Epigenetic modulation of MAGE-A3 antigen expression in multiple myeloma following treatment with the demethylation agent 5-azacitidine and the histone deacetlyase inhibitor MGCD0103

A new histone deacetylase inhibitor remodels the tumor microenvironment by deletion of polymorphonuclear myeloid-derived suppressor cells and sensitizes prostate cancer to immunotherapy

BACKGROUND

Prostate cancer (PCa) is the most common malignancy diagnosed in men. Immune checkpoint blockade (ICB) alone showed disappointing results in PCa. It is partly due to the formation of immunosuppressive tumor microenvironment (TME) could not be reversed effectively by ICB alone.

METHODS

We used PCa cell lines to evaluate the combined effects of CN133 and anti-PD-1 in the subcutaneous and osseous PCa mice models, as well as the underlying mechanisms.

RESULTS

We found that CN133 could reduce the infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and CN133 combination with anti-PD-1 could augment antitumor effects in the subcutaneous PCa of allograft models. However, anti-PD-1 combination with CN133 failed to elicit an anti-tumor response to the bone metastatic PCa mice. Mechanistically, CN133 could inhibit the infiltration of PMN-MDSCs in the TME of soft tissues by downregulation gene expression of PMN-MDSC recruitment but not change the gene expression involved in PMN-MDSC activation in the CN133 and anti-PD-1 co-treatment group relative to the anti-PD-1 alone in the bone metastatic mice model.

CONCLUSIONS

Taken together, our work firstly demonstrated that combination of CN133 with anti-PD-1 therapy may increase the therapeutic efficacy to PCa by reactivation of the positive immune microenvironment in the TME of soft tissue PCa.

Activating STING1-dependent immune signaling in TP53 mutant and wild-type acute myeloid leukemia

DNA methyltransferase inhibitors (DNMTis) reexpress hypermethylated genes in cancers and leukemias and also activate endogenous retroviruses (ERVs), leading to interferon (IFN) signaling, in a process known as viral mimicry. In the present study we show that in the subset of acute myeloid leukemias (AMLs) with mutations in TP53, associated with poor prognosis, DNMTis, important drugs for treatment of AML, enable expression of ERVs and IFN and inflammasome signaling in a STING-dependent manner. We previously reported that in solid tumors poly ADP ribose polymerase inhibitors (PARPis) combined with DNMTis to induce an IFN/inflammasome response that is dependent on STING1 and is mechanistically linked to generation of a homologous recombination defect (HRD). We now show that STING1 activity is actually increased in TP53 mutant compared with wild-type (WT) TP53 AML. Moreover, in TP53 mutant AML, STING1-dependent IFN/inflammatory signaling is increased by DNMTi treatment, whereas in AMLs with WT TP53, DNMTis alone have no effect. While combining DNMTis with PARPis increases IFN/inflammatory gene expression in WT TP53 AML cells, signaling induced in TP53 mutant AML is still several-fold higher. Notably, induction of HRD in both TP53 mutant and WT AMLs follows the pattern of STING1-dependent IFN and inflammatory signaling that we have observed with drug treatments. These findings increase our understanding of the mechanisms that underlie DNMTi + PARPi treatment, and also DNMTi combinations with immune therapies, suggesting a personalized approach that statifies by TP53 status, for use of such therapies, including potential immune activation of STING1 in AML and other cancers.

Comprehensive Analysis to Identify MAGEA3 Expression Correlated With Immune Infiltrates and Lymph Node Metastasis in Gastric Cancer

Gastric cancer (GC) is an aggressive malignant tumor and causes a significant number of deaths every year. With the coming of the age of cancer immunotherapy, search for a new target in gastric cancer may benefit more advanced patients. Melanoma-associated antigen-A3 (MAGEA3), one of the members of the cancer-testis antigen (CTA) family, was considered an important part of cancer immunotherapy. We evaluate the potential role of MAGEA3 in GC through the TCGA database. The result revealed that MAGEA3 is upregulated in GC and linked to poor OS and lymph node metastasis. MAGEA3 was also correlated with immune checkpoints, TMB, and affected the tumor immune microenvironment and the prognosis of GC through CIBERSORT, TIMER, and Kaplan-Meier plotter database analysis. In addition, GSEA-identified MAGEA3 is involved in the immune regulation of GC. Moreover, the protein-protein interaction (PPI) networks of MAGEA3 were constructed through STRING database and MAGEA3-correlated miRNAs were screened based on the joint analysis of multiple databases. In terms of experimental verification, we constructed pET21a (+)/MAGEA3 restructuring plasmids and transformed to Escherichia coli Rosetta. MAGEA3 protein was used as an antigen after being expressed and purified and can effectively detect the specific IgG in 93 GC patients' serum specimens with 44.08% sensitivity and 92.54% specificity. Through further analysis, the positive rate of MAGEA3 was related to the stage and transfer number of lymph nodes. These results indicated that MAGEA3 is a novel biomarker and correlated with lymph node metastasis and immune infiltrates in GC, which could be a new target for immunotherapy.

Immunotherapy for Hepatocellular Carcinoma: Current Limits and Prospects

Although many approaches have been used to treat hepatocellular carcinoma (HCC), the clinical benefits remain limited, particularly for late stage HCC. In recent years, studies have focused on immunotherapy for HCC. Immunotherapies have shown promising clinical outcomes in several types of cancers and potential therapeutic effects for advanced HCC. In this review, we summarize the immune tolerance and immunotherapeutic strategies for HCC as well as the main challenges of current therapeutic approaches. We also present alternative strategies for overcoming these limitations.

Immune System Alterations in Multiple Myeloma: Molecular Mechanisms and Therapeutic Strategies to Reverse Immunosuppression

Simple Summary

A common characteristic of multiple myeloma (MM) is the dysfunction of patients’ immune system, a condition termed immunosuppression. This state is mainly due to alterations in the number and functionality of the principal immune populations. In this setting, immunotherapy has acquired high relevance in the last years and the investigation of agents that boost the immune system represent a field of interest. In the present review, we will summarize the main cellular and molecular alterations observed in MM patients’ immune system. Furthermore, we will describe the mechanisms of action of the four immunotherapeutic drugs approved so far for the treatment of MM, which are part of the group of monoclonal antibodies (mAbs). Finally, the immune-stimulating effects of several therapeutic agents are described due to their potential role in reversing immunosuppression and, therefore, in favoring the efficacy of immunotherapy drugs, such as mAbs, as part of future pharmacological combinations.

Abstract

Immunosuppression is a common feature of multiple myeloma (MM) patients and has been associated with disease evolution from its precursor stages. MM cells promote immunosuppressive effects due to both the secretion of soluble factors, which inhibit the function of immune effector cells, and the recruitment of immunosuppressive populations. Alterations in the expression of surface molecules are also responsible for immunosuppression. In this scenario, immunotherapy, as is the case of immunotherapeutic monoclonal antibodies (mAbs), aims to boost the immune system against tumor cells. In fact, mAbs exert part of their cytotoxic effects through different cellular and soluble immune components and, therefore, patients’ immunosuppressive status could reduce their efficacy. Here, we will expose the alterations observed in symptomatic MM, as compared to its precursor stages and healthy subjects, in the main immune populations, especially the inhibition of effector cells and the activation of immunosuppressive populations. Additionally, we will revise the mechanisms responsible for all these alterations, including the interplay between MM cells and immune cells and the interactions among immune cells themselves. We will also summarize the main mechanisms of action of the four mAbs approved so far for the treatment of MM. Finally, we will discuss the potential immune-stimulating effects of non-immunotherapeutic drugs, which could enhance the efficacy of immunotherapeutic treatments.

Immunological and functional aspects of MAGEA3 cancer/testis antigen

Identification of ectopic gene activation in cancer cells serves as a basis for both gene signature-guided tumor targeting and unearthing of oncogenic mechanisms to expand the understanding of tumor biology/oncogenic process. Proteins expressed only in germ cells of testis and/or placenta (immunoprivileged organs) and in malignancies are called cancer testis antigens; they are antigenic because of the lack of antigen presentation by those specific cell types (germ cells), which limits the exposure of the proteins to the immune cells. Since the Cancer Testis Antigens (CTAs) are immunogenic and expressed in a wide variety of cancer types, CT antigens have become interesting target for immunotherapy against cancer. Among CT antigens MAGEA family is reported to have 12 members (MAGEA1 to MAGEA12). The current review highlights the studies on MAGEA3 which is a CT antigen and reported in almost all types of cancer. MAGEA3 is well tried for cancer immunotherapy. Recent advances on its functional and immunological aspect warranted much deliberation on effective therapeutic approach, thus making it a more interesting target for cancer therapy.

The HDAC Inhibitor Domatinostat Promotes Cell-Cycle Arrest, Induces Apoptosis, and Increases Immunogenicity of Merkel Cell Carcinoma Cells

Merkel cell carcinoma (MCC) is a rare, highly aggressive skin cancer for which immune modulation by immune checkpoint inhibitors shows remarkable response rates. However, primary or secondary resistance to immunotherapy prevents benefits in a significant proportion of patients. For MCC, one immune escape mechanism is insufficient for recognition by T cells owing to the downregulation of major histocompatibility complex I surface expression. Histone deacetylase inhibitors have been demonstrated to epigenetically reverse the low major histocompatibility complex I expression caused by the downregulation of the antigen-processing machinery. Domatinostat, an orally available small-molecule inhibitor targeting histone deacetylase class I, is currently in clinical evaluation to overcome resistance to immunotherapy. In this study, we present preclinical data on domatinostat's efficacy and mode of action in MCC. Single-cell RNA sequencing revealed a distinct gene expression signature of antigen processing and presentation, cell-cycle arrest, and execution phase of apoptosis on treatment. Accordingly, functional assays showed that domatinostat induced G2M arrest and apoptosis. In the surviving cells, antigen-processing machinery component gene transcription and translation were upregulated, consequently resulting in increased major histocompatibility complex I surface expression. Altogether, domatinostat not only exerts direct antitumoral effects but also restores HLA class I surface expression on MCC cells, therefore, restoring surviving MCC cells' susceptibility to recognition and elimination by cognate cytotoxic T cells.

Deregulation of Adaptive T Cell Immunity in Multiple Myeloma: Insights Into Mechanisms and Therapeutic Opportunities

Immunotherapy has recently emerged as a promising treatment option for multiple myeloma (MM) patients. Profound immune dysfunction and evasion of immune surveillance are known to characterize MM evolution and disease progression. Along with genomic changes observed in malignant plasma cells, the bone marrow (BM) milieu creates a protective environment sustained by the complex interaction of BM stromal cells (BMSCs) and malignant cells that using bidirectional connections and cytokines released stimulate disease progression, drug resistance and enable immune escape. Local immune suppression and T-cell exhaustion are important mediating factors of clinical outcomes and responses to immune-based approaches. Thus, further characterization of the defects present in the immune system of MM patients is essential to develop novel therapies and to repurpose the existing ones. This review seeks to provide insights into the mechanisms that promote tumor escape, cause inadequate T-cell stimulation and impaired cytotoxicity in MM. Furthermore, it highlights current immunotherapies being used to restore adaptive T-cell immune responses in MM and describes strategies created to escape these multiple immune evasion mechanisms.

Domatinostat favors the immunotherapy response by modulating the tumor immune microenvironment (TIME)

Background

The efficacy of PD-(L)1 blockade depends on the composition of the tumor immune microenvironment (TIME) and is generally higher in tumors with pre-existing cytotoxic T cells (CTL) than in those with low CTL numbers. Nonetheless, a significant proportion of patients with pre-existing immunity fail to respond, indicating a therapeutic potential for combining PD-(L)1 blockade with additional immunomodulatory agents in both CTL-high and -low immune phenotypes. Here, we evaluated domatinostat (4SC-202), a class I-selective histone deacetylase (HDAC) inhibitor, for its effect on the TIME and its antitumoral efficacy using syngeneic mouse models with CTL-high or CTL-low tumors.

Methods

Domatinostat was evaluated in PD-1 blockade-insensitive CTL-low (CT26) and CTL-high (C38) syngeneic models alone and in combination with different immune-inhibitory and -stimulatory approaches. Effects on the immunophenotype were assessed via flow cytometry and RNA-seq analyses. The changes in RNA-seq-based immune signatures determined in a murine setting were investigated in patient samples from the first-dose cohort of the SENSITIZE trial (NCT03278665) evaluating domatinostat combined with pembrolizumab in advanced-stage melanoma patients refractory/nonresponding to PD-1 blockade.

Results

Domatinostat increased the expression of antigen-presenting machinery (APM) genes and MHC class I and II molecules, along with CTL infiltration, in tumors of both immune phenotypes. In combination with PD-(L)1 blockade, domatinostat augmented antitumor effects substantially above the effects of single-agent therapies, displaying greater benefit in tumors with pre-existing CTLs. In this setting, the combination of domatinostat with agonistic anti-4-1BB or both PD-1 and LAG3 blockade further increased the antitumor efficacy.

In CTL-low tumors, domatinostat enhanced the expression of genes known to reinforce immune responses against tumors. Specifically, domatinostat increased the expression of Ifng and genes associated with responses to pembrolizumab and nivolumab.

Clinically, these findings were confirmed in patients with advanced melanoma treated with domatinostat for 14 days, who demonstrated elevated expression of APM and MHC genes, the IFNG gene, and the IFN-γ and pembrolizumab response signatures in individual tumor samples.

Conclusion

In summary, these data suggest a promising potential of domatinostat in combination with immunotherapy to improve the outcome of refractory cancer patients.

The emerging role of epigenetic therapeutics in immuno-oncology

The past decade has seen the emergence of immunotherapy as a prime approach to cancer treatment, revolutionizing the management of many types of cancer. Despite the promise of immunotherapy, most patients do not have a response or become resistant to treatment. Thus, identifying combinations that potentiate current immunotherapeutic approaches will be crucial. The combination of immune-checkpoint inhibition with epigenetic therapy is one such strategy that is being tested in clinical trials, encompassing a variety of cancer types. Studies have revealed key roles of epigenetic processes in regulating immune cell function and mediating antitumour immunity. These interactions make combined epigenetic therapy and immunotherapy an attractive approach to circumvent the limitations of immunotherapy alone. In this Review, we highlight the basic dynamic mechanisms underlying the synergy between immunotherapy and epigenetic therapies and detail current efforts to translate this knowledge into clinical benefit for patients.

Epigenetic treatment of multiple myeloma mediates tumor intrinsic and extrinsic immunomodulatory effects

Immune evasion is an important driver of disease progression in the plasma cell malignancy multiple myeloma. Recent work highlights the potential of epigenetic modulating agents as tool to enhance anti-tumor immunity. The immune modulating effects of the combination of a DNA methyltransferase inhibitor and a histone deacetylase inhibitor in multiple myeloma is insufficiently characterized. Therefore, we used the murine immunocompetent 5T33MM model to investigate hallmarks of immunogenic cell death as well as alterations in the immune cell constitution in the bone marrow of diseased mice in response to the DNA methyltransferase inhibitor decitabine and the histone deacetylase inhibitor quisinostat. Vaccination of mice with 5T33 cells treated with epigenetic compounds delayed tumor development upon a subsequent tumor challenge. In vitro, epigenetic treatment induced ecto-calreticulin and CD47, as well as a type I interferon response. Moreover, treated 5T33vt cells triggered dendritic cell maturation. The combination of decitabine and quisinostat in vivo resulted in combinatory anti-myeloma effects. In vivo, epigenetic treatment increased tumoral ecto-calreticulin and decreased CD47 and PD-L1 expression, increased dendritic cell maturation and reduced CD11b positive cells. Moreover, epigenetic treatment induced a temporal increase in presence of CD8-positive and CD4-positive T cells with naive and memory-like phenotypes based on CD62L and CD44 expression levels, and reduced expression of exhaustion markers PD-1 and TIM3. In conclusion, a combination of a DNA methyltransferase inhibitor and a histone deacetylase inhibitor increased the immunogenicity of myeloma cells and altered the immune cell constitution in the bone marrow of myeloma-bearing mice.

Epigenetic Therapy Ties MYC Depletion to Reversing Immune Evasion and Treating Lung Cancer

Combining DNA-demethylating agents (DNA methyltransferase inhibitors [DNMTis]) with histone deacetylase inhibitors (HDACis) holds promise for enhancing cancer immune therapy. Herein, pharmacologic and isoform specificity of HDACis are investigated to guide their addition to a DNMTi, thus devising a new, low-dose, sequential regimen that imparts a robust anti-tumor effect for non-small-cell lung cancer (NSCLC). Using in-vitro-treated NSCLC cell lines, we elucidate an interferon α/β-based transcriptional program with accompanying upregulation of antigen presentation machinery, mediated in part through double-stranded RNA (dsRNA) induction. This is accompanied by suppression of MYC signaling and an increase in the T cell chemoattractant CCL5. Use of this combination treatment schema in mouse models of NSCLC reverses tumor immune evasion and modulates T cell exhaustion state towards memory and effector T cell phenotypes. Key correlative science metrics emerge for an upcoming clinical trial, testing enhancement of immune checkpoint therapy for NSCLC.

MAGE-A11 is activated through TFCP2/ZEB1 binding sites de-methylation as well as histone modification and facilitates ESCC tumor growth

Recently, we have reported that the product of Melanoma Antigens Genes (MAGE) family member MAGE-A11 is an independent poor prognostic marker for esophageal squamous cell carcinoma (ESCC). However, the reason how MAGE-A11 is activated in ESCC progression still remains unclear. In the current study, we demonstrated that DNA methylation and the subsequent histone posttranslational modifications play crucial roles in the regulation of MAGE-A11 in ESCC progression. We found that the methylation rate of TFCP2/ZEB1 binding site on MAGE-A11 promoter in ESCC tissues and cells is higher than the normal esophageal epithelial tissues and cells. Transcription factors TFCP2 and ZEB1 directly bind MAGE-A11 promoter and regulate the endogenous MAGE-A11 expression in a methylation-dependent manner in ESCC cells. Following MAGE-A11 promoter methylation, the methyl-CpG-binding protein MeCP2 was found to bind the methylated MAGE-A11 promoter to mediate histone deactylation by recruiting HDAC1 and HDAC2. Simultaneously, histone inactivation marks including H3K27me3 as well as H3K9me3 were increased, whereas histone activation mark H3K4me3 was decreased. HDAC inhibitor Trichostatin A (TSA) increased DNA methylase inhibitor Decitabine (DAC)-induced MAGE-A11 expression. siRNA-mediated knockdown of histone methltransferase EZH2 or DZNep (a EZH2 inhibitor) treatment increased DAC-induced MAGE-A11 expression. Our results indicate that MAGE-A11 is activated through DNA demethylation, histone acetylation and histone methylation in ESCC, and its activation promotes ESCC tumor growth.

A novel multi-epitope vaccine from MMSA-1 and DKK1 for multiple myeloma immunotherapy

The identification of novel tumour-associated antigens is urgently needed to improve the efficacy of immunotherapy for multiple myeloma (MM). In this study, we identified a membrane protein MMSA-1 (multiple myeloma special antigen-1) that was specifically expressed in MM and exhibited significantly positive correlation with MM. We then identified HLA-A*0201-restricted MMSA-1 epitopes and tested their cytotoxic T lymphocyte (CTL) response. The MMSA-1 epitope SLSLLTIYV vaccine was shown to induce an obvious CTL response in vitro. To improve the immunotherapy, we constructed a multi-epitope peptide vaccine by combining epitopes derived from MMSA-1 and Dickkopf-1 (DKK1). The effector T cells induced by multi-epitope peptide vaccine-loaded dendritic cells lysed U266 cells more effectively than MMSA-1/DKK1 single-epitope vaccine. In myeloma-bearing severe combined immunodeficient mice, the multi-epitope vaccine improved the survival rate significantly compared with single-epitope vaccine. Consistently, multi-epitope vaccine decreased the tumour volume greatly and alleviated bone destruction. The frequencies of CD4⁺ and CD8⁺ T cells was significantly increased in mouse blood induced by the multi-epitope vaccine, indicating that it inhibits myeloma growth by changing T cell subsets and alleviating immune paralysis. This study identified a novel peptide from MMSA-1 and the multi-epitope vaccine will be used to establish appropriate individualized therapy for MM.

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.

Melanoma associated antigen (MAGE)-A3 promotes cell proliferation and chemotherapeutic drug resistance in gastric cancer

BACKGROUND

Melanoma-associated antigen (MAGE)-A3 is a member of the family of cancer-testis antigens and has been found to be epigenetically regulated and aberrantly expressed in various cancer types. It has also been found that MAGE-A3 expression may correlate with an aggressive clinical course and with chemo-resistance. The objectives of this study were to assess the relationship between MAGE-A3 promoter methylation and expression and (1) gastric cancer patient survival and (2) its functional consequences in gastric cancer-derived cells.

METHODS

Samples from two independent gastric cancer cohorts (including matched non-malignant gastric samples) were included in this study. MAGE-A3 methylation and mRNA expression levels were determined by methylation-specific PCR (MSP) and quantitative real-time PCR (qPCR), respectively. MAGE-A3 expression was knocked down in MKN1 gastric cancer-derived cells using miRNAs. In addition, in vitro cell proliferation, colony formation, apoptosis, cell cycle, drug treatment, immunohistochemistry and Western blot assays were performed.

RESULTS

Clinical analysis of 223 primary patient-derived samples (ntumor = 161, nnormal = 62) showed a significant inverse correlation between MAGE-A3 promoter methylation and expression in the cancer samples (R = -0.63, p = 5.99e-19). A lower MAGE-A3 methylation level was found to be associated with a worse patient survival (HR: 1.5, 95 % CI: 1.02-2.37, p = 0.04). In addition, we found that miRNA-mediated knockdown of MAGE-A3 expression in MKN1 cells caused a reduction in its proliferation and colony forming capacities, respectively. Under stress conditions MAGE-A3 was found to regulate the expression of Bax and p21. MAGE-A3 knock down also led to an increase in Puma and Noxa expression, thus contributing to an enhanced docetaxel sensitivity in the gastric cancer-derived cells.

CONCLUSIONS

From our results we conclude that MAGE-A3 expression is regulated epigenetically by promoter methylation, and that its expression contributes to gastric cell proliferation and drug sensitivity. This study underscores the potential implications of MAGE-A3 as a therapeutic target and prognostic marker in gastric cancer patients.

Targeting Histone Deacetylases in Diseases: Where Are We?

SIGNIFICANCE

Epigenetic inactivation of pivotal genes involved in cell growth is a hallmark of human pathologies, in particular cancer. Histone acetylation balance obtained through opposing actions of histone deacetylases (HDACs) and histone acetyltransferases is one epigenetic mechanism controlling gene expression and is, thus, associated with disease etiology and progression. Interfering pharmacologically with HDAC activity can correct abnormalities in cell proliferation, migration, vascularization, and death.

RECENT ADVANCES

Histone deacetylase inhibitors (HDACi) represent a new class of cytostatic agents that interfere with the function of HDACs and are able to increase gene expression by indirectly inducing histone acetylation. Several HDACi, alone or in combination with DNA-demethylating agents, chemopreventive, or classical chemotherapeutic drugs, are currently being used in clinical trials for solid and hematological malignancies, and are, thus, promising candidates for cancer therapy.

CRITICAL ISSUES

(i) Non-specific (off-target) HDACi effects due to activities unassociated with HDAC inhibition. (ii) Advantages/disadvantages of non-selective or isoform-directed HDACi. (iii) Limited number of response-predictive biomarkers. (iv) Toxicity leading to dysfunction of critical biological processes.

FUTURE DIRECTIONS

Selective HDACi could achieve enhanced clinical utility by reducing or eliminating the serious side effects associated with current first-generation non-selective HDACi. Isoform-selective and pan-HDACi candidates might benefit from the identification of biomarkers, enabling better patient stratification and prediction of response to treatment.

T cell-based targeted immunotherapies for patients with multiple myeloma

Despite high-dose chemotherapy followed by autologs stem-cell transplantation as well as novel therapeutic agents, multiple myeloma (MM) remains incurable. Following the general trend towards personalized therapy, targeted immunotherapy as a new approach in the therapy of MM has emerged. Better progression-free survival and overall survival after tandem autologs/allogeneic stem cell transplantation suggest a graft versus myeloma effect strongly supporting the usefulness of immunological therapies for MM patients. How to induce a powerful antimyeloma effect is the key issue in this field. Pivotal is the definition of appropriate tumor antigen targets and effective methods for expansion of T cells with clinical activity. Besides a comprehensive list of tumor antigens for T cell-based approaches, eight promising antigens, CS1, Dickkopf-1, HM1.24, Human telomerase reverse transcriptase, MAGE-A3, New York Esophageal-1, Receptor of hyaluronic acid mediated motility and Wilms' tumor gene 1, are described in detail to provide a background for potential clinical use. Results from both closed and on-going clinical trials are summarized in this review. On the basis of the preclinical and clinical data, we elaborate on three encouraging therapeutic options, vaccine-enhanced donor lymphocyte infusion, chimeric antigen receptors-transfected T cells as well as vaccines with multiple antigen peptides, to pave the way towards clinically significant immune responses against MM.

Efficient lysis of epithelial ovarian cancer cells by MAGE-A3-induced cytotoxic T lymphocytes using rAAV-6 capsid mutant vector

MAGE-A3 is highly expressed in epithelial ovarian cancer (EOC), making it a promising candidate for immunotherapy. We investigated whether dendritic cells (DCs) transduced with a rAAV-6 capsid mutant vector Y445F could elicit effective MAGE-A3-specific anti-tumor cytotoxic T lymphocyte (CTL) responses in vitro. MAGE-A3 was cloned and rAAV-6-MAGE-A3 purified, followed by proviral genome detection using real-time PCR. Immunofluorescence detection of rAAV-6-Y445F-MAGE-A3-transduced DCs demonstrated 60% transduction efficiency. Fluorescent in situ hybridization analysis confirmed chromosomal integration of rAAV vectors. Flow cytometric analysis of transduced DCs showed unaltered expression of critical monocyte-derived surface molecules with retention of allo-stimulatory activity. Co-culture of autologous T lymphocytes with MAGE-A3-expressing DCs produced CTLs that secreted IFN-γ, and efficiently killed MAGE-A3+ EOC cells. This form of rAAV-based DC immunotherapy, either alone or more likely in combination with other immune-enhancing protocols, may prove useful in the clinical setting for management of EOC.

Epigenetic modulating agents as a new therapeutic approach in multiple myeloma

Multiple myeloma (MM) is an incurable B-cell malignancy. Therefore, new targets and drugs are urgently needed to improve patient outcome. Epigenetic aberrations play a crucial role in development and progression in cancer, including MM. To target these aberrations, epigenetic modulating agents, such as DNA methyltransferase inhibitors (DNMTi) and histone deacetylase inhibitors (HDACi), are under intense investigation in solid and hematological cancers. A clinical benefit of the use of these agents as single agents and in combination regimens has been suggested based on numerous studies in pre-clinical tumor models, including MM models. The mechanisms of action are not yet fully understood but appear to involve a combination of true epigenetic changes and cytotoxic actions. In addition, the interactions with the BM niche are also affected by epigenetic modulating agents that will further determine the in vivo efficacy and thus patient outcome. A better understanding of the molecular events underlying the anti-tumor activity of the epigenetic drugs will lead to more rational drug combinations. This review focuses on the involvement of epigenetic changes in MM pathogenesis and how the use of DNMTi and HDACi affect the myeloma tumor itself and its interactions with the microenvironment.

Epigenetic induction of adaptive immune response in multiple myeloma: sequential azacitidine and lenalidomide generate cancer testis antigen-specific cellular immunity

Patients with multiple myeloma (MM) undergoing high dose therapy and autologous stem cell transplantation (SCT) remain at risk for disease progression. Induction of the expression of highly immunogenic cancer testis antigens (CTA) in malignant plasma cells in MM patients may trigger a protective immune response following SCT. We initiated a phase II clinical trial of the DNA hypomethylating agent, azacitidine (Aza) administered sequentially with lenalidomide (Rev) in patients with MM. Three cycles of Aza and Rev were administered and autologous lymphocytes were collected following the 2nd and 3rd cycles of Aza-Rev and cryopreserved. Subsequent stem cell mobilization was followed by high-dose melphalan and SCT. Autologous lymphocyte infusion (ALI) was performed in the second month following transplantation. Fourteen patients have completed the investigational therapy; autologous lymphocytes were collected from all of the patients. Thirteen patients have successfully completed SCT and 11 have undergone ALI. Six patients tested have demonstrated CTA up-regulation in either unfractionated bone marrow (n = 4) or CD138+ cells (n = 2). CTA (CTAG1B)-specific T cell response has been observed in all three patients tested and persists following SCT. Epigenetic induction of an adaptive immune response to cancer testis antigens is safe and feasible in MM patients undergoing SCT.

Improving T-cell therapy for relapsed EBV-negative Hodgkin lymphoma by targeting upregulated MAGE-A4

PURPOSE

Patients with Hodgkin lymphoma (HL) relapsing after hematopoietic stem cell transplant have limited options for long-term cure. We have shown that infused cytotoxic T cells (CTL) targeting Epstein Barr virus (EBV)-derived proteins induced complete remissions in EBV(+) HL patients. A limitation of this approach is that up to 70% of relapsed HL tumors are EBV-negative. For these patients, an alternative is to target the cancer/testis antigen MAGE-A4 present in EBV antigen-negative HL tumors. Furthermore, epigenetic modification by clinically available demethylating agents can enhance MAGE-A4 expression in previously MAGE-negative tumors.

EXPERIMENTAL DESIGN

We explored the feasibility of combining adoptive T cell therapy with epigenetic modification of tumor antigen expression. We further characterized MAGE-A4-specific T-cell phenotype and function, and examined the effects of the epigenetic modifying drug decitabine on these T cells.

RESULTS

Cytotoxic T cells were generated specifically recognizing MAGE-A4 expressed by autologous HL targets and tumor cell lines. Decitabine-previously shown to increase tumor antigen expression in HL-did not compromise MAGE-A4-specific T-cell phenotype and function. In patients treated with decitabine, expanded MAGE-A4-specific T cells had a broader antitumor T cell repertoire, consistent with increased antigen stimulation in vivo.

CONCLUSIONS

Adoptive transfer of MAGE-A4-specific T cells, combined with epigenetic modifying drugs to increase expression of the protein, may improve treatment of relapsed HL.