Preclinical Development of T Cells Engineered to Express a T-Cell Antigen Coupler Targeting Claudin 18.2-Positive Solid Tumors.

The T-cell antigen coupler (TAC) is a chimeric receptor that facilitates tumor antigen-specific activation of T cells by co-opting the endogenous T-cell receptor complex in the absence of tonic signaling. Previous data demonstrate that the TAC affords T cells with the ability to induce durable and safe antitumor responses in preclinical models of hematologic and solid tumors. In this study, we describe the preclinical pharmacology and safety of an autologous Claudin 18.

Glycogen synthase kinase 3 inhibition lowers PD-1 expression, promotes long-term survival and memory generation in antigen-specific CAR-T cells.

Successful remission in hematological cancers by CAR-T cell immunotherapy has yet to be replicated in solid tumors like GBM. A significant impediment of CAR-T immunotherapy in solid tumors is poor exposure of T cells to tumor antigens resulting in suboptimal CAR-T cell activation, which ultimately fails to induce a robust anti-tumor immune response. Costimulatory moieties in advanced-generation CARs, along with additional IL2 therapy has been shown to be insufficient to overcome this hurdle and have its cytotoxic limitations.

Development of a Function-Blocking Antibody Against Fibulin-3 as a Targeted Reagent for Glioblastoma.

We sought a novel approach against glioblastomas (GBM) focused on targeting signaling molecules localized in the tumor extracellular matrix (ECM). We investigated fibulin-3, a glycoprotein that forms the ECM scaffold of GBMs and promotes tumor progression by driving Notch and NFκB signaling. We used deletion constructs to identify a key signaling motif of fibulin-3.

Updates On Chimeric Antigen Receptor-Mediated Glioblastoma Immunotherapy.

Glioblastoma multiforme (GBM) is the most malignant of the primary central nervous system (CNS) neoplasms, accounting for nearly 80% of all primary brain tumors and is associated with high morbidity and mortality. Immunotherapy is proving to be a fertile ground for next-generation GBM therapy, with large translational research projects and clinical trials currently underway. One particularly promising area is the chimeric antigen receptors (CARs) in the context of lymphocyte adoptive cell therapy (ACT), which has achieved success in the treatment of hematological malignancies.

Interleukin-13 receptor alpha 2-targeted glioblastoma immunotherapy.

Glioblastoma (GBM) is the most lethal primary brain tumor, and despite several refinements in its multimodal management, generally has very poor prognosis. Targeted immunotherapy is an emerging field of research that shows great promise in the treatment of GBM. One of the most extensively studied targets is the interleukin-13 receptor alpha chain variant 2 (IL13Rα2).

Significance of interleukin-13 receptor alpha 2-targeted glioblastoma therapy.

Glioblastoma multiforme (GBM) remains one of the most lethal primary brain tumors despite surgical and therapeutic advancements. Targeted therapies of neoplastic diseases, including GBM, have received a great deal of interest in recent years. A highly studied target of GBM is interleukin-13 receptor α chain variant 2 (IL13Rα2).

Impact of temozolomide on immune response during malignant glioma chemotherapy.

Malignant glioma, or glioblastoma, is the most common and lethal form of brain tumor with a median survival time of 15 months. The established therapeutic regimen includes a tripartite therapy of surgical resection followed by radiation and temozolomide (TMZ) chemotherapy, concurrently with radiation and then as an adjuvant. TMZ, a DNA alkylating agent, is the most successful antiglioma drug and has added several months to the life expectancy of malignant glioma patients.

Suppression of human glioma xenografts with second-generation IL13R-specific chimeric antigen receptor-modified T cells.

Purpose: Glioblastoma multiforme (GBM) remains highly incurable, with frequent recurrences after standard therapies of maximal surgical resection, radiation, and chemotherapy. To address the need for new treatments, we have undertaken a chimeric antigen receptor (CAR) "designer T cell" (dTc) immunotherapeutic strategy by exploiting interleukin (IL)13 receptor α-2 (IL13Rα2) as a GBM-selective target.

Experimental Design: We tested a second-generation IL13 "zetakine" CAR composed of a mutated IL13 extracellular domain linked to intracellular signaling elements of the CD28 costimulatory molecule and CD3ζ.

Mechanisms of immune evasion by gliomas.

A major contributing factor to glioma development and progression is its ability to evade the immune system. This chapter will explore the mechanisms utilized by glioma to mediate immunosuppression and immune evasion. These include intrinsic mechanisms linked to its location within the brain and interactions between glioma cells and immune cells.

Thymus-derived rather than tumor-induced regulatory T cells predominate in brain tumors.

Glioblastoma multiforme (GBM) is a highly malignant brain tumor with an average survival time of 15 months. Previously, we and others demonstrated that CD4(+)FoxP3(+) regulatory T cells (Tregs) infiltrate human GBM as well as mouse models that recapitulate malignant brain tumors. However, whether brain tumor-resident Tregs are thymus-derived natural Tregs (nTregs) or induced Tregs (iTregs), by the conversion of conventional CD4(+) T cells, has not been established.

Enhanced transduction and replication of RGD-fiber modified adenovirus in primary T cells.

Background: Adenoviruses are often used as vehicles to mediate gene delivery for therapeutic purposes, but their research scope in hematological cells remains limited due to a narrow choice of host cells that express the adenoviral receptor (CAR). T cells, which are attractive targets for gene therapy of numerous diseases, remain resistant to adenoviral infection because of the absence of CAR expression. Here, we demonstrate that this resistance can be overcome when murine or human T cells are transduced with an adenovirus incorporating the RGD-fiber modification (Ad-RGD).

The presence of IL-17A and T helper 17 cells in experimental mouse brain tumors and human glioma.

Background: Recently, CD4(+)IL-17A(+) T helper 17 (Th17) cells were identified and reported in several diseased states, including autoimmunity, infection and various peripheral nervous system tumors. However, the presence of Th17 in glia-derived tumors of the central nervous system has not been studied.

Methodology/principal Findings: In this report, we demonstrate that mRNA expression for the Th17 cell cytokine IL-17A, as well as Th17 cells, are present in human glioma.

Short hairpin RNA-mediated fibronectin knockdown delays tumor growth in a mouse glioma model.

Glioblastoma multiforme is the most common and lethal primary brain tumor. Glioma progression depends on the rapid proliferation of tumor cells accompanied by an acute immunosuppressive environment, facilitated mainly by tumor infiltration of regulatory T cells (Tregs). In this study, we characterize the role of fibronectin, a high-molecular weight extracellular matrix glycoprotein secreted by tumor cells, in controlling glioma progression and in mediating immunosuppression.

Bone marrow mesenchymal stem cells loaded with an oncolytic adenovirus suppress the anti-adenoviral immune response in the cotton rat model.

Oncolytic adenoviral virotherapy is an attractive treatment modality for cancer. However, following intratumoral injections, oncolytic viruses fail to efficiently migrate away from the injection site and are rapidly cleared by the immune system. We have previously demonstrated enhanced viral delivery and replicative persistence in vivo using human bone marrow-derived mesenchymal stem cells (MSCs) as delivery vehicles.

Mesenchymal stem cells modified with a single-chain antibody against EGFRvIII successfully inhibit the growth of human xenograft malignant glioma.

Background: Glioblastoma multiforme is the most lethal brain tumor with limited therapeutic options. Antigens expressed on the surface of malignant cells are potential targets for antibody-mediated gene/drug delivery.

Principal Findings: In this study, we investigated the ability of genetically modified human mesenchymal stem cells (hMSCs) expressing a single-chain antibody (scFv) on their surface against a tumor specific antigen, EGFRvIII, to enhance the therapy of EGFRvIII expressing glioma cells in vivo.

Challenges in clinical design of immunotherapy trials for malignant glioma.

Glioblastoma multiforme (GBM) is the most common and lethal primary malignant brain tumor. The traditional treatments for GBM, including surgery, radiation, and chemotherapy, only modestly improve patient survival. Therefore, immunotherapy has emerged as a novel therapeutic modality.

Adjuvant induced glucose uptake by activated T cells is not correlated with increased survival.

Authors contributed equally to this manuscript Natural adjuvants, such as bacterial lipopolysaccharide (LPS), activate antigen presenting cells via Toll-like receptors and, indirectly, increase the survival of antigen-activated T cells. The molecular mechanisms leading to increased survival remain poorly defined. Because T cell clonal expansion leads to high energy demands, we hypothesized that increased glucose uptake and/or utilization in adjuvant-activated T cells could be important molecular event(s) that would lead to adjuvant-associated T cell survival advantage.

Unrestrained glycogen synthase kinase-3 beta activity leads to activated T cell death and can be inhibited by natural adjuvant.

Activated T cell death (ATCD) after peak clonal expansion is required for effective homeostasis of the immune system. Using a mouse model of T cell clonal expansion and contraction, we found that regulation of the proapoptotic kinase glycogen synthase kinase (GSK)-3beta plays a decisive role in determining the extent to which T cells are eliminated after activation. Involvement of GSK-3beta in ATCD was tested by measuring T cell survival after GSK-3beta inhibition, either ex vivo with chemical and pharmacological inhibitors or in vivo by retroviral expression of a dominant-negative form of GSK-3.

Adjuvant-induced survival signaling in clonally expanded T cells is associated with transient increases in pAkt levels and sustained uptake of glucose.

Immunological adjuvants help increase the number of T cells responding to an immunizing antigen. Part of the increase is due to promotion of survival of clonally expanded T cells in the face of waning antigen load and subsequent growth-factor withdrawal. The phosphatidylinositide-3 kinase (PI3-kinase)/Akt pathway is activated upon T cell stimulation and plays a critical role in clonal expansion by mediating several aspects of co-stimulation in a growth-factor-dependent manner.