Journal Articles

Adoptive T cell therapy

T cell therapies based on tumor infiltrating T lymphocytes and chimeric antigen receptor or T cell receptor engineered T cells

Bispecific chimeric antigen receptors targeting the CD4 binding site and high-mannose Glycans of gp120 optimized for anti-human immunodeficiency virus potency and breadth with minimal immunogenicity

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BACKGROUND AIMS: Chimeric antigen receptors (CARs) offer great potential toward a functional cure of human immunodeficiency virus (HIV) infection. To achieve the necessary long-term virus suppression, we believe that CARs must be designed for optimal potency and anti-HIV specificity, and also for minimal probability of virus escape and CAR immunogenicity. CARs containing antibody-based motifs are problematic in the latter regard due to epitope mutation and anti-idiotypic immune responses against the variable regions. METHODS: We designed bispecific CARs, each containing a segment of human CD4 linked to the carbohydrate recognition domain of a human C-type lectin. These CARs target two independent regions on HIV-1 gp120 that presumably must be conserved on clinically significant virus variants (i.e., the primary receptor binding site and the dense oligomannose patch). Functionality and specificity of these bispecific CARs were analyzed in assays of CAR-T cell activation and spreading HIV-1 suppression. RESULTS: T cells expressing a CD4-dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DCSIGN) CAR displayed robust stimulation upon encounter with Env-expressing targets, but negligible activity against intercellular adhesion molecule (ICAM)-2 and ICAM-3, the natural dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin ligands. Moreover, the presence of the lectin moiety prevented the CD4 from acting as an entry receptor on CCR5-expressing cells, including CD8(+) T cells. However, in HIV suppression assays, the CD4-DCSIGN CAR and the related CD4-liver/lymph node-specific intercellular adhesion molecule-3-grabbing non-integrin CAR displayed only minimally increased potency compared with the CD4 CAR against some HIV-1 isolates and reduced potency against others. By contrast, the CD4-langerin and CD4-mannose binding lectin (MBL) CARs uniformly displayed enhanced potency compared with the CD4 CAR against all the genetically diverse HIV-1 isolates examined. Further experimental data, coupled with known biological features, suggest particular advantages of the CD4-MBL CAR. DISCUSSION: These studies highlight features of bispecific CD4-lectin CARs that achieve potency enhancement by targeting two distinct highly conserved Env determinants while lacking immunogenicity-prone antibody-based motifs.

Author Info: (1) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (2) Laboratory of Viral Diseases, National

Author Info: (1) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (2) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (3) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (4) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (5) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (6) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (7) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (8) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. (9) Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. Electronic address: edward_berger@nih.gov.

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T cell responses in the microenvironment of primary renal cell carcinoma - Implications for adoptive cell therapy

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In vitro expansion of large numbers of highly potent tumor-reactive T cells appears a prerequisite for effective adoptive cell therapy (ACT) with autologous tumor-infiltrating lymphocytes (TIL) as shown in metastatic melanoma (MM). We therefore sought to determine whether renal cell carcinomas (RCC) are infiltrated with tumor-reactive T cells that could be efficiently employed for adoptive transfer immunotherapy. TILs and autologous tumor cell lines (TCLs) were successfully generated from 22 (92%) and 17 (77%) of 24 consecutive primary RCC specimens and compared to those generated from MM. Immune recognition of autologous TCLs or fresh tumor digests (FTD) was observed in CD8+ TILs from 82% of patients (18/22). Cytotoxicity assays confirmed the tumoricidal capacity of RCC-TILs. The overall expansion capacity of RCC-TILs was similar to MM-TILs. However, the magnitude, poly-functionality, and ability to expand in classical expansion protocols of CD8+ T-cell responses was lower compared to MM-TILs. The RCC-TILs that did react to the tumor were functional and antigen presentation and processing on RCC-tumors was similar to MM-TILs. Direct recognition of tumors with cytokine-induced overexpression of human leukocyte antigen (HLA) class II was observed from CD4+ T cells (6/12; 50%). Thus, TILs from primary RCC specimens could be isolated, expanded, and could recognize tumors. However, immune responses of expanded CD8+ RCC-TILs were typically weaker than MM-TILs and displayed a mono-/oligo- functional pattern. The ability to select, enrich, and expand tumor-reactive poly-functional T cells may be critical in developing effective ACT with TILs for RCC.

Author Info: (1) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen. (2) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital

Author Info: (1) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen. (2) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen. (3) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen. (4) Institute of Medical Immunology, Martin Luther University Halle-Wittenberg. (5) Division for Immunology and Vaccinology, Technical University of Denmark. (6) Division for Immunology and Vaccinology, Technical University of Denmark. (7) Department of Oncology, Herlev Hospital, University of Copenhagen. (8) Institute of Medical Immunology, Martin Luther University Halle-Wittenberg. (9) Department of Urology, Herlev Hospital, University of Copenhagen. (10) Department of Pathology, Herlev Hospital, University of Copenhagen. (11) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen. (12) Department of Hematology, Center for Cancer Immune Therapy, Herlev Hospital, University of Copenhagen inge.marie.svane@regionh.dk.

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Translating Science into Survival: Report on the Third International Cancer Immunotherapy Conference

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On September 6 to 9, 2017, in Mainz, Germany, the Third International Cancer Immunotherapy Conference was hosted jointly by the Cancer Research Institute, the Association for Cancer Immunotherapy, the European Academy of Tumor Immunology, and the American Association for Cancer Research. For the third straight year, more than 1,400 people attended the four-day event, which covered the latest advances in cancer immunology and immunotherapy. This report provides an overview of the main topics discussed. Cancer Immunol Res; 6(1); 10-13. (c)2017 AACR.

Author Info: (1) TRON - Translational Oncology, University Medical Center of Johannes Gutenberg University, Mainz, Germany. (2) TRON - Translational Oncology, University Medical Center of Johannes Gutenberg

Author Info: (1) TRON - Translational Oncology, University Medical Center of Johannes Gutenberg University, Mainz, Germany. (2) TRON - Translational Oncology, University Medical Center of Johannes Gutenberg University, Mainz, Germany. (3) Cancer Research Institute, New York, New York. abrodsky@cancerresearch.org.

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Anti-GD2/4-1BB chimeric antigen receptor T cell therapy for the treatment of Chinese melanoma patients

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BACKGROUND: Chimeric antigen receptor (CAR)-engineered T cells have demonstrated promising clinical efficacy in patients with B cell lymphoma. However, the application of CAR-T cell therapy in the treatment of other solid tumors has been limited. We incorporated 4-1BB into the anti-GD2 CAR-T cells to test their cytotoxicity in melanoma in vitro and in vivo. Moreover, we reported the expression of ganglioside GD2 in non-Caucasian melanoma populations for the first time, thus providing a basis for future clinical research. METHODS: This study included tumor samples from 288 melanoma patients at the Peking University Cancer Hospital & Institute. Clinical data were collected. Immunohistochemical assays using antibodies against ganglioside GD2 were performed on formalin-fixed, paraffin-embedded specimens. The ability of ganglioside GD2 CAR-T cells to kill ganglioside GD2(+) melanoma cells was evaluated in vitro and in a patient-derived xenograft (PDX) model. RESULTS: Among the 288 samples, 49.3% of cases (142/288) demonstrated positive staining with ganglioside GD2. The median survival time in patients exhibiting ganglioside GD2 expression was significantly shorter than that in patients without ganglioside GD2 expression (31 vs. 47.1 months, P < 0.001). In the present study, CAR was constructed using a GD2-specific scFv (14.G2a), T cell receptor CD3zeta chain, and the CD137 (4-1BB) costimulatory motif. In addition, the GD2.BBzeta CAR-T cells demonstrated specific lysis of ganglioside GD2-expressing melanoma cells in vitro. In two PDX models, mice that received intravenous or local intratumor injections of GD2.BBzeta CAR-T cells experienced rapid tumor regression. CONCLUSIONS: These data demonstrate that the rate of GD2 expression in Chinese patients is 49.3%. GD2.BBzeta CAR-T cells can both efficiently lyse melanoma in a GD2-specific manner and release Th1 cytokines in an antigen-dependent manner in vitro and in vivo. Anti-GD2/4-1BB CAR-T cells represent a clinically appealing treatment strategy for Chinese melanoma patients exhibiting GD2 expression and provide a basis for future studies of the clinical application of immunotherapy for melanoma.

Author Info: (1) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational

Author Info: (1) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (2) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (3) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (4) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (5) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (6) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (7) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (8) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (9) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (10) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (11) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (12) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. (13) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. k-yan08@163.com. (14) Department of Renal Cancer and Melanoma, Peking University Cancer Hospital & Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Beijing, 100142, China. guoj307@126.com.

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mSA2 affinity-enhanced biotin-binding CAR T cells for universal tumor targeting

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Chimeric antigen receptor T cells (CAR-Ts) are promising cancer therapeutics. However, since cancer cells can lose the CAR-targeted antigen and avoid destruction, targeting multiple antigens with multiple CARs has been proposed. We illustrate here a less cumbersome alternative, anti-tag CARs (AT-CARs) that bind to tags on tumor-targeting antibodies. We have created novel AT-CARs, using the affinity-enhanced monomeric streptavidin 2 (mSA2) biotin-binding domain that when expressed on T cells can target cancer cells coated with biotinylated antibodies. Human T cells expressing mSA2 CARs with CD28-CD3zeta and 4-1BB-CD3zeta signaling domains were activated by plate-immobilized biotin and by tumor cells coated with biotinylated antibodies against the tumor-associated antigens CD19 and CD20. Furthermore, mSA2 CAR T cells were capable of mediating cancer cell lysis and IFNgamma production in an antibody dose-dependent manner. The mSA2 CAR is a universal AT-CAR that can be combined with biotinylated tumor-specific antibodies to potentially target many different tumor types.

Author Info: (1) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA USA. (2) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA

Author Info: (1) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA USA. (2) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA USA. Carnegie Mellon University, Department of Biomedical Engineering, Pittsburgh, PA USA. (3) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA USA. (4) University of Pittsburgh School of Medicine, Department of Immunology, Pittsburgh, PA USA.

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Substrate-bound CCL21 and ICAM1 combined with soluble IL-6 collectively augment the expansion of antigen-specific murine CD4(+) T cells

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Immune processes within the complex microenvironment of the lymph node involve multiple intercellular, cell-matrix, and paracrine interactions, resulting in the expansion of antigen-specific T cells. Inspired by the lymph node microenvironment, we aimed to develop an ex vivo "synthetic immune niche" (SIN), which could effectively stimulate the proliferation of antigen-activated CD4(+) T cells. This engineered SIN consisted of surfaces coated with the chemokine C-C motif ligand 21 (CCL21) and with the intercellular adhesion molecule 1 (ICAM1), coupled with the soluble cytokine interleukin 6 (IL-6) added to the culture medium. When activated by ovalbumin-loaded dendritic cells, OT-II T cells growing on regular uncoated culture plates form nonadherent, dynamic clusters around the dendritic cells. We found that functionalization of the plate surface with CCL21 and ICAM1 and the addition of IL-6 to the medium dramatically increases T-cell proliferation and transforms the culture topology from that of suspended 3-dimensional cell clusters into a firm, substrate-attached monolayer of cells. Our findings demonstrate that the components of this SIN collectively modulate T-cell interactions and augment both the proliferation and survival of T cells in an antigen-specific manner, potentially serving as a powerful approach for expanding immunotherapeutic T cells.

Author Info: (1) Department of Molecular Cell Biology. (2) Department of Immunology. (3) Electron Microscopy Unit, and. (4) Electron Microscopy Unit, and. (5) Life Sciences Core Facilities

Author Info: (1) Department of Molecular Cell Biology. (2) Department of Immunology. (3) Electron Microscopy Unit, and. (4) Electron Microscopy Unit, and. (5) Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel. (6) Department of Molecular Cell Biology. (7) Department of Immunology.

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Bevacizumab-mediated tumor vasculature remodelling improves tumor infiltration and antitumor efficacy of GD2-CAR T cells in a human neuroblastoma preclinical model

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GD2-redirected chimeric antigen receptor (CAR) T lymphocytes represent a promising therapeutic option for immunotherapy of neuroblastoma (NB). However, despite the encouraging therapeutic effects observed in some hematological malignancies, clinical results of CAR T cell immunotherapy in solid tumors are still modest. Tumor driven neo-angiogenesis supports an immunosuppressive microenvironment that influences treatment responses and is amenable to targeting with antiangiogenic drugs. The latter agents promote lymphocyte tumor infiltration by transiently reprogramming tumor vasculature, and may represent a valid combinatorial approach with CAR T cell immunotherapy. In light of these considerations, we investigated the anti-NB activity of GD2-CAR T cells combined with bevacizumab (BEV) in an orthotopic xenograft model of human NB. Two weeks after tumor implantation, mice received BEV or GD2-CAR T cells or both by single intravenous administration. GD2-CAR T cells exerted a significant anti-NB activity only in combination with BEV, even at the lowest concentration tested, which per se did not inhibit tumor growth. When combined with BEV, GD2-CAR T cells massively infiltrated tumor mass where they produced interferon-gamma (IFN-gamma), which, in turn, induced expression of CXCL10 by NB cells. IFN-gamma, and possibly other cytokines, upregulated NB cell expression of PD-L1, while tumor infiltrating GD2-CAR T cells expressed PD-1. Thus, the PD-1/PD-L1 axis can limit the anti-tumor efficacy of the GD2-CAR T cell/BEV association. This study provides a strong rationale for testing the combination of GD2-CAR T cells with BEV in a clinical trial enrolling NB patients. PD-L1 silencing or blocking strategies may further enhance the efficacy of such combination.

Author Info: (1) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy. (2) Anatomic Pathology and Molecular Medicine, Dep. of Medicine and Sciences

Author Info: (1) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy. (2) Anatomic Pathology and Molecular Medicine, Dep. of Medicine and Sciences of Aging, "G. d'Annunzio" University, Chieti, Italy. Ce. S. I.-MeT, Aging Research Center, Pathological Anatomy and Immuno-Oncology Unit, "G. d'Annunzio" University, Chieti, Italy. (3) Laboratory of Cell and Gene Therapy of Pediatric Tumors, Dep. of Hematology/Oncology, IRCCS Ospedale Pediatrico Bambino Gesu, Roma, Italy. (4) S.S.D. Animal Facility, Ospedale Policlinico San Martino, IRCCS per l'Oncologia, Genova, Italy. (5) S.S.D. Animal Facility, Ospedale Policlinico San Martino, IRCCS per l'Oncologia, Genova, Italy. (6) Laboratory of Cell and Gene Therapy of Pediatric Tumors, Dep. of Hematology/Oncology, IRCCS Ospedale Pediatrico Bambino Gesu, Roma, Italy. (7) Laboratory of Cell and Gene Therapy of Pediatric Tumors, Dep. of Hematology/Oncology, IRCCS Ospedale Pediatrico Bambino Gesu, Roma, Italy. Dipartimento di Medicina Clinica e Chirurgia, Universita degli Studi di Napoli Federico II, Napoli, Italy. (8) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy. (9) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy. (10) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy. (11) Laboratory of Cell and Gene Therapy of Pediatric Tumors, Dep. of Hematology/Oncology, IRCCS Ospedale Pediatrico Bambino Gesu, Roma, Italy. Department of Pediatrics, Universita di Pavia, Pavia, Italy. (12) Immunology Area, IRCCS Ospedale Pediatrico Bambino Gesu, Roma, Italy. (13) Laboratory of Oncology, Dep. of Translational Research, IRCCS Istituto G. Gaslini, Genova, Italy.

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Intra-tumoral production of IL18, but not IL12, by TCR-engineered T cells is non-toxic and counteracts immune evasion of solid tumors

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Adoptive therapy with engineered T cells shows promising results in treating patients with malignant disease, but is challenged by incomplete responses and tumor recurrences. Here, we aimed to direct the tumor microenvironment in favor of a successful immune response by local secretion of interleukin (IL-) 12 and IL-18 by sadministered T cells. To this end, we engineered T cells with a melanoma-specific T cell receptor (TCR) and murine IL-12 and/or IL-18 under the control of a nuclear-factor of activated T-cell (NFAT)-sensitive promoter. These T cells produced IL-12 or IL-18, and consequently enhanced levels of IFNgamma, following exposure to antigen-positive but not negative tumor cells. Adoptive transfer of T cells with a TCR and inducible (i)IL-12 to melanoma-bearing mice resulted in severe, edema-like toxicity that was accompanied by enhanced levels of IFNgamma and TNFalpha in blood, and reduced numbers of peripheral TCR transgene-positive T cells. In contrast, transfer of T cells expressing a TCR and iIL-18 was without side effects, enhanced the presence of therapeutic CD8(+) T cells within tumors, reduced tumor burden and prolonged survival. Notably, treatment with TCR+iIL-12 but not iIL-18 T cells resulted in enhanced intra-tumoral accumulation of macrophages, which was accompanied by a decreased frequency of therapeutic T cells, in particular of the CD8 subset. In addition, when administered to mice, iIL-18 but not iIL-12 demonstrated a favorable profile of T cell co-stimulatory and inhibitory receptors. In conclusion, we observed that treatment with T cells engineered with a TCR and iIL18 T cells is safe and able to skew the tumor microenvironment in favor of an improved anti-tumor T cell response.

Author Info: (1) Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. (2) Department I of Internal Medicine, University Hospital Cologne

Author Info: (1) Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. (2) Department I of Internal Medicine, University Hospital Cologne and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany. (3) Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. (4) Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. (5) Department I of Internal Medicine, University Hospital Cologne and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany. (6) Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.

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Blockade of CD7 expression in T cells for effective chimeric antigen receptor targeting of T-cell malignancies

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Effective immunotherapies for T-cell malignancies are lacking. We devised a novel approach based on chimeric antigen receptor (CAR)-redirected T lymphocytes. We selected CD7 as a target because of its consistent expression in T-cell acute lymphoblastic leukemia (T-ALL), including the most aggressive subtype, early T-cell precursor (ETP)-ALL. In 49 diagnostic T-ALL samples (including 14 ETP-ALL samples), median CD7 expression was >99%; CD7 expression remained high at relapse (n = 14), and during chemotherapy (n = 54). We targeted CD7 with a second-generation CAR (anti-CD7-41BB-CD3zeta), but CAR expression in T lymphocytes caused fratricide due to the presence of CD7 in the T cells themselves. To downregulate CD7 and control fratricide, we applied a new method (protein expression blocker [PEBL]), based on an anti-CD7 single-chain variable fragment coupled with an intracellular retention domain. Transduction of anti-CD7 PEBL resulted in virtually instantaneous abrogation of surface CD7 expression in all transduced T cells; 2.0% +/- 1.7% were CD7(+) vs 98.1% +/- 1.5% of mock-transduced T cells (n = 5; P < .0001). PEBL expression did not impair T-cell proliferation, interferon-gamma and tumor necrosis factor-alpha secretion, or cytotoxicity, and eliminated CAR-mediated fratricide. PEBL-CAR T cells were highly cytotoxic against CD7(+) leukemic cells in vitro and were consistently more potent than CD7(+) T cells spared by fratricide. They also showed strong anti-leukemic activity in cell line- and patient-derived T-ALL xenografts. The strategy described in this study fits well with existing clinical-grade cell manufacturing processes and can be rapidly implemented for the treatment of patients with high-risk T-cell malignancies.

Author Info: (1) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (2) Department of Pediatrics, Yong Loo Lin School of Medicine

Author Info: (1) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (2) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (3) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (4) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (5) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. (6) Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

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Immunotherapy for acute lymphoblastic leukemia: from famine to feast

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Publisher's Note: This article has a companion Point by Jabbour and Kantarjian. Publisher's Note: Join in the discussion of these articles at Blood Advances Community Conversations. Recent advances have realized the decades-old desire to harness the power of the immune system to eradicate malignant cells. It is now indisputable that immunotherapy can provide benefits for cancer patients that cannot be achieved with traditional cancer therapeutics. The potency of immunotherapy has been particularly notable in B-cell acute lymphoblastic leukemia (B-ALL), where chimeric antigen receptors (CARs) targeting CD19 and the CD3-CD19 bispecific T-cell engager blinatumomab both demonstrate impressive effects. Once a pipe dream, clinicians are now faced with a choice of immunotherapies to offer patients with relapsed or refractory B-ALL, presenting a new challenge: how to choose the best immunotherapy approach. Herein we provide a commentary on the relative merits and challenges of CD19-CAR T cells vs blinatumomab for relapsed/refractory B-ALL based on currently available data, focused on response rates, feasibility, toxicity, activity in extramedullary disease, and durability of effects.

Author Info: (1) Department of Pediatrics and. (2) Department of Pediatrics and. Department of Medicine, Stanford University, Stanford, CA.

Author Info: (1) Department of Pediatrics and. (2) Department of Pediatrics and. Department of Medicine, Stanford University, Stanford, CA.

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