Chimeric antigen receptors (CARs) are synthetic molecules designed to redirect T cells to specific antigens. CAR-modified T cells can mediate long-term durable remissions in B cell malignancies, but expanding this platform to solid tumors requires the discovery of surface targets with limited expression in normal tissues. The variant III mutation of the epidermal growth factor receptor (EGFRvIII) results from an in-frame deletion of a portion of the extracellular domain, creating a neoepitope. We chose a vector backbone encoding a second-generation CAR based on efficacy of a murine scFv–based CAR in a xenograft model of glioblastoma. Next, we generated a panel of humanized scFvs and tested their specificity and function as soluble proteins and in the form of CAR-transduced T cells; a low-affinity scFv was selected on the basis of its specificity for EGFRvIII over wild-type EGFR. The lead candidate scFv was tested in vitro for its ability to direct CAR-transduced T cells to specifically lyse, proliferate, and secrete cytokines in response to antigen-bearing targets. We further evaluated the specificity of the lead CAR candidate in vitro against EGFR-expressing keratinocytes and in vivo in a model of mice grafted with normal human skin. EGFRvIII-directed CAR T cells were also able to control tumor growth in xenogeneic subcutaneous and orthotopic models of human EGFRvIII+ glioblastoma. On the basis of these results, we have designed a phase 1 clinical study of CAR T cells transduced with humanized scFv directed to EGFRvIII in patients with either residual or recurrent glioblastoma (NCT02209376).

Based on the evidence that IL-17 is a key cytokine involved in various inflammatory diseases, we explored the critical role of IL-17-producing cd T cells for tumor development in tumor-bearing mouse model. IL-17 À/À mice exhibited a significant reduction of tumor growth, concomitantly with the decrease of vascular density at lesion area, indicating a pro-tumor property of IL-17. Among tumor-infiltrating lymphocytes (TIL), cd T cells were the major cellular source of IL-17. Analysis of TCR repertoires in TIL-cd T cells showed that circulating cd T cells, but not skin resident Vc5 1 cd T cells, produced IL-17. Neutralizing antibodies against IL-23, IL-6, and TGF-b, which were produced within the tumor microenvironment, inhibited the induction of IL-17-producing cd T cells. IL-17 production by tumor-infiltrating cd T cells was blocked by anti-cdTCR or anti-NKG2D antibodies, indicating that these ligands, expressed within the tumor microenvironment, are involved in cd T-cell activation. The IL-17-producing TIL-cd T cells exhibited reduced levels of perforin mRNA expression, but increased levels of COX-2 mRNA expression. Together, our findings support the novel concept that IL-17-producing cd T cells, generated in response to tumor microenvironment, act as tumor-promoting cells by inducing angiogenesis. IntroductionIn order to understand how tumor cells can escape immune surveillance mechanisms and thus develop anti-tumor therapies, it is critically important to investigate the mechanisms by which the immune system interacts with the tumor microenvironment. The tumor microenvironment, which is mainly composed of tumor cells, stromal cells, and tumor-infiltrating immune cells, is entirely different from noncancerous tissues. This unique microenvironment potently inhibits immune responses against tumor cells via various soluble mediators and contact-dependent mechanisms [1,2]. Previously, it was suggested that T-cell Eur. J. Immunol. 2010. 40: 1927-1937 DOI 10.1002 Cellular immune response 1927 responses within the local tumor tissue are completely inhibited. However, this concept was abandoned following the discovery of the regulatory T-cell and Th17 cell subsets, which are activated rather than suppressed in the tumor microenvironment via TGF-b and/or IL-6. Thus, the tumor microenvironment is conducive to IL-17 production. In fact, it has been shown that IL-17 is produced in human and murine tumor tissues [3][4][5]. Tumor cells promote neo-vascularization into tumor tissues through hyperproduction of angiogenic factors, which also support their own abnormal proliferation and survival [6]. It has been reported that tumor cells over-expressing IL-17 significantly promote new vessel growth into the tumor tissues [5]; however, physiological effects of IL-17 on tumor progression remain to be defined. Th17 differentiation from naïve CD4 1 T cells is regulated by TGF-b and IL-6. Proliferation, maintenance and full maturation of these cells are controlled by . Recently, it has been shown that IL-17 is produced by diverse T...

While type-I interferons (IFN) play critical roles in antiviral and antitumor activity, it remains to be elucidated how type-I IFNs are produced in sterile conditions of the tumor microenvironment and directly impacts tumor-infiltrating immune cells. Mouse de novo gliomas show increased expression of type-I IFN messages, and in mice, CD11b+ brain-infiltrating leukocytes (BIL) are the main source of type-I IFNs that are induced partially in a STING (stimulator of IFN genes)-dependent manner. Consequently, glioma-bearing StingGt/Gt mice showed shorter survival, and lower expression levels of Ifns compared with wild-type mice. Furthermore, BILs of StingGt/Gt mice show increased CD11b+ Gr-1+ immature myeloid suppressor and CD25+ Foxp3+ regulatory T (Treg) cells, and decreased IFNγ-producing CD8+ T cells. CD4+ and CD8+ T cells that received direct type-I IFN signals demonstrate lesser degrees of regulatory activity and increased levels of antitumor activity, respectively. Finally, intratumoral administration of a STING agonist (cyclic diguanylate monophosphate; c-di-GMP) improves the survival of glioma-bearing mice associated with enhanced type-I IFN signaling, Cxcl10 and Ccl5 and T-cell migration into the brain. In a combination with subcutaneous OVA peptide-vaccination, c-di-GMP increased OVA-specific cytotoxicity of BILs and prolonged the survival. These data demonstrate significant contributions of STING to antitumor immunity via enhancement of the type-I IFN signaling in the tumor microenvironment, and suggest a potential use of STING agonists for development of effective immunotherapy, such as the combination with antigen-specific vaccinations.