Abstract A043: Anti-CD19 CAR T-cells with a CRISPR/Cas9-mediated T-cell receptor knockout show high functionality in the absence of alloreactivity in vitro

2019 ◽  
Author(s):  
Dana Stenger ◽  
Tanja Stief ◽  
Theresa Käuferle ◽  
Semjon Manuel Willier ◽  
Felicitas Rataj ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Car T Cells ◽  
Car T

Chimeric Antigen Receptor Transgenic, T Cell Receptor/CD3 Negative Monospecific T Cells Generated from Cord Blood CD34 Positive Cells

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3087-3087 ◽  
Author(s):  
Yasmine van Caeneghem ◽  
Glenn Goetgeluk ◽  
Karin Weening ◽  
Greet Verstichel ◽  
Sarah Bonte ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cord Blood ◽  
T Cell Receptor ◽  
First Generation ◽  
Cell Receptor ◽  
Car T Cells ◽  
Car T

Abstract Autologous T cells transduced to express chimeric antigen receptors (CAR) directed against CD19, a B cell antigen, are reported to induce complete remission in patients with leukemia or lymphoma of the B cell lineage. Although potentially very effective, this treatment strategy has major drawbacks. First, CAR therapy is based on autologous T cells and therefore dependent on the nature and quality of T cells present in the peripheral blood of these patients at the time of treatment. Poor quality of the T cells may cause treatment failure in some patients. In addition, therapy based on autologous cells is tailor-made i.e. CAR+ T cells have to be generated de novo for every patient. Finally, autologous cell therapy requires different, more complicated logistics than conventional therapy. We therefore investigate whether a general purpose, allogeneic CAR therapy based on HLA-matched cord blood obtained from cord blood banks can be devised. Here, we investigated whether functional CAR+ T cells can be generated in vitro that do not express an endogenous T cell receptor to avoid alloreactivity causing graft versus host reactions. We compared carcino-embryonic antigen (CEA)- specific CARs of the first generation (intracellular CD3ζ signaling chain), of the 2nd generation (intracellular CD3ζ and CD28 signaling chain) and of the 3rd generation (intracellular CD3ζ, CD28 and OX40 signaling chain). CD34+ progenitor cells were isolated from human cord blood or postnatal thymus and subsequently transduced with one of the three green fluorescent protein (GFP)-encoding CAR constructs. Transduced cells were subsequently co-cultured on OP9DL1 in the presence of stem cell factor, Flt3-ligand and interleukin-7. Unlike T cell receptor transduced precursors (1), expansion was not enhanced by transduction of the chimeric receptor. Expansion was highest with first generation CARs whereas second and third generation CARs displayed only restricted expansion. Similar to T cell receptor transduced progenitors, CAR transduced cells show an accelerated differentiation during co-culture compared to the non-transduced cells: first committed CD5+ CD7+ T precursors appear, then CD4+ CD8+ double positive cells (DP) and finally CD1- CD27- single positive or double negative (DN) mature T cells. In cultures transduced with 2nd and 3rd generation CARs, few transduced cells passed through the proliferative DP pathway but rather differentiated to mature CD1- CD27- non-proliferative DN cells without passing through the DP stage. This phenomenon is responsible for the limited expansion seen with precursors transgenic for 2nd or 3rd generation CARs. However, in all cultures CAR+ DP cells were generated and, as shown for TCR transgenic cells (1), we were able to induce CEA specific maturation after co-culturing these DP cells with a cell line expressing CEA or by antibody-induced cross-linking of the CAR, giving rise to CD1- CD27+ matured cells. The observations described above are compatible with data obtained in mice showing that strong T cell receptor (TCR) activation during thymocyte differentiation inhibits the generation of DP cells and induces maturation to DN cells. Both the spontaneously and induced mature CAR+ cells were TCR and CD3 negative, suggesting that the expression of a CAR in early T cell precursors shuts down rearrangements of the endogenous TCR chains. Moreover, these cells lack NK marker expression (CD56, NKG2D) and show expression of T cell markers (CD5, CD7, CD2), confirming their T cell nature. In conclusion, the CAR+ CD3/TCR negative cells are T cells as these are derived from T cell precursors (CD5+, DP cells) and express various membrane and nuclear T cell markers. Mature CD1- CD27- CAR+ cells can be expanded to large cell numbers using T cell expansion protocols. They displayed cytokine production specific for CEA+ tumor lines as well as specific cytotoxicity. Moreover, the 2nd and 3rd generation CAR expressing cells showed increased specific cytokine production when compared to the first generation CAR expressing cells. These results show that the cord blood-derived CAR+ cells have potent functional activity similar to peripheral blood derived CAR+ T cells. We believe that these in vitro generated CAR+ cells developed from HLA-matched cord blood progenitors may be ideal as an adjunct to cord blood transplantation. (1) Snauwaert et al, Leukemia, 2014 Disclosures No relevant conflicts of interest to declare.

scholarly journals Armored CAR T-cells: utilizing cytokines and pro-inflammatory ligands to enhance CAR T-cell anti-tumour efficacy

2016 ◽  
Vol 44 (2) ◽  
pp. 412-418 ◽  
Author(s):  
Oladapo O. Yeku ◽  
Renier J. Brentjens
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Second Generation ◽  
Cell Receptor ◽  
Tumour Microenvironment ◽  
Interleukin 12 ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chimaeric antigen receptor (CAR) T-cells are T-cells that have been genetically modified to express an artificial construct consisting of a synthetic T-cell receptor (TCR) targeted to a predetermined antigen expressed on a tumour. Coupling the T-cell receptor to a CD3ζ signalling domain paved the way for first generation CAR T-cells that were efficacious against cluster of differentiation (CD)19-expressing B-cell malignancies. Optimization with additional signalling domains such as CD28 or 4-1BB in addition to CD3ζ provided T-cell activation signal 2 and further improved the efficacy and persistence of these second generation CAR T-cells. Third generation CAR T-cells which utilize two tandem costimulatory domains have also been reported. In this review, we discuss a different approach to optimization of CAR T-cells. Through additional genetic modifications, these resultant armored CAR T-cells are typically modified second generation CAR T-cells that have been further optimized to inducibly or constitutively secrete active cytokines or express ligands that further armor CAR T-cells to improve efficacy and persistence. The choice of the ‘armor’ agent is based on knowledge of the tumour microenvironment and the roles of other elements of the innate and adaptive immune system. Although there are several variants of armored CAR T-cells under investigation, here we focus on three unique approaches using interleukin-12 (IL-12), CD40L and 4-1BBL. These agents have been shown to further enhance CAR T-cell efficacy and persistence in the face of a hostile tumour microenvironment via different mechanisms.

scholarly journals 200. Generation of CAR-T Cells Lacking T Cell Receptor and Human Leukocyte Antigen Using Engineered Meganucleases

2016 ◽  
Vol 24 ◽  
pp. S78 ◽  
Author(s):  
Christina Pham ◽  
Aaron Martin ◽  
Jeyaraj Antony ◽  
Daniel MacLeod ◽  
Audrey Brown ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Human Leukocyte Antigen ◽  
T Cell Receptor ◽  
Human Leukocyte ◽  
Cell Receptor ◽  
Leukocyte Antigen ◽  
Car T Cells ◽  
Car T

scholarly journals Preclinical Evaluation of Human Placental-Derived Allogeneic CD19 CAR-T Cells Against B Cell Malignancies

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3222-3222
Author(s):  
Kathy Karasiewicz ◽  
Shuyang He ◽  
Mary Ng ◽  
Kristina Tess ◽  
Weifang Ling ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Receptor ◽  
Employment Equity ◽  
Car T Cells ◽  
Car T ◽  
Equity Ownership ◽  
Robust Process

Celularity, Inc. is developing a CD19 CAR-T Cell therapy using an allogeneic platform derived from postpartum human placental cells. T cells isolated from placenta/ umbilical cord blood and genetically modified to express CD19 chimeric antigen receptor (CAR), termed Placental-derived (P-) CD19 CAR T cells, are in development for the treatment of B cell malignancies. Unlike adult peripheral blood mononuclear cell (PBMC)-derived T cells, P-T cells are mostly naïve (CD45RA+) and can be readily expanded while maintaining an earlier differentiation phenotype such as greater expression of naïve/ memory markers, lower expression of effector/ exhaustion markers, allowing for greater proliferative potential of these cells ex vivo. These cells are also known to have greater immune tolerance to HLA mismatch and display impaired allogeneic activation, contributing to lower incidences of severe graft-verse-host disease (GvHD) (Barker, et. al. Blood, 2001; Chen, et al. Biology of Blood and Marrow Transplantation, 2006), making them an attractive cell population for use as an allogeneic, adoptive cell therapy. A robust process for the isolation, transduction, and expansion of placental-derived T cells to generate "off-the-shelf" allogeneic P-CD19 CAR T cells was developed. Twenty-One day expanded, non-modified P-T cells (N=3) were compared to adult PBMCs for their allo-reactivity in a Xenogeneic GvHD model in NCG mice. P-T cells did not induce xeno-GvHD whereas PBMCs did, as evidenced by significant weight loss and death of all mice (N=5) by Day 28 post infusion. Despite expanded P-T cells demonstrating lack of in vivo GvHD, current manufacture of P-CD19 CAR T cells does include a CRISPR-mediated T-cell receptor a constant (TRAC) knockout (KO) step as an additional risk-mitigation strategy to circumvent any potential GvHD stemming from expression of endogenous T cell receptor. CD19 CAR transduction using a retrovirus provided by Sorrento Therapeutics, Inc., followed by TRAC knockout with CRISPR results in both high efficiency of CD19 CAR expression (~30% CD19 Fc+) and TCR KO (>96% CD3-/ TCR a/b-). In vitro, the functional activity of P-CD19 CAR-TRAC KO T cells against CD19+ Burkitt's Lymphoma (Daudi) and Acute lymphoblastic Leukemia (NALM6) cell lines was assessed in cytotoxicity and cytokine release assays. P-CD19 CAR T cells specifically lyse CD19+ Daudi/ Nalm6 targets in both 4-hour endpoint FACS and ACEA kinetic cytotoxicity assays, and in most cases at levels equivalent to or greater than PBMC-derived CD19 CAR T cells. When P-CD19 CAR T cells were co-cultured with CD19+ Daudi/ Nalm6 target cells for 24-hours, they secreted pro-inflammatory cytokines and effector proteins in an antigen-specific manner. In vivo, the anti-tumor activity of P-CD19 CAR T cells was assessed using a disseminated lymphoma xenograft model in NSG mice. Luciferase expressing Daudi cells (3×106) were intravenously (IV) injected on Day 0, followed by IV injection of P-CD19 CAR T cells (14×106) on Day 7. Bioluminescence Imaging (BLI) and survival were used as primary study endpoints. P- CD19 CAR T cells were well tolerated and safe. P-CD19 CAR T cells significantly reduced tumor burden, and improved survival. Four weeks after treatment, the vehicle group had a 100% mortality rate, while all animals from P-CD19 CAR T-treated group (N=5) remained alive without clinical symptoms including weight loss or changes in their fur. In summary, Celularity has defined a robust process for the generation and expansion of CD19 CAR T cells from human placenta. These cells exhibit potent anti-tumor activity both in vitro and in vivo with little evidence of acute GvHD induction, highlighting their potential as an allogeneic, adoptive cell therapeutic agent. Future in vivo GvHD studies will include assessment of both CD19 CAR and TRAC KO genetically modified P-T cells. Disclosures Karasiewicz: Celgene: Equity Ownership; Celularity, Inc.: Employment, Equity Ownership, Patents & Royalties: Patent Inventor. He:Celularity Inc: Employment. Ng:Celularity, Inc.: Employment. Tess:Celularity, Inc.: Employment. Ling:Celularity Inc: Employment. Kaufmann:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Zeldis:Sorrento Therapeutics Inc: Employment, Equity Ownership. Ji:Celularity, Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Sorrento Therapeutics Inc: Employment, Equity Ownership, Patents & Royalties. Hariri:Celularity Inc: Employment. Zhang:Celularity Inc: Employment.

scholarly journals Generation of Multiplexed Engineered, Off-the-Shelf CAR T Cells Uniformly Carrying Multiple Anti-Tumor Modalities to Prevent Tumor Relapse

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 11-11
Author(s):  
Chiawei Chang ◽  
Eigen Peralta ◽  
Gloria Hsia ◽  
Bi-Huei Yang ◽  
Wen-I Yeh ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Fold Increase ◽  
Cell Receptor ◽  
Control Group ◽  
Antigen Specificity ◽  
Car T Cells ◽  
Car T ◽  
Specific Cytotoxicity

The development of chimeric antigen receptor (CAR) T cell therapeutics is widely recognized as a significant advancement for the treatment of cancer. However, several obstacles currently impede the broad use of CAR T cells, including the inherent process variability, cost of manufacturing, the absolute requirement for precise and uniform genetic editing in the allogeneic setting, and the challenge to keep pace with clonal heterogeneity and tumor growth. Utilizing our previously described induced pluripotent stem cell (iPSC)-derived T (iT) cell platform, we illustrate here the unique ability to address these challenges by creating a consistent CAR iT cell product that can be repeatedly manufactured in large quantities from a renewable iPSC master cell bank that has been engineered to mitigate the occurrence of graft versus host disease (GvHD), antigen escape and tumor relapse. Utilizing our proprietary cellular reprogramming and engineering platform and stage-specific T cell differentiation protocol, we demonstrate that iPSC can be engineered at the single cell level to generate a fully characterized clonal iPSC line, which can then be accessed routinely to yield CAR iT cells in a highly scalable manufacturing process (>100,000 fold expansion). Through bi-allelic targeting of a CAR into the T cell receptor alpha constant (TRAC) region, we generated CAR iT cells with uniform CAR expression (99.0 ± 0.5% CAR+) and complete elimination of T cell receptor (TCR) expression to avoid GvHD in the allogeneic setting. We elected to utilize the 1XX-CAR configuration, which has demonstrated superior anti-tumor performance relative to other CAR designs and when introduced into iT cells displayed enhanced antigen specificity (% specific cytotoxicity at E:T=10:1, antigen positive group: 86.4 ± 7.8; antigen null group: 8.9 ± 3.5). To enhance persistence without reliance on exogenous cytokine support, we engineered signaling-fusion complexes, including IL-7 receptor fusion (RF), into iPSC and studied its impact on iT phenotype, persistence, and efficacy. In vitro, IL-7RF clones demonstrated improved anti-tumor activity in a serial antigen dependent tumor challenge assay (Day 10, relative tumor counts, IL-7RF group: 1.95 ± 0.01; control group: 57.56 ± 4.55, P<0.000001). In a preclinical in vivo model of disseminated leukemia, IL-7RF clones demonstrate enhanced tumor growth inhibition (Day 34, Log [BLI], IL-7RF group: 6.68 ± 1.93; control group: 9.99 ± 0.23, P=0.0143). We next investigated a unique strategy to incorporate multi-antigen targeting potential into anti-CD19 1XX CAR iT cells with the addition of a high-affinity non-cleavable CD16 (hnCD16) Fc receptor. The combination of hnCD16 with anti-CD19 1XX CAR culminated in iT cells capable of multi-antigen specificity through combinatorial use with monoclonal antibodies to tackle antigen escape. Utilizing CD19 negative leukemia cells as targets, superior antibody-dependent cellular cytotoxicity (ADCC) was demonstrated by the combination of hnCD16 CAR iT and Rituximab (% specific cytotoxicity at E:T=1:1, hnCD16 group + Rituximab: 75.64 ± 2.12; control group + Rituximab: 16.98 ± 3.87, P<0.001). To address T cell fitness, the role of CD38 knockout (KO) in T cells was investigated, which we have previously shown to mediate NK cell resistance to oxidative stress induced apoptosis. CD38 gene was disrupted at the iPSC stage to generate 1XX-CAR T cells that lack CD38 expression (% CD38+ population, CD38WT group: 69.67 ± 24.34; CD38KO group: 0.12 ± 0.11) and upon antigen mediated stimulation, CD38KO CAR iT cells showed higher percentages of degranulation (2.3-fold increase in CD107a/b), and IFNγ (4.1-fold increase) and TNFα (2.5-fold increase) production. Antigen specific in vitro tumor killing also was enhanced in CD38KO CAR iT cells (EC50, 3.2-fold decrease). Lastly, to avoid the potential host-mediated rejection, the inclusion of allogeneic defense receptor (ADR) which has been shown to significantly reduce host-mediated rejection will be discussed. Collectively, the described studies demonstrate that iPSCs are an ideal cellular source to generate large-quantities of uniformly multi-edited off-the-shelf CAR T cell products that include a best-in-class CAR design, enhanced product modalities, and complete elimination of TCR expression to avoid the potential of GvHD while maintaining high anti-tumor efficacy in allogeneic setting. Disclosures Hsia: Fate Therapeutics Inc.: Current Employment. Clarke:Fate Therapeutics Inc.: Current Employment, Current equity holder in publicly-traded company. Lee:Fate Therapeutics, Inc.: Current Employment. Robbins:Fate Therapeutics, Inc.: Current Employment. Denholtz:Fate Therapeutics, Inc: Current Employment. Hanok:Fate Therapeutics, Inc.: Current Employment. Carron:Fate Therapeutics, Inc.: Current Employment. Navarrete:Fate Therapeutics, Inc.: Current Employment. ORourke:Fate Therapeutics, Inc.: Current Employment. Sung:Fate Therapeutics, Inc.: Current Employment. Gentile:Fate Therapeutics, Inc.: Current Employment. Nguyen:Fate Therapeutics, Inc.: Current Employment. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company.

scholarly journals CAR T Cells: Precision Cancer Immunotherapy

2018 ◽  
Vol 10 (3) ◽  
pp. 203-16
Author(s):  
Anna Meiliana ◽  
Nurrani Mustika Dewi ◽  
Andi Wijaya
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Cancer Immunotherapy ◽  
Tumor Cells ◽  
T Cell Receptor ◽  
Adoptive Cell Therapy ◽  
Cell Receptor ◽  
Car T Cells ◽  
Car T

BACKGROUND: Current cancer drugs and treatments are aiming at eradicating tumor cells, but often are more toxic then effective, killing also the normal cells and not selectively the tumor cells. There is good personalized cancer therapy that involves administration to the cancer-bearing host of immune cells with direct anticancer activity, which called adoptive cell therapy (ACT). A review of the unique biology of T cell therapy and of recent clinical experience compels a reassessment of target antigens that traditionally have been viewed from the perspective of weaker immunotherapeutic modalities.CONTENT: Chimeric antigen receptors (CAR) are recombinant receptors which provide both antigen-binding and T cell-activating functions. Many kind of CARs has been reported for the past few years, targeting an array of cell surface tumor antigens. Their biologic functions have extremely changed following the introduction of tripartite receptors comprising a costimulatory domain, termed second-generation CARs. The combination of CARs with costimulatory ligands, chimeric costimulatory receptors, or cytokines can be done to further enhance T cell potency, specificity and safety. CARs reflects a new class of drugs with exciting potential for cancer immunotherapy.SUMMARY: CAR-T cells have been arising as a new modality for cancer immunotherapy because of their potent efficacy against terminal cancers. They are known to exert higher efficacy than monoclonal antibodies and antibodydrug conjugates, and act via mechanisms distinct from T cell receptor-engineered T cells. These cells are constructed by transducing genes encoding fusion proteins of cancer antigen-recognizing single-chain Fv linked to intracellular signaling domains of T cell receptors.KEYWORDS: chimeric antigen receptor, CAR T cells, adoptive cell therapy, ACT, T cell receptor, TCR, cancer, immunotherapy

scholarly journals Common trajectories of highly effective CD19-specific CAR T cells identified by endogenous T cell receptor lineages

2021 ◽  
Author(s):  
Taylor L. Wilson ◽  
Hyunjin Kim ◽  
Ching-Heng Chou ◽  
Deanna Langfitt ◽  
E. Kaitlynn Allen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Post Infusion

AbstractCurrent chimeric antigen receptor-modified (CAR) T cell therapy products are evaluated in bulk, without assessment of the possible heterogeneity in effector potential between cells. Conceivably, only a subset of the pre-infusion product differentiates into optimal effectors. We generated a comprehensive single-cell gene expression and T cell receptor (TCR) sequencing dataset using both pre- and post-infusion CD19-CAR T cells from peripheral blood and bone marrow of pediatric patients with B cell acute lymphoblastic leukemia (B-ALL). We identified potent effector post-infusion cells with identical TCRs to a subset of pre-infusion CAR T cells. Effector precursor CAR T cells exhibited a unique transcriptional profile compared to other pre-infusion cells, and the number of effector precursor cells infused correlated with peak CAR T cell expansion. Additionally, we identified an unexpected cell surface phenotype (TIGIT+, CD62Llo, CD27-), conventionally associated with inhibiting effective T cell responses, that we used to successfully enrich for subsequent effector potential. Collectively, these results demonstrate that highly diverse effector potentials are present among cells in pre-infusion cell products, which can be exploited for diagnostic and therapeutic applications. Furthermore, we provide an integrative experimental and analytical framework for elucidating the biological mechanisms underlying effector development in other CAR T cell therapy products.

94 The T cell antigen coupler (TAC) redirects T cell oncolysis while limiting tonic signaling to create a safer engineered T cell product with a higher threshold for activation

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A105-A105
Author(s):  
Duane Moogk ◽  
Vivian Lau ◽  
Arya Afsahi ◽  
Anna Dvorkin-Gheva ◽  
Ksenia Bezverbnaya ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Binding Domain ◽  
Antigen Binding ◽  
Car T Cells ◽  
Car T

BackgroundThe T cell Antigen Couper (TAC) is a chimeric receptor that redirects the endogenous T cell receptor (TCR) against a tumor target via an extracellular antigen-binding domain to induce activation and oncolysis. TAC-engineered T cells (TAC-T cells) showed a similar capacity to activate T cells against the tumor-associated antigen HER2 as their classical chimeric antigen receptor (CAR)-engineered counterparts in vitro. However, in a xenograft model, anti-HER2 CAR-T cells gave rise to lethal off-target toxicity while TAC-T cells were efficacious and well-tolerated, despite utilizing the same antigen-binding domain.1 2 Here, we describe differences in T cell activation by TAC (canonical via endogenous TCR) and CAR (non-canonical independent of TCR) that make CAR-T cells less discriminate towards an off-target stimulus than TAC-T cells.MethodsPaired sets of TAC- and CAR-engineered human T cells, utilizing a variety of antigen-binding domains, were compared in vitro to determine their propensity for tonic signaling and requirements for triggering T cell activation.ResultsTranscriptional profiling of CAR- and TAC- T cells in the absence of antigenic stimulus revealed an elevated basal activation status in CAR-T cells. Unstimulated CAR-T cells displayed elevated expression levels of activation and exhaustion markers, as well as basal cytokine production, versus their TAC-T cell counterparts. The degree of basal activation varied with the binding domain incorporated into the CAR, where some binding domains triggered functional exhaustion. Regardless of the binding domain, unstimulated TAC-T cells were indistinguishable from control T cells that expressed no synthetic receptor. Further, TAC-T cells displayed no evidence of functional exhaustion. TCR knock-out studies confirmed that TAC receptors signal via the endogenous TCR, whereas CAR signaling is TCR-independent. Consistent with TCR-dependent signaling, ligation of TAC receptors resulted in the formation of conventional immunological synapses, whereas ligation of CARs produced unconventional synapses. Despite these functional differences, CARs and TAC receptors demonstrated a similar capacity to activate T cells against antigen-positive tumor cell targets. However, CAR-T cells displayed reactivity to antigen-negative cells, due to interaction with a cross-reactive antigen; TAC-T cells displayed no reactivity to antigen-negative cells.ConclusionsTonic signaling in CAR-T cells reduces their activation threshold and increases their propensity to be activated by cross-reactive antigen. In contrast, TAC receptors do not deliver tonic signals, which increases the stringency of activation and reduces the likelihood of off-target responses. This feature of the TAC platform is advantageous to safeguard against the unexpected cross-reactivity that may occur when a new antigen-binding domain is deployed in vivo.Ethics ApprovalUse of human materials was approved by the Hamilton Integrated Research Ethics Board (HiREB).ReferencesHelsen C, Hammill JA, Lau VWC, Mwawasi KA, Afsahi A, Bezverbnaya K, Newhook L, Hayes DL, Aarts C, Bojovic B, Denisova GF, Kwiecien JM, Brain I, Derocher H, Milne K, Nelson BH, Bramson JL. The chimeric TAC receptor co-opts the T cell receptor yielding robust anti-tumor activity without toxicity. Nat Commun 2018;9:3049.Hammill JA, Kwiecien JM, Dvorkin-Gheva A, Lau VWC, Baker C, Wu Y, Bezverbnaya K, Aarts C, Helsen CW, Denisova GF, Derocher H, Milne K, Nelson BH, Bramson JL. A cross-reactive small protein binding domain provides a model to study off-tumor CAR-T cell toxicity. Mol Ther Oncolytics 2020;17:278–292.

98 ATA3271: an armored, next-generation off-the-shelf, allogeneic, mesothelin-CAR T cell therapy for solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A109-A109
Author(s):  
Jiangyue Liu ◽  
Xianhui Chen ◽  
Jason Karlen ◽  
Alfonso Brito ◽  
Tiffany Jheng ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Next Generation ◽  
Phase 3 ◽  
T Cell Therapy ◽  
Cell Therapies ◽  
Car T Cells ◽  
Car T

BackgroundMesothelin (MSLN) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein with high expression levels in an array of malignancies including mesothelioma, ovaria, non-small cell lung cancer, and pancreatic cancers and is an attractive target antigen for immune-based therapies. Early clinical evaluation of autologous MSLN-targeted chimeric antigen receptor (CAR)-T cell therapies for malignant pleural mesothelioma has shown promising acceptable safety1 and have recently evolved with incorporation of next-generation CAR co-stimulatory domains and armoring with intrinsic checkpoint inhibition via expression of a PD-1 dominant negative receptor (PD1DNR).2 Despite the promise that MSLN CAR-T therapies hold, manufacturing and commercial challenges using an autologous approach may prove difficult for widespread application. EBV T cells represent a unique, non-gene edited approach toward an off-the-shelf, allogeneic T cell platform. EBV-specific T cells are currently being evaluated in phase 3 trials [NCT03394365] and, to-date, have demonstrated a favorable safety profile including limited risks for GvHD and cytokine release syndrome.3 4 Clinical proof-of-principle studies for CAR transduced allogeneic EBV T cell therapies have also been associated with acceptable safety and durable response in association with CD19 targeting.5 Here we describe the first preclinical evaluation of ATA3271, a next-generation allogeneic CAR EBV T cell therapy targeting MSLN and incorporating PD1DNR, designed for the treatment of solid tumor indications.MethodsWe generated allogeneic MSLN CAR+ EBV T cells (ATA3271) using retroviral transduction of EBV T cells. ATA3271 includes a novel 1XX CAR signaling domain, previously associated with improved signaling and decreased CAR-mediated exhaustion. It is also armored with PD1DNR to provide intrinsic checkpoint blockade and is designed to retain functional persistence.ResultsIn this study, we characterized ATA3271 both in vitro and in vivo. ATA3271 show stable and proportional CAR and PD1DNR expression. Functional studies show potent antitumor activity of ATA3271 against MSLN-expressing cell lines, including PD-L1-high expressors. In an orthotopic mouse model of pleural mesothelioma, ATA3271 demonstrates potent antitumor activity and significant survival benefit (100% survival exceeding 50 days vs. 25 day median for control), without evident toxicities. ATA3271 maintains persistence and retains central memory phenotype in vivo through end-of-study. Additionally, ATA3271 retains endogenous EBV TCR function and reduced allotoxicity in the context of HLA mismatched targets. ConclusionsOverall, ATA3271 shows potent anti-tumor activity without evidence of allotoxicity, both in vitro and in vivo, suggesting that allogeneic MSLN-CAR-engineered EBV T cells are a promising approach for the treatment of MSLN-positive cancers and warrant further clinical investigation.ReferencesAdusumilli PS, Zauderer MG, Rusch VW, et al. Abstract CT036: A phase I clinical trial of malignant pleural disease treated with regionally delivered autologous mesothelin-targeted CAR T cells: Safety and efficacy. Cancer Research 2019;79:CT036-CT036.Kiesgen S, Linot C, Quach HT, et al. Abstract LB-378: Regional delivery of clinical-grade mesothelin-targeted CAR T cells with cell-intrinsic PD-1 checkpoint blockade: Translation to a phase I trial. Cancer Research 2020;80:LB-378-LB-378.Prockop S, Doubrovina E, Suser S, et al. Off-the-shelf EBV-specific T cell immunotherapy for rituximab-refractory EBV-associated lymphoma following transplantation. J Clin Invest 2020;130:733–747.Prockop S, Hiremath M, Ye W, et al. A Multicenter, Open Label, Phase 3 Study of Tabelecleucel for Solid Organ Transplant Subjects with Epstein-Barr Virus-Driven Post-Transplant Lymphoproliferative Disease (EBV+PTLD) after Failure of Rituximab or Rituximab and Chemotherapy. Blood 2019; 134: 5326–5326.Curran KJ, Sauter CS, Kernan NA, et al. Durable remission following ‘Off-the-Shelf’ chimeric antigen receptor (CAR) T-Cells in patients with relapse/refractory (R/R) B-Cell malignancies. Biology of Blood and Marrow Transplantation 2020;26:S89.

Sign in / Sign up

Export Citation Format

Share Document