'Off-the-Shelf' Immunotherapy: Manufacture of CD8+ T Cells Derived from Hematopoietic Stem Cells

The fulfilled promise and unmet potential of umbilical cord blood

PURPOSE OF REVIEW

Here, we review classic and emerging uses of umbilical cord blood and highlight strategies to improve its utility, focusing on selection of the appropriate units and cell types for the intended applications.

RECENT LITERATURE

Recent studies have shown advancements in cord blood cell utility in a variety of cellular therapies and have made strides in elucidating manners to select the best units for therapy and target new ways to improve the various cell subpopulations for their respective applications.

SUMMARY

Umbilical cord blood is a proven source of cells for hematopoietic cell transplantation and research and is an important potential source for additional cellular therapies. However, cord blood utility is limited by low "doses" of potent cells that can be obtained from individual units, a limitation that is specific to cord blood as a donor source. In addition to traditional CD34 + progenitor cells, cord blood lymphocytes are being pursued as therapeutic entities with their own unique properties and characteristics. Thus, selection of ideal units depends on the intended therapeutic entity and target, and identification of differential potency parameters is critical to drive effective banking strategies accommodating successful clinical use of cord blood in broader cell therapy settings.

Allogeneic CAR-T Therapy Technologies: Has the Promise Been Met?

This last decade, chimeric antigen receptor (CAR) T-cell therapy has become a real treatment option for patients with B-cell malignancies, while multiple efforts are being made to extend this therapy to other malignancies and broader patient populations. However, several limitations remain, including those associated with the time-consuming and highly personalized manufacturing of autologous CAR-Ts. Technologies to establish "off-the-shelf" allogeneic CAR-Ts with low alloreactivity are currently being developed, with a strong focus on gene-editing technologies. Although these technologies have many advantages, they have also strong limitations, including double-strand breaks in the DNA with multiple associated safety risks as well as the lack of modulation. As an alternative, non-gene-editing technologies provide an interesting approach to support the development of allogeneic CAR-Ts in the future, with possibilities of fine-tuning gene expression and easy development. Here, we will review the different ways allogeneic CAR-Ts can be manufactured and discuss which technologies are currently used. The biggest hurdles for successful therapy of allogeneic CAR-Ts will be summarized, and finally, an overview of the current clinical evidence for allogeneic CAR-Ts in comparison to its autologous counterpart will be given.

The Progress and Prospects of Immune Cell Therapy for the Treatment of Cancer

Immune cell therapy as a revolutionary treatment modality, significantly transformed cancer care. It is a specialized form of immunotherapy that utilizes living immune cells as therapeutic reagents for the treatment of cancer. Unlike traditional drugs, cell therapies are considered "living drugs," and these products are currently customized and require advanced manufacturing techniques. Although chimeric antigen receptor (CAR)-T cell therapies have received tremendous attention in the industry regarding the treatment of hematologic malignancies, their effectiveness in treating solid tumors is often restricted, leading to the emergence of alternative immune cell therapies. Tumor-infiltrating lymphocytes (TIL) cell therapy, cytokine-induced killer (CIK) cell therapy, dendritic cell (DC) vaccines, and DC/CIK cell therapy are designed to use the body's natural defense mechanisms to target and eliminate cancer cells, and usually have fewer side effects or risks. On the other hand, cell therapies, such as chimeric antigen receptor-T (CAR-T) cell, T cell receptor (TCR)-T, chimeric antigen receptor-natural killer (CAR-NK), or CAR-macrophages (CAR-M) typically utilize either autologous stem cells, allogeneic or xenogeneic cells, or genetically modified cells, which require higher levels of manipulation and are considered high risk. These high-risk cell therapies typically hold special characteristics in tumor targeting and signal transduction, triggering new anti-tumor immune responses. Recently, significant advances have been achieved in both basic and clinical researches on anti-tumor mechanisms, cell therapy product designs, and technological innovations. With swift technological integration and a high innovation landscape, key future development directions have emerged. To meet the demands of cell therapy technological advancements in treating cancer, we comprehensively and systematically investigate the technological innovation and clinical progress of immune cell therapies in this study. Based on the therapeutic mechanisms and methodological features of immune cell therapies, we analyzed the main technical advantages and clinical transformation risks associated with these therapies. We also analyzed and forecasted the application prospects, providing references for relevant enterprises with the necessary information to make informed decisions regarding their R&D direction selection.

Mitochondria Dictate Function and Fate of HSCs and T Cells

Hematopoietic stem cells (HSC) and T cells are intimately related, lineage-dependent cell populations that are extensively used as therapeutic products for the treatment of hematologic malignancies and certain types of solid tumors. These cellular therapies can be life-saving treatments; however, their efficacies are often limited by factors influencing their activity and cellular properties. Among these factors is mitochondrial metabolism, which influences the function and fate commitment of both HSCs and T cells. Mitochondria, besides being the "cellular powerhouse," provide metabolic intermediates that are used as substrates for epigenetic modifications and chromatin remodeling, thus, driving cell fate decisions during differentiation. Moreover, mitochondrial fitness and mitochondrial quality control mechanisms are closely related to cellular function, and impairment of these mitochondrial properties associates with cellular dysfunction due to factors such as T-cell exhaustion and aging. Here, we give an overview of the role of mitochondria in shaping the behavior of these lineage-related cell populations. Moreover, we discuss the potential of novel mitochondria-targeting strategies for enhancing HSC- and T cell-based cancer immunotherapies and highlight how design and application of such approaches requires consideration of the metabolic similarities and differences between HSCs and T cells. See related article on p. 1302.

Current approaches to develop "off-the-shelf" chimeric antigen receptor (CAR)-T cells for cancer treatment: a systematic review

Chimeric antigen receptor (CAR)-T cell therapy is one of the most promising advances in cancer treatment. It is based on genetically modified T cells to express a CAR, which enables the recognition of the specific tumour antigen of interest. To date, CAR-T cell therapies approved for commercialisation are designed to treat haematological malignancies, showing impressive clinical efficacy in patients with relapsed or refractory advanced-stage tumours. However, since they all use the patient´s own T cells as starting material (i.e. autologous use), they have important limitations, including manufacturing delays, high production costs, difficulties in standardising the preparation process, and production failures due to patient T cell dysfunction. Therefore, many efforts are currently being devoted to contribute to the development of safe and effective therapies for allogeneic use, which should be designed to overcome the most important risks they entail: immune rejection and graft-versus-host disease (GvHD). This systematic review brings together the wide range of different approaches that have been studied to achieve the production of allogeneic CAR-T cell therapies and discuss the advantages and disadvantages of every strategy. The methods were classified in two major categories: those involving extra genetic modifications, in addition to CAR integration, and those relying on the selection of alternative cell sources/subpopulations for allogeneic CAR-T cell production (i.e. γδ T cells, induced pluripotent stem cells (iPSCs), umbilical cord blood T cells, memory T cells subpopulations, virus-specific T cells and cytokine-induced killer cells). We have observed that, although genetic modification of T cells is the most widely used approach, new approaches combining both methods have emerged. However, more preclinical and clinical research is needed to determine the most appropriate strategy to bring this promising antitumour therapy to the clinical setting.

Fine-Tuning through Generations: Advances in Structure and Production of CAR-T Therapy

Chimeric antigen receptor (CAR)-T cell therapy is a promising form of immunotherapy that has seen significant advancements in the past few decades. It involves genetically modifying T cells to target cancer cells expressing specific antigens, providing a novel approach to treating various types of cancer. However, the initial success of first-generation CAR-T cells was limited due to inadequate proliferation and undesirable outcomes. Nonetheless, significant progress has been made in CAR-T cell engineering, leading to the development of the latest fifth-generation CAR-T cells that can target multiple antigens and overcome individual limitations. Despite these advancements, some shortcomings prevent the widespread use of CAR-T therapy, including life-threatening toxicities, T-cell exhaustion, and inadequate infiltration for solid tumors. Researchers have made considerable efforts to address these issues by developing new strategies for improving CAR-T cell function and reducing toxicities. This review provides an overview of the path of CAR-T cell development and highlights some of the prominent advances in its structure and manufacturing process, which include the strategies to improve antigen recognition, enhance T-cell activation and persistence, and overcome immune escape. Finally, the review briefly covers other immune cells for cancer therapy and ends with the discussion on the broad prospects of CAR-T in the treatment of various diseases, not just hematological tumors, and the challenges that need to be addressed for the widespread clinical application of CAR-T cell therapies.

Multiplex HDR for disease and correction modeling of SCID by CRISPR genome editing in human HSPCs

Severe combined immunodeficiency (SCID) is a group of disorders caused by mutations in genes involved in the process of lymphocyte maturation and function. CRISPR-Cas9 gene editing of the patient's own hematopoietic stem and progenitor cells (HSPCs) ex vivo could provide a therapeutic alternative to allogeneic hematopoietic stem cell transplantation, the current gold standard for treatment of SCID. To eliminate the need for scarce patient samples, we engineered genotypes in healthy donor (HD)-derived CD34⁺ HSPCs using CRISPR-Cas9/rAAV6 gene-editing, to model both SCID and the therapeutic outcomes of gene-editing therapies for SCID via multiplexed homology-directed repair (HDR). First, we developed a SCID disease model via biallelic knockout of genes critical to the development of lymphocytes; and second, we established a knockin/knockout strategy to develop a proof-of-concept single-allelic gene correction. Based on these results, we performed gene correction of RAG2-SCID patient-derived CD34⁺ HSPCs that successfully developed into CD3⁺ T cells with diverse TCR repertoires in an in vitro T cell differentiation platform. In summary, we present a strategy to determine the optimal configuration for CRISPR-Cas9 gene correction of SCID using HD-derived CD34⁺ HSPCs, and the feasibility of translating this gene correction approach in patient-derived CD34⁺ HSPCs.