TCR gene-engineered cell therapy for solid tumors

CRISPR-Cas9 potential for identifying novel therapeutic targets in muscle-invasive bladder cancer

Gene editing technologies help identify the genetic perturbations driving tumour initiation, growth, metastasis and resistance to therapeutics. This wealth of information highlights tumour complexity and is driving cancer research towards precision medicine approaches based on an individual's tumour genetics. Bladder cancer is the 11th most common cancer in the UK, with high rates of relapse and low survival rates in patients with muscle-invasive bladder cancer (MIBC). MIBC is highly heterogeneous and encompasses multiple molecular subtypes, each with different responses to therapeutics. This evidence highlights the need to identify innovative therapeutic targets to address the challenges posed by this heterogeneity. CRISPR-Cas9 technologies have been used to advance our understanding of MIBC and determine novel drug targets through the identification of drug resistance mechanisms, targetable cell-cycle regulators, and novel tumour suppressor and oncogenes. However, the use of these technologies in the clinic remains a substantial challenge and will require careful consideration of dosage, safety and ethics. CRISPR-Cas9 offers considerable potential for revolutionizing bladder cancer therapies, but substantial research is required for validation before these technologies can be used in the clinical setting.

EBV promotes TCR-T-cell therapy resistance by inducing CD163+M2 macrophage polarization and MMP9 secretion

BACKGROUND

Epstein-Barr virus (EBV) is a double-stranded DNA oncogenic virus. Several types of solid tumors, such as nasopharyngeal carcinoma, EBV-associated gastric carcinoma, and lymphoepithelioma-like carcinoma of the lung, have been linked to EBV infection. Currently, several TCR-T-cell therapies for EBV-associated tumors are in clinical trials, but due to the suppressive immune microenvironment of solid tumors, the clinical application of TCR-T-cell therapy for EBV-associated solid tumors is limited. Figuring out the mechanism by which EBV participates in the formation of the tumor immunosuppressive microenvironment will help T cells or TCR-T cells break through the limitation and exert stronger antitumor potential.

METHODS

Flow cytometry was used for analyzing macrophage differentiation phenotypes induced by EBV-infected and EBV-uninfected tumors, as well as the function of T cells co-cultured with these macrophages. Xenograft model in mice was used to explore the effects of M2 macrophages, TCR-T cells, and matrix metalloprotein 9 (MMP9) inhibitors on the growth of EBV-infected tumors.

RESULTS

EBV-positive tumors exhibited an exhaustion profile of T cells, despite the presence of a large T-cell infiltration. EBV-infected tumors recruited a large number of mononuclear macrophages with CCL5 and induced CD163+M2 macrophages polarization through the secretion of CSF1 and the promotion of autocrine IL10 production by mononuclear macrophages. Massive secretion of MMP9 by this group of CD163+M2 macrophages induced by EBV infection was an important factor contributing to T-cell exhaustion and TCR-T-cell therapy resistance in EBV-positive tumors, and the use of MMP9 inhibitors improved the function of T cells cocultured with M2 macrophages. Finally, the combination of an MMP9 inhibitor with TCR-T cells targeting EBV-positive tumors significantly inhibited the growth of xenografts in mice.

CONCLUSIONS

MMP9 inhibitors improve TCR-T cell function suppressed by EBV-induced M2 macrophages. TCR-T-cell therapy combined with MMP9 inhibitors was an effective therapeutic strategy for EBV-positive solid tumors.

Structure-Based Rational and General Strategy for Stabilizing Single-Chain T-Cell Receptors to Enhance Affinity

The T-cell receptor (TCR) is a crucial molecule in cellular immunity. The single-chain T-cell receptor (scTCR) is a potential format in TCR therapeutics because it eliminates the possibility of αβ-TCR mispairing. However, its poor stability and solubility impede the in vitro study and manufacturing of therapeutic applications. In this study, some conserved structural motifs are identified in variable domains regardless of germlines and species. Theoretical analysis helps to identify those unfavored factors and leads to a general strategy for stabilizing scTCRs by substituting residues at exact IMGT positions with beneficial propensities on the consensus sequence of germlines. Several representative scTCRs are displayed to achieve stability optimization and retain comparable binding affinities with the corresponding αβ-TCRs in the range of μM to pM. These results demonstrate that our strategies for scTCR engineering are capable of providing the affinity-enhanced and specificity-retained format, which are of great value in facilitating the development of TCR-related therapeutics.

Development of T cell receptor-engineered T cells targeting the sarcoma-associated antigen papillomavirus binding factor

We previously identified papillomavirus binding factor (PBF) as an osteosarcoma antigen recognized by an autologous cytotoxic T lymphocyte clone. Vaccination with PBF-derived peptide presented by HLA-A24 (PBF peptide) elicited strong immune responses. In the present study, we generated T cell receptor-engineered T cells (TCR-T cells) directed against the PBF peptide (PBF TCR-T cells). PBF TCR was successfully transduced into T cells and detected using HLA-A*24:02/PBF peptide tetramer. PBF TCR-T cells generated from a healthy donor were highly expanded and recognized T2-A24 cells pulsed with PBF peptide, HLA-A24+ 293T cells transfected with PBF cDNA, and sarcoma cell lines. To establish an adoptive cell therapy model, we modified the PBF TCR by replacing both α and β constant regions with those of mice (hybrid PBF TCR). Hybrid PBF TCR-T cells also showed reactivity against T2-A24 cells pulsed with PBF peptide and to HLA-A24+ 293T cells transfected with various lengths of PBF cDNA including the PBF peptide sequence. Subsequently, we generated target cell lines highly expressing PBF (MFH03-PBF [short] epitope [+]) containing PBF peptide with in vivo tumorigenicity. Hybrid PBF TCR-T cells exhibited antitumor effects compared with mock T cells in NSG mice xenografted with MFH03-PBF (short) epitope (+) cells. CD45+ T cells significantly infiltrated xenografted tumors only in the hybrid PBF TCR T cell group and most of these cells were CD8-positive. CD8+ T cells also showed Ki-67 expression and surrounded the CD8-negative tumor cells expressing Ki-67. These findings suggest that PBF TCR-T cell therapy might be a candidate immunotherapy for sarcoma highly expressing PBF.

Vector-Mediated Delivery of Human Major Histocompatibility Complex-I into Hepatocytes Enables Investigation of T Cell Receptor-Redirected Hepatitis B Virus-Specific T Cells in Mice, and in Macaque Cell Cultures

Adoptive T cell therapy using natural T cell receptor (TCR) redirection is a promising approach to fight solid cancers and viral infections in liver and other organs. However, clinical efficacy of such TCR+-T cells has been limited so far. One reason is that syngeneic preclinical models to evaluate safety and efficacy of TCR+-T cells are missing. We, therefore, developed an efficient viral vector strategy mediating expression of human major histocompatibility complex (MHC)-I in hepatocytes, which allows evaluation of TCR-T cell therapies targeting diseased liver cells. We designed adeno-associated virus (AAV) and adenoviral vectors encoding either the human-mouse chimeric HLA-A*02-like molecule, or fully human HLA-A*02 and human β2 microglobulin (hβ2m). Upon transduction of murine hepatocytes, the HLA-A*02 construct proved superior in terms of expression levels, presentation of endogenously processed peptides and activation of murine TCR+-T cells grafted with HLA-A*02-restricted, hepatitis B virus (HBV)-specific TCRs. In vivo, these T cells elicited effector function, controlled HBV replication, and reduced HBV viral load and antigen expression in livers of those mice that had received AAV-HBV and AAV-HLA-A*02. We then demonstrated the broad utility of this approach by grafting macaque T cells with the HBV-specific TCRs and enabling them to recognize HBV-infected primary macaque hepatocytes expressing HLA-A*02 upon adenoviral transduction. In conclusion, AAV and adenovirus vectors are suitable for delivery of HLA-A*02 and hβ2m into mouse and macaque hepatocytes. When recognizing their cognate antigen in HLA-A*02-transduced mouse livers or on isolated macaque hepatocytes, HLA-A*02-restricted, HBV-specific TCR+-T cells become activated and exert antiviral effector functions. This approach is applicable to any MHC restriction and target disease, paving the way for safety and efficacy studies of human TCR-based therapies in physiologically relevant preclinical animal models.

Cancer chemotherapy and beyond: Current status, drug candidates, associated risks and progress in targeted therapeutics

Cancer is an abnormal state of cells where they undergo uncontrolled proliferation and produce aggressive malignancies that causes millions of deaths every year. With the new understanding of the molecular mechanism(s) of disease progression, our knowledge about the disease is snowballing, leading to the evolution of many new therapeutic regimes and their successive trials. In the past few decades, various combinations of therapies have been proposed and are presently employed in the treatment of diverse cancers. Targeted drug therapy, immunotherapy, and personalized medicines are now largely being employed, which were not common a few years back. The field of cancer discoveries and therapeutics are evolving fast as cancer type-specific biomarkers are progressively being identified and several types of cancers are nowadays undergoing systematic therapies, extending patients' disease-free survival thereafter. Although growing evidence shows that a systematic and targeted approach could be the future of cancer medicine, chemotherapy remains a largely opted therapeutic option despite its known side effects on the patient's physical and psychological health. Chemotherapeutic agents/pharmaceuticals served a great purpose over the past few decades and have remained the frontline choice for advanced-stage malignancies where surgery and/or radiation therapy cannot be prescribed due to specific reasons. The present report succinctly reviews the existing and contemporary advancements in chemotherapy and assesses the status of the enrolled drugs/pharmaceuticals; it also comprehensively discusses the emerging role of specific/targeted therapeutic strategies that are presently being employed to achieve better clinical success/survival rate in cancer patients.

Lung cancer immunotherapy: progress, pitfalls, and promises

Lung cancer is the primary cause of mortality in the United States and around the globe. Therapeutic options for lung cancer treatment include surgery, radiation therapy, chemotherapy, and targeted drug therapy. Medical management is often associated with the development of treatment resistance leading to relapse. Immunotherapy is profoundly altering the approach to cancer treatment owing to its tolerable safety profile, sustained therapeutic response due to immunological memory generation, and effectiveness across a broad patient population. Different tumor-specific vaccination strategies are gaining ground in the treatment of lung cancer. Recent advances in adoptive cell therapy (CAR T, TCR, TIL), the associated clinical trials on lung cancer, and associated hurdles are discussed in this review. Recent trials on lung cancer patients (without a targetable oncogenic driver alteration) reveal significant and sustained responses when treated with programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) checkpoint blockade immunotherapies. Accumulating evidence indicates that a loss of effective anti-tumor immunity is associated with lung tumor evolution. Therapeutic cancer vaccines combined with immune checkpoint inhibitors (ICI) can achieve better therapeutic effects. To this end, the present article encompasses a detailed overview of the recent developments in the immunotherapeutic landscape in targeting small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Additionally, the review also explores the implication of nanomedicine in lung cancer immunotherapy as well as the combinatorial application of traditional therapy along with immunotherapy regimens. Finally, ongoing clinical trials, significant obstacles, and the future outlook of this treatment strategy are also highlighted to boost further research in the field.

Current Best Practice in Hepatitis B Management and Understanding Long-term Prospects for Cure

The hepatitis B virus (HBV) is a major cause of cirrhosis and hepatocellular carcinoma worldwide. Despite an effective vaccine, the prevalence of chronic infection remains high. Current therapy is effective at achieving on-treatment, but not off-treatment, viral suppression. Loss of hepatitis B surface antigen, the best surrogate marker of off-treatment viral suppression, is associated with improved clinical outcomes. Unfortunately, this end point is rarely achieved with current therapy because of their lack of effect on covalently closed circular DNA, the template of viral transcription and genome replication. Major advancements in our understanding of HBV virology along with better understanding of immunopathogenesis have led to the development of a multitude of novel therapeutic approaches with the prospect of achieving functional cure (hepatitis B surface antigen loss) and perhaps complete cure (clearance of covalently closed circular DNA and integrated HBV DNA). This review will cover current best practice for managing chronic HBV infection and emerging novel therapies for HBV infection and their prospect for cure.

Current and emerging immunotherapeutic approaches for biliary tract cancers

BACKGROUND

Biliary tract cancers (BTCs) comprise a heterogeneous group of aggressive malignancies with unfavorable prognoses. The benefit of chemotherapy seems to have reached a bottleneck and, therefore, new effective therapeutic strategies for advanced BTCs are needed. Molecularly targeted therapies in selected patients are rapidly changing the situation. However, the low frequency of specific driver alterations in BTCs limits their wide application. Recently, immunotherapeutic approaches are also under active investigation in BTCs, but the role of immunotherapy in BTCs remains controversial.

DATA SOURCES

PubMed, Web of Science, and meeting resources were searched for relevant articles published from January 2017 to May 2022. The search aimed to identify current and emerging immunotherapeutic approaches for BTCs. Information on clinical trials was obtained from https://clinicaltrials.gov/ and http://www.chictr.org.cn/.

RESULTS

Immunotherapy in BTC patients is currently under investigation, and most of the investigations focused on the application of immune checkpoint inhibitors (ICIs). However, only a subgroup of BTCs with microsatellite-instability high (MSI-H)/DNA mismatch repair-deficient (dMMR) or tumor mutational burden-high (TMB-H) benefit from monotherapy of ICIs, and limited activity was observed in the second or subsequent settings. Nevertheless, promising results come from studies of ICIs in combination with other therapeutic approaches, including chemotherapy, in advanced BTCs, with a moderate toxicity profile. Recent studies demonstrated that compared to GEMCIS alone, durvalumab plus GEMCIS significantly improved patient survival (TOPAZ-1 trial) and that ICIs-combined chemoimmunotherapy is poised to become a new frontline therapy option, regardless of TMB and MMR/MSI status. Adoptive cell therapy and peptide- or dendritic-based cancer vaccines are other immunotherapeutic options that are being studied in BTCs. Numerous biomarkers have been investigated to define their predictive role in response to ICIs, but no predictive biomarker has been validated, except MSI-H/dMMR.

CONCLUSIONS

The role of immunotherapy in BTCs is currently under investigation and the results of ongoing studies are eagerly anticipated. Several studies have demonstrated the safety and efficacy of ICIs in combination with chemotherapy in treatment-naive patients, such as the phase III TOPAZ-1 trial, which will change the standard care of first-line chemotherapy for advanced BTCs. However, further research is needed to understand the best combination with immunotherapy and to discover more predictive biomarkers to guide clinical practice.

Novel cellular therapies for hepatobiliary malignancies

BACKGROUND

The mortalities of hepatobiliary malignancies are high. With the failure of conventional chemotherapy and unsatisfactory outcome of molecular targeted drugs, immune-based therapy has become a new focus of research in hepatobiliary cancers treatment.

DATA SOURCES

We performed a PubMed search with relevant articles published up to May 2022 and the following keywords: cellular immunotherapy, hepatobiliary cancer, antigen receptor T cell therapy, and receptor-engineered T cell. Information of clinical trials was obtained from https://clinicaltrials.gov/.

RESULTS

Cell therapies for hepatobiliary malignancies are at early stage of development. The current review showed that cellular therapies are safe and feasible in patients. These findings provide an important platform for future lager scale clinical trials on immunotherapy in patients with hepatobiliary malignancies.

CONCLUSIONS

With the continuous advances of cellular immunotherapy, the combination of cellular immunotherapy with surgery, chemotherapy and radiotherapy will be new therapeutic strategies for patients with hepatobiliary cancer.

T-Cell Receptor Repertoire Sequencing and Its Applications: Focus on Infectious Diseases and Cancer

The immune system is a dynamic feature of each individual and a footprint of our unique internal and external exposures. Indeed, the type and level of exposure to physical and biological agents shape the development and behavior of this complex and diffuse system. Many pathological conditions depend on how our immune system responds or does not respond to a pathogen or a disease or on how the regulation of immunity is altered by the disease itself. T-cells are important players in adaptive immunity and, together with B-cells, define specificity and monitor the internal and external signals that our organism perceives through its specific receptors, TCRs and BCRs, respectively. Today, high-throughput sequencing (HTS) applied to the TCR repertoire has opened a window of opportunity to disclose T-cell repertoire development and behavior down to the clonal level. Although TCR repertoire sequencing is easily accessible today, it is important to deeply understand the available technologies for choosing the best fit for the specific experimental needs and questions. Here, we provide an updated overview of TCR repertoire sequencing strategies, providers and applications to infectious diseases and cancer to guide researchers’ choice through the multitude of available options. The possibility of extending the TCR repertoire to HLA characterization will be of pivotal importance in the near future to understand how specific HLA genes shape T-cell responses in different pathological contexts and will add a level of comprehension that was unthinkable just a few years ago.

TCR engineered T cells for solid tumor immunotherapy

T cell immunotherapy remains an attractive approach for cancer immunotherapy. T cell immunotherapy mainly employs chimeric antigen receptor (CAR)- and T cell receptor (TCR)-engineered T cells. CAR-T cell therapy has been an essential breakthrough in treating hematological malignancies. TCR-T cells can recognize antigens expressed both on cell surfaces and in intracellular compartments. Although TCR-T cells have not been approved for clinical application, a number of clinical trials have been performed, particularly for solid tumors. In this article, we summarized current TCR-T cell advances and their potential advantages for solid tumor immunotherapy.