T cell receptor (TCR) gene therapy provides patients with autologous T cells that are genetically engineered with TCRalphabeta chains and constitutes a promising approach for the treatment of tumors and virus infections. Among the current challenges of TCR gene therapy is the optimization of TCRalpha and beta transgene pairing to enhance the functional avidity of therapeutic T cells. Recently, various genetically modified TCRs have been developed that enhance TCR pairing and minimize mispairing, i.e. pairing between transgenic and endogenous TCR chains. Here, we classify such receptors according to their CD3-dependence for surface expression and review their abilities to address functional T cell avidity. In addition, we discuss the anticipated clinical value of these and other strategies to generate high-avidity T cells.
"Therefore, TCR optimization through affinity alteration must include the evaluation of optimal T cell responsiveness and lack of cross-reactivity to ensure the safety of TCR-engineered T cells in clinical trials. Moreover, it must further include the development of new strategies to minimize the extent of mispairing (reviewed in Govers et al., 2010; Daniel-Meshulam et al., 2012), as elegantly shown by Aggen et al. (2012), describing the use of stabilized VαVβ single-chain TCRs (scTv; Figure 2). Unfortunately, unexpected auto-reactive responses may never be completely excluded. "
[Show abstract][Hide abstract] ABSTRACT: Cytotoxic CD8 T cells mediate immunity to pathogens and they are able to eliminate malignant cells. Immunity to viruses and bacteria primarily involves CD8 T cells bearing high affinity T cell receptors (TCRs), which are specific to pathogen-derived (non-self) antigens. Given the thorough elimination of high affinity self/tumor-antigen reactive T cells by central and peripheral tolerance mechanisms, anti-cancer immunity mostly depends on TCRs with intermediate-to-low affinity for self-antigens. Because of this, a promising novel therapeutic approach to increase the efficacy of tumor-reactive T cells is to engineer their TCRs, with the aim to enhance their binding kinetics to pMHC complexes, or to directly manipulate the TCR-signaling cascades. Such manipulations require a detailed knowledge on how pMHC-TCR and co-receptors binding kinetics impact the T cell response. In this review, we present the current knowledge in this field. We discuss future challenges in identifying and targeting the molecular mechanisms to enhance the function of natural or TCR-affinity optimized T cells, and we provide perspectives for the development of protective anti-tumor T cell responses.
Frontiers in Immunology 06/2013; 4:154. DOI:10.3389/fimmu.2013.00154
"These requirements can be met by transferring highly effective TCR α/β chain gene pairs from donor antigen-specific T cells into recipient CD8+ T cells, thereby reprogramming them to display the antigen specificity of the donor cell , , , , , , , , , , , , . Indeed, TCR-engineered autologous T cells have recently been successfully used in human clinical trials to treat melanoma , , , , , , . "
[Show abstract][Hide abstract] ABSTRACT: The SIV/rhesus macaque model for HIV/AIDS is a powerful system for examining the contribution of T cells in the control of AIDS viruses. To better our understanding of CD8(+) T-cell control of SIV replication in CD4(+) T cells, we asked whether TCRs isolated from rhesus macaque CD8(+) T-cell clones that exhibited varying abilities to suppress SIV replication could convey their suppressive properties to CD8(+) T cells obtained from an uninfected/unvaccinated animal.
We transferred SIV-specific TCR genes isolated from rhesus macaque CD8(+) T-cell clones with varying abilities to suppress SIV replication in vitro into CD8(+) T cells obtained from an uninfected animal by retroviral transduction. After sorting and expansion, transduced CD8(+) T-cell lines were obtained that specifically bound their cognate SIV tetramer. These cell lines displayed appropriate effector function and specificity, expressing intracellular IFNγ upon peptide stimulation. Importantly, the SIV suppression properties of the transduced cell lines mirrored those of the original TCR donor clones: cell lines expressing TCRs transferred from highly suppressive clones effectively reduced wild-type SIV replication, while expression of a non-suppressing TCR failed to reduce the spread of virus. However, all TCRs were able to suppress the replication of an SIV mutant that did not downregulate MHC-I, recapitulating the properties of their donor clones.
Our results show that antigen-specific SIV suppression can be transferred between allogenic T cells simply by TCR gene transfer. This advance provides a platform for examining the contributions of TCRs versus the intrinsic effector characteristics of T-cell clones in virus suppression. Additionally, this approach can be applied to develop non-human primate models to evaluate adoptive T-cell transfer therapy for AIDS and other diseases.
PLoS ONE 08/2011; 6(8):e23703. DOI:10.1371/journal.pone.0023703 · 3.23 Impact Factor
"In addition, methods to optimize transgenic α and β pairing may bypass or reduce the likelihood of this scenario (Govers et al., 2010). As will be discussed below, an approach utilizing human HSCs may overcome many of these problems by allowing natural developmental mechanisms to produce genetically engineered immune cells that target HIV infection that are tolerant of the host and possess prolonged self-renewal capability. "
[Show abstract][Hide abstract] ABSTRACT: Human stem cell-based therapeutic intervention strategies for treating HIV infection have recently undergone a renaissance as a major focus of investigation. Unlike most conventional antiviral therapies, genetically engineered hematopoietic stem cells possess the capacity for prolonged self-renewal that would continuously produce protected immune cells to fight against HIV. A successful strategy therefore has the potential to stably control and ultimately eradicate HIV from patients by a single or minimal treatment. Recent progress in the development of new technologies and clinical trials sets the stage for the current generation of gene therapy approaches to combat HIV infection. In this review, we will discuss two major approaches that are currently underway in the development of stem cell-based gene therapy to target HIV: one that focuses on the protection of cells from productive infection with HIV, and the other that focuses on targeting immune cells to directly combat HIV infection.
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