Histone deacetylase inhibitor chidamide induces growth inhibition and apoptosis in NK/T lymphoma cells through ATM-Chk2-p53-p21 signalling pathway

Converting "cold" to "hot": epigenetics strategies to improve immune therapy effect by regulating tumor-associated immune suppressive cells

Significant developments in cancer treatment have been made since the advent of immune therapies. However, there are still some patients with malignant tumors who do not benefit from immunotherapy. Tumors without immunogenicity are called "cold" tumors which are unresponsive to immunotherapy, and the opposite are "hot" tumors. Immune suppressive cells (ISCs) refer to cells which can inhibit the immune response such as tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), regulatory T (Treg) cells and so on. The more ISCs infiltrated, the weaker the immunogenicity of the tumor, showing the characteristics of "cold" tumor. The dysfunction of ISCs in the tumor microenvironment (TME) may play essential roles in insensitive therapeutic reaction. Previous studies have found that epigenetic mechanisms play an important role in the regulation of ISCs. Regulating ISCs may be a new approach to transforming "cold" tumors into "hot" tumors. Here, we focused on the function of ISCs in the TME and discussed how epigenetics is involved in regulating ISCs. In addition, we summarized the mechanisms by which the epigenetic drugs convert immunotherapy-insensitive tumors into immunotherapy-sensitive tumors which would be an innovative tendency for future immunotherapy in "cold" tumor.

Epigenetic alterations and advancement of lymphoma treatment

Lymphomas, complex and heterogeneous malignant tumors, originate from the lymphopoietic system. These tumors are notorious for their high recurrence rates and resistance to treatment, which leads to poor prognoses. As ongoing research has shown, epigenetic modifications like DNA methylation, histone modifications, non-coding RNA regulation, and RNA modifications play crucial roles in lymphoma pathogenesis. Epigenetic modification-targeting drugs have exhibited therapeutic efficacy and tolerability in both monotherapy and combination lymphoma therapy. This review discusses pathogenic mechanisms and potential epigenetic therapeutic targets in common lymphomas, offering new avenues for lymphoma diagnosis and treatment. We also discuss the shortcomings of current lymphoma treatments, while suggesting potential areas for future research, in order to improve the prediction and prognosis of lymphoma.

The combination of brentuximab vedotin and chidamide synergistically suppresses the proliferation of T-cell lymphoma cells through the enhancement of apoptosis

PURPOSE

Peripheral T-cell lymphoma (PTCL) is an aggressive disease with a poor prognosis. Brentuximab vedotin (BV), an anti-CD30 monoclonal antibody linked to a microtubule-disrupting agent, has been approved for the treatment of PTCL. We evaluated a new effective combination partner of BV using non-clinical approaches that could potentially identify agents capable of improving survival times for patients with PTCL.

METHODS

A high-throughput screening test was used to select the most synergistic partner of BV from 14 candidate drugs that were under development or available in clinical practice for PTCL. HH cells, originating from an aggressive cutaneous T-cell lymphoma, were used as an experimental model of PTCL. Apoptotic effects of the synergistic partner of BV were further investigated in vitro and in vivo using HH-cell xenograft mice.

RESULTS

Chidamide (tucidinostat), a novel histone deacetylase inhibitor, was found to have the greatest synergistic effect with BV on HH cells. The combined effects of chidamide and BV were demonstrated in a study of HH-cell xenograft mice; mean tumor size following combined treatment was 22% of that observed in the control group, compared with 71% and 58% following chidamide and BV monotherapy, respectively. Further investigations in vitro and in vivo revealed that the levels of an anti-apoptotic protein, Bcl-2, and a rate-limiting factor of DNA replication, CDC45, were reduced in HH cells treated with chidamide combined with BV compared with the control group.

CONCLUSION

The use of chidamide in conjunction with BV may positively affect and enhance T-cellular apoptotic pathways without offsetting each other.

Investigation of the applicability of the zebrafish model for the evaluation of aristolochic acid-related nephrotoxicity

BACKGROUND

The risk of compounds/drugs, including aristolochic acid-induced nephrotoxicity remains high and is a significant public health concern. Therefore, it is particularly important to select reasonable animal models for rapid screening and evaluation of different samples with complex chemical systems. The zebrafish (Danio rerio) has been used to study chemical-induced renal toxicity. However, most of the published literature was performed on individual components or drugs, and the key evidence confirming the applicability of zebrafish larvae for the evaluation of aristolochic acid-related nephrotoxicity in complex chemical systems, such as in traditional Chinese medicine (TCM), was insufficient.

METHODS

High-performance liquid chromatography (HPLC) was used to determine the content of aristolochic acid (AA) in herbs and Chinese patent medicines. The zebrafish larvae at 4 days post-fertilization (dpf) were used to evaluate the nephrotoxicity of various samples, respectively, based on the phenotype of the kidney and histological, and biochemical. Transcriptome technology was used to investigate the related signaling pathways and potential mechanisms after treatment with AA, which was verified by RT-PCR technology.

RESULTS

The results showed that the total amounts of AAI, AAII, and ALI ranged from 0.0004 to 0.1858 g·g-1( %) from different samples, including Aristolochia debilis, Fibraurea recisa, Asarum, Wantongjingu tablets, Jiuweiqianghuo granules, and Xiaoqinglong granules in descending order. Moreover, compared with the negative/blank control, substantial changes in phenotype, histomorphology and biochemical parameters of renal function were observed in the groups challenged with the sublethal concentration of drugs. The transcriptomics results showed the upregulation of most genes in PERK/ATF4/CHOP, ATM/Chk2/p53, Caspase/Bax/Bcl-2a, TGF/Smad/ERK, PI3K/Akt, induced by aristolochic acid analogues, which were essentially consistent with those of the q-RT-PCR experiments, highlighting the similar toxicity response to the previously published article with the other traditional evaluation model.

CONCLUSION

The stability, accuracy and feasibility of the zebrafish larval model in screening and evaluating the nephrotoxicity of TCM were validated for the first time on the AAs-related drugs in a unified manner, confirming and promoting the applicability of zebrafish in assessing nephrotoxicity of samples with complex chemical character.

Chidamide Induces Epstein-Barr Virus (EBV) Lytic Infection and Acts Synergistically with Tenofovir to Eliminate EBV-Positive Burkitt Lymphoma

Epstein-Barr virus (EBV) is a type of human γ-herpesvirus, and its reactivation plays an important role in the development of EBV-driven Burkitt lymphoma (BL). Despite intensive chemotherapy, the prognosis of relapsed/refractory BL patients remains unfavorable, and a definitive method to completely eliminate latent EBV infection is lacking. Previous studies have demonstrated that histone deacetylase (HDAC) inhibitors can induce the transition of EBV from latency to the lytic phase. The lytic activation of EBV can be inhibited by tenofovir, a potent inhibitor of DNA replication. Herein, we explored the antitumor effect and EBV clearance potential of a novel HDAC inhibitor called chidamide, combined with tenofovir, in the treatment of EBV-positive BL. In the study, chidamide exhibited inhibitory activity against HDAC. Moreover, chidamide inhibited BL cell proliferation, arrested cell cycle progression, and induced BL cell apoptosis primarily by regulating the MAPK pathways. Additionally, chidamide promoted the transcription of lytic genes, including BZLF1, BMRF1, and BMLF1 Compared with chidamide alone, the addition of tenofovir further induced growth arrest and apoptosis in EBV-positive BL cells and inhibited the transcriptions of EBV lytic genes induced by chidamide alone. Furthermore, our in vivo data demonstrated that the combination of chidamide and tenofovir had superior tumor-suppressive effects in a mouse model of BL cell tumors. The aforementioned findings confirm the synergistic effect of chidamide combined with tenofovir in inducing growth inhibition and apoptosis in EBV-positive BL cells and provide an effective strategy for eliminating EBV and EBV-associated malignancies. SIGNIFICANCE STATEMENT: High levels of Epstein-Barr virus (EBV)-DNA have consistently been associated with unfavorable progression-free survival and overall survival in EBV-associated lymphomas. Therefore, identifying novel strategies to effectively eradicate tumor cells and eliminate EBV is crucial for lymphoma patients. This study confirmed, for the first time, the synergistic effect of chidamide combined with tenofovir in the treatment of Burkitt lymphoma and the eradication of EBV virus.

Oral HDAC inhibitor tucidinostat in patients with relapsed or refractory peripheral T-cell lymphoma: phase IIb results

Tucidinostat (formerly known as chidamide) is an orally available, novel benzamide class of histone deacetylase (HDAC) inhibitor that selectively blocks class I and class IIb HDAC. This multicenter phase IIb study aimed to investigate the efficacy and safety of tucidinostat, 40 mg twice per week (BIW), in patients with relapsed/refractory (R/R) peripheral T-cell lymphoma (PTCL). The primary endpoint was overall response rate (ORR) assessed by an independent overall efficacy review committee. Between March 2017 and March 2019, 55 patients were treated, and 46 and 55 were evaluated for efficacy and safety, respectively. Twenty-one of 46 patients achieved objective responses with an ORR of 46% (95% confidence interval : 30.9-61.0), including five patients with complete response (CR). Responses were observed across various PTCL subtypes. In angioimmunoblastic T-cell lymphoma, there were two CR and five partial responses (PR) among eight patients, achieving an ORR of 88%. The disease control rate (CR + PR + stable disease) was 72% (33/46). The median progression-free survival, duration of response, and overall survival were 5.6 months, 11.5 months, 22.8 months, respectively. The most common adverse events (AE) (all grades) were thrombocytopenia, neutropenia, leukopenia, anemia, and diarrhea. The grade ≥3 AE emerging in ≥20% of patients included thrombocytopenia (51%), neutropenia (36%), lymphopenia (22%), and leukopenia (20%). Importantly, most of the AE were manageable by supportive care and dose modification. In conclusion, the favorable efficacy and safety profiles indicate that tucidinostat could be a new therapeutic option in patients with R/R PTCL (clinicaltrials gov. Identifier: NCT02953652).

Sintilimab combined with chidamide in the treatment of extranodal nature killer/T-cell lymphoma with secondary hemophagocytic lymphohistiocytosis: Two case reports and literature review

RATIONALE

Extranodal nature killer/T-cell lymphoma (ENKTL) failing in asparaginase-containing treatments is fatal, it has a higher mortality rate when accompanied by secondary hemophagocytic lymphohistiocytosis (HLH). The study reported 2 ENKTL-related HLH patients.

PATIENT CONCERNS

Patient 1 visited for nasal congestion and runny nose for 6 months then got a fever and serious myelosuppression after P-GEP (pegaspargase, gemcitabine, etoposide, and methylprednisolone) chemotherapy. Patient 2 complained of painless lymphadenectasis in the right neck for 4 months and experienced recurrent fever and poor performance status after 3 cycles of P-Gemox (pegaspargase, gemcitabine, and oxaliplatin) chemotherapy.

DIAGNOSES

Patient 1 and patient 2 were diagnosed as ENKTL failing in asparaginase-based chemotherapy and involving secondary HLH.

INTERVENTIONS

The dose of chidamide was 20 mg twice a week for 2 weeks and sintilimab was 200 mg once every 3 weeks.

OUTCOMES

ENKTL was relieved and the HLH was resolved after the therapy of sintilimab and chidamide. The patients had achieved durable survival without immune-related adverse events.

LESSONS

ENKTL-related HLH needs early diagnosis and treatment. The combined strategy of sintilimab plus chidamide help deal with HLH and solve ENKTL, it may be a useful treatment option for ENKTL-related HLH.

Germline CHEK2 and ATM Variants in Myeloid and Other Hematopoietic Malignancies

PURPOSE OF REVIEW

An intact DNA damage response is crucial to preventing cancer development, including in myeloid and lymphoid malignancies. Deficiencies in the homologous recombination (HR) pathway can lead to defective DNA damage responses, and this can occur through inherited germline mutations in HR pathway genes, such as CHEK2 and ATM. We now understand that germline mutations can be identified frequently (~ 5-10%) in patients with myeloid and lymphoid malignancies, and among the most common of these are CHEK2 and ATM. We review the role that deleterious germline CHEK2 and ATM variants play in the development of hematopoietic malignancies, and how this influences clinical practice, including cancer screening, hematopoietic stem cell transplantation, and therapy choice.

RECENT FINDINGS

In recent large cohorts of patients diagnosed with myeloid or lymphoid malignancies, deleterious germline loss of function variants in CHEK2 and ATM are among the most common identified. Germline CHEK2 variants predispose to a range of myeloid malignancies, most prominently myeloproliferative neoplasms and myelodysplastic syndromes (odds ratio range: 2.1-12.3), and chronic lymphocytic leukemia (odds ratio 14.83). Deleterious germline ATM variants have been shown to predispose to chronic lymphocytic leukemia (odds ratio range: 1.7-10.1), although additional studies are needed to demonstrate the risk they confer for myeloid malignancies. Early studies suggest there may also be associations between deleterious germline CHEK2 and ATM variants and development of clonal hematopoiesis. Identifying CHEK2 and ATM variants is crucial for the optimal management of patients and families affected by hematopoietic malignancies. OPENING CLINICAL CASE: "A 45 year-old woman presents to your clinic with a history of triple-negative breast cancer diagnosed five years ago, treated with surgery, radiation, and chemotherapy. About six months ago, she developed cervical lymphadenopathy, and a biopsy demonstrated small lymphocytic leukemia. Peripheral blood shows a small population of lymphocytes with a chronic lymphocytic leukemia immunophenotype, and FISH demonstrates a complex karyotype: gain of one to two copies of IGH and FGFR3; gain of two copies of CDKN2C at 1p32.3; gain of two copies of CKS1B at 1q21; tetrasomy for chromosome 3; trisomy and tetrasomy for chromosome 7; tetrasomy for chromosome 9; tetrasomy for chromosome 12; gain of one to two copies of ATM at 11q22.3; deletion of chromosome 13 deletion positive; gain of one to two copies of TP53 at 17p13.1). Given her history of two cancers, you arrange for germline genetic testing using DNA from cultured skin fibroblasts, which demonstrates pathogenic variants in ATM [c.1898 + 2 T > G] and CHEK2 [p.T367Metfs]. Her family history is significant for multiple cancers. (Fig. 1)." Fig. 1 Representative pedigree from a patient with germline pathogenic ATM and CHEK2 variants who was affected by early onset breast cancer and chronic lymphocytic leukemia. Arrow indicates proband. Colors indicate cancer type/disease: purple, breast cancer; blue, lymphoma; brown, melanoma; yellow, colon cancer; and green, autoimmune disease.

Combination of atezolizumab and chidamide to maintain long-term remission in refractory metastatic extranodal natural killer/T-cell lymphoma: A case report

BACKGROUND

The prognosis of refractory extranodal natural killer/T-cell lymphoma (ENKTL) is poor. Recent data have indicated that immune checkpoint blockade with a programmed cell death protein-1 (PD-1) antibody in combination with administration of histone deacetylase inhibitors represents a potentially effective treatment strategy. Compared with PD-1 antibodies, programmed death-ligand 1 antibodies have fewer side effects. Here, we present a rare case of a patient with refractory metastatic ENKTL who achieved sustained remission of approximately 10 mo with minor adverse effects after combination therapy with atezolizumab, chidamide, and radiotherapy.

CASE SUMMARY

A 56-year-old woman underwent resection of a tumour in her left nasal cavity and was diagnosed with ENKTL (nasal type). Medical examination revealed tumours observed in the bilateral nasal mucosa, the subcutaneous soft tissue of the inner side of the left eye, the soft tissue of the nasopharynx, the bilateral tonsils, and the left preauricular, right hilar, bilateral neck lymph nodes and bone marrow. However, tomography/computed tomography showed increased metabolism of the bilateral nasal mucosa and subcutaneous soft tissue of the inner side of the left eye and newly increased metabolism of the left cervical lymph node after chemotherapy. Therefore, combination therapy with chidamide, atezolizumab, and radiotherapy was performed. Fortunately, the patient achieved a complete response following 10 mo of combination therapy.

CONCLUSION

The outcome in this case suggests that the combination of atezolizumab, chidamide, and radiotherapy is a promising regimen for treating refractory metastatic ENKTL following chemotherapy treatment failure.

Chidamide and mitomycin C exert synergistic cytotoxic effects against bladder cancer cells in vitro and suppress tumor growth in a rat bladder cancer model

Intravesical instillation (IVI) of Bacillus Calmette-Guerin (BCG) can prevent bladder cancer recurrence, but this agent has been out of stock in recent years. IVI of other agents, like chidamide, a histone deacetylase (HDAC) inhibitor, may have the potential to exert a therapeutic effect against bladder cancer by modifying the gene expression profiles associated with histone modifications that occur during cancer tumorigenesis. Here, we investigated the in vitro therapeutic effect of chidamide and/or mitomycin C in bladder cancer cell lines and screened related molecular pathways using an antibody array. We also quantitatively analyzed the synergistic effect of IVI of chidamide and mitomycin C in vivo in an N-methyl-N-nitrosourea (MNU)-induced rat bladder cancer model. The synergistic cytotoxic effect of chidamide plus mitomycin C was confirmed in both T24 and UMUC3 cells (combination index <0.6), with significantly greater induction of apoptosis elicited with chidamide plus mitomycin C than with either drug alone. The antibody array identified the Axl signaling pathway as the key target of the synergistic effect. Expression of Axl and its related downstream molecules, including claspin and survivin, was significantly suppressed. In the rat bladder cancer model, IVI of chidamide plus mitomycin C reduced tumor burden (Ki67 index) to a greater extent than either drug alone (p < 0.01). Our results suggest that chidamide and mitomycin act synergistically to reduce MNU-induced bladder cancer. These findings provide new insights into a new and potentially effective approach to treating bladder cancer.

New Approaches for Treatment of Advanced Extranodal NK/T-Cell Lymphoma

Extranodal NK/T cell lymphoma (ENKL) is a rare subtype of lymphoma that shows a poor clinical outcome. The most common sites are the nasal cavity, nasopharynx, paranasal sinuses, tonsils and larynx. Because of P-glycoprotein expression on ENKL cells, ENKL is resistant to anthracycline-based chemotherapy. L-asparaginase-based chemotherapy with or without radiotherapy shows promising outcomes for advanced ENKL, but has limited efficacy in relapsed/refractory ENKL. immune-checkpoint inhibitors, histone deacetylase inhibitors, and monoclonal antibodies are being investigated. In this review, we summarize the new treatments for ENKL.

The Mechanism of Nano-Particles Intervening Invasion and Metastasis of Lymphoma Based on Autophagy Targeted with miR-36b and Orienteering Analysis on Apoptosis Gene

Whether the expression of gene P53 related with autophagy and apoptosis and action was regulated by miR-36b was discussed in our study. And the action of orienteering nano-particles on intervening invasion and metastasis of lymphoma was analyzed. The normal lymphoid tissue collected from the patients with simple lymphatic hyperplasia was set as control. The lymphoma samples from patients with early indolent lymphoma were collected. The level of mRNA in miR-36b and P53 was detected by PCR. The level of P53 protein and level of mRNA in miR-36b and P53 among normal lymphoid cell, cell strain of low metastatic lymphoma and cell strain of high metastatic lymphoma was compared. They were divided into four groups: miR-NC group, orienteering nano-particles’ group, siRNA-NC group and siRNA-P53 group. The cell proliferative capacity was detected by FCM. The quantity of cell invasion and metastasis was detected by transwell. The expression quantity of P53 mRNA in lymphoma tissue was increased obviously compared with control group. The expression of miR-36b was lower while the expression of P53 was higher along with the later staging of TNM. And the express was related with the staging of TNM. The expression quantity of P53 mRNA in lymphoma cell was higher in normal cell notably. But expression quantity of miR-36b in lymphoma cell was lower in normal cell notably. The decreased of expression of miR-36b and increased of expression of P53 was related with enhancing the ability of invasion and metastasis of lymphoma cells.

Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is one of the most dangerous hematological malignancies, with high tumor heterogeneity and poor prognosis. More than 60% of T-ALL patients carry NOTCH1 gene mutations, leading to abnormal expression of downstream target genes and aberrant activation of various signaling pathways. We found that chidamide, an HDAC inhibitor, exerts an antitumor effect on T-ALL cell lines and primary cells including an anti-NOTCH1 activity. In particular, chidamide inhibits the NOTCH1-MYC signaling axis by down-regulating the level of the intracellular form of NOTCH1 (NICD1) as well as MYC, partly through their ubiquitination and degradation by the proteasome pathway. We also report here the preliminary results of our clinical trial supporting that a treatment by chidamide reduces minimal residual disease (MRD) in patients and is well tolerated. Our results highlight the effectiveness and safety of chidamide in the treatment of T-ALL patients, including those with NOTCH1 mutations and open the way to a new therapeutic strategy for these patients.

Chidamide triggers BTG1-mediated autophagy and reverses the chemotherapy resistance in the relapsed/refractory B-cell lymphoma

Rituximab/chemotherapy relapsed and refractory B cell lymphoma patients have a poor overall prognosis, and it is urgent to develop novel drugs for improving the therapy outcomes. Here, we examined the therapeutic effects of chidamide, a new histone deacetylase (HDAC) inhibitor, on the cell and mouse models of rituximab/chemotherapy resistant B-cell lymphoma. In Raji-4RH/RL-4RH cells, the rituximab/chemotherapy resistant B-cell lymphoma cell lines (RRCL), chidamide treatment induced growth inhibition and G0/G1 cell cycle arrest. The primary B-cell lymphoma cells from Rituximab/chemotherapy relapsed patients were sensitive to chidamide. Interestingly, chidamide triggered the cell death with the activation of autophagy in RRCLs, likely due to the lack of the pro-apoptotic proteins. Based on the RNA-seq and chromatin immunoprecipitation (ChIP) analysis, we identified BTG1 and FOXO1 as chidamide target genes, which control the autophagy and the cell cycle, respectively. Moreover, the combination of chidamide with the chemotherapy drug cisplatin increased growth inhibition on the RRCL in a synergistic manner, and significantly reduced the tumor burden of a mouse lymphoma model established with engraftment of RRCL. Taken together, these results provide a theoretic and mechanistic basis for further evaluation of the chidamide-based treatment in rituximab/chemotherapy relapsed and refractory B-cell lymphoma patients.

Network Pharmacology and Experimental Validation Reveal the Effects of Chidamide Combined With Aspirin on Acute Myeloid Leukemia-Myelodysplastic Syndrome Cells Through PI3K/AKT Pathway

Chidamide (CDM), a novel histone deacetylase inhibitor, is currently used for patients with peripheral T-cell lymphoma. Aspirin (ASA), an anti-inflammatory drug, has been shown to exert anticancer activity. Herein, we investigated the effect of CDM combined with ASA on myelodysplastic syndromes-derived acute myeloid leukemia (AML-MDS) cells and explored the underlying mechanism. The putative targets of CDM and ASA were predicted by network pharmacology approach. GO functional and KEGG pathway enrichment analyses were performed by DAVID. Furthermore, experimental validation was conducted by Cell Counting Kit-8 assay, Flow cytometry and Western blotting. Network pharmacology analysis revealed 36 AML-MDS-related overlapping genes that were targets of CDM and ASA, while 10 hub genes were identified by the plug-in cytoHubba in Cytoscape. Pathway enrichment analysis indicated CDM and ASA significantly affected PI3K/AKT signaling pathway. Functional experiments demonstrated that the combination of CDM and ASA had a remarkable synergistic anti-proliferative effect by blocking the cell cycle in G0/G1 phase and inducing apoptosis. Mechanistically, the combination treatment significantly down-regulated the phosphorylation levels of PI3K and AKT. In addition, insulin-like growth factor 1 (IGF-1), an activator of PI3K/AKT pathway, reversed the effects of the combination treatment. Our findings suggested that CDM combined with ASA exerted a synergetic inhibitory effect on cell growth by inactivating PI3K/AKT pathway, which might pave the way for effective treatments of AML-MDS.

The epigenetic immunomodulator, HBI-8000, enhances the response and reverses resistance to checkpoint inhibitors

Background

Treatment with immune checkpoint inhibitors (ICIs) targeting CTLA-4 and the PD-1/PD-L1 axis is effective against many cancer types. However, due in part to unresponsiveness or acquired resistance, not all patients experience a durable response to ICIs. HBI-8000 is a novel, orally bioavailable class I selective histone deacetylase inhibitor that directly modifies antitumor activity by inducing apoptosis, cell cycle arrest, and resensitization to apoptotic stimuli in adult T cell lymphoma patients. We hypothesized that HBI-8000 functions as an epigenetic immunomodulator to reprogram the tumor microenvironment from immunologically cold (nonresponsive) to hot (responsive).

Method

Mice bearing syngeneic tumors (MC38 and CT26 murine colon carcinoma and A20 B-cell lymphoma were treated daily with HBI-8000 (orally), alone or in combination with PD-1, PD-1 L, or CTLA-4 antibodies. MC38 tumors were also analyzed in nanoString gene expression analysis.

Results

HBI-8000 augmented the activity of ICI antibodies targeting either PD-1, PD-L1 or CTLA-4, and significantly increased tumor regression (p < 0.05) in the above models. Gene expression analysis of the treated MC38 tumors revealed significant changes in mRNA expression of immune checkpoints, with enhanced dendritic cell and antigen-presenting cell functions, and modulation of MHC class I and II molecules.

Conclusions

These findings suggest that HBI-8000 mediates epigenetic modifications in the tumor microenvironment, leading to improved efficacy of ICIs, and provide strong rationale for combination therapies with ICIs and HBI-8000 in the clinical setting.

Precis

As an HDACi, HBI-8000 plays an important role in priming the immune system in the tumor microenvironment. The current preclinical data further justifies testing combination of HBI-8000 and ICIs in the clinic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08702-x.

Drugs and Epigenetic Molecular Functions. A Pharmacological Data Scientometric Analysis

Interactions of drugs with the classical epigenetic mechanism of DNA methylation or histone modification are increasingly being elucidated mechanistically and used to develop novel classes of epigenetic therapeutics. A data science approach is used to synthesize current knowledge on the pharmacological implications of epigenetic regulation of gene expression. Computer-aided knowledge discovery for epigenetic implications of current approved or investigational drugs was performed by querying information from multiple publicly available gold-standard sources to (i) identify enzymes involved in classical epigenetic processes, (ii) screen original biomedical scientific publications including bibliometric analyses, (iii) identify drugs that interact with epigenetic enzymes, including their additional non-epigenetic targets, and (iv) analyze computational functional genomics of drugs with epigenetic interactions. PubMed database search yielded 3051 hits on epigenetics and drugs, starting in 1992 and peaking in 2016. Annual citations increased to a plateau in 2000 and show a downward trend since 2008. Approved and investigational drugs in the DrugBank database included 122 compounds that interacted with 68 unique epigenetic enzymes. Additional molecular functions modulated by these drugs included other enzyme interactions, whereas modulation of ion channels or G-protein-coupled receptors were underrepresented. Epigenetic interactions included (i) drug-induced modulation of DNA methylation, (ii) drug-induced modulation of histone conformations, and (iii) epigenetic modulation of drug effects by interference with pharmacokinetics or pharmacodynamics. Interactions of epigenetic molecular functions and drugs are mutual. Recent research activities on the discovery and development of novel epigenetic therapeutics have passed successfully, whereas epigenetic effects of non-epigenetic drugs or epigenetically induced changes in the targets of common drugs have not yet received the necessary systematic attention in the context of pharmacological plasticity.

HDAC6 inhibitor ACY1215 inhibits the activation of NLRP3 inflammasome in acute liver failure by regulating the ATM/F-actin signalling pathway

Acute liver failure (ALF) is a rare and critical medical condition. This study was designed to investigate the protective effects and underlying mechanism of ACY1215 in ALF mice. Our findings suggested that ACY1215 treatment ameliorates the pathological hepatic damage of ALF and decreases the serum levels of ALT and AST. Furthermore, ACY1215 pretreatment increased the level of ATM, γ‐H2AX, Chk2, p53, p21, F‐actin and vinculin in ALF. Moreover, ACY1215 inhibited the level of NLRP3, ASC, caspase‐1, IL‐1β and IL‐18 in ALF. The ATM inhibitor KU55933 could decrease the level of ATM, γ‐H2AX, Chk2, p53, p21, F‐actin and vinculin in ALF with ACY1215 pretreatment. The F‐actin inhibitor cytochalasin B decreased the level of F‐actin and vinculin in ALF with ACY1215 pretreatment. However, cytochalasin B had no effect on protein levels of ATM, Chk2, p53 and p21 in ALF with ACY1215 pretreatment. Cytochalasin B could dramatically increase the level of NLRP3, ASC, caspase‐1, IL‐1β and IL‐18 in ALF with ACY1215 pretreatment. These results indicated that ACY1215 exhibited hepatoprotective properties, which was associated with the inhibition of NLRP3 inflammasome, and this effect of ACY1215 was connected with upregulation of the ATM/F‐actin mediated signalling pathways.

Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare and heterogeneous group of clinically aggressive diseases associated with poor prognosis. Except for ALK + anaplastic large-cell lymphoma (ALCL), most peripheral T-cell lymphomas are highly malignant and have an aggressive disease course and poor clinical outcomes, with a poor remission rate and frequent relapse after first-line treatment. Aberrant epigenetic alterations play an important role in the pathogenesis and development of specific types of peripheral T-cell lymphoma, including the regulation of the expression of genes and signal transduction. The most common epigenetic alterations are DNA methylation and histone modification. Histone modification alters the level of gene expression by regulating the acetylation status of lysine residues on the promoter surrounding histones, often leading to the silencing of tumour suppressor genes or the overexpression of proto-oncogenes in lymphoma. DNA methylation refers to CpG islands, generally leading to tumour suppressor gene transcriptional silencing. Genetic studies have also shown that some recurrent mutations in genes involved in the epigenetic machinery, including TET2, IDH2-R172, DNMT3A, RHOA, CD28, IDH2, TET2, MLL2, KMT2A, KDM6A, CREBBP, and EP300, have been observed in cases of PTCL. The aberrant expression of miRNAs has also gradually become a diagnostic biomarker. These provide a reasonable molecular mechanism for epigenetic modifying drugs in the treatment of PTCL. As epigenetic drugs implicated in lymphoma have been continually reported in recent years, many new ideas for the diagnosis, treatment, and prognosis of PTCL originate from epigenetics in recent years. Novel epigenetic-targeted drugs have shown good tolerance and therapeutic effects in the treatment of peripheral T-cell lymphoma as monotherapy or combination therapy. NCCN Clinical Practice Guidelines also recommended epigenetic drugs for PTCL subtypes as second-line therapy. Epigenetic mechanisms provide new directions and therapeutic strategies for the research and treatment of peripheral T-cell lymphoma. Therefore, this paper mainly reviews the epigenetic changes in the pathogenesis of peripheral T-cell lymphoma and the advancement of epigenetic-targeted drugs in the treatment of peripheral T-cell lymphoma (PTCL).

Effective Treatment with PD-1 Antibody, Chidamide, Etoposide, and Thalidomide (PCET) for Relapsed/Refractory Natural Killer/T-Cell Lymphoma: A Report of Three Cases

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is a specific subtype of peripheral T cell lymphoma (PTCL) with a poor prognosis. To date, there exist no standard therapeutic regimens for relapsed/refractory (R/R) ENKTL. More potent treatment strategies are urgently needed to improve the survival of these patients with R/R ENKTL. Herein, we present three R/R ENKTL patients who failed prior therapies (L-asparaginase containing chemotherapy, radiotherapy or biological-cell therapy, etc.) benefited from the combination regimen comprised of anti-programmed-death-1 (PD-1) antibody toripalimab, chidamide, etoposide, and thalidomide. They received the treatment regimen continuously until the disease progression occurs. As of data collection, two patients achieved complete remission (CR) after 4, 6 cycles of treatment, respectively, and another patient was evaluated as partial remission (PR) after 2 cycles. Treatment-related adverse events (AEs) mainly presented grade 2~3 leukocytopenia and anemia, which were controllable. It follows that PD-1 antibody, chidamide, etoposide, and thalidomide (PCET) regimen may be a promising choice for patients with R/R ENKTL and warrants further investigation.

Chidamide acts on the histone deacetylase-mediated miR-34a/Bcl-2 axis to regulate NB4 cell line proliferation and apoptosis

Acute promyelocytic leukemia (APL), a biologically and clinically distinct variant of acute myelogenous leukemia, is characterized by the fusion of the N-terminus of promyelocytic leukemia protein to the C terminus of retinoic acid receptor alpha, mostly due to chromosomal translocation t(15;17). Chidamide, a synthetic analogue of MS-275 identified from a group of benzamide-type compounds, has been found to have efficient anticancer activity in basic and clinical research studies. However, the concrete role and underlying mechanism of Chidamide in the treatment of APL has not been well characterized. Our data demonstrate that Chidamide inhibited the expression of histone deacetylase (HDAC) to induce apoptosis and suppress proliferation in NB4 cells. Mechanistically, Chidamide increases the expression of miR-34a by suppressing HDAC. Furthermore, B-cell lymphoma-2 (Bcl-2) is a direct target of miR-34a, the expression of which is regulated by miR-34a. Functionally, Chidamide inhibits cell proliferation and promotes apoptosis through miR-34a/Bcl-2. Chidamide exerts its anticancer effect via the HDAC-mediated miR-34a/Bcl-2 axis, providing potential targets for APL therapy.

Nasal NK/T cell lymphoma mimicking mucosa-associated lymphoid tissue lymphoma in morphology: A case report

The objective of the present study was to describe the clinicopathological features of a patient with nasal NK/T cell lymphoma that was similar in morphology to mucosa-associated lymphoid tissue lymphoma (MALToma). The clinicopathological data of a patient diagnosed with nasal NK/T cell lymphoma mimicking MALToma was collected, and the clinicopathological characteristics were discussed. The female patient was 43 years old and had suffered from persistent congestion for ten days. The mucosa in the left nasal cavity was inflamed, resulting in congestion and it was also purulent on the surface, as observed by nasal endoscopy. The disease was considered to be inflammatory based on CT scan. A biopsy after operation showed that the tumor consisted of small lymphoid cells that resembled MALToma in morphology. On the basis of the immunohistochemistry and in situ hybridization laboratory tests, a diagnosis of left nasal NK/T cell lymphoma was made. The patient received chemotherapy and radiotherapy, and remission was achieved six months after diagnosis. The patient was in a good condition at 16 months follow-up. In conclusion, NK/T cell lymphoma composed of small cells may be a type of indolent lymphoma with special characteristics of clinical presentation, image, pathology and prognosis. This case highlights that more attention is required by radiologists, pathologists and hematologists to diagnose this type of lymphoma.

Epigenetic Regulation of p21cip1/waf1 in Human Cancer

p21^cip1/waf1 is a central regulator of cell cycle control and survival. While mutations are rare, it is commonly dysregulated in several human cancers due to epigenetic mechanisms influencing its transcriptional control. These mechanisms include promoter hypermethylation as well as additional pathways such as histone acetylation or methylation. The epigenetic regulators include writers, such as DNA methyltransferases (DNMTs); histone acetyltransferases (HATs) and histone lysine methyltransferases; erasers, such as histone deacetylases (HDACs); histone lysine demethylases [e.g., the Lysine Demethylase (KDM) family]; DNA hydroxylases; readers, such as the methyl-CpG-binding proteins (MBPs); and bromodomain-containing proteins, including the bromo- and extraterminal domain (BET) family. We further discuss the roles that long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play in the epigenetic control of p21^cip1/waf1 expression and its function in human cancers.

Chidamide suppresses the glycolysis of triple negative breast cancer cells partially by targeting the miR‑33a‑5p‑LDHA axis

Triple negative breast cancer (TNBC) is one of the most aggressive types of breast cancer and has a poor prognosis. Therefore, the development of novel drugs and understanding the molecular mechanisms that may contribute to the initiation and development of TNBC are urgently required. Chidamide, a histone deacetylase inhibitor, has been reported as possessing anti‑cancer properties in several cancers, however, the function of chidamide in TNBC remains to be elucidated. The present study revealed that chidamide inhibited the proliferation, colony formation and migration of TNBC cells. Experiments investigating the underlying mechanism revealed that chidamide upregulated the expression of microRNA (miR)‑33a‑5p in TNBC cells via RT‑qPCR. Luciferase reporter assay demonstrated that miR‑33a‑5p was bound to the 3'‑untranslated region of lactate dehydrogenase A (LDHA) and decreased the expression of LDHA in TNBC cells. In addition, chidamide suppressed the expression of LDHA and significantly decreased the glycolysis of TNBC cells. Collectively, the results of the present study demonstrated that chidamide reprogramed glucose metabolism, partially by targeting the miR‑33a‑5p/LDHA pathway, in TNBC. These findings indicate that chidamide may be a promising novel drug in the treatment of patients with TNBC.

Chidamide, a histone deacetylase inhibitor, induces growth arrest and apoptosis in multiple myeloma cells in a caspase-dependent manner

Chidamide, a novel histone deacetylase (HDAC) inhibitor, induces antitumor effects in various types of cancer. The present study aimed to evaluate the cytotoxic effect of chidamide on multiple myeloma and the underlying mechanisms involved. Viability of multiple myeloma cells upon chidamide treatment was determined by the Cell Counting Kit-8 assay. Apoptosis induction and cell cycle alteration were detected by flow cytometry. Specific apoptosis-associated proteins and cell cycle proteins were evaluated by western blot analysis. Chidamide suppressed cell viability in a time- and dose-dependent manner. Chidamide treatment markedly suppressed the expression of type I HDACs and further induced the acetylation of histones H3 and H4. In addition, it promoted G₀/G₁ arrest by decreasing cyclin D1 and c-myc expression, and increasing phosphorylated-cellular tumor antigen p53 and cyclin-dependent kinase inhibitor 1 (p21) expression in a dose-dependent manner. Treatment with chidamide induced cell apoptosis by upregulating the apoptosis regulator Bax/B-cell lymphoma 2 ratio in a caspase-dependent manner. In addition, the combination of chidamide with bortezomib, a proteasome inhibitor widely used as a therapeutic agent for multiple myeloma, resulted in enhanced inhibition of cell viability. In conclusion, chidamide induces a marked antimyeloma effect by inducing G₀/G₁ arrest and apoptosis via a caspase-dependent pathway. The present study provides evidence for the clinical application of chidamide in multiple myeloma.