Unlocking the Potential: Overcoming Challenges in CAR-T Cell Therapy for Cancer Treatment (original) (raw)
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Hurdles to breakthrough in CAR T cell therapy of solid tumors
Stem Cell Research & Therapy
Autologous T cells genetically engineered to express chimeric antigen receptor (CAR) have shown promising outcomes and emerged as a new curative option for hematological malignancy, especially malignant neoplasm of B cells. Notably, when T cells are transduced with CAR constructs, composed of the antigen recognition domain of monoclonal antibodies, they retain their cytotoxic properties in a major histocompatibility complex (MHC)-independent manner. Despite its beneficial effect, the current CAR T cell therapy approach faces myriad challenges in solid tumors, including immunosuppressive tumor microenvironment (TME), tumor antigen heterogeneity, stromal impediment, and tumor accessibility, as well as tribulations such as on-target/off-tumor toxicity and cytokine release syndrome (CRS). Herein, we highlight the complications that hamper the effectiveness of CAR T cells in solid tumors and the strategies that have been recommended to overcome these hurdles and improve infused T cell pe...
Solid Tumors Challenges and New Insights of CAR T Cell Engineering
Stem Cell Reviews and Reports, 2019
Adoptive cell therapy using CAR T cells has emerged as a novel treatment strategy with promising results against B cell malignancies; however, CAR T cells have not shown much success against solid malignancies. There are several obstacles which diminish the efficacy of CAR T cells, but the immunosuppressive tumor microenvironment (TME) of the tumor stands out as the most important factor. TME includes Tumor-Associated Stroma, Immunosuppressive cells and cytokines, tumor hypoxia and metabolism, and Immune Inhibitory Checkpoints which affect the CAR T cell efficacy and activity in solid tumors. A precise understanding of the TME could pave the way to engineer novel modifications of CAR T cells which can overcome the immunosuppressive TME. In this review, we will describe different sections of the TME and introduce novel approaches to improve the CAR T cells potential against solid tumors based on recent clinical and preclinical data. Also, we will provide new suggestions on how to modify CARs to augment of CAR T cells efficacy. Since there are also some challenges beyond the TME that are important for CAR function, we will also discuss and provide data about the improvement of CAR T cells trafficking and delivery to the tumor site and how to solve the problem of tumor antigen heterogeneity.
Advances and Hurdles in CAR T Cell Immune Therapy for Solid Tumors
Cancers
Chimeric antigen receptor (CAR) T cells in solid tumors have so far yielded limited results, in terms of therapeutic effects, as compared to the dramatic results observed for hematological malignancies. Many factors involve both the tumor cells and the microenvironment. The lack of specific target antigens and severe, potentially fatal, toxicities caused by on-target off-tumor toxicities constitute major hurdles. Furthermore, the tumor microenvironment is usually characterized by chronic inflammation, the presence of immunosuppressive molecules, and immune cells that can reduce CAR T cell efficacy and facilitate antigen escape. Nonetheless, solid tumors are under investigation as possible targets despite their complexity, which represents a significant challenge. In preclinical mouse models, CAR T cells are able to efficiently recognize and kill several tumor xenografts. Overall, in the next few years, there will be intensive research into optimizing novel cell therapies to improve ...
Frontiers in Immunology
The successful outcomes of chimeric antigen receptor (CAR) T-cell therapy in treating hematologic cancers have increased the previously unprecedented excitement to use this innovative approach in treating various forms of human cancers. Although researchers have put a lot of work into maximizing the effectiveness of these cells in the context of solid tumors, few studies have discussed challenges and potential strategies to overcome them. Restricted trafficking and infiltration into the tumor site, hypoxic and immunosuppressive tumor microenvironment (TME), antigen escape and heterogeneity, CAR T-cell exhaustion, and severe life-threatening toxicities are a few of the major obstacles facing CAR T-cells. CAR designs will need to go beyond the traditional architectures in order to get over these limitations and broaden their applicability to a larger range of malignancies. To enhance the safety, effectiveness, and applicability of this treatment modality, researchers are addressing th...
How to Test Human CAR T Cells in Solid Tumors, the Next Frontier of CAR T Cell Therapy
Methods in Molecular Biology, 2024
Chimeric antigen receptor (CAR) T cell therapy has proven to be a successful treatment option for leukemias and lymphomas. These encouraging outcomes underscore the potential of adoptive cell therapy for other oncology applications, namely, solid tumors. However, CAR T cells are yet to succeed in treating solid tumors. Unlike liquid tumors, solid tumors create a hostile tumor microenvironment (TME). CAR T cells must traffic to the TME, survive, and retain their function to eradicate the tumor. Nevertheless, there is no universal preclinical model to systematically test candidate CARs and CAR targets for their capacity to infiltrate and eliminate human solid tumors in vivo. Here, we provide a detailed protocol to evaluate human CAR CD4 + helper T cells and CD8 + cytotoxic T cells in immunodeficient (NSG) mice bearing antigenexpressing human solid tumors.
Novel approaches to promote CAR T-cell function in solid tumors
Expert Opinion on Biological Therapy, 2019
Article highlights • CAR T cells have demonstrated clear efficacy in hematological cancers, however treatment of solid tumors is more complex. • Discovery of effective targets for CAR T cell recognition is key when designing efficacious and safe therapies. • The tumor microenvironment deploys various mechanisms to suppress CAR T cells, research into how these mechanisms work forms the basis for current advances in CAR T cell development. • To reduce cost, risk of production failure and variability in response rates production of universal CAR T cell products is desirable.
Expert Opinion on Drug Discovery, 2021
Introduction: Chimeric antigen receptor-engineered T-cells typically use the binding domains of antibodies to target cytotoxicity toward tumors. This approach has produced great efficacy against selected hematological cancers, but benefit in solid tumors has been limited. Characteristically, the microenvironment in solid tumors restricts CAR T cell function, thereby limiting success. Enhancing efficacy will depend on novel target discovery to refine specificity and reduce toxicity. Additionally, overcoming immunosuppressive mechanisms may be achieved by altering the structure of the CAR itself, together with ancillary gene expression or additional therapeutic interventions. Areas covered: Herein, the authors discuss approaches for refining and further developing CAR T cell therapies specifically for use with solid malignancies. The authors survey the existing literature and provide perspectives for the future. Expert opinion: Pronounced efficacy in solid tumors will likely require combination therapies, targeting both the tumor itself and associated immunosuppressive mechanisms. Future exploration of CAR T cell therapies for solid tumors is likely to incorporate next-generation designs that couple more precise targeting of cancer-associated targets with enhanced potency and resistance to exhaustion.
CAR T Cell Therapy: A Game Changer in Cancer Treatment
Journal of immunology research, 2016
The development of novel targeted therapies with acceptable safety profiles is critical to successful cancer outcomes with better survival rates. Immunotherapy offers promising opportunities with the potential to induce sustained remissions in patients with refractory disease. Recent dramatic clinical responses in trials with gene modified T cells expressing chimeric antigen receptors (CARs) in B-cell malignancies have generated great enthusiasm. This therapy might pave the way for a potential paradigm shift in the way we treat refractory or relapsed cancers. CARs are genetically engineered receptors that combine the specific binding domains from a tumor targeting antibody with T cell signaling domains to allow specifically targeted antibody redirected T cell activation. Despite current successes in hematological cancers, we are only in the beginning of exploring the powerful potential of CAR redirected T cells in the control and elimination of resistant, metastatic, or recurrent no...
Cells
Although exponential progress in treating advanced malignancy has been made in the modern era with immune checkpoint blockade, survival outcomes remain suboptimal. Cellular immunotherapy, such as chimeric antigen receptor T cells, has the potential to improve this. CAR T cells combine the antigen specificity of a monoclonal antibody with the cytotoxic ‘power’ of T-lymphocytes through expression of a transgene encoding the scFv domain, CD3 activation molecule, and co-stimulatory domains. Although, very rarely, fatal cytokine-release syndrome may occur, CAR T-cell therapy gives patients with refractory CD19-positive B-lymphoid malignancies an important further therapeutic option. However, low-level expression of epithelial tumour-associated-antigens on non-malignant cells makes the application of CAR T-cell technology to common solid cancers challenging, as does the potentially limited ability of CAR T cells to traffic outside the blood/lymphoid microenvironment into metastatic lesion...
Journal of Translational Medicine, 2023
Traditional cancer treatments use nonspecific drugs and monoclonal antibodies to target tumor cells. Chimeric antigen receptor (CAR)-T cell therapy, however, leverages the immune system's T-cells to recognize and attack tumor cells. T-cells are isolated from patients and modified to target tumor-associated antigens. CART therapy has achieved FDA approval for treating blood cancers like B-cell acute lymphoblastic leukemia, large B-cell lymphoma, and multiple myeloma by targeting CD-19 and B-cell maturation antigens. Bi-specific chimeric antigen receptors may contribute to mitigating tumor antigen escape, but their efficacy could be limited in cases where certain tumor cells do not express the targeted antigens. Despite success in blood cancers, CART technology faces challenges in solid tumors, including lack of reliable tumor-associated antigens, hypoxic cores, immunosuppressive tumor environments, enhanced reactive oxygen species, and decreased T-cell infiltration. To overcome these challenges, current research aims to identify reliable tumor-associated antigens and develop cost-effective, tumor microenvironment-specific CART cells. This review covers the evolution of CART therapy against various tumors, including hematological and solid tumors, highlights challenges faced by CART cell therapy, and suggests strategies to overcome these obstacles, such as utilizing single-cell RNA sequencing and artificial intelligence to optimize clinical-grade CART cells. † Tariq Masoodi, Sabah Nisar and Maysaloun Merhi have contributed equally.