CYAD-01, an autologous NKG2D-based CAR T-cell therapy, in relapsed or refractory acute myeloid leukaemia and myelodysplastic syndromes or multiple myeloma (THINK): haematological cohorts of the dose escalation segment of a phase 1 trial.

BACKGROUND: CYAD-01 is an autologous chimeric antigen receptor (CAR) T-cell product based on the natural killer (NK) group 2D (NKG2D) receptor, which binds eight ligands that are overexpressed in a wide range of haematological malignancies but are largely absent on non-neoplastic cells. Initial clinical evaluation of a single infusion of CYAD-01 at a low dose in patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, and multiple myeloma supported the feasibility of the approach and prompted further evaluation of CYAD-01. The aim of the present study was to determine the safety and recommended phase 2 dosing of CYAD-01 administered without preconditioning or bridging chemotherapy. METHODS: The multicentre THINK study was an open-label, dose-escalation, phase 1 study for patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, or multiple myeloma, after at least one previous line of therapy. Patients were recruited from five hospitals in the USA and Belgium. The dose-escalation segment evaluated three dose levels: 3 × 108 (dose level one), 1 × 109 (dose level two), and 3 × 109 (dose level three) cells per infusion with a 3 + 3 Fibonacci study design using a schedule of three infusions at 2-week intervals followed by potential consolidation treatment consisting of three additional infusions. The occurrence of dose-limiting toxicities post-CYAD-01 infusion was assessed as the primary endpoint in the total treated patient population. The trial was registered with ClinicalTrials.gov, NCT03018405, and EudraCT, 2016-003312-12, and has been completed. FINDINGS: Between Feb 6, 2017, and Oct 9, 2018, 25 patients were registered in the haematological dose-escalation segment. Seven patients had manufacturing failure for insufficient yield and two had screening failure. 16 patients were treated with CYAD-01 (three with multiple myeloma and three with acute myeloid leukaemia at dose level one; three with acute myeloid leukaemia at dose level two; and six with acute myeloid leukaemia and one with myelodysplastic syndromes at dose level three). Median follow-up was 118 days (IQR 46-180). Seven patients (44%) had grade 3 or 4 treatment-related adverse events. In total, five patients (31%) had grade 3 or 4 cytokine release syndrome across all dose levels. One dose-limiting toxicity of cytokine release syndrome was reported at dose level three. No treatment-related deaths occurred, and the maximum tolerated dose was not reached. Three (25%) of 12 evaluable patients with relapsed or refractory acute myeloid leukaemia or myelodysplastic syndromes had an objective response. Among responders, two patients with acute myeloid leukaemia proceeded to allogeneic haematopoietic stem-cell transplantation (HSCT) after CYAD-01 treatment, with durable ongoing remissions (5 and 61 months). INTERPRETATION: Treatment with a multiple CYAD-01 infusion schedule without preconditioning is well tolerated and shows anti-leukaemic activity, although without durability outside of patients bridged to allogeneic HSCT. These phase 1 data support the proof-of-concept of targeting NKG2D ligands by CAR T-cell therapy. Further clinical studies with NKG2D-based CAR T-cells are warranted, potentially via combinatorial antigen targeted approaches, to improve anti-tumour activity. FUNDING: Celyad Oncology.

Clinical Grade Manufacture of CYAD-101, a NKG2D-based, First in Class, Non-Gene-edited Allogeneic CAR T-Cell Therapy.

Allogeneic chimeric antigen receptor (CAR) T holds the promise of taking this therapeutic approach to broader patient populations while avoiding the intensive manufacturing demands of autologous cell products. One limitation to delivering an allogeneic CAR T is T-cell receptor (TCR) driven toxicity. In this work, the expression of a peptide to interfere with TCR signaling was assessed for the generation of allogeneic CAR T cells. The expression of a truncated CD3ζ peptide was shown to incorporate into the TCR complex and to result in blunted TCR responses. When coexpressed with a natural killer group 2D (NKG2D) CAR, the allogeneic T cells (called CYAD-101) failed to induce graft-versus-host disease in mouse models while maintaining antitumor activity driven by the CAR in vitro and in vivo. Two clinical grade discrete batches of CYAD-101 cells were produced of single donor apheresis resulting in 48 billion CAR T cells sufficient for the entire dose-escalation phase of the proposed clinical trial. The 2 batches showed high consistency producing a predominantly CD4+ T-cell population that displayed an effector/central memory phenotype with no evidence of exhaustion markers expression. These clinical grade CYAD-101 cells secreted cytokines and chemokines in response to ligands expressing target cells in vitro, demonstrating effector function through the CAR. Moreover, CYAD-101 cells failed to respond to TCR stimulation, indicating a lack of allogeneic potential. This bank of clinical grade, non-gene-edited, allogeneic CYAD-101 cells are used in the alloSHRINK clinical trial (NCT03692429).

Characterization of two new high-grade B-cell lymphoma cell lines with MYC and BCL2 rearrangements that are suitable for in vitro drug sensitivity studies.

High-grade B-cell lymphomas with MYC and BCL2 or BCL6 rearrangements are highly aggressive B-cell lymphomas called double-hit lymphomas (HGBL-DH). They are particularly refractory to standard treatments and carry a poor prognosis. Fragments of resected tumoral lymph nodes from two HGBL-DH patients were put in culture. Continuously proliferating cells were characterized and compared with the original tumors. In both cases, the proliferating cells and the tumor displayed MYC and BCL2 rearrangements. Both cell lines (called LB5848-LYMP and LB5871-LYMP) presented a high proliferation rate and were maintained in culture for more than one year. Upon injection in immunodeficient mice, LB5848-LYMP gave rise to lymphoid tumors. In vitro treatment of these cell lines with a BCL2-inhibitory drug (ABT-199) selectively stopped their proliferation. These new cell lines represent valuable tools for studying HGBL-DH and for the in vitro testing of candidate therapies targeting HGBL-DH. LB5848-LYMP is also suitable for similar experiments in vivo.

Highly Aggressive Metastatic Melanoma Cells Unable to Maintain Telomere Length.

Unlimited replicative potential is one of the hallmarks of cancer cells. In melanoma, hTERT (telomerase reverse transcriptase) is frequently overexpressed because of activating mutations in its promoter, suggesting that telomerase is necessary for melanoma development. We observed, however, that a subset of melanoma metastases and derived cell lines had no telomere maintenance mechanism. Early passages of the latter displayed long telomeres that progressively shortened and fused before cell death. We propose that, during melanoma formation, oncogenic mutations occur in precursor melanocytes with long telomeres, providing cells with sufficient replicative potential, thereby bypassing the need to re-activate telomerase. Our data further support the emerging idea that long telomeres promote melanoma formation. These observations are important when considering anticancer therapies targeting telomerase.