Application and Design of Switches Used in CAR

Engineering CD5-targeting CAR-NK cells from peripheral blood for the treatment of CD5-positive hematological malignancies

BACKGROUND

The therapeutic application of chimeric antigen receptor (CAR) T cells in T-cell malignancies faces substantial limitations owing to fratricide and potential T cell aplasia, primarily attributed to the shared expression of target antigens, such as CD5, between normal and malignant T cells. Although natural killer (NK) cell-based immunotherapy is a promising alternative approach, its efficacy in treating hematologic malignancies remains to be fully elucidated.

METHODS

CD5-targeted CAR-modified primary NK cells, T cells and NK92 cell lines were generated and comprehensively evaluated for their anti-tumor efficacy through in vitro cytotoxicity assays and xenograft mouse models. Furthermore, preliminary investigation of the herpes simplex virus-1 thymidine kinase (HSV-TK) suicide switch system in CAR-NK cells were conducted using ganciclovir (GCV) as the activating agent.

RESULTS

CAR-NK cells exhibited significantly increased cytotoxic activity against CD5-positive cell lines and primary tumor cells, compared to NK, CAR-NK92, and CAR-T cells. Moreover, CAR-NK cells effectively decreased the leukemic burden and extended survival in murine model. Additionally, an off-switch utilizing the HSV-TK switch system successfully eradicated CAR-NK cells for safety considerations.

CONCLUSIONS

This study developed a controllable CD5 CAR-NK cells that exhibit high efficacy against T-cell malignancies, although further validation is necessary to assess their clinical potential.

Synthetic receptor-based cell therapies for autoimmune diseases: an update

Increasing frequency of autoimmune diseases is one of the major problems in modern societies. Despite the introduction of new therapeutic agents for autoimmunity over the past several decades, more progress is needed. Synthetic receptor-based cell therapies are being adopted as an option for treating autoimmune diseases from the field of oncology. Currently evaluated strategies can be summarized into two approaches. The first one is the elimination of autoreactive cells by targeting them, for example, with CAR-T or CAAR-T cells. The second is based on rebalancing the proinflammatory milieu with engineered immunosuppressive cells, for example, CAR-Treg. Both approaches can be supplemented with the use of synthetic systems such as Split-CAR, SynNotch, MESA, GEMS, and SNIPR, or prospective off-the-shelf approaches, for example, in situ use of the in vitro transcribed mRNA, ultimately allowing for enhanced efficacy and safety. The primary goal of our review is to provide some perspective on both strategies in basic, translational, and clinical studies with all their advantages and disadvantages to allow for informed future design of adoptive cell therapies for autoimmune diseases.

Advanced Strategies of CAR-T Cell Therapy in Solid Tumors and Hematological Malignancies

Chimeric antigen receptor T-cells, known as CAR-T cells, represent a promising breakthrough in the realm of adoptive cell therapy. These T-cells are genetically engineered to carry chimeric antigen receptors that specifically target tumors. They have achieved notable success in the treatment of blood-related cancers, breathing new life into this field of medical research. However, numerous obstacles limit chimeric antigen receptors T-cell therapy's efficacy, such as it cannot survive in the body long. It is prone to fatigue and exhaustion, leading to difficult tumor elimination and repeated recurrence, affecting solid tumors and hematological malignancies. The challenges posed by solid tumors, especially in the context of the complex solid-tumor microenvironment, require specific strategies. This review outlines recent advancements in improving chimeric antigen receptors T-cell therapy by focusing on the chimeric antigen receptors protein, modifying T-cells, and optimizing the interaction between T-cells and other components within the tumor microenvironment. This article aims to provide an extensive summary of the latest discoveries regarding CAR-T cell therapy, encompassing its application across various types of human cancers. Moreover, it will delve into the obstacles that have emerged in recent times, offering insights into the challenges faced by this innovative approach. Finally, it highlights novel therapeutic options in treating hematological and solid malignancies with chimeric antigen receptors T-cell therapies.

Challenges of CRISPR/Cas-Based Cell Therapy for Type 1 Diabetes: How Not to Engineer a "Trojan Horse"

Type 1 diabetes mellitus (T1D) is an autoimmune disease caused by the destruction of insulin-producing β-cells in the pancreas by cytotoxic T-cells. To date, there are no drugs that can prevent the development of T1D. Insulin replacement therapy is the standard care for patients with T1D. This treatment is life-saving, but is expensive, can lead to acute and long-term complications, and results in reduced overall life expectancy. This has stimulated the research and development of alternative treatments for T1D. In this review, we consider potential therapies for T1D using cellular regenerative medicine approaches with a focus on CRISPR/Cas-engineered cellular products. However, CRISPR/Cas as a genome editing tool has several drawbacks that should be considered for safe and efficient cell engineering. In addition, cellular engineering approaches themselves pose a hidden threat. The purpose of this review is to critically discuss novel strategies for the treatment of T1D using genome editing technology. A well-designed approach to β-cell derivation using CRISPR/Cas-based genome editing technology will significantly reduce the risk of incorrectly engineered cell products that could behave as a "Trojan horse".

Challenges and solutions for therapeutic TCR-based agents

Recent development of methods to discover and engineer therapeutic T-cell receptors (TCRs) or antibody mimics of TCRs, and to understand their immunology and pharmacology, lag two decades behind therapeutic antibodies. Yet we have every expectation that TCR-based agents will be similarly important contributors to the treatment of a variety of medical conditions, especially cancers. TCR engineered cells, soluble TCRs and their derivatives, TCR-mimic antibodies, and TCR-based CAR T cells promise the possibility of highly specific drugs that can expand the scope of immunologic agents to recognize intracellular targets, including mutated proteins and undruggable transcription factors, not accessible by traditional antibodies. Hurdles exist regarding discovery, specificity, pharmacokinetics, and best modality of use that will need to be overcome before the full potential of TCR-based agents is achieved. HLA restriction may limit each agent to patient subpopulations and off-target reactivities remain important barriers to widespread development and use of these new agents. In this review we discuss the unique opportunities for these new classes of drugs, describe their unique antigenic targets, compare them to traditional antibody therapeutics and CAR T cells, and review the various obstacles that must be overcome before full application of these drugs can be realized.

Chimeric antigen receptor T cells march into T cell malignancies

T cell malignancies represent a diverse collection of leukemia/lymphoma conditions in humans arising from aberrant T cells. Such malignancies are often associated with poor clinical prognoses, cancer relapse, as well as progressive resistance to anti-cancer treatments. While chimeric antigen receptor (CAR) T cell immunotherapy has emerged as a revolutionary treatment strategy that is highly effective for treating B cell malignancies, its application as a treatment for T cell malignancies remains to be better explored. Furthermore, the effectiveness of CAR-T treatment in T cell malignancies is significantly influenced by the quality of contamination-free CAR-T cells during the manufacturing process, as well as by multiple characteristics of such malignancies, including the sharing of antigens across normal and malignant T cells, fratricide, and T cell aplasia. In this review, we provide a detailed account of the current developments in the clinical application of CAR-T therapy to treat T cell malignancies, offer strategies for addressing current challenges, and outline a roadmap toward its effective implementation as a broad treatment option for this condition.

Regulation of CD19 CAR-T cell activation based on an engineered downstream transcription factor

CAR-T cells present a highly effective therapeutic option for several malignant diseases, based on their ability to recognize the selected tumor surface marker in an MHC-independent manner. This triggers cell activation and cytokine production, resulting in the killing of the cancerous cell presenting markers recognized by the chimeric antigen receptor. CAR-T cells are highly potent serial killers that may cause serious side effects, so their activity needs to be carefully controlled. Here we designed a system to control the proliferation and activation state of CARs based on downstream NFAT transcription factors, whose activity can be regulated via chemically induced heterodimerization systems. Chemical regulators were used to either transiently trigger engineered T cell proliferation or suppress CAR-mediated activation when desired or to enhance activation of CAR-T cells upon engagement of cancer cells, shown also in vivo. Additionally, an efficient sensor to monitor activated CD19 CAR-T cells in vivo was introduced. This implementation in CAR-T cell regulation offers an efficient way for on-demand external control of CAR-T cell activity to improve their safety.