiting objective response and two patients (25%) exhibiting disease stabilization with relevant bone marrow blasts decrease.
    • As previously reported, one r/r AML patients achieved a complete response with partial hematological recovery (CRh). This patient was bridged to allotransplant and remains in minimal residual disease negative complete response (CRMRD-) for over 14 months. Two r/r AML patients achieved a complete response with incomplete marrow recovery (CRi) with a duration of one month.
    • Two r/r AML patients treated at dose level 2 experienced disease stabilization with relevant bone marrow blast decrease. One patient experienced a decrease in blast counts from 9.8% to 5.5% after an initial cycle of CYAD-01. This patient subsequently received a second cycle of CYAD-01 at dose level 2, with the first injection of the second cycle administered seven weeks after the last injection of cycle one. Treatment with a second cycle of CYAD-01 was associated with relevant reduction in bone marrow blast in the patient from 12.5% to 5.8%, which could be considered as an induction of a partial response (PR) post hematological relapse between the two cycles. Further analysis showed both patients achieved CYAD-01 engraftment in the bone marrow at day 28 of treatment.
  • A sixth r/r AML patient with adverse risk according the 2017 ELN stratification demonstrated a stabilization of disease at two months and is scheduled to initiate a second cycle of CYAD-01.
  • Only two patients evaluable per protocol progressed in the dose escalation phase of the trial.
  • Two additional r/r AML patients have been enrolled at dose level 3 of the trial and full results from these patients are anticipated during first half 2019.

• CYAD-01 without preconditioning chemotherapy was generally reported to be well-tolerated.
  • Overall, 14 patients with hematological malignancies (AML, myelodysplastic syndrome and multiple myeloma) treated with CYAD-01 in the trial reached the safety follow -up.
  • Overall, six patients experienced grade 3/4 treatment-related AEs, which included cytokine release syndrome (CRS), lymphopenia and thrombocytopenia.
  • CRS occurred in six patients (three grade 1/2 AEs, two grade 3 AEs and one grade 4 AE). Patients experiencing grade 1-3 CRS showed rapid resolution following the appropriate treatment, including tocilizumab.
  • One r/r AML patient experienced a grade 4 CRS, which was considered a dose-limiting toxicity (DLT), following the first injection of CYAD-01 at dose level 3. The single injection resulted in a reduction of peripheral blast counts from 14% to 4%.

Dr. Christian Homsy, CEO of Celyad, commented, "Preliminary data from 14 patients with relapsed or refractory AML enrolled in the THINK trial have exceeded our expectations with five out of eight patients treated with CYAD-01 without preconditioning demonstrating a relevant anti-leukemic activity. In addition, we are encouraged by the initial safety data that shows CYAD-01 is well-tolerated. We are diligently working to enroll additional patients in our multiple ongoing clinical trials evaluating CYAD-01 in patients with acute myeloid leukemia to better assess this CAR T therapy’s ability to drive a potentially meaningful impact on the treatment of the disease."

DEPLETHINK Phase 1 Trial Update

• In October 2018, Celyad enrolled the first patient in the DEPLETHINK Phase 1 trial (NCT03466320). The open-label, dose-escalation trial will evaluate a single injection of CYAD-01 following treatment with the standard preconditioning regimen of cyclophosphamide (300 mg/m²) and fludarabine (30 mg/m²), or CyFlu.
• The trial includes two different intervals between lymphodepletion and administration of CYAD-01. In addition, the trial will evaluate two dose levels of CYAD-01 including 100 million and 300 million cells per injection, respectively. Following disease assessment at day 35, patients presenting no signs of progression are eligible to receive a cycle of three CYAD-01 injections without preconditioning with two-week intervals at their initial dose levels. The primary endpoint of the trial is safety and secondary endpoints include clinical activity and pharmacokinetics.
• As of November 27, 2018, three patients have received an administration of CYAD-01 following preconditioning with CyFlu. Initial data demonstrate that the regimen was well tolerated, with no DLTs nor treatment-related grade 3 or above AEs observed. All three patients were not yet evaluated for clinical response.
• Preliminary data from the DEPLETHINK Phase 1 trial are expected in mid-2019.

THINK Phase 1 Trial – Schedule Optimization Cohort 10

• The THINK trial was recently amended to add a cohort to assess a more frequent dosing schedule of CYAD-01 for the treatment of r/r AML. The cohort will evaluate six injections of CYAD-01 without preconditioning over two months of administration. The first cycle (induction) will include three injections of CYAD-01 separated by one-week intervals. The second cycle will include three injections of CYAD-01 separated by two-week intervals. All patients in enrolled in the cohort will received 1 billion cells per injection.
• Enrollment in the cohort has begun and preliminary data are expected in first half 2019.

EPITHINK Phase 1 Trial Update

• The EPITHINK trial is a dose-escalation trial designed to evaluate the administration of CYAD-01 concurrently with 5-azacytidine in treatment-naïve and/or elderly AML patients ineligible for intensive treatment.
• As of November 27, 2018, no patients have been enrolled in the trial.

CYAD-01 and THINK Trial Design

CYAD-01 is an investigational CAR-T therapy in which a patient's T cells are engineered to express the chimeric antigen receptor NKG2D, a receptor expressed on natural killer (NK) cells that binds to eight stress-induced ligands expressed on tumor cells.

The THINK trial (NCT03018405) is an open-label, dose-escalation Phase 1 trial assessing the safety and clinical activity of multiple CYAD-01 administrations without prior preconditioning in two parallel cohorts: i) patients with hematological malignancies, including r/r AML, and ii) patients with metastatic solid tumors. The dose escalation segment of the study evaluates three dose levels (300 million, 1 billion and 3 billion cells per injection) of one cycle of three CYAD-01 administrations with two-week intervals.