Large-scale manufacturing and characterization of CMV-CD19CAR T cells

Adoptive Immune Effector Cell Therapies in Cancer and Solid Organ Transplantation: A Review

Cancer is one of the most devastating complications of kidney transplantation and constitutes one of the leading causes of morbidity and mortality among solid organ transplantation (SOT) recipients. Immunosuppression, although effective in preventing allograft rejection, inherently inhibits immune surveillance against oncogenic viral infections and malignancy. Adoptive cell therapy, particularly immune effector cell therapy, has long been a modality of interest in both cancer and transplantation, though has only recently stepped into the spotlight with the development of virus-specific T-cell therapy and chimeric antigen receptor T-cell therapy. Although these modalities are best described in hematopoietic cell transplantation and hematologic malignancies, their potential application in the SOT setting may hold tremendous promise for those with limited therapeutic options. In this review, we provide a brief overview of the development of adoptive cell therapies with a focus on virus-specific T-cell therapy and chimeric antigen receptor T-cell therapy. We also describe the current experience of these therapies in the SOT setting as well as the challenges in their application and future directions in their development.

Development of a highly cytotoxic, clinical-grade virus-specific T cell product for adoptive T cell therapy

At present, recipients of allogeneic hematopoietic stem-cells are still suffering from recurrent infections after transplantation. Infusion of virus-specific T cells (VST) post-transplant reportedly fights several viruses without increasing the risk of de novo graft-versus-host disease. This study targeted cytomegalovirus (CMV) for the development of an innovative approach for generating a very specific VST product following Good Manufacturing Practices (GMP) guidelines. We used a sterile disposable compartment named the Leukoreduction System Chamber (LRS-chamber) from the apheresis platelet donation kit as the starting material, which has demonstrated high levels of T cells. Using a combination of IL-2 and IL-7 we could improve expansion of CMV-specific T cells. Moreover, by developing and establishing a new product protocol, we were able to stimulate VST proliferation and favors T cell effector memory profile. The expanded VST were enriched in a closed automated system, creating a highly pure anti-CMV product, which was pre-clinically tested for specificity in vitro and for persistence, biodistribution, and toxicity in vivo using NOD scid mice. Our results demonstrated very specific VST, able to secrete high amounts of interferon only in the presence of cells infected by the human CMV strain (AD169), and innocuous to cells partially HLA compatible without viral infection.

A comprehensive review of quantum bioreactor cell manufacture: Research and clinical applications

The Quantum cell expansion system manufactured by Terumo-BCT is perhaps the most widely reported Good Manufacturing Practice-compliant bioreactor used for the expansion of adherent cell populations, both for research purposes and clinical cell-based therapies/trials. Although the system was originally designed for adherent cell expansion, more recently suspension cultures and extracellular vesicle manufacturing protocols have been published using the Quantum system. Cell therapy research and regenerative medicine in general is a rapidly expanding field and as such it is likely that the use of this system will become even more widespread and perhaps mandatory, for both research and development and in the clinic. The purpose of this review is to describe, compare and discuss the diverse range of research and clinical applications currently using the Quantum system, which to our knowledge has not previously been reviewed. In addition, current and future challenges will also be discussed.

Applications of Anti-Cytomegalovirus T Cells for Cancer (Immuno)Therapy

Infection with cytomegalovirus (CMV) is highly prevalent in the general population and largely controlled by CD8pos T cells. Intriguingly, anti-CMV T cells accumulate over time to extraordinarily high numbers, are frequently present as tumor-resident 'bystander' T cells, and remain functional in cancer patients. Consequently, various strategies for redirecting anti-CMV CD8pos T cells to eliminate cancer cells are currently being developed. Here, we provide an overview of these strategies including immunogenic CMV peptide-loading onto endogenous HLA complexes on cancer cells and the use of tumor-directed fusion proteins containing a preassembled CMV peptide/HLA-I complex. Additionally, we discuss conveying the advantageous characteristics of anti-CMV T cells in adoptive cell therapy. Utilization of anti-CMV CD8pos T cells to generate CAR T cells promotes their in vivo persistence and expansion due to appropriate co-stimulation through the endogenous (CMV-)TCR signaling complex. Designing TCR-engineered T cells is more challenging, as the artificial and endogenous TCR compete for expression. Moreover, the use of expanded/reactivated anti-CMV T cells to target CMV peptide-expressing glioblastomas is discussed. This review highlights the most important findings and compares the benefits, disadvantages, and challenges of each strategy. Finally, we discuss how anti-CMV T cell therapies can be further improved to enhance treatment efficacy.

Current progress in chimeric antigen receptor-modified T cells for the treatment of metastatic breast cancer

Breast cancer is the leading cancer in women. Around 20-30% breast cancer patients undergo invasion or metastasis after radical surgical resection and eventually die. Number of breast cancer patients show poor sensitivity toward treatments despite the advances in chemotherapy, endocrine therapy, and molecular targeted treatments. Therapeutic resistance and tumor recurrence or metastasis develop with the ongoing treatments. Conducive treatment strategies are thus required. Chimeric antigen receptor (CAR)-modified T-cell therapy has progressed as a part of tumor immunotherapy. However, CAR-T treatment has not been effective in solid tumors because of tumor microenvironment complexity, inhibitory effects of extracellular matrix, and lacking ideal tumor antigens. Herein, the prospects of CAR-T cell therapy for metastatic breast cancer are discussed, and the targets for CAR-T therapy in breast cancer (HER-2, C-MET, MSLN, CEA, MUC1, ROR1, EGFR) at clinical level are reviewed. Moreover, solutions are proposed for the challenges of breast cancer CAR-T therapy regarding off-target effects, heterogeneous antigen expression by tumor cells and immunosuppressive tumor microenvironment. Ideas for improving the therapeutics of CAR-T cell therapy in metastatic breast cancer are suggested.

Evaluation of the Elements of Short Hairpin RNAs in Developing shRNA-Containing CAR T Cells

Short hairpin RNAs (shRNAs) have emerged as a powerful tool for gene knockdown in various cellular systems, including chimeric antigen receptor (CAR) T cells. However, the elements of shRNAs that are crucial for their efficacy in developing shRNA-containing CAR T cells remain unclear. In this study, we evaluated the impact of different shRNA elements, including promoter strength, orientation, multiple shRNAs, self-targeting, and sense and antisense sequence composition on the knockdown efficiency of the target gene in CAR T cells. Our findings highlight the importance of considering multiple shRNAs and their orientation to achieve effective knockdown. Moreover, we demonstrate that using a strong promoter and avoiding self-targeting can enhance CAR T cell functionality. These results provide a framework for the rational design of CAR T cells with shRNA-mediated knockdown capabilities, which could improve the therapeutic efficacy of CAR T cell-based immunotherapy.

Pathogen-specific T Cells: Targeting Old Enemies and New Invaders in Transplantation and Beyond

Adoptive immunotherapy with virus-specific cytotoxic T cells (VSTs) has evolved over the last three decades as a strategy to rapidly restore virus-specific immunity to prevent or treat viral diseases after solid organ or allogeneic hematopoietic cell-transplantation (allo-HCT). Since the early proof-of-principle studies demonstrating that seropositive donor-derived T cells, specific for the commonest pathogens post transplantation, namely cytomegalovirus or Epstein-Barr virus (EBV) and generated by time- and labor-intensive protocols, could effectively control viral infections, major breakthroughs have then streamlined the manufacturing process of pathogen-specific T cells (pSTs), broadened the breadth of target recognition to even include novel emerging pathogens and enabled off-the-shelf administration or pathogen-naive donor pST production. We herein review the journey of evolution of adoptive immunotherapy with nonengineered, natural pSTs against infections and virus-associated malignancies in the transplant setting and briefly touch upon recent achievements using pSTs outside this context.

CAR-T cell therapy for hematological malignancies: Limitations and optimization strategies

In the past decade, the emergence of chimeric antigen receptor (CAR) T-cell therapy has led to a cellular immunotherapy revolution against various cancers. Although CAR-T cell therapies have demonstrated remarkable efficacy for patients with certain B cell driven hematological malignancies, further studies are required to broaden the use of CAR-T cell therapy against other hematological malignancies. Moreover, treatment failure still occurs for a significant proportion of patients. CAR antigen loss on cancer cells is one of the most common reasons for cancer relapse. Additionally, immune evasion can arise due to the hostile immunosuppressive tumor microenvironment and the impaired CAR-T cells in vivo persistence. Other than direct antitumor activity, the adverse effects associated with CAR-T cell therapy are another major concern during treatment. As a newly emerged treatment approach, numerous novel preclinical studies have proposed different strategies to enhance the efficacy and attenuate CAR-T cell associated toxicity in recent years. The major obstacles that impede promising outcomes for patients with hematological malignancies during CAR-T cell therapy have been reviewed herein, along with recent advancements being made to surmount them.

Pre-clinical data supporting immunotherapy for HIV using CMV-HIV-specific CAR T cells with CMV vaccine

T cells engineered to express HIV-specific chimeric antigen receptors (CARs) represent a promising strategy to clear HIV-infected cells, but to date have not achieved clinical benefits. A likely hurdle is the limited T cell activation and persistence when HIV antigenemia is low, particularly during antiretroviral therapy (ART). To overcome this issue, we propose to use a cytomegalovirus (CMV) vaccine to stimulate CMV-specific T cells that express CARs directed against the HIV-1 envelope protein gp120. In this study, we use a GMP-compliant platform to engineer CMV-specific T cells to express a second-generation CAR derived from the N6 broadly neutralizing antibody, one of the broadest anti-gp120 neutralizing antibodies. These CMV-HIV CAR T cells exhibit dual effector functions upon in vitro stimulation through their endogenous CMV-specific T cell receptors or the introduced CARs. Using a humanized HIV mouse model, we show that CMV vaccination during ART accelerates CMV-HIV CAR T cell expansion in the peripheral blood and that higher numbers of CMV-HIV CAR T cells were associated with a better control of HIV viral load and fewer HIV antigen p24⁺ cells in the bone marrow upon ART interruption. Collectively, these data support the clinical development of CMV-HIV CAR T cells in combination with a CMV vaccine in HIV-infected individuals.

Genetic Modification of T Cells for the Immunotherapy of Cancer

Immunotherapy is a beneficial treatment approach for multiple cancers, however, current therapies are effective only in a small subset of patients. Adoptive cell transfer (ACT) is a facet of immunotherapy where T cells targeting the tumor cells are transferred to the patient with several primary forms, utilizing unmodified or modified T cells: tumor-infiltrating lymphocytes (TIL), genetically modified T cell receptor transduced T cells, and chimeric antigen receptor (CAR) transduced T cells. Many clinical trials are underway investigating the efficacy and safety of these different subsets of ACT, as well as trials that combine one of these subsets with another type of immunotherapy. The main challenges existing with ACT are improving clinical responses and decreasing adverse events. Current research focuses on identifying novel tumor targeting T cell receptors, improving safety and efficacy, and investigating ACT in combination with other immunotherapies.