Characterization of human T lymphocytes engineered to express interleukin-15 and herpes simplex virus-thymidine kinase

Developing innovative strategies of tumor‑infiltrating lymphocyte therapy for tumor treatment

Cancer is the main cause of global mortality, and thus far, effective therapeutic strategies for cancer treatment are in high demand. Adoptive transfer of tumor‑infiltrating lymphocytes (TILs) represents a promising avenue in immunotherapy for the management of malignancies. The clinical safety and efficacy of TIL‑based therapy have been established through numerous rigorous clinical trials. However, the efficacy of TIL infusion in inducing an anti‑tumor response is limited to a subset of clinical patients with cancer. Therefore, there is an urgent need to develop innovative strategies aimed at enhancing the effectiveness of TIL‑based therapy. In the present review, the developmental history of TIL‑based therapy was systematically summarized and analyzed, while also presenting a unique perspective on enhancing the multi‑dimensional anti‑tumor capabilities of TILs. The insight and conclusions presented in this review may contribute to improving the efficacy of TIL‑based therapy and expediting its development.

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".

Strategies for Reducing Toxicity and Enhancing Efficacy of Chimeric Antigen Receptor T Cell Therapy in Hematological Malignancies

Chimeric antigen receptor T cell (CAR-T) therapy in hematologic malignancies has made great progress, but there are still some problems. First, T cells from tumor patients show an exhaustion phenotype; thus, the persistence and function of the CAR-Ts are poor, and achieving a satisfactory curative effect is difficult. Second, some patients initially respond well but quickly develop antigen-negative tumor recurrence. Thirdly, CAR-T treatment is not effective in some patients and is accompanied by severe side effects, such as cytokine release syndrome (CRS) and neurotoxicity. The solution to these problems is to reduce the toxicity and enhance the efficacy of CAR-T therapy. In this paper, we describe various strategies for reducing the toxicity and enhancing the efficacy of CAR-T therapy in hematological malignancies. In the first section, strategies for modifying CAR-Ts using gene-editing technologies or combining them with other anti-tumor drugs to enhance the efficacy of CAR-T therapy are introduced. The second section describes some methods in which the design and construction of CAR-Ts differ from the conventional process. The aim of these methods is to enhance the anti-tumor activity of CAR-Ts and prevent tumor recurrence. The third section describes modifying the CAR structure or installing safety switches to radically reduce CAR-T toxicity or regulating inflammatory cytokines to control the symptoms of CAR-T-associated toxicity. Together, the knowledge summarized herein will aid in designing better-suited and safer CAR-T treatment strategies.

Cell-mediated enzyme prodrug cancer therapies

Cell-directed gene therapy is a promising new frontier for the field of targeted cancer therapies. Here we discuss the current pre-clinical and clinical use of cell-mediated enzyme prodrug therapy (EPT) directed against solid tumors and avenues for further development. We also discuss some of the challenges encountered upon translating these therapies to clinical trials. Upon sufficient development, cell-mediated enzyme prodrug therapy has the potential to maximize the distribution of therapeutic enzymes within the tumor environment, localizing conversion of prodrug to active drug at the tumor sites thereby decreasing off-target toxicities. New combinatorial possibilities are also promising. For example, when combined with viral gene-delivery vehicles, this may result in new hybrid vehicles that attain heretofore unmatched levels of therapeutic gene expression within the tumor.

Membrane-attached Cytokines Expressed by mRNA Electroporation Act as Potent T-Cell Adjuvants

Proinflammatory cytokines are widely explored in different adoptive cell therapy protocols for enhancing survival and function of the transferred T cells, but their systemic administration is often associated with severe toxicity which limits their clinical use. To confine cytokine availability to the therapeutic T cells, we expressed 3 key cytokines, IL-2, IL-12, and IL-15, as integral T-cell membrane proteins. To prevent permanent activation of growth signaling pathways, we delivered these genes to T cells through mRNA electroporation. The engineered cytokines could be detected on the surface of mRNA-transfected cells and binding to their cell-surface receptors mainly occurred in cis. The 3 human cytokines supported the ex vivo growth of activated human CD8 and CD4 T cells for at least 6 days posttransfection, comparably to high-dose soluble IL-2. Similarly, membrane IL-2, membrane IL-12, and, to a lesser extent, membrane IL-15, were comparable with their soluble counterparts in supporting proliferation of splenic mouse CD8 T cells. Following electroporation of human CD8 T cells and antimelanoma tumor-infiltrating lymphocytes, membrane cytokines synergized with constitutively active toll-like receptor 4 in inducing interferon-γ secretion. Efficient cooperation with TLR4 was also evident in the upregulation of the activation molecules CD25, CD69, CD137 (4-1BB), and CD134 (OX40). Taken together, membrane cytokines expressed through mRNA transfection emerge as effective tools for enhancing T-cell proliferation and function and may have potential use in adoptive T-cell therapy.