CD70-specific CAR T-cells have potent activity against Acute Myeloid Leukemia (AML) without HSC toxicity

Blood ◽  
2021 ◽  
Author(s):  
Tim Sauer ◽  
Kathan Parikh ◽  
Sandhya Sharma ◽  
Bilal Omer ◽  
David Nikolov Sedloev ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Myeloid Leukemia ◽  
Target Antigen ◽  
Single Chain ◽  
Hematopoietic Stem ◽  
Car T Cells ◽  
Car T ◽  
Acute Myeloid

The prognosis of patients with acute myeloid leukemia (AML) remains dismal highlighting the need for novel innovative treatment strategies. The application of chimeric antigen receptor (CAR) T-cell therapy to AML patients has been limited in particular by the lack of a tumor-specific target antigen. CD70 is a promising antigen to target AML as it is expressed on the majority of leukemic blasts, whereas little or no expression is detectable in normal bone marrow samples. To target CD70 on AML cells, we generated a panel of CD70-CARs that contained a common single chain variable fragment (scFv) for antigen detection but differed in size and flexibility of the extracellular spacer, and in the transmembrane and the co-stimulatory domains. These CD70scFv CARs were compared with a CAR construct that contained the human CD27, the ligand of CD70 fused to the CD3z chain (CD27z). The structural composition of the CAR strongly influenced expression levels, viability, expansion and cytotoxic capacities of CD70scFv CAR T-cells, but the CD27z-CAR T-cells demonstrated superior proliferation and anti-tumor activity in vitro and in vivo, compared to all CD70scFv-CARs. While CD70-CAR T-cells recognized activated virus-specific T-cells (VSTs) that expressed CD70, they did not prevent colony formation by normal hematopoietic stem cells (HSCs). Thus, CD70-targeted immunotherapy is a promising new treatment strategy for patients with CD70-positive AML that does not affect normal hematopoiesis but will require monitoring of virus-specific T-cell responses.

scholarly journals Chimeric antigen receptor T cell therapies for acute myeloid leukemia

2020 ◽  
Vol 14 (6) ◽  
pp. 701-710
Author(s):  
Bin Gu ◽  
Jianhong Chu ◽  
Depei Wu
Keyword(s):  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Chimeric Antigen Receptor ◽  
Myeloid Leukemia ◽  
Residual Disease ◽  
Antigen Receptor ◽  
Target Antigen ◽  
Hematopoietic Stem ◽  
Car T ◽  
Acute Myeloid

AbstractChimeric antigen receptor T cell (CAR T) therapies have achieved unprecedented efficacy in B-cell tumors, prompting scientists and doctors to exploit this strategy to treat other tumor types. Acute myeloid leukemia (AML) is a group of heterogeneous myeloid malignancies. Relapse remains the main cause of treatment failure, especially for patients with intermediate or high risk stratification. Allogeneic hematopoietic stem cell transplantation could be an effective therapy because of the graft-versus-leukemia effect, which unfortunately puts the patient at risk of serious complications, such as graft-versus-host disease. Although the identification of an ideal target antigen for AML is challenging, CAR T therapy remains a highly promising strategy for AML patients, particularly for those who are ineligible to receive a transplantation or have positive minimal residual disease. In this review, we focus on the most recent and promising advances in CAR T therapies for AML.

scholarly journals Harnessing T Cells to Target Pediatric Acute Myeloid Leukemia: CARs, BiTEs, and Beyond

Children ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 14
Author(s):  
Rebecca Epperly ◽  
Stephen Gottschalk ◽  
Mireya Paulina Velasquez
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Targeted Therapies ◽  
Myeloid Leukemia ◽  
Immune Therapy ◽  
Bispecific Antibodies ◽  
Car T Cells ◽  
Car T ◽  
Acute Myeloid

Outcomes for pediatric patients with acute myeloid leukemia (AML) remain poor, highlighting the need for improved targeted therapies. Building on the success of CD19-directed immune therapy for acute lymphocytic leukemia (ALL), efforts are ongoing to develop similar strategies for AML. Identifying target antigens for AML is challenging because of the high expression overlap in hematopoietic cells and normal tissues. Despite this, CD123 and CD33 antigen targeted therapies, among others, have emerged as promising candidates. In this review we focus on AML-specific T cell engaging bispecific antibodies and chimeric antigen receptor (CAR) T cells. We review antigens being explored for T cell-based immunotherapy in AML, describe the landscape of clinical trials upcoming for bispecific antibodies and CAR T cells, and highlight strategies to overcome additional challenges facing translation of T cell-based immunotherapy for AML.

scholarly journals Modulating TNFα activity allows transgenic IL15-Expressing CLL-1 CAR T cells to safely eliminate acute myeloid leukemia

2020 ◽  
Vol 8 (2) ◽  
pp. e001229
Author(s):  
Pinar Ataca Atilla ◽  
Mary K McKenna ◽  
Haruko Tashiro ◽  
Madhuwanti Srinivasan ◽  
Feiyan Mo ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Acute Toxicity ◽  
Myeloid Leukemia ◽  
Tnf Alpha ◽  
Car T Cells ◽  
Car T ◽  
Anti Tumor Activity ◽  
Acute Myeloid

BackgroundC-type lectin-like molecule 1 (CLL-1) is highly expressed in acute myeloid leukemia (AML) but is absent in primitive hematopoietic progenitors, making it an attractive target for a chimeric antigen receptor (CAR) T-cell therapy. Here, we optimized our CLL-1 CAR for anti-leukemic activity in mouse xenograft models of aggressive AML.MethodsFirst, we optimized the CLL-1 CAR using different spacer, transmembrane and costimulatory sequences. We used a second retroviral vector to coexpress transgenic IL15. We measured the effects of each construct on T cell phenotype and sequential (recursive) co culture assays with tumor cell targets to determine the durability of the anti tumor activity by flow cytometry. We administered CAR T cells to mice engrafted with patient derived xenografts (PDX) and AML cell line and determined anti tumor activity by bioluminescence imaging and weekly bleeding, measured serum cytokines by multiplex analysis. After euthanasia, we examined formalin-fixed/paraffin embedded sections. Unpaired two-tailed Student’s t-tests were used and values of p<0.05 were considered significant. Survival was calculated using Mantel-Cox log-rank test.ResultsIn vitro, CLL-1 CAR T cells with interleukin-15 (IL15) were less terminally differentiated (p<0.0001) and had superior expansion compared with CD28z-CD8 CAR T cells without IL15 (p<0.001). In both AML PDX and AML cell line animal models, CLL-1 CAR T coexpressing transgenic IL15 initially expanded better than CD28z-CD8 CAR T without IL15 (p<0.0001), but produced severe acute toxicity associated with high level production of human tumor necrosis factor α (TNFα), IL15 and IL2. Histopathology showed marked inflammatory changes with tissue damage in lung and liver. This acute toxicity could be managed by two strategies, individually or in combination. The excessive TNF alpha secretion could be blocked with anti-TNF alpha antibody, while excessive T cell expansion could be arrested by activation of an inducible caspase nine safety switch by administration of dimerizing drug. Both strategies successfully prolonged tumor-free survival.ConclusionCombinatorial treatment with a TNFα blocking antibody and subsequent activation of the caspase-9 control switch increased the expansion, survival and antileukemic potency of CLL-1 CAR T-cells expressing transgenic IL15 while avoiding the toxicities associated with excessive cytokine production and long-term accumulation of activated T-cells.

scholarly journals Demethylating therapy increases anti-CD123 CAR T cell cytotoxicity against acute myeloid leukemia

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nadia El Khawanky ◽  
Amy Hughes ◽  
Wenbo Yu ◽  
Renier Myburgh ◽  
Tony Matschulla ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Intracellular Signaling ◽  
Myeloid Leukemia ◽  
Epithelial Tissue ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Acute Myeloid

AbstractSuccessful treatment of acute myeloid leukemia (AML) with chimeric antigen receptor (CAR) T cells is hampered by toxicity on normal hematopoietic progenitor cells and low CAR T cell persistence. Here, we develop third-generation anti-CD123 CAR T cells with a humanized CSL362-based ScFv and a CD28-OX40-CD3ζ intracellular signaling domain. This CAR demonstrates anti-AML activity without affecting the healthy hematopoietic system, or causing epithelial tissue damage in a xenograft model. CD123 expression on leukemia cells increases upon 5′-Azacitidine (AZA) treatment. AZA treatment of leukemia-bearing mice causes an increase in CTLA-4negative anti-CD123 CAR T cell numbers following infusion. Functionally, the CTLA-4negative anti-CD123 CAR T cells exhibit superior cytotoxicity against AML cells, accompanied by higher TNFα production and enhanced downstream phosphorylation of key T cell activation molecules. Our findings indicate that AZA increases the immunogenicity of AML cells, enhancing recognition and elimination of malignant cells by highly efficient CTLA-4negative anti-CD123 CAR T cells.

CD33-Directed Chimeric Antigen Receptor (CAR) T Cells for the Treatment of Acute Myeloid Leukemia (AML)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2825-2825 ◽  
Author(s):  
Sarwish Rafiq ◽  
Terence J. Purdon ◽  
Liora M. Schultz ◽  
Renier J. Brentjens
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Myeloid Leukemia ◽  
Term Survival ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Acute Myeloid

Abstract Therapies for acute myeloid leukemia (AML) have not improved patient long-term survival for decades. Novel treatment options, such as chimeric antigen receptor (CAR) T cells, are needed for patients with this disease. However, AML cells lack ideal targeting antigens that are safe to target with CAR T cells. CD33, a commonly targeted antigen, is expressed in about 85-90% of AML cases but is also present on normal myeloid progenitors and myelocytes. Our aim was to engineer and validate CD33-directed CAR T cells, with the intention to open a phase I clinical trial in patients with relapsed AML. Given the potential toxicity associated with targeting CD33 in patients, an elimination gene was included in the construct design to allow CAR T cell clearance after disease eradication. We constructed a CAR specific for CD33 by utilizing the variable heavy and light chains of the humanized M-195 antibody (HuM-195), CD28 and zeta signaling domains, and the IL-12 gene. To facilitate CAR T cell elimination if necessary, a truncated epidermal growth factor receptor (EGFRt) gene was also inserted into the retroviral vector to create the EGFRt/HuM195-28z/IL-12 CAR construct. Retroviral transduction with this tri-cistronic construct resulted in high transduction efficiency of human T cells, as determined by detection of EGFRt with fluorescently-labeled cetuximab or CAR with fluorescently-labeled CD33 molecule by flow cytometry. T cells transduced with the EGFRt/HuM195-28z/IL-12 CAR secreted functional IL-12, as assessed by culturing CAR cell supernatant with peripheral blood mononuclear cells and detecting IFN-g produced in response to IL-12. When stimulated through the CAR by co-culturing with the CD33+ AML cell line Molm-13, EGFRt/HuM195-28z/IL-12 CAR T cells proliferated and produced significant levels of the pro-inflammatory cytokines IFN-g and IL-2. In addition, EGFRt/HuM195-28z/IL-12 CAR T cells mediated significantly cytotoxicity against Molm-13 at a range of effector-to-target ratios in standard 51Cr-release assays, as compared to control CAR T cells. The in vivo anti-tumor efficacy of EGFRt/HuM195-28z/IL-12 CAR T cells was tested in two preclinical mouse models of AML. First, SCID/Beige mice were xenografted with Molm-13 cells. Mice subsequently treated with EGFRt/HuM195-28z/IL-12 CAR T cells exhibited significant long-term survival, as compared to untreated or control CAR T cell-treated mice (p = <0.0001). In addition, NSG mice were engrafted with patient-derived CD33+ AML (PDX) cells. PDX mice treated with EGFRt/HuM195-28z/IL-12 CAR T cells exhibited reduction of peripheral CD33+ disease, as compared to untreated or control CAR T cell-treated mice. These studies demonstrate the capacity of the EGFRt/HuM195-28z/IL-12 CAR to redirect the specific anti-tumor function of T cells to CD33+ AML tumor cells. Ongoing studies aim to validate elimination of CAR T cells via EGFRt in vitro in antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity assays, as well as in mice are currently underway. These data support the utilization of CD33-specific CAR T cells in the clinic for patients with relapsed AML as a means to decrease disease burden prior to consolidative therapies such as allogeneic transplantation. Disclosures Brentjens: Juno Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

scholarly journals Driving CAR T Stem Cell Targeting in Acute Myeloid Leukemia: The Roads to Success

Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2816
Author(s):  
Ilaria M. Michelozzi ◽  
Efstratios Kirtsios ◽  
Alice Giustacchini
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Myeloid Leukemia ◽  
Lymphoblastic Leukemia ◽  
Poor Overall Survival ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Acute Myeloid

Current treatment outcome for acute myeloid leukemia (AML) patients is unsatisfactory and characterized by high rates of relapse and poor overall survival. Increasing evidence points to a crucial role of leukemic stem cells (LSC) and the bone marrow (BM) leukemic niche, in which they reside, in AML evolution and chemoresistance. Thus, future strategies aiming at improving AML therapeutic protocols are likely to be directed against LSC and their niche. Chimeric antigen receptor (CAR) T-cells have been extremely successful in the treatment of relapsed/refractory acute lymphoblastic leukemia and B-cell non-Hodgkin lymphoma and comparable results in AML are highly desirable. At present, we are at the dawn of CAR T-cell application in AML, with several preclinical studies and few early phase clinical trials. However, the lack of leukemia-specific targets and the genetic and phenotypic heterogeneity of the disease combined with the leukemia-induced remodeling of the BM microenvironment are limiting CAR T-cell exploitation in AML. Here, we reviewed AML-LSC and AML-BM niche features in the context of their therapeutic targeting using CAR T-cells. We summarized recent progress in CAR T-cell application to the treatment of AML, and we discussed the remaining therapeutic challenges and promising novel strategies to overcome them.

scholarly journals A Novel Target Antigen for the Treatment of Acute Myeloid Leukemia by CAR T Cells

2017 ◽  
Vol 25 (9) ◽  
pp. 1997-1998 ◽  
Author(s):  
Paul A. Beavis ◽  
Kevin Sek ◽  
Phillip K. Darcy
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Antigen ◽  
Car T Cells ◽  
Car T ◽  
Novel Target ◽  
Acute Myeloid

scholarly journals Preclinical Development of Anti-FLT3 CAR-T Therapy for the Treatment of Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 4-5
Author(s):  
Elina Shrestha ◽  
Raymond Liang ◽  
Carina Sirochinsky ◽  
Ronen Ben Jehuda ◽  
Vladislav Sandler
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Acute Myeloid Leukemia ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Car T Cells ◽  
Car T ◽  
Acute Myeloid

FMS-like tyrosine kinase 3 (FLT3) is a class III transmembrane receptor tyrosine kinase involved in survival, proliferation, and differentiation of hematopoietic stem/progenitor cells. It is preferentially expressed on the leukemic cells of myeloid lineage including acute myeloid leukemia (AML) and is mutated in approximately one-third of patients with AML, resulting in constitutive signaling associated with poor disease prognosis. Although small molecule inhibitors targeting FLT3 have shown some success in clinical trials, they only work transiently while resistance develops in virtually all patients. The only proven curative treatment for the relapsed or refractory (R/R) AML is allogenic hematopoietic stem cell transplantation (HSCT) which requires highly toxic conditioning regimens often associated with fatal side effects. Thus, there still remains an urgent need for the development of safe yet effective new therapies for the treatment of AML. We developed a novel chimeric antigen receptor modified T (CAR-T) cell therapy targeting FLT3 to eliminate FLT3+ R/R AML leukemia via cytotoxic T lymphocytes (CTL)-mediated cytolysis. Since FLT3 is also expressed on hematopoietic stem cells (HSCs) as well as on early hematopoietic progenitors (HPs), we evaluated the conditioning efficacy of our anti-FLT3 CAR-T in addition to its anti-leukemic activity. We first discovered a novel mouse monoclonal antibody that binds to the extracellular domain of human FLT3 with high affinity (0.8 nM EC50 in FLT3+ leukemic cell line REH) while not competing with FLT3 ligand in order to achieve unobstructed and efficient binding to FLT3. We next generated humanized single-chain variable fragment (scFv) antibodies and characterized their binding affinities. The scFv clone that exhibited highest binding to FLT3 (3.42 nM EC50 in REH cells) was used to design a third generation CAR construct with CD28 and 4-1BB costimulatory and CD3ζ activation domains. T cells isolated from peripheral blood (PB) were transduced with a lentiviral vector encoding the FLT3-CAR. Transduced cells exhibited stable expression of CAR protein and expanded over 120-fold after 18 days in culture. We demonstrated high cytotoxicity of FLT3-CAR-T cells towards AML-derived cell lines in co-culture experiments, even at effector-to-target cells ratios as low as 1:10. In vivo functionality of FLT3-CART was determined by flow cytometry analysis of leukemia burden in the peripheral blood of mice engrafted with GFP+ MOLM-13 (FLT3+ AML cell line) and treated with two doses of 4x106 control or FLT3-CAR-T cells. Compared to control, the appearance of MOLM-13 cells in peripheral blood was significantly delayed in FLT3-CAR-T treated mice. AML progression in mice was also assessed by detection of physical symptoms such as cachexia and hind-leg paralysis in terminal stages. FLT3-CAR-T treatment extended the median survival to 47 days compared to 24 days in control. Moreover, to test if our CAR-T therapy can also efficiently eliminate FLT3+ HSCs and HPs, humanized mice generated by engrafting human cord blood CD34+ cells were injected with autologous control or FLT3-CAR-T cells. Analysis of bone marrow 18 days post treatment, showed that mice that received FLT3-CAR-T cells exhibited dramatically lower frequencies (by 57% in CD38+ and 86% in CD38-) of human CD34+ hematopoietic stem and progenitor cells than control mice, suggesting the potential of CAR-T therapy for HSCT conditioning. In conclusion, our CAR-T therapy shows robust cytolytic activity against FLT3+ cells, demonstrates high efficacy in eradicating FLT3+ R/R AML leukemia in vivo and enables bone marrow conditioning for potentially curative HSCTs by specifically targeting FLT3+ HSCs and early HPs. To prevent the potentially harmful side effects associated with CAR-T therapies, such as cytokine release syndrome and cytotoxicity towards newly transplanted HSCs post conditioning, we are currently testing FLT3-CAR-T cells equipped with inducible caspase9 or EGFRT expression based safety switch to specifically eliminate CAR-Ts by administering FDA-approved small molecules or biologics. Disclosures Shrestha: Hemogenyx Pharmaceuticals LLC: Current Employment. Liang:Hemogenyx Pharmaceuticals LLC: Current Employment. Sirochinsky:Hemogenyx Pharmaceuticals LLC: Current Employment. Ben Jehuda:Hemogenyx Pharmaceuticals LLC: Current Employment. Sandler:Hemogenyx Pharmaceuticals LLC: Current Employment, Current equity holder in publicly-traded company.

scholarly journals A modular and controllable T cell therapy platform for acute myeloid leukemia

Leukemia ◽  
2021 ◽  
Author(s):  
Mohamed-Reda Benmebarek ◽  
Bruno L. Cadilha ◽  
Monika Herrmann ◽  
Stefanie Lesch ◽  
Saskia Schmitt ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Cell Therapy ◽  
Myeloid Leukemia ◽  
Tumor Antigens ◽  
Adoptive T Cell Therapy ◽  
Single Chain ◽  
T Cell Therapy ◽  
Acute Myeloid

AbstractTargeted T cell therapy is highly effective in disease settings where tumor antigens are uniformly expressed on malignant cells and where off-tumor on-target-associated toxicity is manageable. Although acute myeloid leukemia (AML) has in principle been shown to be a T cell-sensitive disease by the graft-versus-leukemia activity of allogeneic stem cell transplantation, T cell therapy has so far failed in this setting. This is largely due to the lack of target structures both sufficiently selective and uniformly expressed on AML, causing unacceptable myeloid cell toxicity. To address this, we developed a modular and controllable MHC-unrestricted adoptive T cell therapy platform tailored to AML. This platform combines synthetic agonistic receptor (SAR) -transduced T cells with AML-targeting tandem single chain variable fragment (scFv) constructs. Construct exchange allows SAR T cells to be redirected toward alternative targets, a process enabled by the short half-life and controllability of these antibody fragments. Combining SAR-transduced T cells with the scFv constructs resulted in selective killing of CD33+ and CD123+ AML cell lines, as well as of patient-derived AML blasts. Durable responses and persistence of SAR-transduced T cells could also be demonstrated in AML xenograft models. Together these results warrant further translation of this novel platform for AML treatment.

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