Co-expression of IL-7 and PH20 promote anti-GPC3 CAR-T tumour suppressor activity in vivo and in vitro

CAR-T cell technologies that interact with the tumour microenvironment in solid tumours

INTRODUCTION

Chimeric antigen receptor (CAR) T-cells have emerged as a ground-breaking therapy for the treatment of hematological malignancies due to their capacity for rapid tumor-specific killing and long-lasting tumor immunity. However, the same success has not been observed in patients with solid tumors. Largely, this is due to the additional challenges imposed by safe and uniform target selection, inefficient CAR T-cell access to sites of disease and the presence of a hostile immunosuppressive tumor microenvironment.

AREAS COVERED

Literature was reviewed on the PubMed database from the first description of a CAR by Kuwana, Kurosawa and colleagues in December 1987 through to the present day. This literature indicates that in order to tackle solid tumors, CAR T-cells can be further engineered with additional armoring strategies that facilitate trafficking to and infiltration of malignant lesions together with reversal of suppressive immune checkpoints that operate within solid tumor lesions.

EXPERT OPINION

In this review, we describe a number of recent advances in CAR T-cell technology that set out to combat the problems imposed by solid tumors including tumor recruitment, infiltration, immunosuppression, metabolic compromise, and hypoxia.

Advances in IL-7 Research on Tumour Therapy

Interleukin-7 (IL-7) is a versatile cytokine that plays a crucial role in regulating the immune system's homeostasis. It is involved in the development, proliferation, and differentiation of B and T cells, as well as being essential for the differentiation and survival of naïve T cells and the production and maintenance of memory T cells. Given its potent biological functions, IL-7 is considered to have the potential to be widely used in the field of anti-tumour immunotherapy. Notably, IL-7 can improve the tumour microenvironment by promoting the development of Th17 cells, which can in turn promote the recruitment of effector T cells and NK cells. In addition, IL-7 can also down-regulate the expression of tumour growth factor-β and inhibit immunosuppression to promote anti-tumour efficacy, suggesting potential clinical applications for anti-tumour immunotherapy. This review aims to discuss the origin of IL-7 and its receptor IL-7R, its anti-tumour mechanism, and the recent advances in the application of IL-7 in tumour therapy.

Engineered Adoptive T-Cell Therapies for Breast Cancer: Current Progress, Challenges, and Potential

Breast cancer remains a significant health challenge, and novel treatment approaches are critically needed. This review presents an in-depth analysis of engineered adoptive T-cell therapies (E-ACTs), an innovative frontier in cancer immunotherapy, focusing on their application in breast cancer. We explore the evolving landscape of chimeric antigen receptor (CAR) and T-cell receptor (TCR) T-cell therapies, highlighting their potential and challenges in targeting breast cancer. The review addresses key obstacles such as target antigen selection, the complex breast cancer tumor microenvironment, and the persistence of engineered T-cells. We discuss the advances in overcoming these barriers, including strategies to enhance T-cell efficacy. Finally, our comprehensive analysis of the current clinical trials in this area provides insights into the future possibilities and directions of E-ACTs in breast cancer treatment.

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.

Oncofetal protein glypican-3 is a biomarker and critical regulator of function for neuroendocrine cells in prostate cancer

Neuroendocrine (NE) cells comprise ~1% of epithelial cells in benign prostate and prostatic adenocarcinoma (PCa). However, they become enriched in hormonally treated and castration-resistant PCa (CRPC). In addition, close to 20% of hormonally treated tumors recur as small cell NE carcinoma (SCNC), composed entirely of NE cells, which may be the result of clonal expansion or lineage plasticity. Since NE cells do not express androgen receptors (ARs), they are resistant to hormonal therapy and contribute to therapy failure. Here, we describe the identification of glypican-3 (GPC3) as an oncofetal cell surface protein specific to NE cells in prostate cancer. Functional studies revealed that GPC3 is critical to the viability of NE tumor cells and tumors displaying NE differentiation and that it regulates calcium homeostasis and signaling. Since our results demonstrate that GPC3 is specifically expressed by NE cells, patients with confirmed SCNC may qualify for GPC3-targeted therapy which has been developed in the context of liver cancer and displays minimal toxicity due to its tumor-specific expression. © 2023 The Pathological Society of Great Britain and Ireland.

IL-7 and IL-7R in health and disease: An update through COVID times

The role of IL-7 and IL-7R for normal lymphoid development and an adequately functioning immune system has been recognized for long, with severe immune deficiency and lymphoid leukemia as extreme examples of the consequences of deregulation of the IL-7-IL-7R axis. In this review, we provide an update (focusing on the past couple of years) on IL-7 and IL-7R in health and disease. We highlight the findings on IL-7/IL-7R signaling mechanisms and the, sometimes controversial, impact of IL-7 and its receptor on leukocyte biology, COVID-19, acute lymphoblastic leukemia, and different solid tumors, as well as their relevance as therapeutic tools or targets.

Migratory Engineering of T Cells for Cancer Therapy

Adoptive cell therapy (ACT) and chimeric antigen receptor (CAR) T cell therapy in particular represents an adaptive, yet versatile strategy for cancer treatment. Convincing results in the treatment of hematological malignancies have led to FDA approval for several CAR T cell therapies in defined refractory diseases. In contrast, the treatment of solid tumors with adoptively transferred T cells has not demonstrated convincing efficacy in clinical trials. One of the main reasons for ACT failure in solid tumors is poor trafficking or access of transferred T cells to the tumor site. Tumors employ a variety of mechanisms shielding themselves from immune cell infiltrates, often translating to only fractions of transferred T cells reaching the tumor site. To overcome this bottleneck, extensive efforts are being undertaken at engineering T cells to improve ACT access to solid tumors. In this review, we provide an overview of the immune cell infiltrate in human tumors and the mechanisms tumors employ toward immune exclusion. We will discuss ways in which T cells can be engineered to circumvent these barriers. We give an outlook on ongoing clinical trials targeting immune cell migration to improve ACT and its perspective in solid tumors.

Long term complete response of advanced hepatocellular carcinoma to glypican-3 specific chimeric antigen receptor T-Cells plus sorafenib, a case report

The clinical efficacy of current therapies for Hepatocellular carcinoma (HCC) are unsatisfactory. In recent years, chimeric antigen receptor (CAR) T-cell therapies have been developed for solid tumors including advanced HCC (aHCC), but limited progress has been made. Glypican-3 is a promising immunotherapeutic target for HCC since it is specifically highly expressed in HCC. A previous study indicated that GPC3-targeted CAR T-(CAR-GPC3) cells were well-tolerated and had prolonged survival for HCC patients and that Sorafenib could increase the antitumor activities of CAR-GPC3 T-cells against HCC in mouse models. Here, we report a patient with aHCC who achieved a complete response (CR) and a long survival period after the combination therapy of CAR-GPC3 T-cell plus sorafenib.

A 60-year-old Asian male diagnosed with hepatitis B virus (HBV) related HCC developed liver recurrence and lung metastasis after liver tumor resection and trans-arterial chemoembolization therapy. The patient also previously received microwave ablation therapy for lung metastasis. After the enrollment, the patient underwent leukapheresis for CAR-GPC3 T-cells manufacturing. Seven days after leukapheresis, the patient started to receive 400 mg of Sorafenib twice daily. The patient received 4 cycles of CAR-GPC3 T cells (CT011) treatment and each cycle was divided into two infusions. Prior to each cycle of CT011 treatment, lymphodepletion was performed. The lymphodepletion regimen was cyclophosphamide 500 mg/m2/day for 2 to 3 days, and fludarabine 20-25 mg/m2/day for 3 to 4 days. A total of 4×109 CAR-GPC3 T cells were infused. The CT011 plus Sorafenib combination therapy was well tolerated. All the ≥ grade 3 AEs were hematological toxicities which were deemed an expected event caused by the preconditioning regimen. This patient obtained partial responses from the 3rd month and achieved CR in the 12th month after the first cycle of CT011 infusion according to the RECIST1.1 assessment. The tumor had no progression for more than 36 months and maintained the CR status for more than 24 months after the first infusion.

CAR-T Cells in the Treatment of Urologic Neoplasms: Present and Future

In recent years, with the breakthrough of CAR-T cells in the treatment of hematological tumors, they are increasingly being used to treat solid tumors, including urologic neoplasms. There are many relatively specific targets for urologic neoplasms, especially prostate cancer. Besides, urologic neoplasms tend to progress more slowly than tumors in other organs of the body, providing ample time for CAR-T cell application. Therefore, CAR-T cells technology has inherent advantages in urologic neoplasms. CAR-T cells in the treatment of urologic neoplasms have been extensively studied and preliminary achievements have been made. However, no breakthrough has been made due to the problems of targeting extra-tumor cytotoxicity and poor anti-tumor activity. we systematacially summarized the research actuality of CAR-T cells in urologic neoplasms, discussed the potential value and difficulties of the research. The application of CAR-T cells in the treatment of urologic neoplasms requires improvement of function through screening for better targets, modification of CAR structures, or in combination with other antitumor approaches.

Modulating tumor physical microenvironment for fueling CAR-T cell therapy

Chimeric antigen receptor (CAR) T cell therapy has achieved unprecedented clinical success against hematologic malignancies. However, the transition of CAR-T cell therapies for solid tumors is limited by heterogenous antigen expression, immunosuppressive microenvironment (TME), immune adaptation of tumor cells and impeded CAR-T-cell infiltration/transportation. Recent studies increasingly reveal that tumor physical microenvironment could affect various aspects of tumor biology and impose profound impacts on the antitumor efficacy of CAR-T therapy. In this review, we discuss the critical roles of four physical cues in solid tumors for regulating the immune responses of CAR-T cells, which include solid stress, interstitial fluid pressure, stiffness and microarchitecture. We highlight new strategies exploiting these features to enhance the therapeutic potency of CAR-T cells in solid tumors by correlating with the state-of-the-art technologies in this field. A perspective on the future directions for developing new CAR-T therapies for solid tumor treatment is also provided.

Emerging Strategies in TCR-Engineered T Cells

Immunotherapy of cancer has made tremendous progress in recent years, as demonstrated by the remarkable clinical responses obtained from adoptive cell transfer (ACT) of patient-derived tumor infiltrating lymphocytes, chimeric antigen receptor (CAR)-modified T cells (CAR-T) and T cell receptor (TCR)-engineered T cells (TCR-T). TCR-T uses specific TCRS optimized for tumor engagement and can recognize epitopes derived from both cell-surface and intracellular targets, including tumor-associated antigens, cancer germline antigens, viral oncoproteins, and tumor-specific neoantigens (neoAgs) that are largely sequestered in the cytoplasm and nucleus of tumor cells. Moreover, as TCRS are naturally developed for sensitive antigen detection, they are able to recognize epitopes at far lower concentrations than required for CAR-T activation. Therefore, TCR-T holds great promise for the treatment of human cancers. In this focused review, we summarize basic, translational, and clinical insights into the challenges and opportunities of TCR-T. We review emerging strategies used in current ACT, point out limitations, and propose possible solutions. We highlight the importance of targeting tumor-specific neoAgs and outline a strategy of combining neoAg vaccines, checkpoint blockade therapy, and adoptive transfer of neoAg-specific TCR-T to produce a truly tumor-specific therapy, which is able to penetrate into solid tumors and resist the immunosuppressive tumor microenvironment. We believe such a combination approach should lead to a significant improvement in cancer immunotherapies, especially for solid tumors, and may provide a general strategy for the eradication of multiple cancers.

Glypican-3: A Novel and Promising Target for the Treatment of Hepatocellular Carcinoma

Glypican-3 (GPC3) is a membrane-associated proteoglycan that is specifically up-regulated in hepatocellular carcinoma (HCC) although rarely or not expressed in normal liver tissues, making it a perfect diagnostic and treatment target for HCC. Several GPC3-based clinical trials are ongoing and recently several innovative GPC3-targeted therapeutic methods have emerged with exciting results, including GPC3 vaccine, anti-GPC3 immunotoxin, combined therapy with immune checkpoint blockades (ICBs), and chimeric antigen receptor (CAR) T or NK cells. Here, we review the value of GPC3 in the diagnosis and prognosis of HCC, together with its signaling pathways, with a specific focus on GPC3-targeted treatments of HCC and some prospects for the future GPC3-based therapeutic strategies in HCC.

Advances in CAR-T Cell Genetic Engineering Strategies to Overcome Hurdles in Solid Tumors Treatment

During this last decade, adoptive transfer of T lymphocytes genetically modified to express chimeric antigen receptors (CARs) emerged as a valuable therapeutic strategy in hematological cancers. However, this immunotherapy has demonstrated limited efficacy in solid tumors. The main obstacle encountered by CAR-T cells in solid malignancies is the immunosuppressive tumor microenvironment (TME). The TME impedes tumor trafficking and penetration of T lymphocytes and installs an immunosuppressive milieu by producing suppressive soluble factors and by overexpressing negative immune checkpoints. In order to overcome these hurdles, new CAR-T cells engineering strategies were designed, to potentiate tumor recognition and infiltration and anti-cancer activity in the hostile TME. In this review, we provide an overview of the major mechanisms used by tumor cells to evade immune defenses and we critically expose the most optimistic engineering strategies to make CAR-T cell therapy a solid option for solid tumors.

Gene-Edited Interleukin CAR-T Cells Therapy in the Treatment of Malignancies: Present and Future

In recent years, chimeric antigen receptor T cells (CAR-T cells) have been faced with the problems of weak proliferation and poor persistence in the treatment of some malignancies. Researchers have been trying to perfect the function of CAR-T by genetically modifying its structure. In addition to the participation of T cell receptor (TCR) and costimulatory signals, immune cytokines also exert a decisive role in the activation and proliferation of T cells. Therefore, genetic engineering strategies were used to generate cytokines to enhance tumor killing function of CAR-T cells. When CAR-T cells are in contact with target tumor tissue, the proliferation ability and persistence of T cells can be improved by structurally or inductively releasing immunoregulatory molecules to the tumor region. There are a large number of CAR-T cells studies on gene-edited cytokines, and the most common cytokines involved are interleukins (IL-7, IL-12, IL-15, IL-18, IL-21, IL-23). Methods for the construction of gene-edited interleukin CAR-T cells include co-expression of single interleukin, two interleukin, interleukin combined with other cytokines, interleukin receptors, interleukin subunits, and fusion inverted cytokine receptors (ICR). Preclinical and clinical trials have yielded positive results, and many more are under way. By reading a large number of literatures, we summarized the functional characteristics of some members of the interleukin family related to tumor immunotherapy, and described the research status of gene-edited interleukin CAR-T cells in the treatment of malignant tumors. The objective is to explore the optimized strategy of gene edited interleukin-CAR-T cell function.

Human Hyaluronidase PH20 Potentiates the Antitumor Activities of Mesothelin-Specific CAR-T Cells Against Gastric Cancer

T cell infiltration into tumors is essential for successful immunotherapy against solid tumors. Herein, we found that the expression of hyaluronic acid synthases (HAS) was negatively correlated with patient survival in multiple types of solid tumors including gastric cancer. HA impeded in vitro anti-tumor activities of anti-mesothelin (MSLN) chimeric antigen receptor T cells (CAR-T cells) against gastric cancer cells by restricting CAR-T cell mobility in vitro. We then constructed a secreted form of the human hyaluronidase PH20 (termed sPH20-IgG2) by replacing the PH20 signal peptide with a tPA signal peptide and attached with IgG2 Fc fragments. We found that overexpression of sPH20-IgG2 promoted CAR-T cell transmigration through an HA-containing matrix but did not affect the cytotoxicity or cytokine secretion of the CAR-T cells. In BGC823 and MKN28 gastric cancer cell xenografts, sPH20-IgG2 promoted anti-mesothelin CAR-T cell infiltration into tumors. Furthermore, mice infused with sPH20-IgG2 overexpressing anti-MSLN CAR-T cells had smaller tumors than mice injected with anti-MSLN CAR-T cells. Thus, we demonstrated that sPH20-IgG2 can enhance the antitumor activity of CAR-T cells against solid tumors by promoting CAR-T cell infiltration.