TCR-transgenic lymphocytes specific for HMMR/Rhamm limit tumor outgrowth in vivo

Immune-dysregulation harnessing in myeloid neoplasms

Myeloid malignancies arise in bone marrow microenvironments and shape these microenvironments in favor of malignant development. Immune suppression is one of the most important stages in myeloid leukemia progression. Leukemic clone expansion and immune dysregulation occur simultaneously in bone marrow microenvironments. Complex interactions emerge between normal immune system elements and leukemic clones in the bone marrow. In recent years, researchers have identified several of these pathological interactions. For instance, recent works shows that the secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), from bone marrow stromal cells contributes to immune dysregulation and the selective proliferation of JAK2V617F+ clones in myeloproliferative neoplasms. Moreover, inflammasome activation and sterile inflammation result in inflamed microenvironments and the development of myelodysplastic syndromes. Additional immune dysregulations, such as exhaustion of T and NK cells, an increase in regulatory T cells, and impairments in antigen presentation are common findings in myeloid malignancies. In this review, we discuss the role of altered bone marrow microenvironments in the induction of immune dysregulations that accompany myeloid malignancies. We also consider both current and novel therapeutic strategies to restore normal immune system function in the context of myeloid malignancies.

HMMR associates with immune infiltrates and acts as a prognostic biomaker in lung adenocarcinoma

BACKGROUND

To explore the expression of hyaluronan mediated motility receptor (HMMR) in lung adenocarcinoma (LUAD) and its relationship with clinicopathological features and tumor-infiltrating is not clear.

METHODS

The expression of HMMR in Cancer Cell Line Encyclopedia (CCLE) and The Cancer Genome Atlas (TCGA)-LUAD. TCGA was employed to examine the relationship between the clinicopathological characteristics and HMMR expression and the LUAD patients' prognosis. Tumor Immune Estimation Resource (TIMER)database was employed to analyze the relationship between immune infiltration and HMMR. Gene Set Enrichment Analysis was explored through gene enrichment. Gene Expression Omnibus (GEO) data and our hospital data were utilized to confirm the findings.

RESULTS

The expression level of HMMR in lung adenocarcinoma tissue and cells was greater than that in the normal group, which was linked to clinical stage, smoking history, and recurrence, and could increase the progression or recurrence of LUAD. Patients in the pathological grade had a significant expression of HMMR in moderately differentiated LUAD tissues. In addition, HMMR has an impact on LUAD patients' overall survival rate [P = 9.5e-06; hazard ratio (HR) = 2]. The level of HMMR expression in LUAD was significantly linked to neutrophils, CD8+T, and CD4+T cells. TMB analysis showed that HMMR could also affect the tumor microenvironment in LUAD. HMMR might be employed as an independent predictive biomarker of LUAD, according to a multivariate COX regression analysis. The findings of GSEA analysis showed that the samples with high HMMR expression levels were rich in cell cycle, cell metabolism, and DNA replication. The analysis results of GSE31210 data are basically consistent with those of TCGA-LUAD.

CONCLUSIONS

It is suggested that HMMR has an effect on the occurrence and development of lung adenocarcinoma. Besides, HMMR is also linked to the level of immune infiltration of neutrophils, CD8+T cells, and CD4+T cells and LUAD patients' prognosis. HMMR was suggested to be utilized as a biomarker or therapeutic target to judge the prognosis and immune infiltration of LUAD.

A Novel Risk Score Model of Lactate Metabolism for Predicting over Survival and Immune Signature in Lung Adenocarcinoma

Simple Summary

Since the discovery of the WarBurg effect, the veil of the tumorigenic role of lactic acid has been gradually revealed. Recently, it was proposed that lactic acid that is produced by tumor cells was secreted into the extracellular space to create immunosuppressive tumor microenvironment (TME) in a variety of ways. However, the intersection genes and the association with immunotherapy are unclear. At present, we identified six lactate-metabolism-associated genes, which were thought to enable tumor progression, that were related to LUAD immunotherapy and we constructed an LAR-score risk model.

Abstract

Background: The role of lactate acid in tumor progression was well proved. Recently, it was found that lactate acid accumulation induced an immunosuppressive microenvironment. However, these results were based on a single gene and it was unclear that lactate acid genes were associated with immunotherapy and able to predict overall survival. Methods: Genes and survival data were acquired from TCGA, GEO and GENECARDS. PCA and TSNE were used to distinguish sample types according to lactate metabolism-associated gene expression. A Wilcox-test examined the expression differences between normal and tumor samples. The distribution in chromatin and mutant levels were displayed by Circo and MAfTools. The lactate metabolism-associated gene were divided into categories by consistent clustering and visualized by Cytoscape. Immune cell infiltration was evaluated by CIBERSORT and LM22 matrix. Enrichment analysis was performed by GSVA. We used the ConsensusClusterPlus package for consistent cluster analysis. A prognostic model was constructed by Univariate Cox regression and Lasso regression analysis. Clinical specimens were detected their expression of genes in model by IHC. Results: Most lactate metabolism-associated gene were significantly differently expressed between normal and tumor samples. There was a strong correlation between the expression of lactate metabolism-associated gene and the abundance of immune cells. We divided them into two clusters (lactate.cluster A,B) with significantly different survival. The two clusters showed a difference in signal, immune cells, immune signatures, chemokines, and clinical features. We identified 162 differential genes from the two clusters, by which the samples were divided into three categories (gene.cluster A,B,C). They also showed a difference in OS and immune infiltration. Finally, a risk score model that was composed of six genes was constructed. There was significant difference in the survival between the high and low risk groups. ROC curves of 1, 3, 5, and 10 years verified the model had good predictive efficiency. Gene expression were correlated with ORR and PFS in patients who received anti-PD-1/L1. Conclusion: The lactate metabolism-associated genes in LUAD were significantly associated with OS and immune signatures. The risk scoring model that was constructed by us was able to well identify and predict OS and were related with anti-PD-1/L1 therapy outcome.

Antigen-Specific TCR-T Cells for Acute Myeloid Leukemia: State of the Art and Challenges

The cytogenetic abnormalities and molecular mutations involved in acute myeloid leukemia (AML) lead to unique treatment challenges. Although adoptive T-cell therapies (ACT) such as chimeric antigen receptor (CAR) T-cell therapy have shown promising results in the treatment of leukemias, especially B-cell malignancies, the optimal target surface antigen has yet to be discovered for AML. Alternatively, T-cell receptor (TCR)-redirected T cells can target intracellular antigens presented by HLA molecules, allowing the exploration of a broader territory of new therapeutic targets. Immunotherapy using adoptive transfer of WT1 antigen-specific TCR-T cells, for example, has had positive clinical successes in patients with AML. Nevertheless, AML can escape from immune system elimination by producing immunosuppressive factors or releasing several cytokines. This review presents recent advances of antigen-specific TCR-T cells in treating AML and discusses their challenges and future directions in clinical applications.

NcRNA-Mediated High Expression of HMMR as a Prognostic Biomarker Correlated With Cell Proliferation and Cell Migration in Lung Adenocarcinoma

Background

Hyaluronan-mediated motility receptor (HMMR) plays a pivotal role in cell proliferation in various cancers, including lung cancer. However, its function and biological mechanism in lung adenocarcinoma (LUAD) remain unclear.

Methods

Data on HMMR expression from several public databases were extensively analyzed, including the prognosis of HMMR in the Gene Expression Profiling Interactive Analysis (GEPIA) database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed using DAVID and gene set enrichment analysis (GSEA) software. The correlation between HMMR expression and immune cell infiltration was analyzed in the Tumor Immune Estimation Resource (TIMER) database, and the gene and protein networks were examined using the GeneMANIA and STRING databases. Experimentally, the expression of HMMR in LUAD and lung cancer cell lines was determined using immunohistochemistry and quantitative RT-PCR assays. Besides, the function of HMMR on cancer cell proliferation and migration was examined using cell growth curve and colony formation, Transwell, and wound healing assays.

Results

In this study, we found that HMMR was elevated in LUAD and that its high expression was associated with poor clinicopathological features and adverse outcomes in LUAD patients. Furthermore, our results demonstrated that the expression of HMMR was positively correlated with immune cell infiltration and immune modulation. Interestingly, diverse immune cell infiltration affects the prognosis of LUAD. In the functional assay, depletion of HMMR significantly repressed the cancer cell growth and migration of LUAD. Mechanically, we found that that the DNA methylation/TMPO-AS1/let-7b-5p axis mediated the high expression of HMMR in LUAD. Depletion of TMPO-AS1 and overexpression of let-7b-5p could result in the decreased expression of HMMR in LUAD cells. Furthermore, we found that TMPO-AS1 was positively correlated with HMMR, yet negatively correlated with let-7b-5p expression in LUAD.

Conclusions

Our findings elucidated that the DNA methylation/TMPO-AS1/let-7b-5p axis mediated the high expression of HMMR, which may be considered as a biomarker to predict prognosis in LUAD.

Comprehensive Bioinformatics Analysis to Identify the Gene HMMR Associated With Lung Adenocarcinoma Prognosis and Its Mechanism of Action in Multiple Cancers

Background

Lung cancer is the third most frequently diagnosed cancer in the world, with lung adenocarcinoma (LUAD) as the most common pathological type. But studies on the predictive effect of a single gene on LUAD are limited. We aimed to discover new predictive markers for LUAD.

Methods

Differentially high-expressed genes at each stage were obtained from the TCGA and GTEx databases. The functions of these genes were investigated through GO enrichment and KEGG pathway analyses. Then, the key genes were selected by applying whole gene overall survival time. The expression of the key gene was studied in LUAD, and survival analysis was performed using Kaplan-Meier mapper, followed by univariate and multifactorial COX analysis. Finally, the gene expression and its prognostic significance in the pan-cancer were examined.

Results

A total of 10,106 DEGs were obtained from the two datasets. The top 266 differentially upregulated genes intersected with the top 1,497 overall survival-related genes, and 87 key genes were identified. High-expressed HMMR was associated with a poor prognosis of LUAD. Univariate and multifactorial Cox analysis showed that HMMR was an independent prognostic factor for LUAD patients. A high HMMR expression was strongly associated with the overall survival (OS) and disease-specific survival (DSS) in 11 cancer types and with poorer OS, DSS, and PFI in 10 cancer types.

Conclusion

HMMR may be an independent prognostic indicator and an important biomarker in diagnosing and predicting the survival of LUAD patients. Also, HMMR may be a key predictor of a variety of cancers.

Trial Watch: Adoptive TCR-Engineered T-Cell Immunotherapy for Acute Myeloid Leukemia

Simple Summary

Acute myeloid leukemia (AML) is a type of blood cancer with an extremely grim prognosis. This is due to the fact that the majority of patients will relapse after frontline treatment. Overall survival of relapsed AML is very low, and treatment options are few. T lymphocytes harnessed with antitumor T-cell receptors (TCRs) can produce objective clinical responses in certain cancers, such as melanoma, but have not entered the main road for AML. In this review, we describe the current status of the field of TCR-T-cell therapies for AML.

Abstract

Despite the advent of novel therapies, acute myeloid leukemia (AML) remains associated with a grim prognosis. This is exemplified by 5-year overall survival rates not exceeding 30%. Even with frontline high-intensity chemotherapy regimens and allogeneic hematopoietic stem cell transplantation, the majority of patients with AML will relapse. For these patients, treatment options are few, and novel therapies are urgently needed. Adoptive T-cell therapies represent an attractive therapeutic avenue due to the intrinsic ability of T lymphocytes to recognize tumor cells with high specificity and efficiency. In particular, T-cell therapies focused on introducing T-cell receptors (TCRs) against tumor antigens have achieved objective clinical responses in solid tumors such as synovial sarcoma and melanoma. However, contrary to chimeric antigen receptor (CAR)-T cells with groundbreaking results in B-cell malignancies, the use of TCR-T cells for hematological malignancies is still in its infancy. In this review, we provide an overview of the status and clinical advances in adoptive TCR-T-cell therapy for the treatment of AML.

Vaccine and Cell-based Therapeutic Approaches in Acute Myeloid Leukemia

Over the past decade, our increased understanding of the interactions between the immune system and cancer cells has led to paradigm shifts in the clinical management of solid and hematologic malignancies. The incorporation of immune-targeted strategies into the treatment landscape of acute myeloid leukemia (AML), however, has been challenging. While this is in part due to the inability of the immune system to mount an effective tumor-specific immunogenic response against the heterogeneous nature of AML, the decreased immunogenicity of AML cells also represents a major obstacle in the effort to design effective immunotherapeutic strategies. In fact, AML cells have been shown to employ sophisticated escape mechanisms to evade elimination, such as direct immunosuppression of natural killer cells and decreased surface receptor expression leading to impaired recognition by the immune system. Yet, cellular and humoral immune reactions against tumor-associated antigens (TAA) of acute leukemia cells have been reported and the success of allogeneic stem cell transplantation and monoclonal antibodies in the treatment of AML clearly provides proof that an immunotherapeutic approach is feasible in the management of this disease. This review discusses the recent progress and persisting challenges in cellular immunotherapy for patients with AML.

Immunotherapy in AML: a brief review on emerging strategies

Acute myeloid leukemia (AML), the most common form of leukemia amongst adults, is one of the most important hematological malignancies. Epidemiological data show both high incidence rates and low survival rates, especially in secondary cases among adults. Although classic and novel chemotherapeutic approaches have extensively improved disease prognosis and survival, the need for more personalized and target-specific methods with less side effects have been inevitable. Therefore, immunotherapeutic methods are of importance. In the following review, primarily a brief understanding of the molecular basis of the disease has been represented. Second, prior to the introduction of immunotherapeutic approaches, the entangled relationship of AML and patient's immune system has been discussed. At last, mechanistic and clinical evidence of each of the immunotherapy approaches have been covered.

ceRNA network development and tumor-infiltrating immune cell analysis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the primary causes of cancer deaths globally. Despite efforts to understand liver cancer, its high morbidity and mortality remain high. Herein, we constructed two nomograms based on competing endogenous RNA (ceRNA) networks and invading immune cells to describe the molecular mechanisms along with the clinical prognosis of HCC patients. RNA maps of tumors and normal samples were downloaded from The Cancer Genome Atlas database. HTseq counts and fragments per megapons per thousand bases were read from 421 samples, including 371 tumor samples and 50 normal samples. We established a ceRNA network based on differential gene expression in normal versus tumor subjects. CIBERSORT was employed to differentiate 22 immune cell types according to tumor transcriptomes. Kaplan-Meier along with Cox proportional hazard analyses were employed to determine the prognosis-linked factors. Nomograms were constructed based on prognostic immune cells and ceRNAs. We employed Receiver operating characteristic (ROC) and calibration curve analyses to estimate these nomogram. The difference analysis found 2028 messenger RNAs (mRNAs), 128 micro RNAs (miRNAs), and 136 long non-coding RNAs (lncRNAs) to be significantly differentially expressed in tumor samples relative to normal samples. We set up a ceRNA network containing 21 protein-coding mRNAs, 12 miRNAs, and 3 lncRNAs. In Kaplan-Meier analysis, 21 of the 36 ceRNAs were considered significant. Of the 22 cell types, resting dendritic cell levels were markedly different in tumor samples versus normal controls. Calibration and ROC curve analysis of the ceRNA network, as well as immune infiltration of tumor showed restful accuracy (3-year survival area under curve (AUC): 0.691, 5-year survival AUC: 0.700; 3-year survival AUC: 0.674, 5-year survival AUC: 0.694). Our data suggest that Tregs, CD4 T cells, mast cells, SNHG1, HMMR and hsa-miR-421 are associated with HCC based on ceRNA immune cells co-expression patterns. On the basis of ceRNA network modeling and immune cell infiltration analysis, our study offers an effective bioinformatics strategy for studying HCC molecular mechanisms and prognosis.

High Expression of Hyaluronan-Mediated Motility Receptor Predicts Adverse Outcomes: A Potential Therapeutic Target for Head and Neck Squamous Cell Carcinoma

Background: Several studies have shown that the hyaluronan-mediated motility receptor (HMMR) is overexpressed in various cancers and could be a potential prognostic factor. However, further research is still required to determine the prognostic value and potential function of HMMR in head and neck squamous cell carcinoma (HNSCC).

Materials and Methods: Transcriptomic expression data were collected from the Cancer Genome Atlas database (TCGA) and Gene Expression Omnibus and the differences in HMMR expression between normal and tumor tissues were analyzed. The correlation between the methylation level of HMMR and its mRNA expression was analyzed via cBioPortal. Additionally, the data obtained from TCGA was analyzed with MethSurv to determine the prognostic value of the HMMR methylation levels in HNSCC. Gene set enrichment analysis (GSEA) and single sample GSEA (ssGSEA) were used to explore the potential biological functions of HMMR.

Results: HMMR was highly expressed in HNSCC tumor tissue compared to normal tissue (p < 0.001). Multivariate analysis (MAV) showed that high HMMR mRNA expression was an independent prognostic factor of overall survival (OS) in TCGA (HR = 1.628, 95% CI: 1.169–2.266, p = 0.004) and GSE41613 data (HR = 2.238, p = 0.013). The methylation level of HMMR negatively correlated with the HMMR expression (R = −0.12, p < 0.001), and patients with low HMMR methylation had worse OS than patients with high methylation (p < 0.001). GSEA found that HMMR expression was associated with the KARS, EMT, and G2M checkpoint pathways, as well as the interferon-gamma and interferon-alpha responses, whereas ssGSEA showed that HMMR expression positively correlated with the infiltration level of Th2 cells. MAV confirmed that high HMMR protein expression was an inferior independent factor for OS (HR = 2.288, p = 0.045) and progression-free survival (HR = 2.247, p = 0.038) in 70 HNSCC.

Conclusions: This study demonstrated that the upregulation of HMMR mRNA and protein in HNSCC is a biomarker for poor prognosis. The biological functions of HMMR are potentially related to the KARS, EMT, and G2M checkpoint pathways, as well as the interferon-gamma and interferon-alpha responses. These findings help to elucidate the role of HMMR in carcinogenesis and lay a foundation for further study.

Development of a CD8 co-receptor independent T-cell receptor specific for tumor-associated antigen MAGE-A4 for next generation T-cell-based immunotherapy

BACKGROUND

The cancer-testis antigen MAGE-A4 is an attractive target for T-cell-based immunotherapy, especially for indications with unmet clinical need like non-small cell lung or triple-negative breast cancer.

METHODS

An unbiased CD137-based sorting approach was first used to identify an immunogenic MAGE-A4-derived epitope (GVYDGREHTV) that was properly processed and presented on human leukocyte antigen (HLA)-A2 molecules encoded by the HLA-A*02:01 allele. To isolate high-avidity T cells via subsequent multimer sorting, an in vitro priming approach using HLA-A2-negative donors was conducted to bypass central tolerance to this self-antigen. Pre-clinical parameters of safety and activity were assessed in a comprehensive set of in vitro and in vivo studies.

RESULTS

A MAGE-A4-reactive, HLA-A2-restricted T-cell receptor (TCR) was isolated from primed T cells of an HLA-A2-negative donor. The respective TCR-T-cell (TCR-T) product bbT485 was demonstrated pre-clinically to have a favorable safety profile and superior in vivo potency compared with TCR-Ts expressing a TCR derived from a tolerized T-cell repertoire to self-antigens. This natural high-avidity TCR was found to be CD8 co-receptor independent, allowing effector functions to be elicited in transgenic CD4+ T helper cells. These CD4+ TCR-Ts supported an anti-tumor response by direct killing of MAGE-A4-positive tumor cells and upregulated hallmarks associated with helper function, such as CD154 expression and release of key cytokines on tumor-specific stimulation.

CONCLUSION

The extensive pre-clinical assessment of safety and in vivo potency of bbT485 provide the basis for its use in TCR-T immunotherapy studies. The ability of this non-mutated high-avidity, co-receptor-independent TCR to activate CD8+ and CD4+ T cells could potentially provide enhanced cellular responses in the clinical setting through the induction of functionally diverse T-cell subsets that goes beyond what is currently tested in the clinic.

Acute Myeloid Leukemia: From Biology to Clinical Practices Through Development and Pre-Clinical Therapeutics

Recent studies have provided several insights into acute myeloid leukemia. Studies based on molecular biology have identified eight functional mutations involved in leukemogenesis, including driver and passenger mutations. Insight into Leukemia stem cells (LSCs) and assessment of cell surface markers have enabled characterization of LSCs from hematopoietic stem and progenitor cells. Clonal evolution has been described as having an effect similar to that of microenvironment alterations. Such biological findings have enabled the development of new targeted drugs, including drug inhibitors and monoclonal antibodies with blockage functions. Some recently approved targeted drugs have resulted in new therapeutic strategies that enhance standard intensive chemotherapy regimens as well as supportive care regimens. Besides the progress made in adoptive immunotherapy, since allogenic hematopoietic stem cell transplantation enabled the development of new T-cell transfer therapies, such as chimeric antigen receptor T-cell and transgenic TCR T-cell engineering, new promising strategies that are investigated.

Oleate acid-stimulated HMMR expression by CEBPα is associated with nonalcoholic steatohepatitis and hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) is a type of nonalcoholic fatty liver disease and has become a major risk factor for hepatocellular carcinoma (HCC). However, the underlying pathophysiological mechanisms are still elusive. Here, we identify hyaluronan-mediated motility receptor (HMMR) as a critical gene associated with NASH/HCC by combination of bioinformatic analysis and functional experiments. Analysis of differentially expressed genes (DEGs) between normal controls and NASH/HCC identified 5 hub genes (HMMR, UBE2T, TYMS, PTTG1 and GINS2). Based on the common DEGs, analyses of univariate and multivariate Cox regression and the area under the curve (AUC) value of the receiver operating characteristic (ROC) indicate that HMMR is the most significant gene associated with NASH/HCC among five hub genes. Oleate acid (OA), one of fatty acids that induce cellular adipogenesis, stimulates HMMR expression via CCAAT/enhancer-binding protein α (CEBPα). CEBPα increases the expression of HMMR through binding to its promoter. HMMR promotes HCC cell proliferation in vitro via activation of G1/S and G2/M checkpoint transitions, concomitant with a marked increase of the positive cell cycle regulators, including cyclin D1, cyclin E, and cyclin B1. Knockdown of HMMR suppresses HCC tumor growth in nude mice. Our study identifies an important role of HMMR in NASH/HCC, and suggests that HMMR may be a useful target for therapy and prognostic prediction of NASH/HCC patients.

Immune escape and immunotherapy of acute myeloid leukemia

In spite of the recent approval of new promising targeted therapies, the clinical outcome of patients with acute myeloid leukemia (AML) remains suboptimal, prompting the search for additional and synergistic therapeutic rationales. It is increasingly evident that the bone marrow immune environment of AML patients is profoundly altered, contributing to the severity of the disease but also providing several windows of opportunity to prompt or rewire a proficient antitumor immune surveillance. In this Review, we present current evidence on immune defects in AML, discuss the challenges with selective targeting of AML cells, and summarize the clinical results and immunologic insights from studies that are testing the latest immunotherapy approaches to specifically target AML cells (antibodies, cellular therapies) or more broadly reactivate antileukemia immunity (vaccines, checkpoint blockade). Given the complex interactions between AML cells and the many components of their environment, it is reasonable to surmise that the future of immunotherapy in AML lies in the rational combination of complementary immunotherapeutic strategies with chemotherapeutics or other oncogenic pathway inhibitors. Identifying reliable biomarkers of response to improve patient selection and avoid toxicities will be critical in this process.

Cellular immunotherapy for acute myeloid leukemia: How specific should it be?

Significant improvements in the survival of patients with hematological cancers following hematopoietic stem cell transplantation provide evidence supporting the potency of immune cell-mediated anti-leukemic effects. Studies focusing on immune cell-based cancer therapies have made significant breakthroughs in the last few years. Adoptive cellular therapy (ACT), and chimeric antigen receptor (CAR) T cell therapy, in particular, has significantly increased the survival of patients with B cell acute lymphoblastic leukemia and aggressive B cell lymphoma. Despite antigen-negative relapses and severe toxicities such as cytokine release syndrome after treatment, CAR-T cell therapies have been approved by the FDA in some conditions. Although a number of studies have tried to achieve similar results for acute myeloid leukemia (AML), clinical outcomes have not been as promising. In this review, we summarize recent and ongoing studies on cellular therapies for AML patients, with a focus on antigen-specific versus -nonspecific approaches.

T cell receptor-engineered T cells for leukemia immunotherapy

At present, refractory and relapse are major issues for leukemia therapy and a major cause of allogeneic hematopoietic stem cell transplant failure. Over the last decade, many studies have demonstrated that adoptive cancer antigen-specific T cell therapy is an effective option for leukemia therapy. Recently, T cell immunotherapy studies have mainly focused on chimeric antigen receptor- and T cell receptor-engineered T cells. Clinical trials involving chimeric antigen receptor-engineered T cells have been a major breakthrough and became a novel therapy for leukemia. As another potential therapy for leukemia, clinical application of TCR-engineered T cells remains in its infancy. This article presents a review of the current status of anti-leukemia immunotherapy using leukemia antigen-specific TCR-engineered T cells.

A Potent Tumor-Reactive p53-Specific Single-Chain TCR without On- or Off-Target Autoimmunity In Vivo

Genetic engineering of T cells with a T cell receptor (TCR) targeting tumor antigen is a promising strategy for cancer immunotherapy. Inefficient expression of the introduced TCR due to TCR mispairing may limit the efficacy and adversely affect the safety of TCR gene therapy. Here, we evaluated the safety and therapeutic efficiency of an optimized single-chain TCR (scTCR) specific for an HLA-A2.1-restricted (non-mutated) p53(264-272) peptide in adoptive T cell transfer (ACT) models using our unique transgenic mice expressing human p53 and HLA-A2.1 that closely mimic the human setting. Specifically, we showed that adoptive transfer of optimized scTCR-redirected T cells does not induce on-target and off-target autoimmunity. Furthermore, ACT resulted in full tumor protection and led to a long-lived effective, antigen-specific memory T cell response in syngeneic and xenograft models. Taken together, the study demonstrated that our scTCR specific for the broadly expressed tumor-associated antigen p53(264-272) can eradicate p53⁺A2.1⁺ tumor cells without inducing off-target or self-directed toxicities in mouse models of ACT. These data strongly support the improved safety and therapeutic efficacy of high-affinity p53scTCR for TCR-based immunotherapy of p53-associated malignancies.

The tumor-associated antigen RHAMM (HMMR/CD168) is expressed by monocyte-derived dendritic cells and presented to T cells

We formerly demonstrated that vaccination with Wilms’ tumor 1 (WT1)-loaded autologous monocyte-derived dendritic cells (mo-DCs) can be a well-tolerated effective treatment in acute myeloid leukemia (AML) patients. Here, we investigated whether we could introduce the receptor for hyaluronic acid-mediated motility (RHAMM/HMMR/CD168), another clinically relevant tumor-associated antigen, into these mo-DCs through mRNA electroporation and elicit RHAMM-specific immune responses. While RHAMM mRNA electroporation significantly increased RHAMM protein expression by mo-DCs, our data indicate that classical mo-DCs already express and present RHAMM at sufficient levels to activate RHAMM-specific T cells, regardless of electroporation. Moreover, we found that RHAMM-specific T cells are present at vaccination sites in AML patients. Our findings implicate that we and others who are using classical mo-DCs for cancer immunotherapy are already vaccinating against RHAMM.

A CD22-reactive TCR from the T-cell allorepertoire for the treatment of acute lymphoblastic leukemia by TCR gene transfer

CD22 is currently evaluated as a target-antigen for the treatment of B-cell malignancies using chimeric antigen receptor (CAR)-engineered T-cells or monoclonal antibodies (mAbs). CAR- and mAbs-based immunotherapies have been successfully applied targeting other antigens, however, occurrence of refractory disease to these interventions urges the identification of additional strategies. Here, we identified a TCR recognizing the CD22-derived peptide RPFPPHIQL (CD22_RPF) presented in human leukocyte antigen (HLA)-B^*07:02. To overcome tolerance to self-antigens such as CD22, we exploited the immunogenicity of allogeneic HLA. CD22_RPF-specific T-cell clone 9D4 was isolated from a healthy HLA-B^*07:02^neg individual, efficiently produced cytokines upon stimulation with primary acute lymphoblastic leukemia and healthy B-cells, but did not react towards healthy hematopoietic and nonhematopoietic cell subsets, including dendritic cells (DCs) and macrophages expressing low levels of CD22. Gene transfer of TCR-9D4 installed potent CD22-specificity onto recipient CD8+ T-cells that recognized and lysed primary B-cell leukemia. TCR-transduced T-cells spared healthy CD22^neg hematopoietic cell subsets but weakly lysed CD22^low-expressing DCs and macrophages. CD22-specific TCR-engineered T-cells could form an additional immunotherapeutic strategy with a complementary role to CAR- and antibody-based interventions in the treatment of B-cell malignancies. However, CD22 expression on non-B-cells may limit the attractiveness of CD22 as target-antigen in cellular immunotherapy.

Generation of CD20-specific TCRs for TCR gene therapy of CD20low B-cell malignancies insusceptible to CD20-targeting antibodies

Immunotherapy of B-cell leukemia and lymphoma with CD20-targeting monoclonal antibodies (mAbs) has demonstrated clinical efficacy. However, the emergence of unresponsive disease due to low or absent cell surface CD20 urges the need to develop additional strategies. In contrast to mAbs, T-cells via their T-cell receptor (TCR) can recognize not only extracellular but also intracellular antigens in the context of HLA molecules. We hypothesized that T-cells equipped with high affinity CD20-targeting TCRs would be able to recognize B-cell malignancies even in the absence of extracellular CD20. We isolated CD8⁺ T-cell clones binding to peptide-MHC-tetramers composed of HLA-A*02:01 and CD20-derived peptide SLFLGILSV (CD20_SLF) from HLA-A*02:01^neg healthy individuals to overcome tolerance towards self-antigens such as CD20. High avidity T-cell clones were identified that readily recognized and lysed primary HLA-A2^pos B-cell leukemia and lymphoma in the absence of reactivity against CD20-negative but HLA-A2^pos healthy hematopoietic and nonhematopoietic cells. The T-cell clone with highest avidity efficiently lysed malignant cell-lines that had insufficient extracellular CD20 to be targeted by CD20 mAbs. Transfer of this TCR installed potent CD20-specificity onto recipient T-cells and led to lysis of CD20^low malignant cell-lines. Moreover, our approach facilitates the generation of an off-the-shelf TCR library with broad applicability by targeting various HLA alleles. Using the same methodology, we isolated a T-cell clone that efficiently lysed primary HLA-B*07:02^pos B-cell malignancies by targeting another CD20-derived peptide. TCR gene transfer of high affinity CD20-specific TCRs can be a valuable addition to current treatment options for patients suffering from CD20^low B-cell malignancies.

The progress and current status of immunotherapy in acute myeloid leukemia

Recently, there has been remarkable progress in basic and preclinical studies of acute myeloid leukemia (AML). The improved outcomes of AML can largely be attributed to advances in supportive care and hematopoietic cell transplantation as opposed to conventional chemotherapy. However, as the 5-year survival rate remains low due to a high incidence of relapse, novel and effective treatments are urgently needed. Increasing attention is focusing on identifying suitable immunotherapeutic strategies for AML. Here, we describe the immunological features, mechanisms of immune escape, and recent progress in immunotherapy for AML. Problems encountered in the clinic will also be discussed. Although current outcomes may be limited, ongoing preclinical or clinical efforts are aimed at improving immunotherapy modalities and designing novel therapies, such as vaccines, monoclonal antibody therapy, chimeric antibody receptor-engineered T cells (CAR-T), TCR-engineered T cells (TCR-T), and checkpoint inhibitors, which may provide promising and effective therapies with higher specificity and efficacy for AML.

Advances in immunotherapy for pediatric acute myeloid leukemia

INTRODUCTION

Achieving better disease control in patients diagnosed with acute myeloid leukemia (AML) has proven challenging. Overall survival has been impacted by addressing treatment related mortality with focused supportive care measures. Despite this improvement, it remains difficult to induce durable leukemia remissions despite aggressive chemotherapeutic regimens. The addition of hematopoietic stem cell transplants (HSCT) has allowed further treatment intensification and provided the benefit of graft-versus-leukemia (GVL) effect. However, HSCT carries the risk of transplant related morbidities, particularly GVHD, and anti-tumor responsiveness is still suboptimal. Thus, there is a need for alternate therapies. Immunotherapy has the potential to address this need. Areas covered: Expert opinion: The elusiveness of an ideal surface antigen target together with an immunosuppressive leukemic microenvironment add to the already difficult challenge in developing AML-targeted immunotherapies. Though many hurdles remain, recent translational discovery and progressive clinical advances anticipate exciting future developments.

AREAS COVERED

This review highlights promises and challenges to immune-based therapies for AML. It aims to summarize immunotherapeutic strategies trialed in AML patients to date, inclusive of: antibodies, vaccines, and cellular therapy. It emphasizes those being used in the pediatric population, but also includes adult clinical trials and translational science that may ultimately extend to pediatric patients.

TCR-based therapy for multiple myeloma and other B-cell malignancies targeting intracellular transcription factor BOB1

Immunotherapy for hematological malignancies or solid tumors by administration of monoclonal antibodies or T cells engineered to express chimeric antigen receptors or T-cell receptors (TCRs) has demonstrated clinical efficacy. However, antigen-loss tumor escape variants and the absence of currently targeted antigens on several malignancies hamper the widespread application of immunotherapy. We have isolated a TCR targeting a peptide of the intracellular B cell-specific transcription factor BOB1 presented in the context of HLA-B*07:02. TCR gene transfer installed BOB1 specificity and reactivity onto recipient T cells. TCR-transduced T cells efficiently lysed primary B-cell leukemia, mantle cell lymphoma, and multiple myeloma in vitro. We also observed recognition and lysis of healthy BOB1-expressing B cells. In addition, strong BOB1-specific proliferation could be demonstrated for TCR-modified T cells upon antigen encounter. Furthermore, clear in vivo antitumor reactivity was observed of BOB1-specific TCR-engineered T cells in a xenograft mouse model of established multiple myeloma. Absence of reactivity toward a broad panel of BOB1^- but HLA-B*07:02⁺ nonhematopoietic and hematopoietic cells indicated no off-target toxicity. Therefore, administration of BOB1-specific TCR-engineered T cells may provide novel cellular treatment options to patients with B-cell malignancies, including multiple myeloma.

Frequency of expression and generation of T-cell responses against antigens on multiple myeloma cells in patients included in the GMMG-MM5 trial

Background

Raising T-cell response against antigens either expressed on normal and malignant plasma cells (e.g. HM1.24) or aberrantly on myeloma cells only (e.g. cancer testis antigens, CTA) by vaccination is a potential treatment approach for multiple myeloma.

Results

Expression by GEP is found for HM1.24 in all, HMMR in 318/458 (69.4%), MAGE-A3 in 209/458 (45.6%), NY-ESO-1/2 in 40/458 (8.7%), and WT-1 in 4/458 (0.8%) of samples with the pattern being confirmed by RNA-sequencing. T-cell-activation is found in 9/26 (34.6%) of patient samples, i.e. against HM1.24 (4/24), RHAMM-R3 (3/26), RHAMM1-8 (2/14), WT-1 (1/11), NY-ESO-1/2 (1/9), and MAGE-A3 (2/8). In 7/19 T-cell activation responses, myeloma cells lack respective antigen-expression. Expression of MAGE-A3, HMMR and NY-ESO-1/2 is associated with adverse survival.

Experimental design

We assessed expression of HM1.24 and the CTAs MAGE-A3, NY-ESO-1/2, WT-1 and HMMR in CD138-purified myeloma cell samples of previously untreated myeloma patients in the GMMG-MM5 multicenter-trial by gene expression profiling (GEP; n = 458) and RNA-sequencing (n = 152) as potential population regarding vaccination trials. We then validated the feasibility to generate T-cell responses (n = 72) against these antigens by IFN-γ EliSpot-assay (n = 26) related to antigen expression (n = 22). Lastly, we assessed survival impact of antigen expression in an independent cohort of 247 patients treated by high-dose therapy and autologous stem cell transplantation.

Conclusions

As T-cell responses can only be raised in a subfraction of patients despite antigen expression, and the number of responses increases with more antigens used, vaccination strategies should assess patients’ antigen expression and use a “cocktail” of peptide vaccines.

Transgelin-2 in B-Cells Controls T-Cell Activation by Stabilizing T Cell - B Cell Conjugates

The immunological synapse (IS), a dynamic and organized junction between T-cells and antigen presenting cells (APCs), is critical for initiating adaptive immunity. The actin cytoskeleton plays a major role in T-cell reorganization during IS formation, and we previously reported that transgelin-2, an actin-binding protein expressed in T-cells, stabilizes cortical F-actin, promoting T-cell activation in response to antigen stimulation. Transgelin-2 is also highly expressed in B-cells, although no specific function has been reported. In this study, we found that deficiency in transgelin-2 (TAGLN2-/-) in B-cells had little effect on B-cell development and activation, as measured by the expression of CD69, MHC class II molecules, and CD80/86. Nevertheless, in B-cells, transgelin-2 accumulated in the IS during the interaction with T-cells. These results led us to hypothesize that transgelin-2 may also be involved in IS stability in B-cells, thereby influencing T-cell function. Notably, we found that transgelin-2 deficiency in B-cells reduced T-cell activation, as determined by the release of IL-2 and interferon-γ and the expression of CD69. Furthermore, the reduced T-cell activation was correlated with reduced B-cell-T-cell conjugate formation. Collectively, these results suggest that actin stability in B-cells during IS formation is critical for the initiation of adaptive T-cell immunity.

Patient-individualized CD8⁺ cytolytic T-cell therapy effectively combats minimal residual leukemia in immunodeficient mice

Adoptive transfer of donor-derived cytolytic T-lymphocytes (CTL) has evolved as a promising strategy to improve graft-versus-leukemia (GvL) effects in allogeneic hematopoietic stem-cell transplantation. However, durable clinical responses are often hampered by limited capability of transferred T cells to establish effective and sustained antitumor immunity in vivo. We therefore analyzed GvL responses of acute myeloid leukemia (AML)-reactive CD8(+) CTL with central and effector memory phenotype in a new allogeneic donor-patient specific humanized mouse model. CTL lines and clones obtained upon stimulation of naive CD45RA(+) donor CD8(+) T cells with either single HLA antigen-mismatched or HLA-matched primary AML blasts, respectively, elicited strong leukemia reactivity during cytokine-optimized short to intermediate (i.e., 2-8 weeks) culture periods. Single doses of CTL were intravenously infused into NOD/scidIL2Rcg(null) mice when engraftment with patient AML reached bone marrow infiltration of 1-5%, clinically defining minimal residual disease status. This treatment resulted in complete regression of HLA-mismatched and strong reduction of HLA-matched AML infiltration, respectively. Most importantly, mice receiving AML-reactive CTL showed significantly prolonged survival. Transferred CTL were detectable in murine bone marrow and spleen and demonstrated sustained AML-reactivity ex vivo. Moreover, injections with human IL-15 clearly promoted CTL persistence. In summary, we show that naive donor-derived CD8(+) CTL effectively combat patient AML blasts in immunodeficient mice. The donor-patient specific humanized mouse model appears suitable to evaluate therapeutic efficacy of AML-reactive CTL before adoptive transfer into patients. It may further help to identify powerful leukemia rejection antigens and T-cell receptors for redirecting immunity to leukemias even in a patient-individualized manner.

Hyaluronan/RHAMM interactions in mesenchymal tumor pathogenesis: role of growth factors

Fibrosarcoma belongs to the sarcoma cancer group, which are spindle cell malignancies of mesenchymal origin, and owe their name to the predominant cell line that is present within the tumor. The extracellular matrix (ECM) is a complicated structure that surrounds and supports cells within tissues. Its main components are proteoglycans, collagens, glycoproteins, hyaluronan (HA), and several matrix-degrading enzymes. During cancer progression, significant changes can be observed in the structural and mechanical properties of ECM components. The ECM provides a physical scaffold to which tumor cells attach and migrate. Thus, it is required for key cellular events such as cell motility, adhesion, proliferation, invasion, and metastasis. Importantly, fibrosarcomas were shown to have a high content and turnover of ECM components including HA, proteoglycans, collagens, fibronectin, and laminin. In this review, we will focus on the HA component of fibrosarcoma ECM and critically discuss its role and involved mechanisms during fibrosarcoma pathogenesis.

Cellular immunotherapy strategies for Ewing sarcoma

Ewing sarcoma is a rare cancer of bone and soft tissues defined by a specific chromosomal rearrangement. Preclinical development of immunological treatment strategies includes expansion of T cells with native or grafted T-cell receptor specificities for Ewing sarcoma-associated intracellular antigens, and T-cell engineering with chimeric antigen receptors targeting surface antigens. In vitro preactivated NK cells may also have activity in this cancer. Major challenges are the heterogeneity of antigen expression in individual Ewing sarcomas, and the coexpression of most candidate targets on normal cells. Moreover, homing of therapeutic effector cells to both primary and metastatic tumor sites and adequate function within the immunosuppressive tumor microenvironment will have to be ensured to allow for effective immune targeting of this cancer.

Therapeutic targeting of the BCR-associated protein CD79b in a TCR-based approach is hampered by aberrant expression of CD79b

B-cell malignancies were efficiently recognized by T cells expressing high-affinity alloHLA-restricted TCRs specific for CD79b. Aberrant expression of CD79b in non–B cells caused unwanted reactivity, rendering CD79b unsuitable for TCR-based immunotherapies.

Survivin-specific T cell receptor targets tumor but not T cells

Survivin is a tumor-associated antigen (TAA) that inhibits apoptosis and is widely overexpressed in cancer cells; therefore, survivin has potential as a target for cancer immunotherapy. Application of HLA-A2-restricted survivin-specific T cell receptors (TCRs) isolated from allogeneic HLA-mismatched TCR repertoires has, however, been impeded by the inability of these TCRs to distinguish healthy cells expressing low levels of survivin from cancer cells with high survivin expression levels. Here, we identified an HLA-A2-restricted survivin-specific TCR isolated from autologous TCR repertoires that targets tumor cells in vitro and in vivo but does not cause fratricidal toxicity. Molecular modeling of the TCR-peptide-HLA ternary complexes and alanine scanning revealed that the autologously derived TCRs had tighter interactions with the survivin peptide than did fratricidal TCRs. Similar recognition patterns were observed among 7 additional TAA-specific TCRs isolated from allogeneic versus autologous repertoires. Together, the results from this study indicate that maximal peptide recognition is key for TCR selectivity and likely critical for reducing unwanted off-target toxicities. Moreover, isolating TCRs from autologous repertoires to maximize TCR selectivity has potential as a useful strategy to identify and select other shared tumor- and self-antigen-specific TCRs and ensure selective antitumor activity.

Can immunotherapy specifically target acute myeloid leukemic stem cells?

Accumulating evidence supports the role of leukemic stem cells (LSCs) in the high relapse rate of acute myeloid leukemia (AML) patients. The clinical relevance of LSCs, which were originally characterized in xenograft models, has recently been confirmed by the finding that stem cell-like gene expression signatures can predict the clinical outcome of AML patients. The targeted elimination of LSCs might hence constitute an efficient therapeutic approach to AML. Here, we review immunotherapeutic strategies that target LSC-associated antigens, including T cell-mediated and monoclonal antibody-based regimens. Attention is given to the issue of antigen specificity because this is relevant to the therapeutic window and determines the superiority of LSC-targeting immunotherapy.

Limitations for TCR gene therapy by MHC-restricted fratricide and TCR-mediated hematopoietic stem cell toxicity

The clinical use of lymphocytes engineered to express high affinity T-cell receptors (TCRs) specific for two broadly expressed tumor-associated antigens is strongly limited by MHC-restricted fratricide of lymphocytes and TCR-mediated killing of hematopoietic stem cells. Specific clinical applications must therefore be conceived to bypass these limitations.

Common Ewing sarcoma-associated antigens fail to induce natural T cell responses in both patients and healthy individuals

Disseminated or relapsed Ewing sarcoma (EwS) has remained fatal in the majority of patients. A promising approach to preventing relapse after conventional therapy is to establish tumor antigen-specific immune control. Efficient and specific T cell memory against the tumor depends on the expansion of rare T cells with native specificity against target antigens overexpressed by the tumor. Candidate antigens in EwS include six-transmembrane epithelial antigen of the prostate-1 (STEAP1), and the human cancer/testis antigens X-antigen family member 1 (XAGE1) and preferentially expressed antigen in melanoma (PRAME). Here, we screened normal donors and EwS patients for the presence of circulating T cells reactive with overlapping peptide libraries of these antigens by IFN-γ Elispot analysis. The majority of 22 healthy donors lacked detectable memory T cell responses against STEAP1, XAGE1 and PRAME. Moreover, ex vivo detection of T cells specific for these antigens in both blood and bone marrow were limited to a minority of EwS patients and required nonspecific T cell prestimulation. Cytotoxic T cells specific for the tumor-associated antigens were efficiently and reliably generated by in vitro priming using professional antigen-presenting cells and optimized cytokine stimulation; however, these T cells failed to interact with native antigen processed by target cells and with EwS cells expressing the antigen. We conclude that EwS-associated antigens fail to induce efficient T cell receptor (TCR)-mediated antitumor immune responses even under optimized conditions. Strategies based on TCR engineering could provide a more effective means to manipulating T cell immunity toward targeted elimination of tumor cells.

Adoptive T-cell therapy for Leukemia

Allogeneic stem cell transplantation (alloSCT) is the most robust form of adoptive cellular therapy (ACT) and has been tremendously effective in the treatment of leukemia. It is one of the original forms of cancer immunotherapy and illustrates that lymphocytes can specifically recognize and eliminate aberrant, malignant cells. However, because of the high morbidity and mortality that is associated with alloSCT including graft-versus-host disease (GvHD), refining the anti-leukemia immunity of alloSCT to target distinct antigens that mediate the graft-versus-leukemia (GvL) effect could transform our approach to treating leukemia, and possibly other hematologic malignancies. Over the past few decades, many leukemia antigens have been discovered that can separate malignant cells from normal host cells and render them vulnerable targets. In concert, the field of T-cell engineering has matured to enable transfer of ectopic high-affinity antigen receptors into host or donor cells with greater efficiency and potency. Many preclinical studies have demonstrated that engineered and conventional T-cells can mediate lysis and eradication of leukemia via one or more leukemia antigen targets. This evidence now serves as a foundation for clinical trials that aim to cure leukemia using T-cells. The recent clinical success of anti-CD19 chimeric antigen receptor (CAR) cells for treating patients with acute lymphoblastic leukemia and chronic lymphocytic leukemia displays the potential of this new therapeutic modality. In this review, we discuss some of the most promising leukemia antigens and the novel strategies that have been implemented for adoptive cellular immunotherapy of lymphoid and myeloid leukemias. It is important to summarize the data for ACT of leukemia for physicians in-training and in practice and for investigators who work in this and related fields as there are recent discoveries already being translated to the patient setting and numerous accruing clinical trials. We primarily focus on ACT that has been used in the clinical setting or that is currently undergoing preclinical testing with a foreseeable clinical endpoint.

Bioinformatic description of immunotherapy targets for pediatric T-cell leukemia and the impact of normal gene sets used for comparison

Pediatric lymphoid leukemia has the highest cure rate of all pediatric malignancies, yet due to its prevalence, still accounts for the majority of childhood cancer deaths and requires long-term highly toxic therapy. The ability to target B-cell ALL with immunoglobulin-like binders, whether anti-CD22 antibody or anti-CD19 CAR-Ts, has impacted treatment options for some patients. The development of new ways to target B-cell antigens continues at rapid pace. T-cell ALL accounts for up to 20% of childhood leukemia but has yet to see a set of high-value immunotherapeutic targets identified. To find new targets for T-ALL immunotherapy, we employed a bioinformatic comparison to broad normal tissue arrays, hematopoietic stem cells (HSC), and mature lymphocytes, then filtered the results for transcripts encoding plasma membrane proteins. T-ALL bears a core T-cell signature and transcripts encoding TCR/CD3 components and canonical markers of T-cell development predominate, especially when comparison was made to normal tissue or HSC. However, when comparison to mature lymphocytes was also undertaken, we identified two antigens that may drive, or be associated with leukemogenesis; TALLA-1 and hedgehog interacting protein. In addition, TCR subfamilies, CD1, activation and adhesion markers, membrane-organizing molecules, and receptors linked to metabolism and inflammation were also identified. Of these, only CD52, CD37, and CD98 are currently being targeted clinically. This work provides a set of targets to be considered for future development of immunotherapies for T-ALL.

Allogeneic stem cell transplantation for patients with advanced rhabdomyosarcoma: a retrospective assessment

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (allo-SCT) may provide donor cytotoxic T cell-/NK cell-mediated disease control in patients with rhabdomyosarcoma (RMS). However, little is known about the prevalence of graft-vs-RMS effects and only a few case experiences have been reported.

METHODS

We evaluated allo-SCT outcomes of 30 European Group for Blood and Marrow Transplantation (EBMT)-registered patients with advanced RMS regarding toxicity, progression-free survival (PFS) and overall survival (OS) after allo-SCT. Twenty patients were conditioned with reduced intensity and ten with high-dose chemotherapy. Twenty-three patients were transplanted with HLA-matched and seven with HLA-mismatched grafts. Three patients additionally received donor lymphocyte infusions (DLIs). Median follow-up was 9 months.

RESULTS

Three-year OS was 20% (s.e.±8%) with a median survival time of 12 months. Cumulative risk of progression was 67% (s.e.±10%) and 11% (s.e.±6%) for death of complications. Thirteen patients developed acute graft-vs-host disease (GvHD) and five developed chronic GvHD. Eighteen patients died of disease and four of complications. Eight patients survived in complete remission (CR) (median: 44 months). No patients with residual disease before allo-SCT were converted to CR.

CONCLUSION

The use of allo-SCT in patients with advanced RMS is currently experimental. In a subset of patients, it may constitute a valuable approach for consolidating CR, but this needs to be validated in prospective trials.

Molecular characterization of T cell receptor beta variable in the peripheral blood T cell repertoire in subjects with active tuberculosis or latent tuberculosis infection

Background

T cells are closely linked to the clinical manifestations of subjects with Mycobacterium tuberculosis (MTB) infection. T cell receptor beta variable (TCRBV) is a signal and indicative molecule on the membrane of T lymphocytes, reflecting the composition and specificity of T cells. The molecular profiles of TCRBV in peripheral blood mononuclear cells (PBMCs) and their subpopulations (CD4⁺ and CD8⁺ T cells) from subjects with active tuberculosis (TB) or latent TB infection (LTBI) have not been well described.

Methods

In 42 subjects with active TB or LTBI, PMBCs and their subsets were separated and sorted. The molecular profiles of the TCRBV complementarity determining region 3 (CDR3) in the three cell populations were investigated using our recently developed gene melting spectral pattern (GMSP) assay. The TCRBV members were then cloned and sequenced when their GMSP image profiles showed a single-peak.

Results

The average number of skewed TCRBV molecules in the CD4⁺ cell subset was significantly higher than that in PBMCs and CD8⁺ T cells. TCRBV12, BV13.1, BV13.2, and BV24 were expressed more prevalently than other TCRBV gene families in the three cell populations. In addition, relatively conserved amino acid motifs were identified in TCRBV5.1 and BV20 CDR3 in PBMCs and its subsets. The monoclonal TCRBV14 and BV23 expressed were different between active TB and LTBI subjects.

Conclusions

These results indicate that the T cell immune response is complex and multi-specific in active TB and LTBI subjects. Analysis of TCRBV expression in CD4⁺ T cells suggest that it could be useful in assessing the composition and status of circulating T cells. Furthermore, the expression of TCRBV14, BV23 and the sequencing of CDR3 amino acid motifs of TCRBV5.1, BV20 could be used in the differential diagnosis and treatment of subjects with active TB or LTBI.

The roles of hyaluronan/RHAMM/CD44 and their respective interactions along the insidious pathways of fibrosarcoma progression

Fibrosarcomas are rare malignant mesenchymal tumors originating from fibroblasts. Importantly, fibrosarcoma cells were shown to have a high content and turnover of extracellular matrix (ECM) components including hyaluronan (HA), proteoglycans, collagens, fibronectin, and laminin. ECMs are complicated structures that surround and support cells within tissues. During cancer progression, significant changes can be observed in the structural and mechanical properties of the ECM components. Importantly, hyaluronan deposition is usually higher in malignant tumors as compared to benign tissues, predicting tumor progression in some tumor types. Furthermore, activated stromal cells are able to produce tissue structure rich in hyaluronan in order to promote tumor growth. Key biological roles of HA result from its interactions with its specific CD44 and RHAMM (receptor for HA-mediated motility) cell-surface receptors. HA-receptor downstream signaling pathways regulate in turn cellular processes implicated in tumorigenesis. Growth factors, including PDGF-BB, TGFβ2, and FGF-2, enhanced hyaluronan deposition to ECM and modulated HA-receptor expression in fibrosarcoma cells. Indeed, FGF-2 through upregulation of specific HAS isoforms and hyaluronan synthesis regulated secretion and net hyaluronan deposition to the fibrosarcoma pericellular matrix modulating these cells' migration capability. In this paper we discuss the involvement of hyaluronan/RHAMM/CD44 mediated signaling in the insidious pathways of fibrosarcoma progression.

Gene-engineered T cells for cancer therapy

T cells have the capacity to eradicate diseased cells, but tumours present considerable challenges that render T cells ineffectual. Cancer cells often make themselves almost 'invisible' to the immune system, and they sculpt a microenvironment that suppresses T cell activity, survival and migration. Genetic engineering of T cells can be used therapeutically to overcome these challenges. T cells can be taken from the blood of cancer patients and then modified with genes encoding receptors that recognize cancer-specific antigens. Additional genes can be used to enable resistance to immunosuppression, to extend survival and to facilitate the penetration of engineered T cells into tumours. Using genetic modification, highly active, self-propagating 'slayers' of cancer cells can be generated.

Novel cellular therapies for leukemia: CAR-modified T cells targeted to the CD19 antigen

The ability of immune-competent donor T cells to mediate a beneficial graft-versus-leukemia (GVL) effect was first identified in the setting of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for hematologic malignancies. Unfortunately, with the exception of chronic myelogenous leukemia and EBV-induced lymphoproliferative disease, allo-HSCT GVL lacks the potency to significantly affect disease progression or recurrence in most other hematologic malignancies. The inadequacy of a GVL effect using past approaches is particularly evident in patients with lymphoid malignancies. However, with the advent of improved gene transfer technology, genetically modified tumor-specific immune effectors have extended cellular immunotherapy to lymphoid malignancies. One promising strategy entails the introduction of genes encoding artificial receptors called chimeric antigen receptors (CARs), which redirect the specificity and function of immune effectors. CAR-modified T cells targeted to the B cell-specific CD19 antigen have demonstrated promising results in multiple early clinical trials, supporting further investigation in patients with B-cell cancers. However, disparities in clinical trial design and CAR structure have complicated the discovery of the optimal application of this technology. Recent preclinical studies support additional genetic modifications of CAR-modified T cells to achieve optimal clinical efficacy using this novel adoptive cellular therapy.

Novel cellular therapies for leukemia: CAR-modified T cells targeted to the CD19 antigen

The ability of immune-competent donor T cells to mediate a beneficial graft-versus-leukemia (GVL) effect was first identified in the setting of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for hematologic malignancies. Unfortunately, with the exception of chronic myelogenous leukemia and EBV-induced lymphoproliferative disease, allo-HSCT GVL lacks the potency to significantly affect disease progression or recurrence in most other hematologic malignancies. The inadequacy of a GVL effect using past approaches is particularly evident in patients with lymphoid malignancies. However, with the advent of improved gene transfer technology, genetically modified tumor-specific immune effectors have extended cellular immunotherapy to lymphoid malignancies. One promising strategy entails the introduction of genes encoding artificial receptors called chimeric antigen receptors (CARs), which redirect the specificity and function of immune effectors. CAR-modified T cells targeted to the B cell–specific CD19 antigen have demonstrated promising results in multiple early clinical trials, supporting further investigation in patients with B-cell cancers. However, disparities in clinical trial design and CAR structure have complicated the discovery of the optimal application of this technology. Recent preclinical studies support additional genetic modifications of CAR-modified T cells to achieve optimal clinical efficacy using this novel adoptive cellular therapy.

Cancer gene therapy targeting cellular apoptosis machinery

The unraveling of cellular apoptosis machinery provides novel targets for cancer treatment, and gene therapy targeting this suicidal system has been corroborated to cause inflammation-free autonomous elimination of neoplastic cells. The apoptotic machinery can be targeted by introduction of a gene encoding an inducer, mediator or executioner of apoptotic cell death or by inhibition of anti-apoptotic gene expression. Strategies targeting cancer cells, which are achieved by selective gene delivery, specific gene expression or secretion of target proteins via genetic modification of autologous cells, dictate the outcome of apoptosis-based cancer gene therapy. Despite so far limited clinical success, gene therapy targeting the apoptotic machinery has great potential to benefit patients with threatening malignancies provided the availability of efficient and specific gene delivery and administration systems.

RHAMM/HMMR (CD168) is not an ideal target antigen for immunotherapy of acute myeloid leukemia

BACKGROUND

Criteria for good candidate antigens for immunotherapy of acute myeloid leukemia are high expression on leukemic stem cells in the majority of patients with acute myeloid leukemia and low or no expression in vital tissues. It was shown in vaccination trials that Receptor for Hyaluronic Acid Mediated Motility (RHAMM/HMMR) generates cellular immune responses in patients with acute myeloid leukemia and that these responses correlate with clinical benefit. It is not clear however whether this response actually targets the leukemic stem cell, especially since it was reported that RHAMM is expressed maximally during the G2/M phase of the cell cycle. In addition, tumor specificity of RHAMM expression remains relatively unexplored.

DESIGN AND METHODS

Blood, leukapheresis and bone marrow samples were collected from both acute myeloid leukemia patients and healthy controls. RHAMM expression was assessed at protein and mRNA levels on various sorted populations, either fresh or after manipulation.

RESULTS

High levels of RHAMM were expressed by CD34(+)CD38(+) and CD34(-) acute myeloid leukemia blasts. However, only baseline expression of RHAMM was measured in CD34(+)CD38(-) leukemic stem cells, and was not different from that in CD34(+)CD38(-) hematopoietic stem cells from healthy controls. RHAMM was significantly up-regulated in CD34(+) cells from healthy donors during in vitro expansion and during in vivo engraftment. Finally, we demonstrated an explicit increase in the expression level of RHAMM after in vitro activation of T cells.

CONCLUSIONS

RHAMM does not fulfill the criteria of an ideal target antigen for immunotherapy of acute myeloid leukemia. RHAMM expression in leukemic stem cells does not differ significantly from the expression in hematopoietic stem cells from healthy controls. RHAMM expression in proliferating CD34+ cells of healthy donors and activated T cells further compromises RHAMM-specific T-cell-mediated immunotherapy.