DNA demethylating agent decitabine broadens the peripheral T cell receptor repertoire

The DNA methylation landscape across the TCR loci in patients with acute myeloid leukemia

The capacity of T cells to initiate anti-leukemia immune responses is determined by the ability of their receptors (TCRs) to recognize leukemia neoantigens. Epigenetic mechanisms including DNA methylation contribute to shaping the TCR repertoire composition and diversity. The DNA hypomethylating agents (HMAs) have been widely used in the treatment of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Whether DNA HMAs directly influence TCR gene loci methylation patterns remains unknown. By analyzing public datasets, we compared methylation patterns across TCR loci in AML patients and healthy controls. We also explored how HMAs influence TCR loci DNA methylation in patients with AML. While methylation patterns are largely conserved across the TCR loci, certain V genes exhibit high interindividual variability. Although overall methylation levels within the TCR loci did not show significant differences, specific sites, including 32 TRAV and 12 TRBV sites exhibited distinct methylation patterns when comparing T cells from healthy donors to those from patients with AML. In leukemic cells, decitabine treatment demethylates sites across the TRAV and TRBV genes. While not as significant, a similar pattern of demethylation is observed in T cells. Pretreatment AML samples exhibit higher methylation beta values in differentially methylated positions (DMPs) compared with non-DMPs. Methylation levels of certain TRAV and TRBV genes in leukemic cells are associated with patients' risk status. The presence of disease specific TCR loci methylated signatures that are associated with clinical outcome presents an opportunity for therapeutic intervention. HMAs can modulate the TCR loci methylation patterns, yet whether they could reprogram the TCR repertoire composition remains to be explored.

Inhibition of DNMTs increases neoantigen-reactive T-cell toxicity against microsatellite-stable colorectal cancer in combination with radiotherapy

The therapeutic efficacy of immunotherapy is limited in the majority of colorectal cancer patients due to the low mutational and neoantigen burdens in this immunogenically "cold" microsatellite stability-colorectal cancer (MSS-CRC) cohort. Here, we showed that DNA methyltransferase (DNMT) inhibition upregulated neoantigen-bearing gene expression in MSS-CRC, resulting in increased neoantigen presentation by MHC class I in tumor cells and leading to increased neoantigen-specific T-cell activation in combination with radiotherapy. The cytotoxicity of neoantigen-reactive T cells (NRTs) to DNMTi-treated cancer cells was highly cytotoxic, and these cells secreted high IFNγ levels targeting MSS-CRC cells after ex vivo expansion of NRTs with DNMTi-treated tumor antigens. Moreover, the therapeutic efficacy of NRTs further increased when NRTs were combined with radiotherapy in vivo. Administration of DNMTi-augmented NRTs and radiotherapy achieved an ∼50 % complete response and extended survival time in an immunocompetent MSS-CRC animal model. Moreover, remarkably, splenocytes from these mice exhibited neoantigen-specific T-cell responses, indicating that radiotherapy in combination with DNMTi-augmented NRTs prolonged and increased neoantigen-specific T-cell toxicity in MSS-CRC patients. In addition, these DNMTi-augmented NRTs markedly increase the therapeutic efficacy of cancer vaccines and immune checkpoint inhibitors (ICIs). These data suggest that a combination of radiotherapy and epi-immunotherapeutic agents improves the function of ex vivo-expanded neoantigen-reactive T cells and increases the tumor-specific cytotoxic effector population to enhance therapeutic efficacy in MSS-CRC.

Epigenetic drugs as new emerging therapeutics: What is the scale's orientation of application and challenges?

Epigenetics is the study of heritable changes in gene expression or function without altering the DNA sequence. Important factors are part of epigenetic events, such as methylation, DNA histone rearrangements, nucleosome transposition, and non-coding RNAs. Dysregulated epigenetic mechanics are associated with various cancers' initiation, development, and metastasis. It is known that the occurrence and development of cancer can be controlled by regulating unexpected epigenetic events. Epi-drugs are used singly or in combination with chemotherapy and enhance antitumor activity, reduce drug resistance, and stimulate the host immune response. Despite these benefits, epigenetic therapy as a single therapy or in combination with other drugs leads to adverse effects. This review article introduces and compares the advantages, disadvantages, and side effects of using these drugs for the first time since their introduction. Also, this article describes the mechanism of action of various epigenetic drugs. Recommendations for future use of epigenetic drugs as cancer therapeutics are suggested as an overall conclusion.

Profiling the epigenetic landscape of the antigen receptor repertoire: the missing epi-immunogenomics data

High-resolution sequencing methods that capture the epigenetic landscape within the T cell receptor (TCR) gene loci are pivotal for a fundamental understanding of the epigenetic regulatory mechanisms of the TCR repertoire. In our opinion, filling the gaps in our understanding of the epigenetic mechanisms regulating the TCR repertoire will benefit the development of strategies that can modulate the TCR repertoire composition by leveraging the dynamic nature of epigenetic modifications.

Decitabine increases neoantigen and cancer testis antigen expression to enhance T-cell-mediated toxicity against glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults. Despite maximal treatment, median survival remains dismal at 14-24 months. Immunotherapies, such as checkpoint inhibition, have revolutionized management of some cancers but have little benefit for GBM patients. This is, in part, due to the low mutational and neoantigen burden in this immunogenically "cold" tumor.

METHODS

U87MG and patient-derived cell lines were treated with 5-aza-2'-deoxycytidine (DAC) and underwent whole-exome and transcriptome sequencing. Cell lines were then subjected to cellular assays with neoantigen and cancer testis antigen (CTA) specific T cells.

RESULTS

We demonstrate that DAC increases neoantigen and CTA mRNA expression through DNA hypomethylation. This results in increased neoantigen presentation by MHC class I in tumor cells, leading to increased neoantigen- and CTA-specific T-cell activation and killing of DAC-treated cancer cells. In addition, we show that patients have endogenous cancer-specific T cells in both tumor and blood, which show increased tumor-specific activation in the presence of DAC-treated cells.

CONCLUSIONS

Our work shows that DAC increases GBM immunogenicity and consequent susceptibility to T-cell responses in vitro. Our results support a potential use of DAC as a sensitizing agent for immunotherapy.

Clinical evidence for a biological effect of epigenetically active decitabine in relapsed or progressive rhabdoid tumors

BACKGROUND

Refined therapy has helped to improve survival rates in rhabdoid tumors (RT). Prognosis for patients with chemoresistant, recurrent, or progressive RT remains dismal. Although decitabine, an epigenetically active agent, has mainly been evaluated in the management of hematologic malignancies in adults, safety in children has also been demonstrated repeatedly.

MATERIALS AND METHODS

A retrospective series of patients who received decitabine upon relapse or progression following therapy according to the EU-RHAB regimen is presented. Due to the retrospective nature of analyses, response was defined as measurable regression of at least one lesion on imaging. 850k methylation profiling was done whenever tumor tissue was available.

RESULTS

A total of 22 patients with RT of any anatomical localization were included. Most patients (19/22) presented with metastases. All received low-dose decitabine with or preceding conventional chemotherapy. Patients received a median of two (1-6) courses of decitabine; 27.3% (6/22) demonstrated a radiological response. Molecular analyses revealed increased methylation levels in tumors from responders. No excessive toxicity was observed. Clinical benefits for responders included eligibility for early phase trials or local therapy. Responders showed prolonged time to progression and overall survival. Due to small sample size, statistical correction for survivorship bias demonstrated no significant effect on survival for responders.

CONCLUSIONS

Patients with RT demonstrate promising signs of antitumor activity after multiagent relapse therapy including decitabine. Analyses of methylation data suggest a specific effect on an epigenetic level. We propose to consider decitabine and other epigenetic drugs as candidates for further clinical investigations in RT.

Homozygous deletion of the HLA-B gene as an acquired-resistance mechanism to nivolumab in a patient with lung adenocarcinoma: a case report

Immune checkpoint inhibitors (ICIs) have greatly improved the treatment of advanced non-small-cell lung cancer, including lung adenocarcinoma (LUAD). Patients treated with ICIs can have long-term clinical outcomes; however, acquired resistance to ICI therapy has been frequently observed. To date, little is known about the underlying mechanisms. In this study, we report the case of a male smoker with metastatic LUAD who initially received multi-line radiotherapy and chemotherapy and achieved stable disease (SD) for almost 10 years. The patient was treated with nivolumab for about 15 months. However, the disease later progressed rapidly. A genetic profile of the patient revealed the homozygous deletion of the human leukocyte antigen (HLA)-B gene, which may have conferred the acquired resistance. Our study is the first to describe the homozygous deletion of the HLA-B gene as an acquired-resistance mechanism to programmed cell death protein 1 (PD-1) blockade in a patient with LUAD. This evidence suggests that tumor cells can selectively lose HLA-A, B, and C to survive under strong immune pressure. This discovery enriches and develops our understanding of the mechanism of drug resistance in ICI therapy in LUAD. However, further investigations are urgently needed to be conducted to determine how this resistance can be overcome.

HCC and Molecular Targeting Therapies: Back to the Future

Hepatocellular carcinoma (HCC) is one of the leading causes of death from cancer in the world. Recently, the effectiveness of new antiviral therapies and the HBV vaccine have reduced HCC’s incidence, while non-alcoholic steato-hepatitis is an emerging risk factor. This review focuses on antiangiogenic molecules and immune checkpoint inhibitors approved for HCC treatment and possible future approaches. Sorafenib was the first drug approved for the treatment of advanced HCC (aHCC) and it has been shown to increase survival by a few months. Lenvatinib, a multikinase inhibitor, has shown non-inferiority in survival compared with sorafenib and an improvement in progression-free survival (PFS). The combination of atezolizumab (an anti-PDL1 antibody) and bevacizumab (an anti-VEGF antibody) was the first drug combination approved for HCC, demonstrating improved survival compared with sorafenib (19.2 vs. 13.4 months). As a second line of therapy, three regimens (regorafenib, cabozantinib, and ramucirumab) have been approved for the treatment of aHCC after progression on sorafenib according to guidelines. Furthermore, nivolumab, pembrolizumab, and nivolumab plus ipilimumab have been approved by the FDA (2017, 2018, and 2020, respectively). Finally, immune target therapy, cancer vaccines, and epigenetic drugs represent three new possible weapons for the treatment of HCC.

Can the New and Old Drugs Exert an Immunomodulatory Effect in Acute Myeloid Leukemia?

Simple Summary

The advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and of a tolerogenic microenvironment for acute myeloid leukemia (AML) fitness. We reviewed the “off-target” effects on the immune system of different drugs used in the treatment of AML to explore the advantages of this unexpected interaction.

Abstract

Acute myeloid leukemia (AML) is considered an immune-suppressive neoplasm capable of evading immune surveillance through cellular and environmental players. Increasing knowledge of the immune system (IS) status at diagnosis seems to suggest ever more attention of the crosstalk between the leukemic clone and its immunologic counterpart. During the last years, the advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and suppression for leukemia fitness. Considering all these premises, we reviewed the “off-target” effects on the IS of different drugs used in the treatment of AML, focusing on the main advantages of this interaction. The data reported support the idea that a successful therapeutic strategy should consider tailored approaches for performing leukemia eradication by both direct blasts killing and the engagement of the IS.

Relapsed/refractory classical Hodgkin lymphoma effectively treated with low-dose decitabine plus tislelizumab: A case report

BACKGROUND

Academic studies have proved that anti-programmed death-1 (PD-1) monoclonal antibodies demonstrated remarkable activity in relapsed/refractory classical Hodgkin lymphoma (cHL). However, most patients ultimately experienced failure or resistance. It is urgent and necessary to develop a novel strategy for relapsed/refractory cHL. The aim of this case report is to evaluate the combination approach of low-dose decitabine plus a PD-1 inhibitor in relapsed/ refractory cHL patients with prior PD-1 inhibitor exposure.

CASE SUMMARY

The patient was a 27-year-old man who complained of enlarged right-sided cervical lymph nodes and progressive pain aggravation of the right shoulder over the past 3 mo before admission. Histological analysis of lymph node biopsy was suggestive of cHL. The patient experienced failure of eight lines of therapy, including multiple cycles of chemotherapy, PD-1 blockade, and anti-CD47 antibody therapy. Contrast-enhanced CT showed that the tumors of the chest and abdomen significantly shrunk or disappeared after three cycles of treatment with decitabine plus tislelizumab. The patient had been followed for 11.5 mo until March 2, 2021, and no progressive enlargement of the tumor was observed.

CONCLUSION

The strategy of combining low-dose decitabine with tislelizumab could reverse the resistance to PD-1 inhibitors in patients with heavily pretreated relapsed/ refractory cHL. The therapeutic effect of this strategy needs to be further assessed.

Low-Dose Decitabine Augments the Activation and Anti-Tumor Immune Response of IFN-γ+ CD4+ T Cells Through Enhancing IκBα Degradation and NF-κB Activation

BACKGROUND

CD4+ T cells play multiple roles in controlling tumor growth and increasing IFN-γ+ T-helper 1 cell population could promote cell-mediated anti-tumor immune response. We have previously showed that low-dose DNA demethylating agent decitabine therapy promotes CD3+ T-cell proliferation and cytotoxicity; however, direct regulation of purified CD4+ T cells and the underlying mechanisms remain unclear.

METHODS

The effects of low-dose decitabine on sorted CD4+ T cells were detected both in vitro and in vivo. The activation, proliferation, intracellular cytokine production and cytolysis activity of CD4+ T cells were analyzed by FACS and DELFIA time-resolved fluorescence assays. In vivo ubiquitination assay was performed to assess protein degradation. Moreover, phosphor-p65 and IκBα levels were detected in sorted CD4+ T cells from solid tumor patients with decitabine-based therapy.

RESULTS

Low-dose decitabine treatment promoted the proliferation and activation of sorted CD4+ T cells, with increased frequency of IFN-γ+ Th1 subset and enhanced cytolytic activity in vitro and in vivo. NF-κB inhibitor, BAY 11-7082, suppressed decitabine-induced CD4+ T cell proliferation and IFN-γ production. In terms of mechanism, low-dose decitabine augmented the expression of E3 ligase β-TrCP, promoted the ubiquitination and degradation of IκBα and resulted in NF-κB activation. Notably, we observed that in vitro low-dose decitabine treatment induced NF-κB activation in CD4+ T cells from patients with a response to decitabine-primed chemotherapy rather than those without a response.

CONCLUSION

These data suggest that low-dose decitabine potentiates CD4+ T cell anti-tumor immunity through enhancing IκBα degradation and therefore NF-κB activation and IFN-γ production.

Case Report: Low-Dose Decitabine Plus Anti-PD-1 Inhibitor Camrelizumab for Previously Treated Advanced Metastatic Non-Small Cell Lung Cancer

Background: Although the programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors have markedly changed the strategies of cancer treatment, most patients with advanced non-small cell lung cancer (NSCLC) do not respond to PD-1/PD-L1 monotherapy. Epigenetic drugs have been hypothesized to possess the potential to sensitize PD-1/PD-L1 inhibitors.

Case Presentation: Three patients with advanced metastatic NSCLC failed to respond to first-line systemic therapy and had a low tumor mutation burden, low tumor neoantigen burden, low microsatellite instability, and HLA loss of heterozygosity according to their target lesion biopsies, all of which were considered unfavorable factors for PD-1/PD-L1 blockage. However, all three patients responded to low-dose decitabine, an epigenetic drug, in combination with camrelizumab (anti-PD-1 antibody), with only controllable adverse events, indicating that low-dose decitabine can sensitize PD-1/PD-L1 inhibitors.

Summary: We report a novel therapy with low-dose decitabine plus camrelizumab for advanced NSCLC on the basis of successful treatment of three patients, emphasizing the potential of epigenetic drugs to regulate PD-1/PD-L1 inhibitors in advanced NSCLC.

Very-low-dose decitabine treatment for patients with intermediate- or high-risk myelodysplastic syndrome: a retrospective analysis of thirteen cases

Decitabine is a hypomethylating drug that is used to treat myelodysplastic syndrome (MDS) at a recommended dose and schedule (20 mg/m² per day, for 5 consecutive days). However, due to its relatively high incidence of side effects and its effects on neoplastic cells, many studies have begun to explore the clinical application of a low dose of decitabine for treating MDS. In this retrospective study, we examined the effects of a very-low-dose decitabine schedule for treating MDS. A total of 13 patients diagnosed with de novo MDS received a schedule of intravenous decitabine administration at 6 mg/m² per day for 7 days, repeated every 4 weeks. The complete response rate was 30.8%, and the overall response rate was 69.2%. In patients with complete remission, the median time to granulocyte recovery greater than 0.5 × 10⁹/L during complete remission (CR) was 15 days. In patients with remission, the median time to granulocyte recovery greater than 0.5 × 10⁹/L was 10.5 days. The 1-year survival rate was 72.7% and the median survival was 28.0 months. In summary, we demonstrated that a very-low-dose decitabine schedule has an appreciable response and survival rate, as well as appreciable tolerance and medical compliance for treating MDS.

The effects of CTX damage or inhibition of bone marrow hematopoiesis and GM-CSF stimulation of bone marrow hematopoiesis on the peripheral blood TCRβ CDR3 repertoire of BALB/c mice

Objective: This paper aims to investigate the dynamic changes of the T-cell receptor (TCR) β complementarity-determining region 3 (CDR3) repertoire during cyclophosphamide or Cytoxan (CTX) damage or inhibition of bone marrow hematopoiesis caused by a reduction of peripheral blood white blood cells (WBCs) in BALB/c mice.Methods: We analyze TCR CDR3 repertoire of BALB/c mice including (1) NS control group (2) CTX damage group (3) CTX damage + GM-CSF recovery group (4) CTX damage + auto-recovery group.Results: The number of WBCs in the CTX group is significantly lower than that in the NS group and after GM-CSF injection, the GM-CSF group is higher than that in the NS group. The diversity of the CTX damage group is the highest and there is a significant difference in high-frequency clonal proliferation between the CTX damage group and CTX damage + GM-CSF recovery group compared with the NS control group. In addition, the numbers of unique productive CDR3 overlapping numbers in the four experimental groups are similar.Conclusions: These data reveal that CTX significantly reduced the number of WBCs and ratio of high-frequency TCR CDR3 sequences, and indirectly increased the diversity of the TCR CDR3 repertoire. GM-CSF quickly restored the number of WBCs, and partially restored changes in the TCR CDR3 repertoire induced by CTX. Results from monitoring the dynamic changes of the TCR CDR3 repertoire can be used to assess the effects of CTX and GM-CSF on the function of peripheral blood T cells and to explore the possible underlying mechanisms.

Decitabine assists umbilical cord-derived mesenchymal stem cells in improving glucose homeostasis by modulating macrophage polarization in type 2 diabetic mice

Background

Mesenchymal stem cells (MSCs) have emerged as a promising therapy for type 2 diabetes (T2D). Mechanistic researches demonstrate that the anti-diabetic effect of MSCs is partially mediated by eliciting macrophages into an anti-inflammatory phenotype thus alleviating insulin resistance. However, single MSC infusion is insufficient to ameliorate sustained hyperglycemia or normalize blood glucose levels. In this study, we used decitabine (DAC), which is involved in the regulation of macrophage polarization, to test whether MSCs combined with decitabine can prolong and enhance the anti-diabetic effect in T2D mice.

Methods

High-fat diet (HFD) and streptozocin (STZ) were given to induce T2D mouse model. Successfully induced T2D mice were randomly divided into four groups: T2D group, MSC group, DAC group, and MSC + DAC group. Blood glucose was monitored, and glucose tolerance and insulin sensitivity were evaluated during the entire analysis period. Epididymal fat was extracted for analysis of macrophage phenotype and inflammation in adipose tissue. In vitro, we examined the effect of MSC + DAC on macrophage polarization in bone marrow-derived macrophages (BMDMs) and explore the possible mechanism.

Results

MSC infusion effectively improved insulin sensitivity and glucose homeostasis in T2D mice within 1 week, whereas combination therapy of MSCs + DAC extended the anti-diabetic effects of MSCs from 1 to 4 weeks (the end of the observation). Correspondingly, more M2 macrophages in adipose tissue were observed in the combination therapy group over the entire study period. In vitro, compared with the MSC group, MSCs combined with decitabine more effectively polarized M1 macrophages to M2 macrophages. Further analysis showed that the effect of MSC + DAC on macrophage polarization was largely abrogated by the peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662.

Conclusions

Our data suggest that MSCs combined with decitabine can more effectively alleviate insulin resistance and prolong and enhance the anti-diabetic effect of MSCs in T2D mice in part by prompting M2 polarization in a PPARγ-dependent manner. Thus, decitabine may be an applicable addition to MSCs for diabetes therapy.

Graphic Abstract

UC-MSCs combined with decitabine activate the IL4R/STAT6/STAT3/PPARγ axis to further promote M2 macrophage polarization in adipose tissue, reduce inflammation, improve insulin sensitivity, and lead to better glucose metabolism and long-term hypoglycemic effects

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1338-2) contains supplementary material, which is available to authorized users.

Addition of Low-Dose Decitabine to Anti-PD-1 Antibody Camrelizumab in Relapsed/Refractory Classical Hodgkin Lymphoma

PURPOSE

Anti-programmed death-1 (PD-1) monotherapy induces a high response rate in patients with relapsed/refractory classic Hodgkin lymphoma (cHL), but complete remission (CR) is infrequently observed. As decitabine is known to boost T-cell function, we assessed the safety and efficacy of anti-PD-1 camrelizumab alone versus decitabine-primed camrelizumab in patients with relapsed/refractory cHL.

METHODS

This two-arm, open-label, phase II study enrolled patients with relapsed/refractory cHL who had received at least two lines of previous therapy. Anti-PD-1 treatment-naïve patients were randomly assigned (1:2) to camrelizumab (200 mg) monotherapy or decitabine (10 mg/d, days 1 to 5) plus camrelizumab (200 mg, day 8) combination therapy every 3 weeks. Patients who were previously treated with anti-PD-1 were assigned combination therapy. Primary end point was CR rate and safety.

RESULTS

Overall, 86 patients were enrolled and evaluated for response, with a median follow-up of 14.9 months. In anti-PD-1-naïve patients, CR rate was 32% (six of 19 patients) with camrelizumab monotherapy versus 71% (30 of 42 patients) who were administered decitabine plus camrelizumab (P = .003). At the time of analysis, the response duration rate at 6 months was 76% on camrelizumab monotherapy versus 100% on decitabine plus camrelizumab. For patients who were previously treated with anti-PD-1, 28% achieved CR and 24% partial response after decitabine plus camrelizumab. Ten patients maintained a response at more than 6 months and 81% of responders were estimated to have a response at more than 1 year. For both treatments, the most common adverse events were clinically inconsequential cherry hemangiomas and leukocytopenia that were self-limiting.

CONCLUSION

CR rate in patients with relapsed/refractory cHL who were clinically naïve to PD-1 blockade was significantly higher with decitabine plus camrelizumab than with camrelizumab alone. Decitabine plus camrelizumab may reverse resistance to PD-1 inhibitors in patients with relapsed/refractory cHL.

Excessive activated T-cell proliferation after anti-CD19 CAR T-cell therapy

Excessive activated T-cell proliferation was observed in vivo in one patient after an anti-CD19-chimeric antigen receptor (CAR) T-cell infusion. The patient, who had chemotherapy refractory and CD19⁺ diffuse large B-cell lymphoma (DLBCL), received an anti-CD19 CAR T-cell infusion following conditioning chemotherapy (fludarabine/cyclophosphamide). The lymphocyte count in the peripheral blood (PB) increased to 77 × 10⁹/L on day 13 post infusion, and the proportion of CD8⁺ actived T cells was 93.06% of the lymphocytes. Then, the patient suffered from fever and hypoxaemia. Significant increases in serum cytokine, lactate dehydrogenase, aspartate aminotransferase (AST), alanine transaminase (ALT), and glutamic-oxalacetic transaminase (γ-GT) levels were observed. A high-throughput sequencing analysis for T-cell receptors (TCRs) and whole-genome sequencing were used to explore the mechanisms underlying this excessive T-cell proliferation. TCR diversity was demonstrated, but no special gene mutation was found. The patient was found to be infected with the John Cunningham polyomavirus (JCV). It cannot be ruled out the bystander activation pathway induced by JCV infections related the excessive activated T-cell proliferation. Although the clinical and laboratory data do not fully explain the reason for excessive T-cell proliferation after the anti-CD19 CAR T-cell infusion, the risk of this type of toxicity should be emphasized. This study was registered at www.clinicaltrials.gov as NCT01864889.

Waking up dormant tumor suppressor genes with zinc fingers, TALEs and the CRISPR/dCas9 system

The aberrant epigenetic silencing of tumor suppressor genes (TSGs) plays a major role during carcinogenesis and regaining these dormant functions by engineering of sequence-specific epigenome editing tools offers a unique opportunity for targeted therapies. However, effectively normalizing the expression and regaining tumor suppressive functions of silenced TSGs by artificial transcription factors (ATFs) still remains a major challenge. Herein we describe novel combinatorial strategies for the potent reactivation of two class II TSGs, MASPIN and REPRIMO, in cell lines with varying epigenetic states, using the CRISPR/dCas9 associated system linked to a panel of effector domains (VP64, p300, VPR and SAM complex), as well as with protein-based ATFs, Zinc Fingers and TALEs. We found that co-delivery of multiple effector domains using a combination of CRISPR/dCas9 and TALEs or SAM complex maximized activation in highly methylated promoters. In particular, CRISPR/dCas9 VPR with SAM upregulated MASPIN mRNA (22,145-fold change) in H157 lung cancer cells, with accompanying re-expression of MASPIN protein, which led to a concomitant inhibition of cell proliferation and induction of apoptotic cell death. Consistently, CRISPR/dCas9 VP64 with SAM upregulated REPRIMO (680-fold change), which led to phenotypic reprogramming in AGS gastric cancer cells. Altogether, our results outlined novel sequence-specific, combinatorial epigenome editing approaches to reactivate highly methylated TSGs as a promising therapy for cancer and other diseases.

Very-Low-Dose Decitabine Is Effective in Treating Intermediate- or High-Risk Myelodysplastic Syndrome

Nowadays, the regular recommended dose of decitabine for the treatment of myelodysplastic syndrome (MDS) is 20 mg/m2/day for 5 consecutive days with a relatively high incidence of treatment-related morbidities and costs. In this study, a retrospective and multicenter analysis was performed to explore the very-low-dose decitabine schedule for the treatment of patients with IPSS intermediate- or high-risk MDS. A total of 31 newly diagnosed MDS cases from 14 hospitals in Beijing received decitabine monotherapy (decitabine 6 mg/m2/day intravenously for 7 consecutive days, repeated every 4 weeks). With a medium follow-up of 4 months, 10 patients achieved complete remission (32.3%), 8 (25.8%) partial remission, and 3 (9.7%) hematological improvement. The overall response rate (ORR) was 67.7%. Rates of 21.7% for severe infections and 11.6% for severe bleedings were observed among all courses. The median cost of each course was USD 5,300, 3,000, 2,900, and 2,000, respectively. Multivariate analysis identified bone marrow blast cells ≥10% and a Charlson comorbidity index ≥1 as 2 independent factors for efficacy. In conclusion, very-low-dose decitabine showed relatively good efficacy, good tolerance, and low medical cost in the treatment of intermediate- or high-risk MDS. Elderly patients with more than 1 complication or patients with a higher proportion of blast cells may be the most suitable candidates for this regimen.

Conditioning neoadjuvant therapies for improved immunotherapy of cancer

Recent advances in the treatment of melanoma and non-small cell lung cancer (NSCLC) by combining conventional therapies with anti-PD1/PD-L1 immunotherapies, have renewed interests in immunotherapy of cancer. The emerging concept of conventional cancer therapies combined with immunotherapy differs from the classical concept in that it is not simply taking advantage of their additive anti-tumor effects, but it is to use certain therapeutic regimens to condition the tumor microenvironment for optimal response to immunotherapy. To this end, low dose immunogenic chemotherapies, epigenetic modulators and inhibitors of cell cycle progression are potential candidates for rendering tumors highly responsive to immunotherapy. Next generation immunotherapeutics are therefore predicted to be highly effective against cancer, when they are used following appropriate immune modulatory compounds or targeted delivery of tumor cell cycle inhibitors using nanotechnology.

Immunological effects of hypomethylating agents

INTRODUCTION

Epigenetic changes resulting from aberrant methylation patterns are a recurrent observation in hematologic malignancies. Hypomethylating agents have a well-established role in the management of patients with high-risk myelodysplastic syndrome or acute myeloid leukemia. In addition to the direct effects of hypomethylating agents on cancer cells, there are several lines of evidence indicating a role for immune-mediated anti-tumor benefits from hypomethylating therapy. Areas covered: We reviewed the clinical and basic science literature for the effects of hypomethylating agents, including the most commonly utilized therapeutics azacitidine and decitabine, on immune cell subsets. We summarized the effects of hypomethylating agents on the frequency and function of natural killer cells, T cells, and dendritic cells. In particular, we highlight the effects of hypomethylating agents on expression of immune checkpoint inhibitors, leukemia-associated antigens, and endogenous retroviral elements. Expert commentary: In vitro and ex vivo studies indicate mixed effects on the function of natural killer, dendritic cells and T cells following treatment with hypomethylating agents. Clinical correlates of immune function have suggested that hypomethylating agents have immunomodulatory functions with the potential to synergize with immune checkpoint therapy for the treatment of hematologic malignancy, and has become an active area of clinical research.

Clinical and biological effects of demethylating agents on solid tumours - A systematic review

BACKGROUND

It is assumed that DNA methylation plays a key role in both tumour development and therapy resistance. Demethylating agents have been shown to be effective in the treatment of haematological malignancies. Based on encouraging preclinical results, demethylating agents may also be effective in solid tumours. This systematic review summarizes the evidence of the effect of demethylating agents on clinical response, methylation and the immune system in solid tumours.

METHODS

We conducted a systematic literature search from 1949 to December 2016, according to the PRISMA guidelines. Studies which evaluated treatment with azacitidine, decitabine, guadecitabine, hydralazine, procaine, MG98 and/or zebularine in patients with solid tumours were included. Data on clinical response, effects on methylation and immune response were extracted.

RESULTS

Fifty-eight studies were included: in 13 studies complete responses (CR) were observed, 35 studies showed partial responses (PR), 47 studies stable disease (SD) and all studies except two showed progressive disease (PD). Effects on global methylation were observed in 11/15 studies and demethylation/re-expression of tumour specific genes was seen in 15/17 studies. No clear correlation between (de)methylation and clinical response was observed. In 14 studies immune-related responses were reported, such as re-expression of cancer-testis antigens and upregulation of interferon genes.

CONCLUSION

Demethylating agents are able to improve clinical outcome and alter methylation status in patients with solid tumours. Although beneficial effect has been shown in individual patients, overall response is limited. Further research on biomarker predicting therapy efficacy is indicated, particularly in earlier stage and highly methylated tumours.

T cell receptor repertoire usage in cancer as a surrogate marker for immune responses

Characterizing the interaction of cancer cells with the host adaptive immune system is critical for understanding tumor immunology and the modus operandi of immunotherapeutic interventions to treat cancer. As the key cellular effectors of adaptive immunity, T cells are endowed with specialized receptors (the T cell receptor; TCR), to recognize and to eliminate cancer cells. The diversity of the TCR repertoire results from specialized genetic diversification mechanisms that generate an incredible variability allowing recognizing extensive collections of antigens. Based on the attainment and function of the TCR, the TCR repertoire is a mirror of the human immune response, and the dynamic changes of its usage can be assumed as a promising biomarker to monitor immunomodulatory therapies. Recent advances in multiplexed PCR amplification and massive parallel sequencing technologies have facilitated the characterization of TCR repertoires at high resolution even when only biomaterial of limited quantity and quality, such as formalin-fixed paraffin-embedded (FFPE) archived tissues, is available. Here, we review the concept framework and current experimental approaches to characterize the TCR repertoire usage in cancer including inherent technical and biological challenges.