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).

107 Armoring NKG2D CAR T cells with IL-18 improves in vivo anti-tumor activity

Background

Whilst delivering impressive clinical efficacy in certain hematological malignancies, Chimeric Antigen Receptor (CAR) T cell therapy has yet to deliver significant clinical impact across a broader array of cancer indications. Armoring CAR T through the co-expression of immune modifying cytokines is an approach that may aid anti-cancer activity but is currently at an embryonic stage of development. In this study, the potential benefit of expressing IL-18 alongside a NKG2D CAR was assessed.

Methods

A series of retroviral vectors encoding the NKG2D CAR (a fusion of NKG2D with CD3z), a cell surface tag to facilitate cell selection and tracking (truncated CD19) either with or without full length IL-18 were compared. In certain vectors, a single shRNA targeting CD3z was included to generate allogeneic CAR T versions. All transgenes were delivered as a single vector expressed under the control of the retroviral promoter with individual 2A elements ensuring equimolar levels of protein expression. T cells transduced with the individual vectors were challenged in vitro and in vivo to determine the impact of IL-18 upon NKG2D CAR directed function.

Results

Armored NKG2D CAR T cells that included the IL-18 transgene showed high levels of IL-18 secretion in culture and increased levels of interferon gamma secretion upon antigen challenge as compared to non-armored NKG2D CAR T cells. Armored NKG2D CAR T cells also showed prolonged sequential target cell killing as compared to non-armored CAR T versions. Importantly, in an in vivo stress test where the dose of non-armored NKG2D T cells was reduced to a level where minimal anti-tumor activity and survival above control was seen using an established THP-1 model, armored CAR T cells showed enhanced anti-tumor activity (as determined by bioluminescence) and overall survival. Interestingly, at high doses of armored CAR T cells, toxicity was seen in some tumor bearing models. This toxicity was abrogated by systemic infusion of human IL-18 binding protein (IL-18BP).

Conclusions

Armoring NKG2D CAR T cells with IL-18 resulting in increased in vitro and in vivo target-dependent anti-tumor activity. The transient toxicity observed with high doses of the armored CAR T in tumor bearing models was eliminated by IL-18BP. Together, these observations imply that armoring NKG2D CAR T cells with IL-18 is likely to drive improved anti-tumor activity of the CAR T cell in line with previous publications1 2 while the presence of systemic IL-18BP3 should negate possible toxicities arising from high level constitutive expression of the cytokine.

References

Chmielewski M, Abken H. Cell Reports 2017;21(11): 3205–32192.

Hu B, Ren J, Luo Y, Keith B, Young R, Scholler J, Zhao Y, June C. Cell Reports 2017; 20(13): 3025–30333.

Dinarello C, Novick D, Kim S, Kaplamski G. Frontiers in Immunology 2013;4;289

A new transcript in the TCRB locus unveils the human ortholog of the mouse pre-Dß1 promoter

Introduction

While most transcripts arising from the human T Cell Receptor locus reflect fully rearranged genes, several germline transcripts have been identified. We describe a new germline transcript arising from the human TCRB locus.

Methods

cDNA sequencing, promoter, and gene expression analyses were used to characterize the new transcript.

Results

The new germline transcript encoded by the human TCRB locus consists of a new exon of 103 bp, which we named TRBX1 (X1), spliced with the first exon of gene segments Cß1 or Cß2. X1 is located upstream of gene segment Dß1 and is therefore deleted from a V‐DJ rearranged TCRB locus. The X1‐Cß transcripts do not appear to code for a protein. We define their transcription start and minimal promoter. These transcripts are found in populations of mature T lymphocytes from blood or tissues and in T cell clones with a monoallelic TCRB rearrangement. In immature thymocytes, they are already detectable in CD1a⁻CD34⁺CD4⁻CD8⁻ cells, therefore before completion of the TCRB rearrangements.

Conclusions

The X1 promoter appears to be the ortholog of the mouse pre‐Dß1 promoter (PDß1). Like PDß1, its activation is regulated by Eß in T cells and might facilitate the TCRB rearrangement process by contributing to the accessibility of the Dß1 locus.

Lysosomal-associated Transmembrane Protein 4B (LAPTM4B) Decreases Transforming Growth Factor β1 (TGF-β1) Production in Human Regulatory T Cells

Production of active TGF-β1 is one mechanism by which human regulatory T cells (Tregs) suppress immune responses. This production is regulated by glycoprotein A repetitions predominant (GARP), a transmembrane protein present on stimulated Tregs but not on other T lymphocytes (Th and CTLs). GARP forms disulfide bonds with proTGF-β1, favors its cleavage into latent inactive TGF-β1, induces the secretion and surface presentation of GARP·latent TGF-β1 complexes, and is required for activation of the cytokine in Tregs. We explored whether additional Treg-specific protein(s) associated with GARP·TGF-β1 complexes regulate TGF-β1 production in Tregs. We searched for such proteins by yeast two-hybrid assay, using GARP as a bait to screen a human Treg cDNA library. We identified lysosomal-associated transmembrane protein 4B (LAPTM4B), which interacts with GARP in mammalian cells and is expressed at higher levels in Tregs than in Th cells. LAPTM4B decreases cleavage of proTGF-β1, secretion of soluble latent TGF-β1, and surface presentation of GARP·TGF-β1 complexes by Tregs but does not contribute to TGF-β1 activation. Therefore, LAPTM4B binds to GARP and is a negative regulator of TGF-β1 production in human Tregs. It may play a role in the control of immune responses by decreasing Treg immunosuppression.

GARP is regulated by miRNAs and controls latent TGF-β1 production by human regulatory T cells

GARP is a transmembrane protein present on stimulated human regulatory T lymphocytes (Tregs), but not on other T lymphocytes (Th cells). It presents the latent form of TGF-β1 on the Treg surface. We report here that GARP favors the cleavage of the pro-TGF-β1 precursor and increases the amount of secreted latent TGF-β1. Stimulated Tregs, which naturally express GARP, and Th cells transfected with GARP secrete a previously unknown form of latent TGF-β1 that is disulfide-linked to GARP. These GARP/TGF-β1 complexes are possibly shed from the T cell surface. Secretion of GARP/TGF-β1 complexes was not observed with transfected 293 cells and may thus be restricted to the T cell lineage. We conclude that in stimulated human Tregs, GARP not only displays latent TGF-β1 at the cell surface, but also increases its secretion by forming soluble disulfide-linked complexes. Moreover, we identified six microRNAs (miRNAs) that are expressed at lower levels in Treg than in Th clones and that target a short region of the GARP 3’ UTR. In transfected Th cells, the presence of this region decreased GARP levels, cleavage of pro-TGF-β1, and secretion of latent TGF-β1.

Isolation of heat shock-induced Nicotiana tabacum transcription promoters and their potential as a tool for plant research and biotechnology

Transcription promoters of heat shock protein (HSP) genes have been used to control the expression of heterologous proteins in plants and plant cells. To obtain a strong HSP promoter that is functionally active in Nicotiana tabacum BY-2 cells, we set out to identify a promoter of an endogenous gene showing high activation of expression by heat. An N. tabacum BY-2 cell culture was treated for 8 h at 37°C and the cell protein extract analyzed by two-dimensional electrophoresis. A major spot was identified by mass spectrometry as belonging to the small HSP family. The promoter regions and the 5' and 3' untranslated regions of two genes, NtHSP3A and NtHSP3B, with sequences fitting the protein identified were cloned and fused to a hybrid reporter gene coding for β-glucuronidase (GUS) and a yellow fluorescent protein. These constructs were introduced into N. tabacum BY2 cells by Agrobacterium tumefaciens-mediated transformation. Both promoters conferred similar heat-induced GUS expression. In the best heat shock condition, GUS activity was increased 200 fold and reached 285 pmol min(-1) μg protein(-1). Up-scaling in a 4-l bioreactor resulted in similar heat-induced expression. The NtHSP3A promoter was then used to drive the expression of NtPDR1, a plasma membrane transporter belonging to the pleiotropic drug resistance family. No expression was observed at 25°C, while, at 37°C, expression was similar to that obtained using a strong constitutive promoter. These data show that the HSP promoters isolated are useful for high heat-induced expression in N. tabacum BY-2 cells.