Low dose decitabine treatment induces CD80 expression in cancer cells and stimulates tumor specific cytotoxic T lymphocyte responses

The Role of the DNA Methyltransferase Family and the Therapeutic Potential of DNMT Inhibitors in Tumor Treatment

Members of the DNA methyltransferase (DNMT) family have been recognized as major epigenetic regulators of altered gene expression during tumor development. They establish and maintain DNA methylation of the CpG island of promoter and non-CpG region of the genome. The abnormal methylation status of tumor suppressor genes (TSGs) has been associated with tumorigenesis, leading to genomic instability, improper gene silence, and immune evasion. DNMT1 helps preserve methylation patterns during DNA replication, whereas the DNMT3 family is responsible for de novo methylation, creating new methylation patterns. Altered DNA methylation significantly supports tumor growth by changing gene expression patterns. FDA-approved DNMT inhibitors reverse hypermethylation-induced gene repression and improve therapeutic outcomes for cancer. Recent studies indicate that combining DNMT inhibitors with chemotherapies and immunotherapies can have synergistic effects, especially in aggressive metastatic tumors. Improving the treatment schedules, increasing isoform specificity, reducing toxicity, and utilizing genome-wide analyses of CRISPR-based editing to create personalized epigenetic therapies tailored to individual patient needs are promising strategies for enhancing therapeutic outcomes. This review discusses the interaction between DNMT regulators and DNMT1, its binding partners, the connection between DNA methylation and tumors, how these processes contribute to tumor development, and DNMT inhibitors' advancements and pharmacological properties.

Getting the right combination to break the epigenetic code

Rapid advances in the field of epigenetics have facilitated the development of novel therapeutics targeting epigenetic mechanisms that are hijacked by cancer cells to support tumour growth and progression. Several epigenetic agents have been approved by the FDA for the treatment of cancer; however, the efficacy of these drugs is dependent on the underlying biology and drivers of the disease, with inherent differences between solid tumours and haematological malignancies. The efficacy of epigenetic drugs as single agents remains limited across most cancer types, which has spurred the clinical development of combination therapies, with the hope of attaining synergistic activity and/or overcoming treatment resistance. In this Review we discuss clinical advances that have been achieved with the use of epigenetic agents in combination with chemotherapies, immunotherapies or other targeted agents, including epigenetic-epigenetic combinations, as well as limitations and challenges associated with these combinatorial strategies. So far, the success of combination therapies targeting epigenetic mechanisms has generally been confined to haematological malignancies, with limited efficacy observed in patients with solid tumours. Nevertheless, this Review captures the field of epigenetic combination therapies across the spectra of haematology and oncology, highlighting opportunities for precision therapy to effectively harness the potential of epigenetic agents and produce meaningful improvements in clinical outcomes.

Monocytic Differentiation in Acute Myeloid Leukemia Cells: Diagnostic Criteria, Biological Heterogeneity, Mitochondrial Metabolism, Resistance to and Induction by Targeted Therapies

We review the importance of monocytic differentiation and differentiation induction in non-APL (acute promyelocytic leukemia) variants of acute myeloid leukemia (AML), a malignancy characterized by proliferation of immature myeloid cells. Even though the cellular differentiation block is a fundamental characteristic, the AML cells can show limited signs of differentiation. According to the French-American-British (FAB-M4/M5 subset) and the World Health Organization (WHO) 2016 classifications, monocytic differentiation is characterized by morphological signs and the expression of specific molecular markers involved in cellular communication and adhesion. Furthermore, monocytic FAB-M4/M5 patients are heterogeneous with regards to cytogenetic and molecular genetic abnormalities, and monocytic differentiation does not have any major prognostic impact for these patients when receiving conventional intensive cytotoxic therapy. In contrast, FAB-M4/M5 patients have decreased susceptibility to the Bcl-2 inhibitor venetoclax, and this seems to be due to common molecular characteristics involving mitochondrial regulation of the cellular metabolism and survival, including decreased dependency on Bcl-2 compared to other AML patients. Thus, the susceptibility to Bcl-2 inhibition does not only depend on general resistance/susceptibility mechanisms known from conventional AML therapy but also specific mechanisms involving the molecular target itself or the molecular context of the target. AML cell differentiation status is also associated with susceptibility to other targeted therapies (e.g., CDK2/4/6 and bromodomain inhibition), and differentiation induction seems to be a part of the antileukemic effect for several targeted anti-AML therapies. Differentiation-associated molecular mechanisms may thus become important in the future implementation of targeted therapies in human AML.

The CAR macrophage cells, a novel generation of chimeric antigen-based approach against solid tumors

Today, adoptive cell therapy has many successes in cancer therapy, and this subject is brilliant in using chimeric antigen receptor T cells. The CAR T cell therapy, with its FDA-approved drugs, could treat several types of hematological malignancies and thus be very attractive for treating solid cancer. Unfortunately, the CAR T cell cannot be very functional in solid cancers due to its unique features. This treatment method has several harmful adverse effects that limit their applications, so novel treatments must use new cells like NK cells, NKT cells, and macrophage cells. Among these cells, the CAR macrophage cells, due to their brilliant innate features, are more attractive for solid tumor therapy and seem to be a better candidate for the prior treatment methods. The CAR macrophage cells have vital roles in the tumor microenvironment and, with their direct effect, can eliminate tumor cells efficiently. In addition, the CAR macrophage cells, due to being a part of the innate immune system, attended the tumor sites. With the high infiltration, their therapy modulations are more effective. This review investigates the last achievements in CAR-macrophage cells and the future of this immunotherapy treatment method.

Selinexor in Combination with Decitabine Attenuates Ovarian Cancer in Mice

BACKGROUND

High-grade serous ovarian cancer is a lethal gynecologic disease. Conventional therapies, such as platinum-based chemotherapy, are rendered inadequate for disease management as most advanced disease patients develop resistance to this therapy and soon relapse, leading to poor prognosis. Novel immunotherapy and targeted therapy are currently under investigation as treatment options for ovarian cancer, but so far with little success. Epigenetic changes, such as aberrant DNA methylation, have been reported in resistance to platinum-based therapy. Decitabine is a hypomethylating agent which is effective against platinum-resistant disease and also exhibits several anti-tumor immune functions. Selinexor is a selective inhibitor of nuclear protein export. It restored platinum sensitivity in patient-derived ovarian cancer cell lines and is currently in clinical trials for the treatment of platinum-resistant ovarian cancer. We hypothesized that these two agents used in combination could elicit more potent anti-tumor immune responses in vivo than either agent used alone.

METHODS

These studies were designed to investigate the efficacy of these two agents used in combination to treat ovarian cancer by assessing murine models for changes in disease pathology and in anti-tumor responses.

RESULTS

Decitabine priming followed by selinexor treatment significantly limited ascites formation and tumor size. This combination of agents also promoted T cell effector function as measured by granzyme B secretion. Treatment of mice with decitabine and selinexor led to the significant release of a broader range of macrophage and T cell cytokines and chemokines above control PBS and vehicle and above decitabine or selinexor treatment alone.

CONCLUSIONS

These results reveal crucial information for the design of clinical trials which may advance therapy outcomes in ovarian cancer.

Gene mutation landscape of a rare patient with acute megakaryoblastic leukemia after treatment of intracranial germ cell tumor

Introduction

It was first reported that germ cell tumor patients suffer from hematologic malignancies 37 years ago. Since then, the number of relevant reports has increased each year, with most cases being mediastinal germ cell tumor. Theories have been proposed to explain this phenomenon, including a shared origin of progenitor cells, the effects of treatment, and independent development. However, up to now, no widely accepted explanation exists. The case with acute megakaryoblastic leukemia and intracranial germ cell tumor has never been reported before and the association is far less known.

Methods

We used whole exome sequencing and gene mutation analysis to study the relationship between intracranial germ cell tumor and acute megakaryoblastic leukemia of our patient.

Results

We report a patient who developed acute megakaryoblastic leukemia after treatment for an intracranial germ cell tumor. Through whole exome sequencing and gene mutation analysis, we identified that both tumors shared the same mutation genes and mutation sites, suggesting they originated from the same progenitor cells and differentiated in the later stage.

Discussion

Our findings provide the first evidence supporting the theory that acute megakaryoblastic leukemia and intracranial germ cell tumor has the same progenitor cells.

Epigenetic Perspective of Immunotherapy for Cancers

Immunotherapy has brought new hope for cancer patients in recent times. However, despite the promising success of immunotherapy, there is still a need to address major challenges including heterogeneity in response among patients, the reoccurrence of the disease, and iRAEs (immune-related adverse effects). The first critical step towards solving these issues is understanding the epigenomic events that play a significant role in the regulation of specific biomolecules in the context of the immune population present in the tumor immune microenvironment (TIME) during various treatments and responses. A prominent advantage of this step is that it would enable researchers to harness the reversibility of epigenetic modifications for their druggability. Therefore, we reviewed the crucial studies in which varying epigenomic events were captured with immuno-oncology set-ups. Finally, we discuss the therapeutic possibilities of their utilization for the betterment of immunotherapy in terms of diagnosis, progression, and cure for cancer patients.

Epigenetic drugs in somatostatin type 2 receptor radionuclide theranostics and radiation transcriptomics in mouse pheochromocytoma models

Pheochromocytomas and paragangliomas (PCCs/PGLs) are catecholamine-producing tumors. In inoperable and metastatic cases, somatostatin type 2 receptor (SSTR2) expression allows for peptide receptor radionuclide therapy with [¹⁷⁷Lu]Lu-DOTA-TATE. Insufficient receptor levels, however, limit treatment efficacy. This study evaluates whether the epigenetic drugs valproic acid (VPA) and 5-Aza-2'-deoxycytidine (DAC) modulate SSTR2 levels and sensitivity to [¹⁷⁷Lu]Lu-DOTA-TATE in two mouse PCC models (MPC and MTT). Methods: Drug-effects on Sstr2/SSTR2 were investigated in terms of promoter methylation, mRNA and protein levels, and radiotracer binding. Radiotracer uptake was measured in subcutaneous allografts in mice using PET and SPECT imaging. Tumor growth and gene expression (RNAseq) were characterized after drug treatments. Results: DAC alone and in combination with VPA increased SSTR2 levels along with radiotracer uptake in vitro in MPC (high-SSTR2) and MTT cells (low-SSTR2). MTT but not MPC allografts responded to DAC and VPA combination with significantly elevated radiotracer uptake, although activity concentrations remained far below those in MPC tumors. In both models, combination of DAC, VPA and [¹⁷⁷Lu]Lu-DOTA-TATE was associated with additive effects on tumor growth delay and specific transcriptional responses in gene sets involved in cancer and treatment resistance. Effects of epigenetic drugs were unrelated to CpG island methylation of the Sstr2 promoter. Conclusion: This study demonstrates that SSTR2 induction in mouse pheochromocytoma models has some therapeutic benefit that occurs via yet unknown mechanisms. Transcriptional changes in tumor allografts associated with epigenetic treatment and [¹⁷⁷Lu]Lu-DOTA-TATE provide first insights into genetic responses of PCCs/PGLs, potentially useful for developing additional strategies to prevent tumor recurrence.

Recent progress in DNA methyltransferase inhibitors as anticancer agents

DNA methylation mediated by DNA methyltransferase is an important epigenetic process that regulates gene expression in mammals, which plays a key role in silencing certain genes, such as tumor suppressor genes, in cancer, and it has become a promising therapeutic target for cancer treatment. Similar to other epigenetic targets, DNA methyltransferase can also be modulated by chemical agents. Four agents have already been approved to treat hematological cancers. In order to promote the development of a DNA methyltransferase inhibitor as an anti-tumor agent, in the current review, we discuss the relationship between DNA methylation and tumor, the anti-tumor mechanism, the research progress and pharmacological properties of DNA methyltransferase inhibitors, and the future research trend of DNA methyltransferase inhibitors.

Dual epigenetic agents plus rituximab-gemcitabine-oxaliplatin as salvage treatment in relapsed/refractory diffuse large B-cell lymphoma patients failure of salvage chemotherapy

Refractory/relapsed (R/R) diffuse large B-cell lymphoma (DLBCL) patients' failure of salvage chemotherapy had extremely worse prognoses. Herein, 14 R/R DLBCL patients failed to salvage chemotherapy were exposed to dual epigenetic agents (Chidamide 30 mg biw*2w and Decitabine 10 mg/m² qd*d1-d5) and sequential R-GemOx (rituximab 375 mg/m² qd d6; gemcitabine 1 g/m² d7, d14; and oxaliplatin 100 mg/m² d7) for further salvage chemotherapy. Finally, 11/14(78.6%) patients achieved overall response with 6/14(42.9%) achieving complete remission and 2-year overall survival (OS)/progression free survival (PFS) rate was 42.7%, extremely higher than reported previously. Further subgroup analysis demonstrated that 2-year OS/PFS rate was significantly higher in patients achieved complete/partial remission or with low international prognosis index (IPI 0-2) than that in patients with steady disease or high IPI (3-5). Common grade 3-4 adverse events were hematological toxicities. All toxicities were transient and reversible. Our report implicates that combination of dual epigenetic agents and R-GemOx is a safe and promising alternative for R/R DLBCL patients.

Decitabine-primed tandem CD19/CD22 CAR-T therapy in relapsed/refractory diffuse large B-cell lymphoma patients

Chimeric antigen receptor T cell (CAR-T) therapy has emerged as highly effective in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), but only about 40% patients have achieved sustained responses. Here, we conducted a phase II clinical trial testing efficacy and toxicities of CAR-T therapy in R/R non-Hodgkin’s lymphoma patients (NCT03196830). Among enrolled patients, 33 R/R DLBCL patients pretreated with DFC (decitabine, fludarabine plus cyclophosphamide) lymphodepletion chemotherapy and infused with tandem CD19-CD22 based CAR-T cells were drawn out for efficacy and toxicities of CAR-T therapy evaluation. With a median follow-up of 10.9(0.6-29.0) months, the best overall response and complete remission (CR) rates were 90.9% and 63.6%, respectively. The median progression-free survival (PFS) was 10.2 months and overall survival (OS) was undefined. The 2-year OS and PFS rates were 54.3% and 47.2%, respectively. No severe grade 4 cytokine release syndrome (CRS) was observed and grade 3 CRS was observed in only 7 patients; 3 patients developed mild immune effect or cell-associated neurotoxic syndrome. All toxicities were transient and reversible and no CAR-T-related mortality. Further subgroup analysis showed that achieving CR was an independent prognostic factor associated with favorable PFS and OS. The 2-year OS and PFS for patients who achieved CR within 3 months (undefined versus undefined P=0.021 and undefined versus undefined P=0.036) or during the follow-up period were significantly longer than those who did not (undefined versus 4.6 months P < 0.0001 and undefined versus 2.0months P<0.001). While severe CRS was also an independent prognostic factor but associated with inferior PFS and OS. The 2-year OS and PFS for patients with grade 3 CRS were significantly shorter than those with grade 0-2 CRS (4.1 months versus undefined P<0.0001 and 1.7 months versus undefined P=0.0002). This study indicated that CD19/CD22 dual-targeted CAR-T therapy under a decitabine-containing lymphodepletion regimen may be a safe, potent effective approach to R/R DLBCL patients.

Immune Checkpoint Inhibition in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many solid tumors, with limited progress made in the area of myeloid malignancies. The low mutational burden of acute myeloid leukemia (AML) is one potential reason behind the lack of activity of T-cell harnessing ICIs, particularly CTLA-4 and PD-1 inhibitors. Innate immune checkpoints play a critical role in the immune escape of AML and myelodysplastic syndromes (MDS). The CD47 targeting agent, magrolimab, has shown promising activity when combined with azacitidine in early phase trials conducted in AML and higher-risk MDS, especially among patients harboring a TP53 mutation. Similarly, sabatolimab (an anti-TIM-3 monoclonal antibody) plus hypomethylating agents have shown durable responses in higher-risk MDS and AML in early clinical trials. Randomized trials are currently ongoing to confirm the efficacy of these agents. In this review, we will present the current progress and future directions of immune checkpoint inhibition in AML and MDS.

Solute Carrier Nucleoside Transporters in Hematopoiesis and Hematological Drug Toxicities: A Perspective

Simple Summary

Anticancer nucleoside analogs are promising treatments that often result in damaging toxicities and therefore ineffective treatment. Mechanisms of this are not well-researched, but cellular nucleoside transport research in mice might provide additional insight given transport’s role in mammalian hematopoiesis. Cellular nucleoside transport is a notable component of mammalian hematopoiesis due to how mutations within it relate to hematological abnormities. This review encompasses nucleoside transporters, focusing on their inherent properties, hematopoietic role, and their interplay in nucleoside drug treatment side effects. We then propose potential mechanisms to explain nucleoside transport involvement in blood disorders. Finally, we point out and advocate for future research areas that would improve therapeutic outcomes for patients taking nucleoside analog therapies.

Abstract

Anticancer nucleoside analogs produce adverse, and at times, dose-limiting hematological toxicities that can compromise treatment efficacy, yet the mechanisms of such toxicities are poorly understood. Recently, cellular nucleoside transport has been implicated in normal blood cell formation with studies from nucleoside transporter-deficient mice providing additional insights into the regulation of mammalian hematopoiesis. Furthermore, several idiopathic human genetic disorders have revealed nucleoside transport as an important component of mammalian hematopoiesis because mutations in individual nucleoside transporter genes are linked to various hematological abnormalities, including anemia. Here, we review recent developments in nucleoside transporters, including their transport characteristics, their role in the regulation of hematopoiesis, and their potential involvement in the occurrence of adverse hematological side effects due to nucleoside drug treatment. Furthermore, we discuss the putative mechanisms by which aberrant nucleoside transport may contribute to hematological abnormalities and identify the knowledge gaps where future research may positively impact treatment outcomes for patients undergoing various nucleoside analog therapies.

Molecular and Clinical Characterization of CD80 Expression via Large-Scale Analysis in Breast Cancer

Cancer immunotherapy is emerging as a novel promising therapy option for cancer patients. Despite the critical role of CD80 in the regulation of immune responses, the expression and biological functions of CD80 in breast cancer remain unknown. In this study, we aimed to investigate the role of CD80 both clinically and molecularly in breast cancer at a transcriptome level. Herein, we first analyzed the transcriptome profile and relevant clinical information derived from a total of 1090 breast cancer patients recorded in The Cancer Genome Atlas database and then validated this in the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) database (n = 1904). We revealed the associations of CD80 and the main molecular and clinical characteristics of breast cancer. The gene ontology analysis and Gene Set Variation Analysis of the CD80-related genes revealed that CD80 was closely correlated with immune responses and inflammatory activities in breast cancer. Moreover, the CD80 expression showed a remarkable positive correlation with several infiltrated immune cell populations. In summary, the CD80 expression was closely correlated with the malignancy of breast cancer, and our findings suggest that CD80 might be a promising target for immunotherapeutic strategies. To the best of our knowledge, this is the first integrative study characterizing the role of the CD80 expression in breast cancer via large-scale analyses.

Phase 1, dose-escalation study of guadecitabine (SGI-110) in combination with pembrolizumab in patients with solid tumors

Background

Data suggest that immunomodulation induced by DNA hypomethylating agents can sensitize tumors to immune checkpoint inhibitors. We conducted a phase 1 dose-escalation trial (NCT02998567) of guadecitabine and pembrolizumab in patients with advanced solid tumors. We hypothesized that guadecitabine will overcome pembrolizumab resistance.

Methods

Patients received guadecitabine (45 mg/m² or 30 mg/m², administered subcutaneously on days 1–4), with pembrolizumab (200 mg administered intravenously starting from cycle 2 onwards) every 3 weeks. Primary endpoints were safety, tolerability and maximum tolerated dose; secondary and exploratory endpoints included objective response rate (ORR), changes in methylome, transcriptome, immune contextures in pre-treatment and on-treatment tumor biopsies.

Results

Between January 2017 and January 2020, 34 patients were enrolled. The recommended phase II dose was guadecitabine 30 mg/m², days 1–4, and pembrolizumab 200 mg on day 1 every 3 weeks. Two dose-limiting toxicities (neutropenia, febrile neutropenia) were reported at guadecitabine 45 mg/m² with none reported at guadecitabine 30 mg/m². The most common treatment-related adverse events (TRAEs) were neutropenia (58.8%), fatigue (17.6%), febrile neutropenia (11.8%) and nausea (11.8%). Common, grade 3+ TRAEs were neutropaenia (38.2%) and febrile neutropaenia (11.8%). There were no treatment-related deaths. Overall, 30 patients were evaluable for antitumor activity; ORR was 7% with 37% achieving disease control (progression-free survival) for ≥24 weeks. Of 12 evaluable patients with non-small cell lung cancer, 10 had been previously treated with immune checkpoint inhibitors with 5 (42%) having disease control ≥24 weeks (clinical benefit). Reduction in LINE-1 DNA methylation following treatment in blood (peripheral blood mononuclear cells) and tissue samples was demonstrated and methylation at transcriptional start site and 5’ untranslated region gene regions showed enriched negative correlation with gene expression. Increases in intra-tumoural effector T-cells were seen in some responding patients. Patients having clinical benefit had high baseline inflammatory signature on RNAseq analyses.

Conclusions

Guadecitabine in combination with pembrolizumab is tolerable with biological and anticancer activity. Reversal of previous resistance to immune checkpoint inhibitors is demonstrated.

A Randomized Phase 2 Trial of Azacitidine ± Durvalumab as First-line Therapy for Higher-Risk Myelodysplastic Syndromes

This is the first reported randomized trial of immune checkpoint inhibitor therapy in HR-MDS.

Azacitidine combined with the PD-L1 inhibitor durvalumab was feasible but did not improve outcomes over azacitidine alone.

Azacitidine-mediated hypomethylation promotes tumor cell immune recognition but may increase the expression of inhibitory immune checkpoint molecules. We conducted the first randomized phase 2 study of azacitidine plus the immune checkpoint inhibitor durvalumab vs azacitidine monotherapy as first-line treatment for higher-risk myelodysplastic syndromes (HR-MDS). In all, 84 patients received 75 mg/m² subcutaneous azacitidine (days 1-7 every 4 weeks) combined with 1500 mg intravenous durvalumab on day 1 every 4 weeks (Arm A) for at least 6 cycles or 75 mg/m² subcutaneous azacitidine alone (days 1-7 every 4 weeks) for at least 6 cycles (Arm B). After a median follow-up of 15.25 months, 8 patients in Arm A and 6 in Arm B remained on treatment. Patients in Arm A received a median of 7.9 treatment cycles and those in Arm B received a median of 7.0 treatment cycles with 73.7% and 65.9%, respectively, completing ≥4 cycles. The overall response rate (primary end point) was 61.9% in Arm A (26 of 42) and 47.6% in Arm B (20 of 42; P = .18), and median overall survival was 11.6 months (95% confidence interval, 9.5 months to not evaluable) vs 16.7 months (95% confidence interval, 9.8-23.5 months; P = .74). Durvalumab-related adverse events (AEs) were reported by 71.1% of patients; azacitidine-related AEs were reported by 82% (Arm A) and 81% (Arm B). Grade 3 or 4 hematologic AEs were reported in 89.5% (Arm A) vs 68.3% (Arm B) of patients. Patients with TP53 mutations tended to have a worse response than patients without these mutations. Azacitidine increased programmed cell death ligand 1 (PD-L1 [CD274]) surface expression on bone marrow granulocytes and monocytes, but not blasts, in both arms. In summary, combining azacitidine with durvalumab in patients with HR-MDS was feasible but with more toxicities and without significant improvement in clinical outcomes over azacitidine alone. This trial was registered at www.clinicaltrials.gov as #NCT02775903.

Azacitidine and Durvalumab in First-line Treatment of Elderly Patients With Acute Myeloid Leukemia

This is the first reported randomized trial of immune checkpoint inhibitor therapy in older patients with AML.

Azacitidine combined with the PD-L1 inhibitor durvalumab was feasible but did not improve outcomes over azacitidine alone.

Evidence suggests that combining immunotherapy with hypomethylating agents may enhance antitumor activity. This phase 2 study investigated the activity and safety of durvalumab, a programmed death-ligand 1 (PD-L1) inhibitor, combined with azacitidine for patients aged ≥65 years with acute myeloid leukemia (AML), including analyses to identify biomarkers of treatment response. Patients were randomized to first-line therapy with azacitidine 75 mg/m² on days 1 through 7 with (Arm A, n = 64) or without (Arm B, n = 65) durvalumab 1500 mg on day 1 every 4 weeks. Overall response rate (complete response [CR] + CR with incomplete blood recovery) was similar in both arms (Arm A, 31.3%; Arm B, 35.4%), as were overall survival (Arm A, 13.0 months; Arm B, 14.4 months) and duration of response (Arm A, 24.6 weeks; Arm B, 51.7 weeks; P = .0765). No new safety signals emerged with combination treatment. The most frequently reported treatment-emergent adverse events were constipation (Arm A, 57.8%; Arm B, 53.2%) and thrombocytopenia (Arm A, 42.2%; Arm B, 45.2%). DNA methylation, mutational status, and PD-L1 expression were not associated with response to treatment. In this study, first-line combination therapy with durvalumab and azacitidine in older patients with AML was feasible but did not improve clinical efficacy compared with azacitidine alone. ClinicalTrials.gov: NCT02775903.

Acute Myeloid Leukemia Epigenetic Immune Escape From Nature Killer Cells by ICAM-1

Acute myeloid leukemia (AML), a malignant disorder of hemopoietic stem cells. AML can escape immunosurveillance of natural killer (NK) by gene mutation, fusions, and epigenetic modification, while the mechanism is not clearly understood. Here we show that the expression of Intercellular adhesion molecule‐1 (ICAM‐1, CD54) is silenced in AML cells. Decitabine could upregulate ICAM-1 expression, which contributes to the NK-AML cell conjugates and helps NK cells kill AML cells. We also show that ICAM-1 high expression can reverse the AML immune evasion and activate NK cells function in vivo. This study suggests that a combination of the hypomethylating agent and NK cell infusion could be a new strategy to cure AML.

Resistance to Hypomethylating Agents in Myelodysplastic Syndrome and Acute Myeloid Leukemia From Clinical Data and Molecular Mechanism

The nucleoside analogs decitabine (5-AZA-dC) and azacitidine (5-AZA) have been developed as targeted therapies to reverse DNA methylation in different cancer types, and they significantly improve the survival of patients who are not suitable for traditional intensive chemotherapies or other treatment regimens. However, approximately 50% of patients have a response to hypomethylating agents (HMAs), and many patients have no response originally or in the process of treatment. Even though new combination regimens have been tested to overcome the resistance to 5-AZA-dC or 5-AZA, only a small proportion of patients benefited from these strategies, and the outcome was very poor. However, the mechanisms of the resistance remain unknown. Some studies only partially described management after failure and the mechanisms of resistance. Herein, we will review the clinical and molecular signatures of the HMA response, alternative treatment after failure, and the causes of resistance in hematological malignancies.

Epigenetic mechanisms of liver tumor resistance to immunotherapy

Hepatocellular carcinoma (HCC) is the most common primary liver tumor, which stands fourth in rank of cancer-related deaths worldwide. The incidence of HCC is constantly increasing in correlation with the epidemic in diabetes and obesity, arguing for an urgent need for new treatments for this lethal cancer refractory to conventional treatments. HCC is the paradigm of inflammation-associated cancer, since more than 80% of HCC emerge consecutively to cirrhosis associated with a vast remodeling of liver microenvironment. In the recent decade, immunomodulatory drugs have been developed and have given impressive results in melanoma and later in several other cancers. In the present review, we will discuss the recent advancements concerning the use of immunotherapies in HCC, in particular those targeting immune checkpoints, used alone or in combination with other anti-cancers agents. We will address why these drugs demonstrate unsatisfactory results in a high proportion of liver cancers and the mechanisms of resistance developed by HCC to evade immune response with a focus on the epigenetic-related mechanisms.

Epigenetic Therapy Promotes the Ratio of Th1/Th17 Lineage to Reverse Immune Evasion and Treat Leukemia Relapse Post-allogeneic Stem Cell Transplantation in Non-APL AML Patients

To reverse the early-stage relapse post-hematopoietic stem cell transplantation, we investigated the safety and efficacy of a new epigenetic regimen (chidamide and decitabine plus thymalfasin simultaneously) on acute myeloid leukemia patients (excluding acute promyelocytic leukemia). Twenty-four patients were enrolled in this observational study during April 2015 to May 2018. The most common adverse event was reversible CTCAE grade 2 thrombocytopenia (20/24). Strikingly, all 24 patients had response to this epigenetic regimen accompanied with decreased measurable residual disease. The overall survival rate is 79.2% (19/24), with a relapse-free survival rate of 79.2% (19/24). During this regimen treatment, Th1 cells and CD3+CD4-CD8+T cells increased, and Th17 cells decreased gradually. The status of high Th1 and low Th17 cells was still observed on the 3rd month after discontinuation of this regimen. Interestingly, the significantly elevated ratio of Th1/Th17 seemed to reflect the treatment-related immune effect, which may be a valuable marker to be monitored in the early-relapse stage for evaluating the efficacy and prognosis.

A Retrospective Observation of Treatment Outcomes Using Decitabine-Combined Standard Conditioning Regimens Before Transplantation in Patients With Relapsed or Refractory Acute Myeloid Leukemia

Hypomethylating agents, decitabine (DAC) and azacitidine, can act as prophylactic and pre-emptive approaches after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and a non-intensive bridging approach before allo-HSCT. However, they are rarely used as a part of conditioning regimens in patients with relapsed or refractory acute myeloid leukemia (AML). This retrospectively study included a total of 65 patients (median, 37; range, 13–63) with relapsed or refractory AML who were treated by allo-HSCT after myeloablative conditioning regimens without or with DAC (high-dose DAC schedule, 75 mg/m² on day −9 and 50 mg/m² on day −8; low-dose DAC schedule, 25 mg/m²/day on day −10 to −8). DAC exerted no impact on hematopoietic reconstitution. However, patients who were treated with the high-dose DAC schedule had significantly higher incidence of overall survival (OS, 50.0%) and leukemia-free survival (LFS, 35.0%), and lower incidence of relapse (41.1%) and grade II–IV acute graft versus host disease (aGVHD, 10.0%) at 3 years, when compared with those treated with standard conditioning regimens or with the low-dose DAC schedule. In conclusion, high-dose DAC combined with standard conditioning regimens before allo-HSCT is feasible and efficient and might improve outcomes of patients with relapsed or refractory AML, which provides a potential approach to treat these patients.

Epigenetic strategies to boost CAR T cell therapy

Chimeric antigen receptor (CAR) T cell therapy has led to a paradigm shift in cancer immunotherapy, but still several obstacles limit CAR T cell efficacy in cancers. Advances in high-throughput technologies revealed new insights into the role that epigenetic reprogramming plays in T cells. Mechanistic studies as well as comprehensive epigenome maps revealed an important role for epigenetic remodeling in T cell differentiation. These modifications shape the overall immune response through alterations in T cell phenotype and function. Here, we outline how epigenetic modifications in CAR T cells can overcome barriers limiting CAR T cell effectiveness, particularly in immunosuppressive tumor microenvironments. We also offer our perspective on how selected epigenetic modifications can boost CAR T cells to ultimately improve the efficacy of CAR T cell therapy.

Phenotypic and genetic evaluation of human monocyte-derived dendritic cells generated from whole blood for immunotherapy

Background

Dendritic cells (DCs) recognize different pathogens and cancer cells and activate the adaptive immune response. The generation of effective DC-based cancer vaccines depends on the appropriate differentiation of monocytes in vitro. This study aimed to standardize a protocol for the in vitro differentiation of human peripheral blood monocytes into immature DCs upon treatment with growth factors and generate monocyte-derived DCs (MoDCs). Peripheral blood mononuclear cells were separated from peripheral blood. After monocyte enrichment by plastic adhesion, monocytes were cultured for 6 days in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 to generate immature DCs. The cells were examined by microscopy. Using flow cytometry, DCs were evaluated for the expression of the CD83 and HLA-DR surface antigens, for the uptake of fluorescein isothiocyanate conjugated dextran, and also for the expression of CD80 and CD86 mRNA.

Results

CD80 and CD86 genes expression was upregulated at day six and exhibited a significant difference (P < 0.05). DCs showed positive expression of the CD83 and HLA-DR surface antigens by flow cytometry and FITC-conjugated dextran uptake.

Conclusion

This study represents a preliminary trial to generate immature MoDCs in vitro from blood monocytes collected by the flask adherence method. It offers a panel of surface markers for DCs characterization and provides Immature DCs for experimental procedures after 6 incubation days.

Mechanisms of primary and acquired resistance to PD-1/PD-L1 blockade and the emerging role of gut microbiome

As a very promising immunotherapy, PD-1/PD-L1 blockade has revolutionized the treatment of a variety of tumor types, resulting in significant clinical efficacy and lasting responses. However, these therapies do not work for a large proportion of patients initially, which is called primary resistance. And more frustrating is that most patients eventually develop acquired resistance after an initial response to PD-1/PD-L1 blockade. The mechanisms that lead to primary and acquired resistance to PD-1/PD-L1 inhibition have remained largely unclear. Recently, the gut microbiome has emerged as a potential regulator for PD-1/PD-L1 blockade. This review elaborates on the current understanding of the mechanisms in terms of PD-1 related signaling pathways and necessary factors. Moreover, this review discusses new strategies to increase the efficacy of immunotherapy from the perspectives of immune markers and gut microbiome.

Low-dose decitabine as part of a modified Bu-Cy conditioning regimen improves survival in AML patients with active disease undergoing allogeneic hematopoietic stem cell transplantation

Relapse is the major cause of mortality in patients with acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Effective preventive intervention in high-risk AML may be crucial. In this study, we investigated the clinical efficacy and safety of low dose decitabine (DAC) as part of a modified Busulfan-Cyclophosphamide (Bu-Cy) regimen for high-risk AML patients undergoing allo-HSCT to reduce relapse rate. Fifty-nine patients received DAC (20 mg/m²/d, i.v.) for 5 days, followed by modified Bu-Cy (DAC group). A matched-pair control (CON) group of 177 patients (matched 1:3) received modified Bu-Cy only. The differences were more substantial among patients with active disease: 2-year OS, 80.7% (DAC) versus 43.5% (CON), P = 0.011 and 2-year LFS, 64.9% (DAC) versus 39.2% (CON), P = 0.024. Median time to relapse was 8 months (DAC) versus 5 months (CON) for the entire groups and 6.5 months (DAC) versus 3.5 months (CON) for patients with active disease. In summary, our data indicated that the conditioning regimen containing low dose DAC may confer a survival advantage in high-risk AML patients with active disease undergoing allo-HSCT, and a prospective randomized trial is warranted to confirm these observations.

Emerging treatment options for patients with high-risk myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis with peripheral blood cytopenias, dysplastic cell morphology, and a variable risk of progression to acute myeloid leukemia (AML). The hypomethylating agents (HMA) azacitidine and decitabine have been used for over a decade in MDS treatment and lead to a modest survival benefit. However, response rates are only around 40% and responses are mostly transient. For HMA-refractory patients the prognosis is poor and there are no therapies approved by the United States Food and Drug Administration.

Combinations of HMAs, especially along with immune checkpoint inhibitors, have shown promising signals in both the frontline and HMA-refractory setting. Several other novel agents including orally available and longer acting HMAs, the BCL-2 inhibitor venetoclax, oral agents targeting driver mutations (IDH1/2, FLT3), immunotherapies, and new options for intensive chemotherapy have been studied with variable success and will be reviewed herein. Except for the minority of patients with targetable driver mutations, HMAs – likely as part of combination therapies – will remain the backbone of frontline MDS treatment. However, the wider use of genetic testing may enable a more targeted and individualized therapy of MDS patients.

Mechanisms of resistance to immune checkpoint inhibitors and strategies to reverse drug resistance in lung cancer

In recent years, the research of immune checkpoint inhibitors has made a great breakthrough in lung cancer treatment. Currently, a variety of immune checkpoint inhibitors have been applied into clinical practice, including antibodies targeting the programmed cell death-1, programmed cell death-ligand 1, and cytotoxic T-lymphocyte antigen 4, and so on. However, not all patients can benefit from the treatment. Abnormal antigen presentation, functional gene mutation, tumor microenvironment, and other factors can lead to primary or secondary resistance. In this paper, we reviewed the molecular mechanism of immune checkpoint inhibitor resistance and various combination strategies to overcome resistance, in order to expand the beneficial population and enable precision medicine.

The Resistance Mechanisms of Lung Cancer Immunotherapy

Immunotherapy has revolutionized lung cancer treatment in the past decade. By reactivating the host’s immune system, immunotherapy significantly prolongs survival in some advanced lung cancer patients. However, resistance to immunotherapy is frequent, which manifests as a lack of initial response or clinical benefit to therapy (primary resistance) or tumor progression after the initial period of response (acquired resistance). Overcoming immunotherapy resistance is challenging owing to the complex and dynamic interplay among malignant cells and the defense system. This review aims to discuss the mechanisms that drive immunotherapy resistance and the innovative strategies implemented to overcome it in lung cancer.

Immune Surveillance in Clinical Regression of Preinvasive Squamous Cell Lung Cancer

Before squamous cell lung cancer develops, precancerous lesions can be found in the airways. From longitudinal monitoring, we know that only half of such lesions become cancer, whereas a third spontaneously regress. Although recent studies have described the presence of an active immune response in high-grade lesions, the mechanisms underpinning clinical regression of precancerous lesions remain unknown. Here, we show that host immune surveillance is strongly implicated in lesion regression. Using bronchoscopic biopsies from human subjects, we find that regressive carcinoma in situ lesions harbor more infiltrating immune cells than those that progress to cancer. Moreover, molecular profiling of these lesions identifies potential immune escape mechanisms specifically in those that progress to cancer: antigen presentation is impaired by genomic and epigenetic changes, CCL27-CCR10 signaling is upregulated, and the immunomodulator TNFSF9 is downregulated. Changes appear intrinsic to the carcinoma in situ lesions, as the adjacent stroma of progressive and regressive lesions are transcriptomically similar. SIGNIFICANCE: Immune evasion is a hallmark of cancer. For the first time, this study identifies mechanisms by which precancerous lesions evade immune detection during the earliest stages of carcinogenesis and forms a basis for new therapeutic strategies that treat or prevent early-stage lung cancer.See related commentary by Krysan et al., p. 1442.This article is highlighted in the In This Issue feature, p. 1426.

Conjugation of TLR7 Agonist Combined with Demethylation Treatment Improves Whole-Cell Tumor Vaccine Potency in Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) is a malignant hematological disease with high refractory rate. Immune escape of AML cells is one of the underlying mechanisms mediating the relapse of the cancers. Various immunotherapies based on the 'patients' immune response to tumor cells have been developed to targeting the immune escape of AML cells, which lead to the minimal residual disease (MRD) after treatment. But the efficacy of those treatments or the combination of treatments remains unsatisfactory. Methods: A Toll-like receptor (TLR)-7 agonist SZU-106 was chemically synthesized. SZU-106 was conjugated to Decitabine (DAC), a demethylation agent, treated AML cells to construct tumor vaccine. The potency of the newly constructed AML cell vaccine, SZU-106-DAC-AML was tested in vitro and in vivo for the expression of tumor antigens and the activation level of immune responses. Results: Compared to the well characterized TLR7 agonist R848, SZU-106 has a comparable potency to activate TLR7 signaling pathway. SZU-106-DAC-AML, constructed by conjugating SZU-106 to DAC treated tumor cells, exhibited increased expression of tumor antigens, and enhanced the activation of DC cells and T cells in vitro and in vivo. The result of xenograft tumor model showed that SZU-106-DAC-AML tumor vaccine greatly inhibited tumor growth and prolonged animal survival. Conclusions: Conjugation of TLR7 agonist combined with up-regulation of tumor antigen expression improved the effectiveness of whole-cell tumor vaccine in AML.

Mechanisms of Resistance to Checkpoint Blockade Therapy

Immune checkpoint blockades (ICBs), as a major breakthrough in cancer immunotherapy, target CTLA-4 and the PD-1/PD-L1 axis and reinvigorate anti-tumor activities by disrupting co-inhibitory T-cell signaling. With unprecedented performance in clinical trials, ICBs have been approved by FDA for the treatment of malignancies such as melanoma, non-small-cell lung cancer, colorectal cancer, and hepatocellular carcinoma. However, while ICBs are revolutionizing therapeutic algorithms for cancers, the frequently observed innate, adaptive or acquired drug resistance remains an inevitable obstacle to a durable antitumor activity, thus leading to non-response or tumor relapse. Researches have shown that resistance could occur at each stage of the tumor's immune responses. From the current understanding, the molecular mechanisms for the resistance of ICB can be categorized into the following aspects: 1. Tumor-derived mechanism, 2. T cell-based mechanism, and 3. Tumor microenvironment-determined resistance. In order to overcome resistance, potential therapeutic strategies include enhancing antigen procession and presentation, reinforcing the activity and infiltration of T cells, and destroying immunosuppression microenvironment. In future, determining the driving factors behind ICB resistance by tools of precision medicine may maximize clinical benefits from ICBs. Moreover, efforts in individualized dosing, intermittent administration and/or combinatory regimens have opened new directions for overcoming ICB resistance.

DNA Methyltransferase Inhibitors: Catalysts For Antitumour Immune Responses

Epigenetics is a kind of heritable change that involves the unaltered DNA sequence and can have effects on gene expression. The regulatory mechanism mainly includes DNA methylation, histone modification and non-coding RNA regulation. DNA methylation is currently the most studied aspect of epigenetics. It is widely present in eukaryotic cells and is the most important epigenetic mark in the regulation of gene expression in the cell. DNA methyltransferase inhibitors (DNMTi) have been increasingly recognized in the field of cancer immunotherapy, have been approved for the treatment of acute myeloid leukaemia (AML) and are widely being used in clinical trials of cancer immunotherapies. DNMTi promote the reactivation of tumour suppressor genes, enhance tumour immunogenicity, and stimulate a variety of immune cells to secrete cytokines that exert cytotoxic effects, promote tumour cell death, including macrophages, natural killer (NK) cells and CD8+ T cells, and upregulate major histocompatibility complex (MHC) class I expression levels. Here, we mainly summarize the epigenetics related to DNMTi and their regulation of the antitumour immune response and DNMTi combined with immuno-therapeutics or histone deacetylase inhibitors to demonstrate the great development potential and clinical application value of DNMTi.

Immunological Effects of Epigenetic Modifiers

Epigenetic alterations are associated with major pathologies including cancer. Epigenetic dysregulation, such as aberrant histone acetylation, altered DNA methylation, or modified chromatin organization, contribute to oncogenesis by inactivating tumor suppressor genes and activating oncogenic pathways. Targeting epigenetic cancer hallmarks can be harnessed as an immunotherapeutic strategy, exemplified by the use of pharmacological inhibitors of DNA methyltransferases (DNMT) and histone deacetylases (HDAC) that can result in the release from the tumor of danger-associated molecular patterns (DAMPs) on one hand and can (re-)activate the expression of tumor-associated antigens on the other hand. This finding suggests that epigenetic modifiers and more specifically the DNA methylation status may change the interaction of chromatin with chaperon proteins including HMGB1, thereby contributing to the antitumor immune response. In this review, we detail how epigenetic modifiers can be used for stimulating therapeutically relevant anticancer immunity when used as stand-alone treatments or in combination with established immunotherapies.

Low-dose decitabine priming with intermediate-dose cytarabine followed by umbilical cord blood infusion as consolidation therapy for elderly patients with acute myeloid leukemia: a phase II single-arm study

BACKGROUND

Treatment of acute myeloid leukemia (AML) in elderly patients remains a great challenge. In this prospective single arm study (ChiCTR-OPC-15006492), we evaluated the efficacy and safety of a novel consolidation therapy with low-dose decitabine (LD-DAC) priming with intermediate-dose cytarabine (ID-Ara-C) followed by umbilical cord blood (UCB) infusion in elderly patients with AML.

METHODS

A total of 25 patients with a median age of 64-years-old (60-74-years-old) who achieved complete remission (CR) after induction chemotherapy were enrolled in the study.

RESULTS

The 2-year actual overall survival (OS) rate and leukemia-free survival (LFS) was 68.0 and 60.0%, respectively. The hematological and non-hematological toxicity were mild to moderate, and only one patient died in remission due to infection with possible acute graft versus host disease (aGVHD). Compared to a concurrent cohort of patients receiving conventional consolidation therapy, the study group tended to have an improved OS and LFS (p = 0.046 and 0.057, respectively), while the toxicity was comparable between the two groups.

CONCLUSIONS

This study suggested the novel combination of LD-DAC, ID-Ara-C, and UCB infusion might be an optimal consolidation therapy for elderly patients with AML, and a prospective phase III randomized study is warranted to confirm this observation.

TRIAL REGISTRATION

This single-arm phase II clinical trial in elderly AML patients was registered prospectively at www.chictr.org.cn (identifier: ChiCTR-OPC-15006492 ) on June 2, 2015.

[Decitabine-based conditioning regimen is feasible and effective in the treatment of myelodysplastic syndrome and chronic myelomonocytic leukemia]

Objective: To assess the efficacy and toxicity of decitabine-based conditioning regimen in patients with myelodysplastic syndrome (MDS) , acute myeloid leukemia secondary to MDS (MDS-AML) or chronic myelomonocytic leukemia (CMML) . Methods: From March 1, 2013 to May 25, 2015, 22 patients who underwent allogenic hematopoietic stem cell transplantation (allo-HSCT) with decitabine-based conditioning regimen were analyzed retrospectively. Results: ①22 patients, 14 males and 8 females with a median age of 42.5 (24-56) years old, were diagnosed as MDS (n=14) , CMML (n=4) , MDS-AML (n=4) . ②15 patients were treated with the conditioning regimen of decitabine combined with busulfan, cyclophosphamide, fludarabine, and cytarabine, the other 7 cases were treated with decitabine, busulfan, fludarabine, and cytarabine. The dose of decitabine was 20 mg·m(-2)·d(-1) for 5 days.Rabbit anti-human anti-thymocyte globulin (2.5 mg·kg(-1)·d(-1) for 4 days) was involved in conditioning regimen in patients with unrelated donor or haploidentical transplantation. ③Except 1 patient died of infection in 2 months after transplantation, the other patients were engrafted successfully. The median time of granulocyte engraftment was 13 (12-18) days, and the median time of platelet engraftment was 16 (13-81) days. ④The incidence of acute graft versus host disease (aGVHD) was (41.3±10.6) %, and severe aGVHD (grade of III-IV) was (18.4±9.7) %. The incidence of chronic graft versus host disease (cGVHD) was (56.4±11.3) %, and extensive cGVHD was (36.4±12.1) %. ⑤8 patients were suffered with cytomegalovirus (CMV) viremia. Among the 18 patients with definitely infection, 6 occurred during myelosuppression and 12 cases occurred after hematopoietic reconstruction. The 2-year and 3-year non-relapse mortality was (13.9±7.4) % and (24.3±9.5) %, respectively. ⑥The 2-year and 3-year overall survival (OS) was (77.3±8.9) % and (67.9±10.0) %, respectively. The 2-year and 3-year relapse-free survival (RFS) was (72.7±9.5) % and (63.6±10.3) %, respectively. Conclusions: allo-HSCT with decitabine-based conditioning regimen is feasible in the treatment of MDS, MDS-AML or CMML.

Epithelial CD80 promotes immune surveillance of colonic preneoplastic lesions and its expression is increased by oxidative stress through STAT3 in colon cancer cells

BACKGROUND

One of the most potent costimulatory molecules involved in the recognition and killing of tumor cells is CD80. However, its role and the molecular mechanisms regulating its expression in sporadic colorectal carcinogenesis remain elusive. Here, we provide evidence for CD80 overexpression in human colon epithelial cells derived from preneoplastic mucosa.

METHODS

Expression of CD80 on colonic epithelial cells isolated from normal human colonic mucosa, preneoplastic and neoplastic specimens was assessed by flow cytometry. WT and CD80KO mice received azoxymethane to induce colon preneoplastic lesions and sacrificed to perform histology, flow cytometry analysis and immunohistochemistry of colonic mucosa. Some WT mice were treated with a monoclonal anti-CD80 antibody following AOM administration. Primary colon epithelial cells and CT26 cell line were used to quantify the expression of CD80 in response to pro-oxidant stimuli. Specific pharmacological inhibitors and siRNA silencing were used to inhibit MAPK pathways and STAT3.

RESULTS

CD80 expression was significantly increased in colon epithelial cells of human preneoplastic lesions. In the AOM model, CD80 impairment by administration of neutralizing antibodies or use of CD80 knockout mice enhanced dysplasia development. In vitro, CD80 upregulation was induced by oxidative stress in colon cancer cells and primary colon epithelial cells. In addition, reactive oxygen species could induce CD80 expression via the JNK and p38 MAPK pathways, that activated STAT3 transcription factor in colon cancer epithelial cells.

CONCLUSION

This study provide evidence for a major role of CD80 in orchestrating immune surveillance of colon preneoplastic lesions and might help to develop novel approaches that exploit anti-tumor immunity to prevent and control colon cancer.

Immune checkpoint-based therapy in myeloid malignancies: a promise yet to be fulfilled

INTRODUCTION

Immune system evasion is essential for tumor cell survival and is mediated by the immunosuppressive tumor microenvironment and the activation of inhibitory immune checkpoints. While immune checkpoint-based therapy yielded impressive results in several advanced solid malignancies such as melanoma and non-small cell lung cancer, its role in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) is still evolving. Areas covered: Here we review the immunology in the tumor microenvironment in the bone marrow and discuss the current preclinical and clinical data for immune checkpoint-based therapy in myeloid neoplasms. Expert commentary: Clinical trials of immune checkpoint inhibitors (ICI) in AML and MDS are still in early stages and reported results so far have been modest especially for monotherapy use in the refractory settings. However, there are preliminary data for synergistic effects for combination of multiple ICI with hypomethylating agents and conventional chemotherapy. ICI might also be effective in eradicating minimal residual disease and to prevent relapse following induction chemotherapy or hematopoietic stem cell transplant. Additional trials to provide insight into the efficacy and safety profile of immune checkpoint-based therapy, its optimal timing and potential combination with other types of therapy as well as identification of predictive biomarkers are needed.

Mechanisms of Resistance to PD-1 and PD-L1 Blockade

Cancer immunotherapy utilizing blockade of the PD-1/PD-L1 checkpoint has revolutionized the treatment of a wide variety of malignancies, leading to durable therapeutic responses not typically seen with traditional cytotoxic anticancer agents. However, these therapies are ineffective in a significant percentage of patients, and some initial responders eventually develop resistance to these therapies with relapsed disease. The mechanisms leading to both primary and acquired resistance to PD-1/PD-L1 inhibition are varied and can be both multifactorial and overlapping in an individual patient. As the mechanisms of resistance to PD-1/PD-L1 blockade continue to be further characterized, new strategies are being developed to prevent or reverse resistance to therapy, leading to improved patient outcomes.

Epigenetic therapy combinations in acute myeloid leukemia: what are the options?

Epigenetics refers to the regulation of gene expression mainly by changes in DNA methylation and modifications of histone proteins without altering the actual DNA sequence. While epigenetic modifications are essential for normal cell differentiation, several driver mutations in leukemic pathogenesis have been identified in genes that affect epigenetic processes, such as DNA methylation and histone acetylation. Several therapeutic options to target epigenetic alterations in acute myeloid leukemia (AML) have been successfully tested in preclinical studies and various drugs have already been approved for use in clinical practice. Among these already approved therapeutics are hypomethylating agents (azacitidine and decitabine) and isocitrate dehydrogenase inhibitors (ivosidenib, enasidenib). Other agents such as bromodomain-containing epigenetic reader proteins and histone methylation (e.g. DOT1L) inhibitors are currently in advanced clinical testing. As several epigenetic therapies have only limited efficacy when used as single agents, combination therapies that target AML pathogenesis at different levels and exploit synergistic mechanisms are also in clinical trials. Combinations of either epigenetic therapies with conventional chemotherapy, different forms of epigenetic therapies, or epigenetic therapies with immunotherapy are showing promising early results. In this review we summarize the underlying pathophysiology and rationale for epigenetically-based combination therapies, review current preclinical and clinical data and discuss the future directions of epigenetic therapy combinations in AML.

Combinatorial Antitumor Activity of Oxaliplatin with Epigenetic Modifying Agents, 5-Aza-CdR and FK228, in Human Gastric Cancer Cells

Epigenetic silencing is considered to be a major mechanism for loss of activity in tumor suppressors. Reversal of epigenetic silencing by using inhibitors of DNA methyltransferase (DNMT) or histone deacetylases (HDACs) such as 5-Aza-CdR and FK228 has shown to enhance cytotoxic activities of several anticancer agents. This study aims to assess the combinatorial effects of gene-silencing reversal agents (5-Aza-CdR and FK228) and oxaliplatin in gastric cancer cells, i.e., Epstein-Barr virus (EBV)-negative SNU-638 and EBV-positive SNU-719 cells. The doublet combinatorial treatment of 5-Aza-CdR and FK228 exhibited synergistic effects in both cell lines, and this was further corroborated by Zta expression induction in SNU-719 cells. Three drug combinations as 5-Aza-CdR/FK228 followed by oxaliplatin, however, resulted in antagonistic effects in both cell lines. Simultaneous treatment with FK228 and oxaliplatin induced synergistic and additive effects in SNU-638 and SNU-719 cells, respectively. Three drug combinations as 5-Aza-CdR prior to FK228/oxaliplatin, however, again resulted in antagonistic effects in both cell lines. This work demonstrated that efficacy of doublet synergistic combination using DNMT or HDACs inhibitors can be compromised by adding the third drug in pre- or post-treatment approach in gastric cancer cells. This implies that the development of clinical trial protocols for triplet combinations using gene-silencing reversal agents should be carefully evaluated in light of their potential antagonistic effects.

Targeting the Immune Microenvironment in Acute Myeloid Leukemia: A Focus on T Cell Immunity

Immunotherapies, such as chimeric antigen receptor T cells, bispecific antibodies, and immune checkpoint inhibitors, have emerged as promising modalities in multiple hematologic malignancies. Despite the excitement surrounding immunotherapy, it is currently not possible to predict which patients will respond. Within solid tumors, the status of the immune microenvironment provides valuable insight regarding potential responses to immune therapies. Much less is known about the immune microenvironment within hematologic malignancies but the characteristics of this environment are likely to serve a similar predictive role. Acute myeloid leukemia (AML) is the most common hematologic malignancy in adults, and only 25% of patients are alive 5 years following their diagnosis. There is evidence that manipulation of the immune microenvironment by leukemia cells may play a role in promoting therapy resistance and disease relapse. In addition, it has long been documented that through modulation of the immune system following allogeneic bone marrow transplant, AML can be cured, even in patients with the highest risk disease. These concepts, along with the poor prognosis associated with this disease, have encouraged many groups to start exploring the utility of novel immune therapies in AML. While the implementation of these therapies into clinical trials for AML has been supported by preclinical rationale, many questions still exist surrounding their efficacy, tolerability, and the overall optimal approach. In this review, we discuss what is known about the immune microenvironment within AML with a specific focus on T cells and checkpoints, along with their implications for immune therapies.

Novel Therapies for Acute Myeloid Leukemia: Are We Finally Breaking the Deadlock?

Acute myeloid leukemia (AML) is one of the best studied malignancies, and significant progress has been made in understanding the clinical implications of its disease biology. Unfortunately, drug development has not kept pace, as the '7+3' induction regimen remains the standard of care for patients fit for intensive therapy 40 years after its first use. Temporal improvements in overall survival were mostly confined to younger patients and driven by improvements in supportive care and use of hematopoietic stem cell transplantation. Multiple forms of novel therapy are currently in clinical trials and are attempting to bring bench discoveries to the bedside to benefit patients. These novel therapies include improved chemotherapeutic agents, targeted molecular inhibitors, cell cycle regulators, pro-apoptotic agents, epigenetic modifiers, and metabolic therapies. Immunotherapies in the form of vaccines; naked, conjugated and bispecific monoclonal antibodies; cell-based therapy; and immune checkpoint inhibitors are also being evaluated in an effort to replicate the success seen in other malignancies. Herein, we review the scientific basis of these novel therapeutic approaches, summarize the currently available evidence, and look into the future of AML therapy by highlighting key clinical studies and the challenges the field continues to face.

Successful treatment of high-risk myelodysplastic syndrome with decitabine-based chemotherapy followed by haploidentical lymphocyte infusion: A case report and literature review

RATIONALE

The current therapy for elderly patients with high-risk myelodysplastic syndromes (MDSs) remains unsatisfactory. Decitabine, which has been approved to treat MDS, cannot eliminate malignant clones of MDS.

PATIENT CONCERNS

A 68-year-old woman presented with multiple divergent bleeding points in the subcutaneous tissue of the limb. Two years earlier, she had been diagnosed with invasive ductal carcinoma of the left breast and had undergone left modified radical mastectomy and local radiation therapy.

DIAGNOSES

The patient was diagnosed with MDS refractory anemia with excess of blast II and was classified as very high risk according to the revised international prognostic scoring system.

INTERVENTIONS

The chemotherapy regimen consisted of decitabine (20 mg/m intravenously on days 1-5), cytarabine (10 mg/m every 12 hours subcutaneously on days 1-5), aclarubicin hydrochloride (20 mg intravenously on days 1, 3, and 5), and recombinant human granulocyte colony-stimulating factor (250 μg/d subcutaneously from day 0 to day 5). Peripheral mononuclear cells from her son were infused at 36 hours after the end of each chemotherapy cycle. The patient received a total of 4 cycles of the therapy.

OUTCOMES

The patient achieved complete remission after the first cycle of the treatment. There was no clinical evidence of MDS relapse as of 4 years after the completion of the treatment.

LESSONS

The results suggested that decitabine-based chemotherapy and haploidentical lymphocyte infusion may be act synergistically. Combination therapy is a suitable, safe, and effective treatment regimen for elderly patients with high-risk MDS.

Analysis of infantile fibrosarcoma reveals extensive T-cell responses within tumors: Implications for immunotherapy

BACKGROUND

Infantile fibrosarcoma (IFS) is a rare pediatric malignancy with relatively good prognosis, but the risk of progression or recurrence after therapy exists. To understand the immune microenvironment of IFS and determine if immunotherapy is a potential treatment, we analyzed T-cell responses in IFS tumors.

PROCEDURE

IFS tumors were analyzed by immunohistochemistry and multicolor flow cytometry to characterize immune cell infiltration and function. Tumor infiltrating lymphocytes (TILs) were expanded in vitro and evaluated for recognition of autologous tumor cells. Real-time PCR was applied to evaluate tumor expression of chemokines/cytokines and tumor antigens.

RESULTS

Significant infiltration of both CD4+ and CD8+ T cells was found in seven of 10 IFS but rarely found in age- and sex-matched rhabdomyosarcoma tumors. The TILs from recurrent IFS tumors expressed high levels of costimulatory molecules such as CD28, 4-1BB, and OX40, but little or no coinhibitory molecules such as PD-1 and CTLA4, Tim3, Lag3, and CD39. Upon activation, large portions of TILs produced IFN-γ and TNF-α. Eighteen out of 40 T cell lines generated from surgically removed tumors could recognize autologous tumor cells. Moreover, we found that IFS tumors expressed high levels of T-cell chemokines such as CXCL10 and CXCL16, and also classic tumor antigens such as CTAG2, GAGE, and NY-ESO-1, whose expression could be further enhanced by treatment with epigenetic modulator decitabine.

CONCLUSIONS

IFS tumors are highly immunogenic and expansion of TILs followed by adoptive cell transfer could be a potential immunotherapy for IFS patients undergoing tumor recurrence.

Tyrosine kinase inhibitors and immune checkpoint blockade in allogeneic hematopoietic cell transplantation

Advances in the prevention of graft-versus-host disease (GVHD) and opportunistic infection have improved survival after allogeneic hematopoietic cell transplantation (allo-HCT) in the past decade. However, few inroads have been made into the treatment or prevention of relapse of the underlying malignancy for which allo-HCT is being performed. The introduction of US Food and Drug Administration-approved agents with significant activity in a variety of hematologic malignancies provides an opportunity to evaluate these interventions in the allo-HCT setting. Some of the most promising new agents include tyrosine kinase inhibitors (TKIs) directed at bcr-abl, kinase inhibitors targeting fms-like tyrosine kinase 3, and immune checkpoint inhibitors blocking both CTLA4 and PD-1. Data have emerged indicating potential efficacy of these agents in preventing or treating relapse, though definitive evidence remains elusive. However, potential toxicity can be considerable, highlighting the need for further clinical trials to define the therapeutic window. This review explores the immunologic and clinical consequence of treatment with both TKIs and checkpoint inhibitors in the peri- and post-allo-HCT setting.

Epigenetic View on Interferon γ Signalling in Tumour Cells

IFN-γ is a pleiotropic cytokine crucial for both innate and adaptive immunity, which also plays a critical role in immunological surveillance of cancer. Genetic defects or gene silencing in the IFN-γ signal transduction pathways as well as in the expression of IFN-γ-regulated genes represent frequent mechanisms by which tumour cells can escape from immune responses. Epigenetic control of the IFN-γ signalling pathway activation associated with epigenetic changes in the corresponding regulatory gene regions, such as chromatin remodelling, histone acetylation and methylation, and DNA demethylation is frequently dysregulated in tumour cells. Epigenetic silencing of the IFN-γ regulatory pathway components, as well as of the IFN-γ-regulated genes crucial for tumour cell recognition or induction of anti-tumour immune responses, has been documented in various cancer models. Expression of both IFN-γ signalling pathway components and selected IFN-γ-regulated genes can be influenced by epigenetic modifiers, namely DNA methyltransferase and histone deacetylase inhibitors. These agents thus can mimic, restore, or boost the immunomodulatory effects of IFN-γ in tumour cells, which can contribute to their anti-tumour therapeutic efficacies and justifies their potential use in combined epigenetic therapy with immunotherapeutic approaches.