Showing papers on "Vorinostat published in 2018"

Advances and Challenges of HDAC Inhibitors in Cancer Therapeutics.

Abstract: Since the identification and cloning of human histone deacetylases (HDACs) and the rapid approval of vorinostat (Zolinza®) for the treatment of cutaneous T-cell lymphoma, the field of HDAC biology has met many initial successes. However, many challenges remain due to the complexity involved in the lysine posttranslational modifications, epigenetic transcription regulation, and nonepigenetic cellular signaling cascades. In this chapter, we will: review the discovery of the first HDAC inhibitor and present discussion regarding the future of next-generation HDAC inhibitors, give an overview of different classes of HDACs and their differences in lysine deacylation activity, discuss different classes of HDAC inhibitors and their HDAC isozyme preferences, and review HDAC inhibitors' preclinical studies, their clinical trials, their pharmacokinetic challenges, and future direction. We will also discuss the likely reason for the failure of multiple HDAC inhibitor clinical trials in malignancies other than lymphoma and multiple myeloma. In addition, the potential molecular mechanism(s) that may play a key role in the efficacy and therapeutic response rate in the clinic and the likely patient population for HDAC therapy will be discussed.

Targeting Histone Deacetylases with Natural and Synthetic Agents: An Emerging Anticancer Strategy.

Abstract: Cancer initiation and progression are the result of genetic and/or epigenetic alterations. Acetylation-mediated histone/non-histone protein modification plays an important role in the epigenetic regulation of gene expression. Histone modification is controlled by the balance between histone acetyltransferase and (HAT) and histone deacetylase (HDAC) enzymes. Imbalance between the activities of these two enzymes is associated with various forms of cancer. Histone deacetylase inhibitors (HDACi) regulate the activity of HDACs and are being used in cancer treatment either alone or in combination with other chemotherapeutic drugs/radiotherapy. The Food and Drug Administration (FDA) has already approved four compounds, namely vorinostat, romidepsin, belinostat, and panobinostat, as HDACi for the treatment of cancer. Several other HDACi of natural and synthetic origin are under clinical trial for the evaluation of efficiency and side-effects. Natural compounds of plant, fungus, and actinomycetes origin, such as phenolics, polyketides, tetrapeptide, terpenoids, alkaloids, and hydoxamic acid, have been reported to show potential HDAC-inhibitory activity. Several HDACi of natural and dietary origin are butein, protocatechuic aldehyde, kaempferol (grapes, green tea, tomatoes, potatoes, and onions), resveratrol (grapes, red wine, blueberries and peanuts), sinapinic acid (wine and vinegar), diallyl disulfide (garlic), and zerumbone (ginger). HDACi exhibit their antitumor effect by the activation of cell cycle arrest, induction of apoptosis and autophagy, angiogenesis inhibition, increased reactive oxygen species generation causing oxidative stress, and mitotic cell death in cancer cells. This review summarizes the HDACs classification, their aberrant expression in cancerous tissue, structures, sources, and the anticancer mechanisms of HDACi, as well as HDACi that are either FDA-approved or under clinical trials.

HIV latency is reversed by ACSS2-driven histone crotonylation

Abstract: Eradication of HIV-1 (HIV) is hindered by stable viral reservoirs. Viral latency is epigenetically regulated. While the effects of histone acetylation and methylation at the HIV long-terminal repeat (LTR) have been described, our knowledge of the proviral epigenetic landscape is incomplete. We report that a previously unrecognized epigenetic modification of the HIV LTR, histone crotonylation, is a regulator of HIV latency. Reactivation of latent HIV was achieved following the induction of histone crotonylation through increased expression of the crotonyl-CoA-producing enzyme acyl-CoA synthetase short-chain family member 2 (ACSS2). This reprogrammed the local chromatin at the HIV LTR through increased histone acetylation and reduced histone methylation. Pharmacologic inhibition or siRNA knockdown of ACSS2 diminished histone crotonylation-induced HIV replication and reactivation. ACSS2 induction was highly synergistic in combination with either a protein kinase C agonist (PEP005) or a histone deacetylase inhibitor (vorinostat) in reactivating latent HIV. In the SIV-infected nonhuman primate model of AIDS, the expression of ACSS2 was significantly induced in intestinal mucosa in vivo, which correlated with altered fatty acid metabolism. Our study links the HIV/SIV infection-induced fatty acid enzyme ACSS2 to HIV latency and identifies histone lysine crotonylation as a novel epigenetic regulator for HIV transcription that can be targeted for HIV eradication.

PU.1 regulates Alzheimer’s disease-associated genes in primary human microglia

Abstract: Microglia play critical roles in the brain during homeostasis and pathological conditions. Understanding the molecular events underpinning microglial functions and activation states will further enable us to target these cells for the treatment of neurological disorders. The transcription factor PU.1 is critical in the development of myeloid cells and a major regulator of microglial gene expression. In the brain, PU.1 is specifically expressed in microglia and recent evidence from genome-wide association studies suggests that reductions in PU.1 contribute to a delayed onset of Alzheimer’s disease (AD), possibly through limiting neuroinflammatory responses. To investigate how PU.1 contributes to immune activation in human microglia, microarray analysis was performed on primary human mixed glial cultures subjected to siRNA-mediated knockdown of PU.1. Microarray hits were confirmed by qRT-PCR and immunocytochemistry in both mixed glial cultures and isolated microglia following PU.1 knockdown. To identify attenuators of PU.1 expression in microglia, high throughput drug screening was undertaken using a compound library containing FDA-approved drugs. NanoString and immunohistochemistry was utilised to investigate the expression of PU.1 itself and PU.1-regulated mediators in primary human brain tissue derived from neurologically normal and clinically and pathologically confirmed cases of AD. Bioinformatic analysis of gene expression upon PU.1 silencing in mixed glial cultures revealed a network of modified AD-associated microglial genes involved in the innate and adaptive immune systems, particularly those involved in antigen presentation and phagocytosis. These gene changes were confirmed using isolated microglial cultures. Utilising high throughput screening of FDA-approved compounds in mixed glial cultures we identified the histone deacetylase inhibitor vorinostat as an effective attenuator of PU.1 expression in human microglia. Further characterisation of vorinostat in isolated microglial cultures revealed gene and protein changes partially recapitulating those seen following siRNA-mediated PU.1 knockdown. Lastly, we demonstrate that several of these PU.1-regulated genes are expressed by microglia in the human AD brain in situ. Collectively, these results suggest that attenuating PU.1 may be a valid therapeutic approach to limit microglial-mediated inflammatory responses in AD and demonstrate utility of vorinostat for this purpose.

Phase I/II trial of vorinostat combined with temozolomide and radiation therapy for newly diagnosed glioblastoma: results of Alliance N0874/ABTC 02.

Abstract: Background Vorinostat, a histone deacetylase (HDAC) inhibitor, has shown radiosensitizing properties in preclinical studies. This open-label, single-arm trial evaluated the maximum tolerated dose (MTD; phase I) and efficacy (phase II) of vorinostat combined with standard chemoradiation in newly diagnosed glioblastoma. Methods Patients received oral vorinostat (300 or 400 mg/day) on days 1-5 weekly during temozolomide chemoradiation. Following a 4- to 6-week rest, patients received up to 12 cycles of standard adjuvant temozolomide and vorinostat (400 mg/day) on days 1-7 and 15-21 of each 28-day cycle. Association between vorinostat response signatures and progression-free survival (PFS) and overall survival (OS) was assessed based on RNA sequencing of baseline tumor tissue. Results Phase I and phase II enrolled 15 and 107 patients, respectively. The combination therapy MTD was vorinostat 300 mg/day and temozolomide 75 mg/m2/day. Dose-limiting toxicities were grade 4 neutropenia and thrombocytopenia and grade 3 aspartate aminotransferase elevation, hyperglycemia, fatigue, and wound dehiscence. The primary efficacy endpoint in the phase II cohort, OS rate at 15 months, was 55.1% (median OS 16.1 mo), and consequently, the study did not meet its efficacy objective. Most common treatment-related grade 3/4 toxicities in the phase II component were lymphopenia (32.7%), thrombocytopenia (28.0%), and neutropenia (21.5%). RNA expression profiling of baseline tumors (N = 76) demonstrated that vorinostat resistance (sig-79) and sensitivity (sig-139) signatures had a reverse and positive association with OS/PFS, respectively. Conclusions Vorinostat combined with standard chemoradiation had acceptable tolerability in newly diagnosed glioblastoma. Although the primary efficacy endpoint was not met, vorinostat sensitivity and resistance signatures could facilitate patient selection in future trials.

Targeting epigenetic DNA and histone modifications to treat kidney disease.

Abstract: Epigenetics refers to heritable changes in gene expression patterns not caused by an altered nucleotide sequence, and includes non-coding RNAs and covalent modifications of DNA and histones. This review focuses on functional evidence for the involvement of DNA and histone epigenetic modifications in the pathogenesis of kidney disease and the potential therapeutic implications. There is evidence of activation of epigenetic regulatory mechanisms in acute kidney injury (AKI), chronic kidney disease (CKD) and the AKI-to-CKD transition of diverse aetiologies, including ischaemia-reperfusion injury, nephrotoxicity, ureteral obstruction, diabetes, glomerulonephritis and polycystic kidney disease. A beneficial in vivo effect over preclinical kidney injury has been reported for drugs that decrease DNA methylation by either inhibiting DNA methylation (e.g. 5-azacytidine and decitabine) or activating DNA demethylation (e.g. hydralazine), decrease histone methylation by inhibiting histone methyltransferases, increase histone acetylation by inhibiting histone deacetylases (HDACs, e.g. valproic acid, vorinostat, entinostat), increase histone crotonylation (crotonate) or interfere with histone modification readers [e.g. inhibits of bromodomain and extra-terminal proteins (BET)]. Most preclinical studies addressed CKD or the AKI-to-CKD transition. Crotonate administration protected from nephrotoxic AKI, but evidence is conflicting on DNA methylation inhibitors for preclinical AKI. Several drugs targeting epigenetic regulators are in clinical development or use, most of them for malignancy. The BET inhibitor apabetalone is in Phase 3 trials for atherosclerosis, kidney function being a secondary endpoint, but nephrotoxicity was reported for DNA and HDAC inhibitors. While research into epigenetic modulators may provide novel therapies for kidney disease, caution should be exercised based on the clinical nephrotoxicity of some drugs.

Effects of novel HDAC inhibitors on urothelial carcinoma cells

Abstract: Histone deacetylase inhibitors (HDACi) are promising anti-cancer drugs that could also be employed for urothelial carcinoma (UC) therapy. It is unclear, however, whether inhibition of all 11 zinc-dependent HDACs or of individual enzymes is more efficacious and specific. Here, we investigated the novel HDACi 19i (LMK235) with presumed preferential activity against class IIA HDAC4/5 in comparison to the pan-HDACi vorinostat (SAHA) and the HDAC4-specific HDACi TMP269 in UC cell lines with basal expression of HDAC4 and characterized two HDAC4-overexpressing UC cell lines. Cytotoxic concentrations 50% (CC50s) for HDACi were determined by MTT assay and high-content analysis-based fluorescent live/dead assay in UC cell lines with different expression of HDAC4 and as well as in normal urothelial cell cultures, HBLAK and HEK-293 cell lines. Effects of HDACis were analyzed by flow cytometry; molecular changes were followed by qRT-PCR and Western blots. UC lines overexpressing HDAC4 were established by lentiviral transduction. Inhibitor activity profiles of HDACi were obtained by current state in vitro assays, and docking analysis was performed using an updated crystal structure of HDAC4. In UC cell lines, 19i CC50s ranged around 1 μM; control lines were similarly or less sensitive. Like SAHA, 19i increased the G2/M-fraction, disturbed mitosis, and elicited apoptosis or in some cells senescence. Thymidylate synthase expression was diminished, and p21CIP1 was induced; global histone acetylation and α-tubulin acetylation also increased. In most cell lines, 19i as well as SAHA induced HDAC5 and HDAC4 mRNAs while rather repressing HDAC7. UC cell lines overexpressing HDAC4 were not significantly less sensitive to 19i. Reevaluation of the in vitro HDAC isoenzyme activity inhibition profile of 19i and its docking to HDAC4 using current assays suggested rather low activity against class IIA HDACs. The specific class IIA HDAC inhibitor TMP269 impeded proliferation of UC cell lines only at concentrations > 10 μM. Anti-neoplastic effects of 19i on UC cells appear to be exerted by targeting class I HDACs. In fact, HDAC4 may rather impede UC growth. Our results suggest that targeting of class IIA HDACs 4/5 may not be optimal for UC therapy. Moreover, our investigation provides further evidence for cross-regulation of class IIA HDACs by class I HDACs.

Differential Mechanisms of Cell Death Induced by HDAC Inhibitor SAHA and MDM2 Inhibitor RG7388 in MCF-7 Cells.

Abstract: Gene expression is often altered by epigenetic modifications that can significantly influence the growth ability and progression of cancers. SAHA (Suberoylanilide hydroxamic acid, also known as Vorinostat), a well-known Histone deacetylase (HDAC) inhibitor, can stop cancer growth and metastatic processes through epigenetic alterations. On the other hand, Letrozole is an aromatase inhibitor that can elicit strong anti-cancer effects on breast cancer through direct and indirect mechanisms. A newly developed inhibitor, RG7388 specific for an oncogene-derived protein called MDM2, is in clinical trials for the treatment of various cancers. In this paper, we performed assays to measure the effects of cell cycle arrest resulting from individual drug treatments or combination treatments with SAHA + letrozole and SAHA + RG7388, using the MCF-7 breast cancer cells. When SAHA was used individually, or in combination treatments with RG7388, a significant increase in the cytotoxic effect was obtained. Induction of cell cycle arrest by SAHA in cancer cells was evidenced by elevated p21 protein levels. In addition, SAHA treatment in MCF-7 cells showed significant up-regulation in phospho-RIP3 and MLKL levels. Our results confirmed that cell death caused by SAHA treatment was primarily through the induction of necroptosis. On the other hand, the RG7388 treatment was able to induce apoptosis by elevating BAX levels. It appears that, during combination treatments, with SAHA and RG7388, two parallel pathways might be induced simultaneously, that could lead to increased cancer cell death. SAHA appears to induce cell necroptosis in a p21-dependent manner, and RG7388 seems to induce apoptosis in a p21-independent manner, outlining differential mechanisms of cell death induction. However, further studies are needed to fully understand the intracellular mechanisms that are triggered by these two anti-cancer agents.

Pharmacological or transcriptional inhibition of both HDAC1 and 2 leads to cell cycle blockage and apoptosis via p21Waf1/Cip1 and p19INK4d upregulation in hepatocellular carcinoma

Abstract: Objectives Histone deacetylases (HDACs) are commonly dysregulated in cancer and represent promising therapeutic targets. However, global HDAC inhibitors have shown limited efficacy in the treatment of solid tumours, including hepatocellular carcinoma (HCC). In this study, we investigated the therapeutic effect of selectively inhibiting HDAC1 and 2 in HCC. Methods HDAC1 inhibitor Tacedinaline (CI994), HDAC2 inhibitor Santacruzamate A (CAY10683), HDAC1/2 common inhibitor Romidepsin (FK228) and global HDAC inhibitor Vorinostat (SAHA) were used to treat HCC cells. Cell cycle, apoptosis and the protein levels of CDKs and CDKNs were performed to evaluate HCC cell growth. Inhibition of HDAC1/2 by RNAi was further investigated. Results Combined inhibition of HDAC1/2 led to HCC cell morphology changes, growth inhibition, cell cycle blockage and apoptosis in vitro and suppressed the growth of subcutaneous HCC xenograft tumours in vivo. p21Waf1/Cip1 and p19INK4d, which play roles in cell cycle blockage and apoptosis induction, were upregulated. Inhibition of HDAC1/2 by siRNA further demonstrated that HDAC1 and 2 cooperate in blocking the cell cycle and inducing apoptosis via p19INK4d and p21Waf1/Cip1 upregulation. Finally, H3K18, H3K56 and H4K12 in the p19INK4d and p21Waf1/Cip1 promoter regions were found to be targets of HDAC1/2. Conclusions Pharmacological or transcriptional inhibition of HDAC1/2 increases p19INK4d and p21Waf1/Cip1 expression, decreases CDK expression and arrests HCC growth. These results indicated a potential pharmacological mechanism of selective HDAC1/2 inhibitors in HCC therapy.

Histone deacetylase inhibitors in hepatocellular carcinoma: A therapeutic perspective

Abstract: Hepatocellular carcinoma (HCC) is a major contributor to the global cancer burden. Given the current limited options to treat advanced HCC, understanding the molecular basis of HCC carcinogenesis and pinpointing druggable targets will be important to identify future HCC treatments. Epigenetic modification by inhibiting histone deacetylases (HDAC) is an emerging approach with promising results in cancer treatment. In the preclinical setting, HDAC inhibitors such as valproic acid sodium, panobinostat, vorinostat, trichostatin A, sodium butyrate, belinostat and romidepsin have demonstrated antitumor efficacy via activation of classic and alternative cell death molecular cascades. Combination regimens with the tyrosine kinase inhibitor sorafenib, poly(ADP-ribose) polymerases, proteasome and mammalian target of rapamycin inhibitors have shown promise. Phase I/II clinical studies with belinostat monotherapy and the combination of resminostat with sorafenib have suggested response and survival benefits. The safety profile was favorable with manageable adverse events and a low incidence of grade 3/4 toxicity. We herein review the role and potential therapeutic impact of epigenetic regulation through histone deacetylase inhibitors (HDACi) in the treatment of HCC.

The first-in-class alkylating deacetylase inhibitor molecule tinostamustine shows antitumor effects and is synergistic with radiotherapy in preclinical models of glioblastoma.

Abstract: The original article [1] contained an error whereby Fig. 4 displayed incorrect magnification scales.

A novel metabolism-based phenotypic drug discovery platform in zebrafish uncovers HDACs 1 and 3 as a potential combined anti-seizure drug target.

Abstract: Despite the development of newer anti-seizure medications over the past 50 years, 30-40% of patients with epilepsy remain refractory to treatment. One explanation for this lack of progress is that the current screening process is largely biased towards transmembrane channels and receptors, and ignores intracellular proteins and enzymes that might serve as efficacious molecular targets. Here, we report the development of a novel drug screening platform that harnesses the power of zebrafish genetics and combines it with in vivo bioenergetics screening assays to uncover therapeutic agents that improve mitochondrial health in diseased animals. By screening commercially available chemical libraries of approved drugs, for which the molecular targets and pathways are well characterized, we were able to reverse-identify the proteins targeted by efficacious compounds and confirm the physiological roles that they play by utilizing other pharmacological ligands. Indeed, using an 870-compound screen in kcna1-morpholino epileptic zebrafish larvae, we uncovered vorinostat (Zolinza™; suberanilohydroxamic acid, SAHA) as a potent anti-seizure agent. We further demonstrated that vorinostat decreased average daily seizures by ∼60% in epileptic Kcna1-null mice using video-EEG recordings. Given that vorinostat is a broad histone deacetylase (HDAC) inhibitor, we then delineated a specific subset of HDACs, namely HDACs 1 and 3, as potential drug targets for future screening. In summary, we have developed a novel phenotypic, metabolism-based experimental therapeutics platform that can be used to identify new molecular targets for future drug discovery in epilepsy.

Epigenetic priming of both tumor and NK cells augments antibody-dependent cellular cytotoxicity elicited by the anti-PD-L1 antibody avelumab against multiple carcinoma cell types.

Abstract: Checkpoint inhibitors targeting the PD-1/PD-L1 axis are promising immunotherapies shown to elicit objective responses against multiple tumor types, yet these agents fail to benefit most patients with carcinomas. This highlights the need to develop effective therapeutic strategies to increase responses to PD-1/PD-L1 blockade. Histone deacetylase (HDAC) inhibitors in combination with immunotherapies have provided preliminary evidence of anti-tumor effects. We investigated here whether exposure of either natural killer (NK) cells and/or tumor cells to two different classes of HDAC inhibitors would augment (a) NK cell‒mediated direct tumor cell killing and/or (b) antibody-dependent cellular cytotoxicity (ADCC) using avelumab, a fully human IgG1 monoclonal antibody targeting PD-L1. Treatment of a diverse array of human carcinoma cells with a clinically relevant dose of either the pan-HDAC inhibitor vorinostat or the class I HDAC inhibitor entinostat significantly enhanced the expression of multiple NK ligands and death receptors resulting in enhanced NK cell‒mediated lysis. Moreover, HDAC inhibition enhanced tumor cell PD-L1 expression both in vitro and in carcinoma xenografts. These data demonstrate that treatment of a diverse array of carcinoma cells with two different classes of HDAC inhibitors results in enhanced NK cell tumor cell lysis and avelumab-mediated ADCC. Furthermore, entinostat treatment of NK cells from healthy donors and PBMCs from cancer patients induced an activated NK cell phenotype, and heightened direct and ADCC-mediated healthy donor NK lysis of multiple carcinoma types. This study thus extends the mechanism and provides a rationale for combining HDAC inhibitors with PD-1/PD-L1 checkpoint blockade to increase patient responses to anti-PD-1/PD-L1 therapies.

Vorinostat, a pan-HDAC inhibitor, abrogates productive HPV-18 DNA amplification.

Abstract: Human papillomaviruses (HPVs) cause epithelial proliferative diseases. Persistent infection of the mucosal epithelia by the high-risk genotypes can progress to high-grade dysplasia and cancers. Viral transcription and protein activities are intimately linked to regulation by histone acetyltransferases and histone deacetylases (HDACs) that remodel chromatin and regulate gene expression. HDACs are also essential to remodel and repair replicating chromatin to enable the progression of replication forks. As such, Vorinostat (suberoylanilide hydroximic acid), and other pan-HDAC inhibitors, are used to treat lymphomas. Here, we investigated the effects of Vorinostat on productive infection of the high-risk HPV-18 in organotypic cultures of primary human keratinocytes. HPV DNA amplifies in the postmitotic, differentiated cells of squamous epithelia, in which the viral oncoproteins E7 and E6 establish a permissive milieu by destabilizing major tumor suppressors, the pRB family proteins and p53, respectively. We showed that Vorinostat significantly reduced these E6 and E7 activities, abrogated viral DNA amplification, and inhibited host DNA replication. The E7-induced DNA damage response, which is critical for both events, was also compromised. Consequently, Vorinostat exposure led to DNA damage and triggered apoptosis in HPV-infected, differentiated cells, whereas uninfected tissues were spared. Apoptosis was attributed to highly elevated proapoptotic Bim isoforms that are known to be repressed by EZH2 in a repressor complex containing HDACs. Two other HDAC inhibitors, Belinostat and Panobinostat, also inhibited viral DNA amplification and cause apoptosis. We suggest that HDAC inhibitors are promising therapeutic agents to treat benign HPV infections, abrogate progeny virus production, and hence interrupt transmission.

BET inhibition in advanced cutaneous T cell lymphoma is synergistically potentiated by BCL2 inhibition or HDAC inhibition.

Abstract: While several systemic therapies are approved for cutaneous T cell lymphoma (CTCL), a non-Hodgkin lymphoma of skin-homing T cells that may involve lymph nodes and peripheral blood in advanced stages, relapses are common. Mutational analysis of CTCL cells has revealed frequent amplification of the MYC oncogene, and bromodomain and extraterminal (BET) protein inhibitors have been shown to repress MYC expression in various malignancies. Towards a potential novel therapy, we thus sought to examine the effect of BET inhibition on CTCL cells in vitro. Each of the four tested BET inhibitors (JQ1, ABBV-075, I-BET762, CPI-0610) consistently induced dose-dependent decreases in viability of isolated patient-derived CTCL cells and established CTCL cell lines (MyLa, Sez4, HH, Hut78). This effect was synergistically potentiated by combination of BET inhibition with BCL2 inhibition (e.g. venetoclax) or histone deacetylase (HDAC) inhibition (e.g. vorinostat or romidepsin). There was also a marked increase in caspase 3/7 activation when JQ1 was combined with either vorinostat or romidepsin, confirming that the observed synergies are due in major part to induction of apoptosis. Furthermore, MYC and BCL2 expression were each synergistically repressed when CTCL cells were treated with JQ1 plus HDAC inhibitors, suggesting cooperative activities at the level of epigenetic regulation. Taken together, these data indicate that targeting BET proteins in CTCL represents a promising novel therapeutic strategy that may be substantially potentiated by combination with BCL2 or HDAC inhibition.

Enhanced Solubility, Permeability and Anticancer Activity of Vorinostat Using Tailored Mesoporous Silica Nanoparticles.

Abstract: Suberoylanilide hydroxamic acid (SAHA) or vorinostat (VOR) is a potent inhibitor of class I histone deacetylases (HDACs) that is approved for the treatment of cutaneous T-cell lymphoma. However, it has the intrinsic limitations of low water solubility and low permeability which reduces its clinical potential especially when given orally. Packaging of drugs within ordered mesoporous silica nanoparticles (MSNs) is an emerging strategy for increasing drug solubility and permeability of BCS (Biopharmaceutical Classification System) class II and IV drugs. In this study, we encapsulated vorinostat within MSNs modified with different functional groups, and assessed its solubility, permeability and anti-cancer efficacy in vitro. Compared to free drug, the solubility of vorinostat was enhanced 2.6-fold upon encapsulation in pristine MSNs (MCM-41-VOR). Solubility was further enhanced when MSNs were modified with silanes having amino (3.9 fold) or phosphonate (4.3 fold) terminal functional groups. Moreover, permeability of vorinostat into Caco-2 human colon cancer cells was significantly enhanced for MSN-based formulations, particularly MSNs modified with amino functional group (MCM-41-NH₂-VOR) where it was enhanced ~4 fold. Compared to free drug, vorinostat encapsulated within amino-modified MSNs robustly induced histone hyperacetylation and expression of established histone deacetylase inhibitor (HDACi)-target genes, and induced extensive apoptosis in HCT116 colon cancer cells. Similar effects were observed on apoptosis induction in HH cutaneous T-cell lymphoma cells. Thus, encapsulation of the BCS class IV molecule vorinostat within MSNs represents an effective strategy for improving its solubility, permeability and anti-tumour activity.

HDAC is indispensable for IFN-γ-induced B7-H1 expression in gastric cancer.

Abstract: B7 homolog 1 (B7-H1) overexpression on tumor cells is an important mechanism of immune evasion in gastric cancer (GC). Elucidation of the regulation of B7-H1 expression is urgently required to guide B7-H1-targeted cancer therapy. Interferon gamma (IFN-γ) is thought to be the main driving force behind B7-H1 expression, and epigenetic factors including histone acetylation are recently linked to the process. Here, we investigated the potential role of histone deacetylase (HDAC) in IFN-γ-induced B7-H1 expression in GC. The effect of Vorinostat (SAHA), a small molecular inhibitor of HDAC, on tumor growth and B7-H1 expression in a mouse GC model was also evaluated. RNA-seq data from The Cancer Genome Atlas revealed that expression of B7-H1, HDAC1–3, 6–8, and 10 and SIRT1, 3, 5, and 6 was higher, and expression of HDAC5 and SIRT4 was lower in GC compared to that in normal gastric tissues; that HDAC3 and HDAC1 expression level significantly correlated with B7-H1 in GC with a respective r value of 0.42 (p < 0.001) and 0.21 (p < 0.001). HDAC inhibitor (Trichostatin A, SAHA, and sodium butyrate) pretreatment suppressed IFN-γ-induced B7-H1 expression on HGC-27 cells. HDAC1 and HDAC3 gene knockdown had the same effect. SAHA pretreatment or HDAC knockdown resulted in impaired IFN-γ signaling, demonstrated by the reduction of JAK2, p-JAK1, p-JAK2, and p-STAT1 expression and inefficient STAT1 nuclear translocation. Furthermore, SAHA pretreatment compromised IFN-γ-induced upregulation of histone H3 lysine 9 acetylation level in B7-H1 gene promoter. In the grafted mouse GC model, SAHA treatment suppressed tumor growth, inhibited B7-H1 expression, and elevated the percentage of tumor-infiltrating CD8+ T cells. HDAC is indispensable for IFN-γ-induced B7-H1 in GC. The study suggests the possibility of targeting B7-H1 using small molecular HDAC inhibitors for cancer treatment.

The Role of Histone Deacetylase Inhibitors in Uveal Melanoma: Current Evidence.

Abstract: Uveal melanoma is the most common intraocular malignancy in adults, representing approximately 3% of all melanoma cases. Despite progress in chemotherapy, radiation and surgical treatment options, the prognosis and survival rates remain poor. Acetylation of histone proteins causes transcription of genes involved in cell growth, DNA replication and progression of cell cycle. Overexpression of histone deacetylases occurs in a wide spectrum of malignancies. Histone deacetylase inhibitors block the action of histone deacetylases, leading to inhibition of tumor cell proliferation. This article reviewed the potential therapeutic effects of histone deacetylase inhibitors on uveal melanoma. MEDLINE database was used under the key words/phrases: histone deacetylase, inhibitors, uveal melanoma and targeted therapies for uveal melanoma. A total of 47, English articles, not only referring to uveal melanoma, published up to February 2018 were used. Valproic acid, trichostatin A, tenovin-6, depsipeptide, panobinostat (LBH-589), vorinostat (suberanilohydroxamic acid) entinostat (MS-275), quisinostat, NaB, JSL-1, MC1568 and MC1575 are histone deacetylase inhibitors that have demonstrated promising antitumor effects against uveal melanoma. Histone deacetylase inhibitors represent a promising therapeutic approach for the treatment of uveal melanoma.

A phase I/II trial of vorinostat (SAHA) in combination with rituximab-CHOP in patients with newly diagnosed advanced stage diffuse large B-cell lymphoma (DLBCL): SWOG S0806.

Abstract: Loss of major histocompatibility Class II expression (MHCII) in diffuse large B-cell lymphoma (DLBCL) correlates with decreased survival. MHCII transcription is in part regulated by histone acetylation. We tested the hypothesis that combination of histone deacetylase inhibitor (HDACI) with standard chemotherapy would improve outcomes in DLBCL in part through increased MHCII expression. S0806 was a single arm phase I/II trial of vorinostat given at 400 mg po daily on days 1-9 (subsequently amended to days 1-5 due to toxicity), combined with R-CHOP given on day 3 of a 21-day cycle for 8 cycles, with primary phase II endpoint of 2-year progression free survival (PFS). With 72 evaluable patients, at median follow up of 3 years, 2-year PFS estimate was 73%, and OS estimate was 86%. Considering that the regimen fell short of predefined efficacy improvement and was associated with high rates of febrile neutropenia (38%) and sepsis (19%), it cannot be recommended for general use. Consistent with our hypothesis, patients with low MCHII expression on S0806 had numerically superior outcomes compared to those from trial S0433 which did not use an HDACI, but the difference was not statistically significant. Current studies are focused on finding biomarkers of response to HDACI.

Inhibition of glioblastoma cell proliferation, invasion, and mechanism of action of a novel hydroxamic acid hybrid molecule

Abstract: Glioblastoma multiforme is one of the most aggressive brain tumors and current therapies with temozolomide or suberoylanilide hydroxamic acid (SAHA, vorinostat) show considerable limitations. SAHA is a histone deacetylase (HDAC) inhibitor that can cause undesirable side effects due to the lack of selectivity. We show here properties of a novel hybrid molecule, sahaquine, which selectively inhibits cytoplasmic HDAC6 at nanomolar concentrations without markedly suppressing class I HDACs. Inhibition of HDAC6 leads to significant α-tubulin acetylation, thereby impairing cytoskeletal organization in glioblastoma cells. The primaquine moiety of sahaquine reduced the activity of P-glycoprotein, which contributes to glioblastoma multiforme drug resistance. We propose the mechanism of action of sahaquine to implicate HDAC6 inhibition together with suppression of epidermal growth factor receptor and downstream kinase activity, which are prominent therapeutic targets in glioblastoma multiforme. Sahaquine significantly reduces the viability and invasiveness of glioblastoma tumoroids, as well as brain tumor stem cells, which are key to tumor survival and recurrence. These effects are augmented with the combination of sahaquine with temozolomide, the natural compound quercetin or buthionine sulfoximine, an inhibitor of glutathione biosynthesis. Thus, a combination of agents disrupting glioblastoma and brain tumor stem cell homeostasis provides an effective anti–cancer intervention.

The Existing Drug Vorinostat as a New Lead Against Cryptosporidiosis by Targeting the Parasite Histone Deacetylases.

Abstract: Background Cryptosporidiosis affects all human populations, but can be much more severe or life-threatening in children and individuals with weak or weakened immune systems. However, current options to treat cryptosporidiosis are limited. Methods An in vitro phenotypic screening assay was employed to screen 1200 existing drugs for their anticryptosporidial activity and to determine the inhibitory kinetics of top hits. Selected top hits were further evaluated in mice. The action of the lead compound vorinostat on the parasite histone deacetylase (HDAC) was biochemically validated. Results Fifteen compounds exhibited anticryptosporidial activity at nanomolar level in vitro. Among them, the histone deacetylase (HDAC) inhibitor vorinostat retained outstanding efficacy in vitro (half maximal effective concentration, EC50 = 203 nM) and in an interleukin 12 knockout mouse model (50% inhibition dose = 7.5 mg/kg). Vorinostat was effective on various parasite developmental stages and could irreversibly kill the parasite. Vorinostat was highly effective against the parasite native HDAC enzymes (half maximal inhibitory concentration, IC50 = 90.0 nM) and a recombinant Cryptosporidium parvum HDAC (the inhibitor constant, Ki = 123.0 nM). Conclusions These findings suggest the potential for repurposing of vorinostat to treat cryptosporidiosis, and imply that the parasite HDAC can be explored for developing more selective anticryptosporidial therapeutics.

Phase I study of vorinostat in combination with isotretinoin in patients with refractory/recurrent neuroblastoma: A new approaches to Neuroblastoma Therapy (NANT) trial

Abstract: Background Vorinostat combined with retinoids produces additive antitumor effects in preclinical studies of neuroblastoma. Higher systemic exposures of vorinostat than achieved in pediatric phase I trials with continuous daily dosing are necessary for in vivo increased histone acetylation and cytotoxic activity. We conducted a phase I trial in children with relapsed/refractory neuroblastoma to determine the maximum tolerated dose (MTD) of vorinostat on an interrupted schedule, escalating beyond the previously identified pediatric MTD. Methods Isotretinoin (cis-13-retinoic acid) 80 mg/m2 /dose was administered by mouth twice daily on days 1-14 in combination with escalating doses of daily vorinostat up to 430 mg/m2 /dose (days 1-4; 8-11) in each 28-day cycle using the standard 3 + 3 design. Vorinostat pharmacokinetic testing and histone acetylation assays were performed. Results Twenty-nine patients with refractory or relapsed neuroblastoma were enrolled and 28 were evaluable for dose escalation decisions. Median number of cycles completed was two (range 1-15); 11 patients received four or more cycles. Three patients experienced cycle 1 dose-limiting toxicities. A total of 18 patients experienced grade 3/4 toxicities related to study therapy. The maximum intended dose of vorinostat (430 mg/m2 /day, days 1-4; 8-11) was tolerable and led to increased histone acetylation in surrogate tissues when compared to lower doses of vorinostat (P = 0.009). No objective responses were seen. Conclusions Increased dose vorinostat (430 mg/m2 /day) on an interrupted schedule is tolerable in combination with isotretinoin. This dose led to increased vorinostat exposures and demonstrated increased histone acetylation. Prolonged stable disease in patients with minimal residual disease warrants further investigation.

Vorinostat and quinacrine have synergistic effects in T-cell acute lymphoblastic leukemia through reactive oxygen species increase and mitophagy inhibition.

Abstract: Despite recent progress in the treatment, the outcome of adult acute T-cell lymphoblastic leukemia (T-ALL) is poor. Development of novel approach to combat this disease is urgently required. Vorinostat, a pan-histone deacetylase (HDAC) inhibitor, exerts promising anticancer activity in a variety of solid and hematologic malignancies. However, the efficacy of vorinostat monotherapy is unsatisfactory. Here, we show that quinacrine (QC), an anti-malaria drug with potent autophagy inhibitory activity, could synergistically enhance vorinostat-induced cell death at a non-toxic concentration. Compared to the single treatment, QC plus vorinostat significantly induced apoptosis, disrupted the mitochondrial transmembrane potential, and decreased Mcl-1 and Bcl-2/Bax ratio. Interestingly, the application of QC plus vorinostat resulted in mitophagy blockade, as reflected by the increase in the K63-linked ubiquitination of mitochondria protein and the formation of mitochondrial aggresomes. QC plus vorinostat markedly increased the reactive oxygen species (ROS) level in cells. Moreover, the ROS scavenger N-acetylcysteine (NAC) abrogated QC plus vorinostat-induced ROS, decreased the ubiquitination of mitochondria proteins, and cell death. Finally, using a xenograft mouse model, we demonstrated that QC plus vorinostat significantly reduced cell proliferation and induced cell death in vivo. Taken together, our results showed that the combination of QC with vorinostat may represent a novel regimen for the treatment of T-cell acute lymphoblastic leukemia, which deserves clinical evaluation in the future.

ASXL1 and SETBP1 mutations promote leukaemogenesis by repressing TGFβ pathway genes through histone deacetylation.

Abstract: Mutations in ASXL1 and SETBP1 genes have been frequently detected and often coexist in myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). We previously showed that coexpression of mutant ASXL1 and SETBP1 in hematopoietic progenitor cells induced downregulation of TGFβ pathway genes and promoted the development of MDS/AML in a mouse model of bone marrow transplantation. However, whether the repression of TGFβ pathway in fact contributes to leukaemogenesis remains unclear. Moreover, mechanisms for the repression of TGFβ pathway genes in ASXL1/SETBP1-mutated MDS/AML cells have not been fully understood. In this study, we showed that expression of a constitutively active TGFβ type I receptor (ALK5-TD) inhibited leukaemic proliferation of MDS/AML cells expressing mutant ASXL1/SETBP1. We also found aberrantly reduced acetylation of several lysine residues on histone H3 and H4 around the promoter regions of multiple TGFβ pathway genes. The histone deacetylase (HDAC) inhibitor vorinostat reversed histone acetylation at these promoter regions, and induced transcriptional derepression of the TGFβ pathway genes. Furthermore, vorinostat showed robust growth-inhibitory effect in cells expressing mutant ASXL1, whereas it showed only a marginal effect in normal bone marrow cells. These data indicate that HDAC inhibitors will be promising therapeutic drugs for MDS and AML with ASXL1 and SETBP1 mutations.

Vorinostat enhances the anticancer effect of oxaliplatin on hepatocellular carcinoma cells.

Abstract: Oxaliplatin-based systemic chemotherapy has been proposed to have efficacy in hepatocellular carcinoma (HCC). We investigated the combination of vorinostat and oxaliplatin for possible synergism in HCC cells. SMMC7721, BEL7402, and HepG2 cells were treated with vorinostat and oxaliplatin. Cytotoxicity assay, tumorigenicity assay in vitro, cell cycle analysis, apoptosis analysis, western blot analysis, animal model study, immunohistochemistry, and quantitative PCR were performed. We found that vorinostat and oxaliplatin inhibited the proliferation of SMMC7721, BEL7402, and HepG2 cells. The combination index (CI) values were all <1, and the dose-reduction index values were all greater than 1 in the three cell lines, indicating a synergistic effect of combination of the two agents. Coadministration of vorinostat and oxaliplatin induced G2/M phase arrest, triggered caspase-dependent apoptosis, and decreased tumorigenicity both in vitro and in vivo. Vorinostat suppressed the expression of BRCA1 induced by oxaliplatin. In conclusion, cotreatment with vorinostat and oxaliplatin exhibited synergism in HCC cells. The combination inhibited cell proliferation and tumorigenicity both in vitro and in vivo through induction of cell cycle arrest and apoptosis. Our results predict that a combination of vorinostat and oxaliplatin may be useful in the treatment of advanced HCC.