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Adoptive T-cell transfer (ACT) therapies, including of tumor infiltrating lymphocytes (TILs) and T cells gene-modified to express either a T cell receptor (TCR) or a chimeric antigen receptor (CAR), have demonstrated clinical efficacy for a proportion of patients and cancer-types. The field of ACT has been driven forward by the clinical success of CD19-CAR therapy against various advanced B-cell malignancies, including curative responses for some leukemia patients. However, relapse remains problematic, in particular for lymphoma. Moreover, for a variety of reasons, relative limited efficacy has been demonstrated for ACT of non-hematological solid tumors. Indeed, in addition to pre-infusion challenges including lymphocyte collection and manufacturing, ACT failure can be attributed to several biological processes post-transfer including, (i) inefficient tumor trafficking, infiltration, expansion and retention, (ii) chronic antigen exposure coupled with insufficient costimulation resulting in T-cell exhaustion, (iii) a range of barriers in the tumor microenvironment (TME) mediated by both tumor cells and suppressive immune infiltrate, (iv) tumor antigen heterogeneity and loss, or down-regulation of antigen presentation machinery, (v) gain of tumor intrinsic mechanisms of resistance such as to apoptosis, and (vi) various forms of toxicity and other adverse events in patients. Affinity-optimized TCRs can improve T-cell function and innovative CAR designs as well as gene-modification strategies can be used to coengineer specificity, safety, and function into T cells. Coengineering strategies can be designed not only to directly support the transferred T cells, but also to block suppressive barriers in the TME and harness endogenous innate and adaptive immunity. Here, we review a selection of the remarkable T-cell coengineering strategies, including of tools, receptors, and gene-cargo, that have been developed in recent years to augment tumor control by ACT, more and more of which are advancing to the clinic., (© 2023 The Authors. Immunological Reviews published by John Wiley & Sons Ltd.)

Summary: A synthetic circuit in a biological system involves the designed assembly of genetic elements, biomolecules, or cells to create a defined function. These circuits are central in synthetic biology, enabling the reprogramming of cellular behavior and the engineering of cells with customized responses. In cancer therapeutics, engineering T cells with circuits have the potential to overcome the challenges of current approaches, for example, by allowing specific recognition and killing of cancer cells. Recent advances also facilitate engineering integrated circuits for the controlled release of therapeutic molecules at specified locations, for example, in a solid tumor. In this review, we discuss recent strategies and applications of synthetic receptor circuits aimed at enhancing immune cell functions for cancer immunotherapy. We begin by introducing the concept of circuits in networks at the molecular and cellular scales and provide an analysis of the development and implementation of several synthetic circuits in T cells that have the goal to overcome current challenges in cancer immunotherapy. These include specific targeting of cancer cells, increased T‐cell proliferation, and persistence in the tumor microenvironment. By harnessing the power of synthetic biology, and the characteristics of certain circuit architectures, it is now possible to engineer a new generation of immune cells that recognize cancer cells, while minimizing off‐target toxicities. We specifically discuss T‐cell circuits for antigen density sensing. These circuits allow targeting of solid tumors that share antigens with normal tissues. Additionally, we explore designs for synthetic circuits that could control T‐cell differentiation or T‐cell fate as well as the concept of synthetic multicellular circuits that leverage cellular communication and division of labor to achieve improved therapeutic efficacy. As our understanding of cell biology expands and novel tools for genome, protein, and cell engineering are developed, we anticipate further innovative approaches to emerge in the design and engineering of circuits in immune cells. [ABSTRACT FROM AUTHOR]

Summary: Cell therapies are powerful technologies in which human cells are reprogrammed for therapeutic applications such as killing cancer cells or replacing defective cells. The technologies underlying cell therapies are increasing in effectiveness and complexity, making rational engineering of cell therapies more difficult. Creating the next generation of cell therapies will require improved experimental approaches and predictive models. Artificial intelligence (AI) and machine learning (ML) methods have revolutionized several fields in biology including genome annotation, protein structure prediction, and enzyme design. In this review, we discuss the potential of combining experimental library screens and AI to build predictive models for the development of modular cell therapy technologies. Advances in DNA synthesis and high‐throughput screening techniques enable the construction and screening of libraries of modular cell therapy constructs. AI and ML models trained on this screening data can accelerate the development of cell therapies by generating predictive models, design rules, and improved designs. [ABSTRACT FROM AUTHOR]

Summary: Chimeric antigen receptor (CAR)‐T cell therapy has emerged as a promising approach for cancer treatment. CAR is a synthetic immune receptor that recognizes tumor antigen and activates T cells through multiple signaling pathways. However, the current CAR design is not as robust as T cell receptor (TCR), a natural antigen receptor with high sensitivity and efficiency. TCR signaling relies on specific molecular interactions, and thus electrostatic force, the major force of molecular interactions, play critical roles. Understanding how electrostatic charge regulates TCR/CAR signaling events will facilitate the development of next‐generation T cell therapies. This review summarizes recent findings on the roles of electrostatic interactions in both natural and synthetic immune receptor signaling, specifically that in CAR clustering and effector molecule recruitments, and highlights potential strategies for engineering CAR‐T cell therapy by leveraging charge‐based interactions. [ABSTRACT FROM AUTHOR]

Summary: During an immune response, the duration of T cell residence in lymphoid and non‐lymphoid tissues likely affects T cell activation, differentiation, and memory development. The factors that govern T cell transit through inflamed tissues remain incompletely understood, but one important determinant of T cell exit from tissues is sphingosine 1‐phosphate (S1P) signaling. In homeostasis, S1P levels are high in blood and lymph compared to lymphoid organs, and lymphocytes follow S1P gradients out of tissues into circulation using varying combinations of five G‐protein coupled S1P receptors. During an immune response, both the shape of S1P gradients and the expression of S1P receptors are dynamically regulated. Here we review what is known, and key questions that remain unanswered, about how S1P signaling is regulated in inflammation and in turn how S1P shapes immune responses. [ABSTRACT FROM AUTHOR]

Afferent lymphatics mediate the transport of antigen and leukocytes, especially of dendritic cells (DCs) and T cells, from peripheral tissues to draining lymph nodes (dLNs). As such they play important roles in the induction and regulation of adaptive immunity. Over the past 15 years, great advances in our understanding of leukocyte trafficking through afferent lymphatics have been made through time‐lapse imaging studies performed in tissue explants and in vivo, allowing to visualize this process with cellular resolution. Intravital imaging has revealed that intralymphatic leukocytes continue to actively migrate once they have entered into lymphatic capillaries, as a consequence of the low flow conditions present in this compartment. In fact, leukocytes spend considerable time migrating, patrolling and interacting with the lymphatic endothelium or with other intralymphatic leukocytes within lymphatic capillaries. Cells typically only start to detach once they arrive in downstream‐located collecting vessels, where vessel contractions contribute to enhanced lymph flow. In this review, we will introduce the biology of afferent lymphatic vessels and report on the presumed significance of DC and T cell migration via this route. We will specifically highlight how time‐lapse imaging has contributed to the current model of lymphatic trafficking and the emerging notion that ‐ besides transport – lymphatic capillaries exert additional roles in immune modulation. [ABSTRACT FROM AUTHOR]

Despite recent significant progress in cancer immunotherapies based on adoptive cell transfer(s)(ACT), the eradication of cancers still represents a major clinical challenge. In particular, the efficacy of current ACT‐based therapies against solid tumors is dramatically reduced by physical barriers that prevent tumor infiltration of adoptively transferred effectors, and the tumor environment that suppress their anti‐tumor functions. Novel immunotherapeutic strategies are thus needed to circumvent these issues. Human peripheral blood Vγ9Vδ2 T cells, a non‐alloreactive innate‐like T lymphocyte subset, recently proved to be a promising anti‐tumor effector subset for ACT‐based immunotherapies. Furthermore, new cell engineering tools that leverage the potential of CRISPR/Cas technology open astounding opportunities to optimize their anti‐tumor effector functions. In this review, we present the current ACT strategies based on engineered T cells and their limitations. We then discuss the potential of engineered Vγ9Vδ2 T cell to overcome these limitations and improve ACT‐based cancer immunotherapies. [ABSTRACT FROM AUTHOR]

Advances in the development of immunotherapies have offered exciting new options for the treatment of malignant diseases that are refractory to conventional cytotoxic chemotherapies. The adoptive transfer of T cells expressing chimeric antigen receptors (CARs) has demonstrated dramatic results in clinical trials and highlights the promise of novel immune‐based approaches to the treatment of cancer. As experience with CAR T cells has expanded with longer follow‐up and to a broader range of diseases, new obstacles have been identified which limit the potential lifelong benefits of CAR T cell therapy. These obstacles highlight not only the gaps in knowledge of the optimal clinical application of this "living drug", but also gaps in our understanding of the fundamental biology of CAR T cells themselves. In this review, we discuss the obstacles facing CAR T cell therapy, how these relate to our current understanding of CAR T cell biology and approaches to enhance the clinical efficacy of this therapy. [ABSTRACT FROM AUTHOR]

The advent of chimeric antigen receptor T (CAR‐T) and the burgeoning field of cellular therapy has revolutionized the treatment of relapsed/refractory leukemia and lymphoma. This personalized "living therapy" is highly effective against a number of malignancies, but this efficacy is tempered by side effects relatively unique to immunotherapies, including CAR‐T. The overwhelming release of cytokines and chemokines by activated CAR‐T and other secondarily activated immune effector cells can lead to cytokine release syndrome (CRS), which can have clinical and pathophysiology similarities to systemic inflammatory response syndrome and macrophage activating syndrome/hemophagocytic lymphohistiocytosis. Tocilizumab, an anti‐IL6 receptor antibody, was recently FDA approved for treatment of CRS after CAR‐T based on its ability to mitigate CRS in many patients. Unfortunately, some patients are refractory and additional therapies are needed. Patients treated with CAR‐T can also develop neurotoxicity and, as the biology is poorly understood, current therapeutic interventions are limited to supportive care. Nevertheless, a number of recent studies have shed new light on the pathophysiology of CAR‐T‐related neurotoxicity, which will hopefully lead to effective treatments. In this review we discuss some of the mechanistic contributions intrinsic to the CAR‐T construct, the tumor being treated, and the individual patient that impact the development and severity of CRS and neurotoxicity. As CAR‐T and cellular therapy have redefined the concept of personalized medicine, so too will personalization be necessary in managing the unique side effects of these therapies. [ABSTRACT FROM AUTHOR]

Summary: A large proportion of memory T cells disseminated throughout the body are non‐recirculating cells whose maintenance and function is regulated by tissue‐specific environmental cues. These sessile cells are referred to as tissue‐resident memory T (TRM) cells and similar populations of non‐recirculating cells also exist among unconventional T cells and innate lymphocyte cells. The pool of TRM cells is highly diverse with respect to anatomical positioning, phenotype, molecular regulation and effector function. Nevertheless, certain transcriptional programs are shared and appear as important unifying features for the overall population of TRM cells and tissue‐resident lymphocytes. It is now widely appreciated that TRM cells are a critical component of our immune defense by acting as peripheral sentinels capable of rapidly mobilizing protective tissue immunity upon pathogen recognition. This function is of particular importance in anatomical sites that are not effectively surveilled by blood‐borne memory T cells in absence of inflammation, such as neuronal tissues or epithelial compartments in skin and mucosae. Focusing on the well‐characterized subtype of CD8+ CD69+ CD103+ TRM cells, we will review current concepts on the generation, persistence and function of TRM cells and will summarize commonly used tools to study these cells. Furthermore, we will discuss accumulating data that emphasize localized TRM responses as an important determinant of tissue homeostasis and immune defense in the context of microbiota‐immune interactions, persistent infections and cancer surveillance. [ABSTRACT FROM AUTHOR]