Abstract PR08: Armored CAR T cells genetically modified to secrete IL-12 show enhanced efficacy and overcome a hostile tumor microenvironment in mouse ovarian peritoneal carcinomatosis

Abstract T cells armed with a chimeric antigen receptor, CAR T cells, have shown extraordinary activity against certain B lymphocyte malignancies, when targeted towards the CD19 B cell surface marker. These results have led to the regulatory approval of two CAR T cell approaches. Translation of this result to the solid tumor setting has been problematic until now. A number of differences between liquid and solid tumors are likely to cause this discrepancy. The main ones of these are undoubtedly the uncomplicated availability of the target cell within the blood compartment and the abundant expression of the target molecule on the cancerous cells in the case of hematological malignancies. Targets expressed by solid tumor cells are hard to engage due to the non-adhesive and abnormal vasculature, while conditions in the tumor microenvironment can be extremely immunosuppressive. Targets in the tumor vasculature are readily reachable by CAR T cells and reside outside the immunosuppressive tumor microenvironment. It is therefore hypothesized that targeting CAR T cells towards the tumor vasculature of solid tumors may share the excellent effects of CAR T cell therapy with that against hematological malignancies. A few reports have shown promising results. Suggestions are provided for further improvement.

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Dominant-negative PD1-armored CART cells induce remission in refractory diffuse large B-cell lymphoma (DLBCL) patients.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.e19028 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. e19028-e19028 ◽

Cited By ~ 1

Author(s):

Tong Chen ◽

Yan Yuan ◽

Liansheng Huang ◽

Chengfei Pu ◽

Tianling Ding ◽

...

Keyword(s):

Clinical Trials ◽

T Cells ◽

Tumor Microenvironment ◽

B Cell ◽

B Cell Lymphoma ◽

Dominant Negative ◽

Car T Cells ◽

Car T ◽

Tumor Killing ◽

Large B Cell

e19028 Background: The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to relapse/refractory B cell malignancy. However, tumor microenvironment influences and affects CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated Programmed cell death protein 1 (PD1) during T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy. Methods: We generated CAR T cells including an anti-CD19 second generation (2G) CAR molecule and a dominant negative PD1 molecule (Figure A). Compared with conventional CART cells, these “armored” CART cells show the enhanced capability of tumor killing after multiple-round tumor challenging and more “memory-like” phenotypes (Figure B). These results suggest dominant negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment. Results: We report clinical trials of three refractory diffuse large B cell lymphomas (DLBCLs) patients that were successfully treated using the armored CAR T cells described above. All of these three patients failed to achieve response after multiple rounds of chemotherapy and radiotherapy. However, after infused with autologous CART cells at 5.23×10^6/kg and 1.97×10^6/kg, respectively, they showed significant tumor mass decrease and SUV max declines in PET/CT results and ongoing responses (e.g., from 34.48 to 3.89 at day 27, from 25.02 to 2.38 at day 31, respectively, see Figure C). Conclusions: These three clinical trials revealed the significant anti-bulky lymphoma response with respect to these armored CAR T cells and limited and tolerated cytokine release syndrome and central nervous system toxicity. Also, dominant negative PD1 molecules may augment CAR T cells persistence in patients after activation by lymphoma cells, thus enhancing the efficacy of CAR T cells in the treatment of hematomas. Finally, the techniques described herein are a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to recruit more patients for the clinical trials. Clinical trial information: ChiCTR1900021295.

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Overcoming the breast tumor microenvironment by targeting MDSCs through CAR-T cell therapy.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.1032 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. 1032-1032

Author(s):

Saisha Abhay Nalawade ◽

Paul Shafer ◽

Pradip Bajgain ◽

Katie McKenna ◽

Arushana Ali ◽

...

Keyword(s):

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Nuclear Translocation ◽

T Cell Proliferation ◽

Tumor Site ◽

Car T Cells ◽

Car T

1032 Background: Successful targeting of solid tumors such as breast cancer (BC) using CAR T cells (CARTs) has proven challenging, largely due to the immune suppressive tumor microenvironment (TME). Myeloid derived suppressor cells (MDSCs) inhibit CART’s function and persistence within the breast TME. We generated CAR T cells targeting tumor-expressed mucin 1 (MUC1) (Bajgain P et al, 2018) for BC. To potentiate expansion and persistence of MUC1 CARTs and modulate the suppressive TME, we developed a novel chimeric co-stimulatory receptor, TR2.4-1BB, encoding a ScFv derived from a TNF-related apoptosis-inducing ligand receptor 2 (TR2) mAb followed by a 4-1BB endodomain. We hypothesize that engagement with TR2 expressed on TME-resident MDSCs, will lead to both MDSC apoptosis and CART co-stimulation, promoting T cell persistence and expansion at tumor site. Methods: Function of the novel TR2.4-1BB receptor, was assessed by exposing non-transduced (NT) and TR2.4-1BB transduced T cells to recombinant TR2 and nuclear translocation of NFκB was measured by ELISA. Functionality of in vitro generated MDSCs was determined by the suppression assay. In vitro CART/costimulatory receptor T cell function was measured by cytotoxicity assays using MUC1+ tumor targets in presence or absence of MDSCs. In vivo anti-tumor activity was assessed using MDSC enriched tumor-bearing mice using calipers to assess tumor volume and bioluminescence imaging to track T cells. Results: Nuclear translocation of NFκB was detected only in TR2.4-1BB T cells. MDSCs significantly attenuated T cell proliferation by 50±5% and IFNγ production by half compared with T cells cultured alone. Additionally, presence of MDSCs, diminished cytotoxic potential of MUC1 CARTs against MUC1+ BC cell lines by 25%. However, TR2.4-1BB expression on CAR.MUC1 T cells induced MDSC apoptosis thereby restoring the cytotoxic activity of CAR.MUC1 against MUC1+ BC lines in presence of TR2.4-1BB (67±8.5%). There was an approximate two-fold increase in tumor growth due enhanced angiogenesis and fibroblast accumulation in mice receiving tumors + MDSCs compared to tumors alone. Treatment of these MDSC-enriched tumors with MUC1.TR2.4-1BB CARTs led to superior tumor cell killing and significant reduction in tumor growth (24.54±8.55 mm3) compared to CAR.MUC1 (469.79.9±81.46mm3) or TR2.4-1BB (434.86±64.25 mm3) T cells alone (Day 28 after T cell injection). The treatment also improved T cell proliferation and persistence at the tumor site. Thereby, leading to negligible metastasis demonstrating ability of CARTs to eliminate tumor and prevent dissemination. We observed similar results using HER2.TR2.4-1BB CARTs in a HER2+ BC model. Conclusions: Our findings demonstrate that CARTs co-expressing our novel TR2.4-1BB receptor have higher anti-tumor potential against BC tumors and infiltrating MDSCs, resulting in TME remodeling and improved T cell proliferation at the tumor site.

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T Cells Demonstrate Enhanced Specificity for CD19+ Malignancies When Stimulated with IL-21.

Blood ◽

10.1182/blood.v112.11.1539.1539 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1539-1539

Author(s):

Harjeet Singh ◽

Mary Helen Huls ◽

Margaret J. Dawson ◽

Tiejuan Mi ◽

Gianpietro Dotti ◽

...

Keyword(s):

T Cells ◽

Peripheral Blood ◽

Genetically Modified ◽

Sleeping Beauty ◽

Antigen Receptors ◽

Therapeutic Success ◽

Car T Cells ◽

Car T ◽

Early Phase Clinical Trials ◽

Quiescent T Cells

Abstract T cells genetically modified to express CD19-specific chimeric antigen receptors (CARs) are being evaluated in early-phase clinical trials in patients with B-lineage malignancies. Therapeutic success is predicted by ability of infused CAR+ T cells to both persist and kill in an antigen-dependent fashion. The first of these dual goals can be achieved by altering the CAR molecule to provide T-cell survival signals through a chimeric CD28 endodomain (designated CD19RCD28). We now report that altering the culturing microenvironment with IL-21 improves antigen-dependent cytolysis of T cells when propagated on CD19+ artificial antigen presenting cells (aAPC) derived from K562. To test whether IL-21 acts in conjunction with CD28 signaling to support acquisition of redirected effector functions we electro-transferred quiescent T cells from peripheral blood with Sleeping Beauty system DNA plasmids to introduce CD19RCD28 CAR transposon. Selective outgrowth of CAR+ T cells was achieved on CD19+ aAPC that provide co-stimulation with the addition of exogenous IL-2 and/or IL-21. When IL-21 was present there was preferential numeric expansion of CD19-specific CD8+ T cells which lysed and produced IFN-g in response to CD19 (Figure). Furthermore, the CD8+CAR+ T cells displayed a central memory (CM) cell surface phenotype characterized as CD62L+ and CD28+. In contrast, genetically modified T cells propagated with exogenous IL-2 resulted in predominately CD19-specific CM CD4+ T cells. Thus, cytokines can be used to tailor the CD8/CD4 ratio of CAR+ T cells derived from peripheral blood. These data demonstrate that the dual goals of persistence and lysis can be achieved by altering CAR and the cytokine milieu and have implications for infusing CAR+ T cells in next-generation immunotherapy trials. Figure Figure

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