panobinostat and romidepsin

Dysregulation of histone deacetylase (HDAC) activity is an epigenetic hallmark of multiple myeloma (MM), leading to aberrant gene expression and cellular signaling in myeloma cell growth, survival and resistance to therapy. Hyper-methylation at diagnosis is a frequent observation, which eventually may convert to hypo-methylation during advanced phases.. A literature search on 'HDAC inhibitors' and 'multiple myeloma' was carried out using PubMed and Google Scholar in the preparation of this overview on clinical efficacy and safety data.. First-generation non-selective HDAC inhibitors have demonstrated minimal single-agent activity in refractory MM. Subsequently, combination therapy has proven an improvement in progression-free survival (PFS) but not response rates. The main concerns are associated with toxicities. Ongoing studies on new and more selective agents, i.e. Romidepsin or Ricolinostat, are promising in terms of better efficacy and less toxicity.

Topics: Animals; Antineoplastic Agents; Depsipeptides; Disease-Free Survival; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Multiple Myeloma; Panobinostat; Treatment Outcome

Despite the success of antiretroviral therapy (ART), there is currently no HIV cure and treatment is life long. HIV persists during ART due to long-lived and proliferating latently infected CD4+ T cells. One strategy to eliminate latency is to activate virus production using latency reversing agents (LRAs) with the goal of triggering cell death through virus-induced cytolysis or immune-mediated clearance. However, multiple studies have demonstrated that activation of viral transcription alone is insufficient to induce cell death and some LRAs may counteract cell death by promoting cell survival. Here, we review new approaches to induce death of latently infected cells through apoptosis and inhibition of pathways critical for cell survival, which are often hijacked by HIV proteins. Given advances in the commercial development of compounds that induce apoptosis in cancer chemotherapy, these agents could move rapidly into clinical trials, either alone or in combination with LRAs, to eliminate latent HIV infection.

Topics: Anti-HIV Agents; Bryostatins; CD4-Positive T-Lymphocytes; Depsipeptides; HIV Infections; HIV-1; Humans; Hydroxamic Acids; Indoles; Panobinostat; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Virus Activation; Virus Latency; Vorinostat

Histone deacetylases (HDACs) are epigenetic drug targets that have gained major scientific attention. Inhibition of these important regulatory enzymes is used to treat cancer, and has the potential to treat a host of other diseases. However, currently marketed HDAC inhibitors lack selectivity for the various HDAC isoenzymes. Several studies have shown that HDAC3, in particular, plays an important role in inflammation and degenerative neurological diseases, but the development of selective HDAC3 inhibitors has been challenging. This review provides an up-to-date overview of selective HDAC3 inhibitors, and aims to support the development of novel HDAC3 inhibitors in the future.

Topics: Antineoplastic Agents; Chemistry Techniques, Synthetic; Depsipeptides; Drug Design; Epigenesis, Genetic; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Indoles; Inflammation; Isoenzymes; Neoplasm Proteins; Neoplasms; Neurodegenerative Diseases; Panobinostat; Structure-Activity Relationship; Sulfonamides; Vorinostat

Histone deacetylase inhibitors (HDAC inhibitors) are used to treat malignancies such as cutaneous T cell lymphoma and peripheral T cell lymphoma. Only four drugs are approved by the US Food and Drug Administration, namely vorinostat, romidepsin, panobinostat and belinostat, while chidamide has been approved in China. There are a number of bioanalytical methods reported for the measurement of HDAC inhibitors in clinical (human plasma and serum) and preclinical (mouse plasma, rat plasma, urine and tissue homogenates, etc.) studies. This review covers various HDAC inhibitors such as vorinostat, romidepsin, panobinostat, belinostat and chidamide. In addition to providing a comprehensive review of the available methods for the above mentioned HDAC inhibitors, it also provides case studies with perspectives for chosen drugs. Based on the review, it is concluded that the published methodologies using either HPLC or LC-MS/MS are well suited for the quantification of HDAC inhibitors in various biological fluids to delineate pharmacokinetic data.

Topics: Aminopyridines; Animals; Benzamides; Chromatography, High Pressure Liquid; Depsipeptides; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Neoplasms; Panobinostat; Sulfonamides; Tandem Mass Spectrometry; Vorinostat

The histone deacetylase inhibitor valproic acid (VPA) has been used for many decades in neurology and psychiatry. The more recent introduction of the histone deacetylase inhibitors (HDIs) belinostat, romidepsin and vorinostat for treatment of hematological malignancies indicates the increasing popularity of these agents. Belinostat, romidepsin and vorinostat are metabolized or transported by polymorphic enzymes or drug transporters. Thus, genotype-directed dosing could improve pharmacotherapy by reducing the risk of toxicities or preventing suboptimal treatment. This review provides an overview of clinical studies on the effects of polymorphisms on the pharmacokinetics, efficacy or toxicities of HDIs including belinostat, romidepsin, vorinostat, panobinostat, VPA and a number of novel compounds currently being tested in Phase I and II trials. Although pharmacogenomic studies for HDIs are scarce, available data indicate that therapy with belinostat (UGT1A1), romidepsin (ABCB1), vorinostat (UGT2B17) or VPA (UGT1A6) could be optimized by upfront genotyping.

Topics: Depsipeptides; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Panobinostat; Pharmacogenetics; Sulfonamides; Valproic Acid; Vorinostat

Cutaneous T-cell lymphomas (CTCLs) are non-Hodgkin's T-cell lymphomas that present as skin lesions. Mycosis fungoides with large cell transformation has a 5-year overall survival of 32% with involved skin and 7% with extracutaneous involvement. Failure to cure advanced MF with large cell transformation and peripheral T-cell lymphoma has resulted in a search for novel targeted agents including antibodies and gene modulators. Histone deacetylase inhibitors are small molecules that seem to be particularly active for T-cell lymphoma.

Topics: Depsipeptides; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Lymphoma, T-Cell, Cutaneous; Panobinostat; Skin Neoplasms; Sulfonamides; Vorinostat

Topics: Aminopyridines; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Clinical Trials as Topic; Depsipeptides; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Indoles; Neoplasms; Panobinostat; Sulfonamides; Vorinostat

Over the last 5 years, a plethora of histone deacetylase inhibitors (HDACi) have been evaluated in clinical trials. These drugs have in common the ability to hyperacetylate both histone and nonhistone targets, resulting in a variety of effects on cancer cells, their microenvironment, and immune responses. To date, responses with single agent HDACi have been predominantly observed in advanced hematologic malignancies including T-cell lymphoma, Hodgkin lymphoma, and myeloid malignancies. Therefore, in this review we focus upon hematologic malignancies. Generally HDACi are well tolerated with the most common acute toxicities being fatigue, gastrointestinal, and transient cytopenias. Of note, few patients have been treated for prolonged periods of time and little is known about long-term toxicities. The use of the biomarker of histone hyperacetylation has been useful as a guide to target specificity, but generally does not predict for response and the search for more clinically relevant biomarkers must continue.

Topics: Antibiotics, Antineoplastic; Benzamides; Clinical Trials as Topic; Depsipeptides; Drug Therapy, Combination; Enzyme Inhibitors; Hematologic Neoplasms; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Panobinostat; Pyridines; Pyrimidines; Sulfonamides; Vorinostat

Histone deacetylase inhibitors (HDACi) are a new class of antineoplastic agents with demonstrable preclinical antitumor activity in both in vitro and in vivo studies in a wide range of malignancies. Based on these preclinical findings, in recent years HDACi have undergone a rapid phase of clinical development with many HDACi entering Phase I-III clinical trials, both as single agents and in combination with other therapies. Favorable clinical responses have been demonstrated in cutaneous T-cell lymphoma with emerging evidence of clinical activity in other types of lymphoma and, to date, a good toxicity profile. Solid tumor responses to single agent and combination therapies have also been reported, paving the way for larger studies in this field. In this review we discuss the recent advances in the clinical development of HDACi and their current therapeutic role in lymphoma and solid malignancies.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Depsipeptides; Drug Resistance, Neoplasm; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Lymphoma; Neoplasm Recurrence, Local; Neoplasms; Panobinostat; Pyridines; Pyrimidines; Vorinostat

Overall survival rates for patients with advanced osteosarcoma have remained static for over three decades. An in vitro analysis of osteosarcoma cell lines for sensitivity to an array of approved cancer therapies revealed that panobinostat, a broad spectrum histone deacetalyase (HDAC) inhibitor, is highly effective at triggering osteosarcoma cell death. Using in vivo models of orthotopic and metastatic osteosarcoma, here we report that panobinostat impairs the growth of primary osteosarcoma in bone and spontaneous metastasis to the lung, the most common site of metastasis for this disease. Further, pretreatment of mice with panobinostat prior to tail vein inoculation of osteosarcoma prevents the seeding and growth of lung metastases. Additionally, panobinostat impaired the growth of established lung metastases and improved overall survival, and these effects were also manifest in the lung metastatic SAOS2-LM7 model. Mechanistically, the efficacy of panobinostat was linked to high expression of HDAC1 and HDAC2 in osteosarcoma, and silencing of HDAC1 and 2 greatly reduced osteosarcoma growth in vitro. In accordance with these findings, treatment with the HDAC1/2 selective inhibitor romidepsin compromised the growth of osteosarcoma in vitro and in vivo. Analysis of patient-derived xenograft osteosarcoma cell lines further demonstrated the sensitivity of the disease to panobinostat or romidepsin. Collectively, these studies provide rationale for clinical trials in osteosarcoma patients using the approved therapies panobinostat or romidepsin.

Topics: Animals; Bone Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Depsipeptides; Gene Expression Regulation, Neoplastic; Histone Deacetylase 1; Histone Deacetylase 2; Histone Deacetylase Inhibitors; Humans; Lung Neoplasms; Mice; Osteosarcoma; Panobinostat; Survival Analysis; Xenograft Model Antitumor Assays

Metaplastic breast carcinoma (MBC) is a clinically aggressive and rare subtype of breast cancer, with similar features to basal-like breast cancers. Due to rapid growth rates and characteristic heterogeneity, MBC is often unresponsive to standard chemotherapies; and novel targeted therapeutic discovery is urgently needed. Histone deacetylase inhibitors (DACi) suppress tumor growth and metastasis through regulation of the epithelial-to-mesenchymal transition axis in various cancers, including basal-like breast cancers. We utilized a new MBC patient-derived xenograft (PDX) to examine the effect of DACi therapy on MBC. Cell morphology, cell cycle-associated gene expressions, transwell migration, and metastasis were evaluated in patient-derived cells and tumors after treatment with romidepsin and panobinostat. Derivations of our PDX model, including cells, spheres, organoids, explants, and in vivo implanted tumors were treated. Finally, we tested the effects of combining DACi with approved chemotherapeutics on relative cell biomass. DACi significantly suppressed the total number of lung metastasis in vivo using our PDX model, suggesting a role for DACi in preventing circulating tumor cells from seeding distal tissue sites. These data were supported by our findings that DACi reduced cell migration, populations, and expression of mesenchymal-associated genes. While DACi treatment did affect cell cycle-regulating genes in vitro, tumor growth was not affected compared to controls. Importantly, gene expression results varied depending on the cellular or tumor system used, emphasizing the importance of using multiple derivations of cancer models in preclinical therapeutic discovery research. Furthermore, DACi sensitized and produced a synergistic effect with approved oncology therapeutics on inherently resistant MBC. This study introduced a role for DACi in suppressing the migratory and mesenchymal phenotype of MBC cells through regulation of the epithelial-mesenchymal transition axis and suppression of the CTC population. Preliminary evidence that DACi treatment in combination with MEK1/2 inhibitors exerts a synergistic effect on MBC cells was also demonstrated.

Topics: Animals; Breast Neoplasms; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Cell Survival; Depsipeptides; Drug Synergism; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; Lung Neoplasms; Mice; Middle Aged; Neoplastic Cells, Circulating; Panobinostat; Patient-Specific Modeling; Protein Kinase Inhibitors

The latent human immunodeficiency virus type 1 (HIV-1) reservoir represents a major barrier to a cure. Based on the levels of HIV-1 DNA in naive (TN) vs resting memory CD4+ T cells, it is widely hypothesized that this reservoir resides primarily within memory cells. Here, we compared virus production from TN and central memory (TCM) CD4+ T cells isolated from HIV-1-infected individuals on suppressive therapy.. CD4+ TN and TCM cells were purified from the blood of 7 HIV-1-infected individuals. We quantified total HIV-1 DNA in the CD4+ TN and TCM cells. Extracellular virion-associated HIV-1 RNA or viral outgrowth assays were used to assess latency reversal following treatment with anti-CD3/CD28 monoclonal antibodies (mAbs), phytohaemagglutinin/interleukin-2, phorbol 12-myristate 13-acetate/ionomycin, prostratin, panobinostat, or romidepsin.. HIV-1 DNA was significantly higher in TCM compared to TN cells (2179 vs 684 copies/106 cells, respectively). Following exposure to anti-CD3/CD28 mAbs, virion-associated HIV-1 RNA levels were similar between TCM and TN cells (15 135 vs 18 290 copies/mL, respectively). In 4/7 donors, virus production was higher for TN cells independent of the latency reversing agent used. Replication-competent virus was recovered from both TN and TCM cells.. Although the frequency of HIV-1 infection is lower in TN compared to TCM cells, as much virus is produced from the TN population after latency reversal. This finding suggests that quantifying HIV-1 DNA alone may not predict the size of the inducible latent reservoir and that TN cells may be an important reservoir of latent HIV-1.

Topics: Adult; CD28 Antigens; CD4-Positive T-Lymphocytes; Depsipeptides; Female; Flow Cytometry; HIV-1; Humans; Interleukin-2; Male; Middle Aged; Panobinostat; Phorbol Esters; Phytohemagglutinins

The major obstacle impeding human immunodeficiency virus-1 (HIV-1) eradication in antiretroviral treatment (ART) treated HIV-1 subjects is the establishment of long-lived latently infected resting CD4. J89GFP lymphocyte and THP89GFP monocyte derived cell lines latently infected with HIV-1 p89GFP were used as an in vitro model of latency for our study. Viability assays by 3-(4-5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) were performed to determine the working concentrations of dendrimers and LRAs. Both cell lines were treated with G1-S4, G2-S16 and G3-S16 either alone or in combination with bryostatin (BRY), romidepsin (RMD) or panobinostat (PNB) for 24 and 48 h. The expression pattern of GFP was measured by flow cytometry and referred as measure of viral reactivation.. The combination treatment of the dendrimers with the protein kinase C (PKC) agonist did not modify the antilatency activity in J89GFP lymphocyte cell line. Interestingly enough, G3-S16 dendrimer alone and its combination with BRY, RMD or PNB showed a significant increased expression of GFP in the THP89GFP monocyte cell line.. We showed for the first time that nanoparticles, in this case, G3-S16 anionic carbosilan dendrimer may play an important role in new treatments against HIV-1 infection.

Topics: Adjuvants, Immunologic; Anti-HIV Agents; Bryostatins; Cell Line; Cell Survival; Dendrimers; Depsipeptides; Drug Liberation; Drug Therapy, Combination; HIV Infections; HIV-1; Humans; Lymphocytes; Monocytes; Panobinostat; Particle Size; Polyelectrolytes; Polymers; Silanes; Surface Properties

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of three human malignancies, the endothelial cell cancer Kaposi's sarcoma, and two B cell cancers, Primary Effusion Lymphoma and multicentric Castleman's disease. KSHV has latent and lytic phases of the viral life cycle, and while both contribute to viral pathogenesis, lytic proteins contribute to KSHV-mediated oncogenesis. Reactivation from latency is driven by the KSHV lytic gene transactivator RTA, and RTA transcription is controlled by epigenetic modifications. To identify host chromatin-modifying proteins that are involved in the latent to lytic transition, we screened a panel of inhibitors that target epigenetic regulatory proteins for their ability to stimulate KSHV reactivation. We found several novel regulators of viral reactivation: an inhibitor of Bmi1, PTC-209, two additional histone deacetylase inhibitors, Romidepsin and Panobinostat, and the bromodomain inhibitor (+)-JQ1. All of these compounds stimulate lytic gene expression, viral genome replication, and release of infectious virions. Treatment with Romidepsin, Panobinostat, and PTC-209 induces histone modifications at the RTA promoter, and results in nucleosome depletion at this locus. Finally, silencing Bmi1 induces KSHV reactivation, indicating that Bmi1, a member of the Polycomb repressive complex 1, is critical for maintaining KSHV latency.

Topics: Cell Line; Chromatin Assembly and Disassembly; Depsipeptides; Epigenesis, Genetic; Genome, Viral; Herpesvirus 8, Human; Heterocyclic Compounds, 2-Ring; Histone Deacetylase Inhibitors; Host-Pathogen Interactions; Humans; Immediate-Early Proteins; Panobinostat; Polycomb Repressive Complex 1; Promoter Regions, Genetic; RNA Interference; Thiazoles; Trans-Activators; Virus Activation; Virus Latency

Viral-host interactomes map the complex architecture of an evolved arms race during host cell invasion. mRNA and protein interactomes reveal elaborate targeting schemes, yet evidence is lacking for genetic coupling that results in the co-regulation of promoters. Here we compare viral and human promoter sequences and expression to test whether genetic coupling exists and investigate its phenotypic consequences. We show that viral-host co-evolution is imprinted within promoter gene sequences before transcript or protein interactions. Co-regulation of human immunodeficiency virus (HIV) and human C-X-C chemokine receptor-4 (CXCR4) facilitates migration of infected cells. Upon infection, HIV can actively replicate or remain dormant. Migrating infected cells reactivate from dormancy more than non-migrating cells and exhibit differential migration-reactivation responses to drugs. Cells producing virus pose a risk for reinitiating infection within niches inaccessible to drugs, and tuning viral control of migration and reactivation improves strategies to eliminate latent HIV. Viral-host genetic coupling establishes a mechanism for synchronizing transcription and guiding potential therapies.

Topics: CD4-Positive T-Lymphocytes; Cell Movement; Depsipeptides; Gene Expression Regulation; HIV Long Terminal Repeat; HIV-1; HL-60 Cells; Host-Pathogen Interactions; Humans; Hydroxamic Acids; Indoles; Ionomycin; Jurkat Cells; Panobinostat; Phorbol Esters; Primary Cell Culture; Promoter Regions, Genetic; Receptors, CXCR4; Tamoxifen; tat Gene Products, Human Immunodeficiency Virus; Transcription, Genetic; Tumor Necrosis Factor-alpha; Virus Activation; Virus Latency; Vorinostat

Topics: Acetylation; Administration, Oral; Animals; Depsipeptides; HEK293 Cells; Histone Deacetylase Inhibitors; Histone Deacetylases; Histones; Humans; Hydroxamic Acids; Indoles; Inhibitory Concentration 50; Leishmania; Life Cycle Stages; Malaria; Mice; Panobinostat; Parasitemia; Plasmodium berghei; Plasmodium knowlesi; Schistosoma mansoni; Sulfonamides; Vorinostat

Antiretroviral-free HIV remission requires substantial reduction of the number of latently infected cells and enhanced immune control of viremia. Latency-reversing agents (LRAs) aim to eliminate latently infected cells by increasing the rate of reactivation of HIV transcription, which exposes these cells to killing by the immune system. As LRAs are explored in clinical trials, it becomes increasingly important to assess the effect of an increased HIV reactivation rate on the decline of latently infected cells and to estimate LRA efficacy in increasing virus reactivation. However, whether the extent of HIV reactivation is a good predictor of the rate of decline of the number of latently infected cells is dependent on a number of factors. Our modeling shows that the mechanisms of maintenance and clearance of the reservoir, the life span of cells with reactivated HIV, and other factors may significantly impact the relationship between measures of HIV reactivation and the decline in the number of latently infected cells. The usual measures of HIV reactivation are the increase in cell-associated HIV RNA (CA RNA) and/or plasma HIV RNA soon after administration. We analyze two recent studies where CA RNA was used to estimate the impact of two novel LRAs, panobinostat and romidepsin. Both drugs increased the CA RNA level 3- to 4-fold in clinical trials. However, cells with panobinostat-reactivated HIV appeared long-lived (half-life > 1 month), suggesting that the HIV reactivation rate increased by approximately 8%. With romidepsin, the life span of cells that reactivated HIV was short (2 days), suggesting that the HIV reactivation rate may have doubled under treatment.

Topics: Anti-HIV Agents; Depsipeptides; HIV Infections; HIV-1; Humans; Hydroxamic Acids; Indoles; Models, Theoretical; Panobinostat; RNA, Viral; Transcription, Genetic; Viremia; Virus Activation; Virus Latency

Latency-reversing agents (LRAs), including histone deacetylase inhibitors (HDACi), are being investigated as a strategy to eliminate latency in HIV-infected patients on suppressive antiretroviral therapy. The effectiveness of LRAs in activating latent infection in HIV strains derived from the central nervous system (CNS) is unknown. Here we show that CNS-derived HIV-1 strains possess polymorphisms within and surrounding the Sp transcription factor motifs in the long terminal repeat (LTR). These polymorphisms result in decreased ability of the transcription factor specificity protein 1 to bind CNS-derived LTRs, reducing the transcriptional activity of CNS-derived viruses. These mutations result in CNS-derived viruses being less responsive to activation by the HDACi panobinostat and romidepsin compared with lymphoid-derived viruses from the same subjects. Our findings suggest that HIV-1 strains residing in the CNS have unique transcriptional regulatory mechanisms, which impact the regulation of latency, the consideration of which is essential for the development of HIV-1 eradication strategies.

Topics: Adult; Brain; CD4-Positive T-Lymphocytes; Central Nervous System; Cohort Studies; Depsipeptides; Histone Deacetylase Inhibitors; HIV Infections; HIV-1; Humans; Hydroxamic Acids; Indoles; Jurkat Cells; Male; Middle Aged; Panobinostat; Polymorphism, Genetic; Terminal Repeat Sequences; Transcriptional Activation; Virus Latency

Despite the success of combination antiretroviral therapy (cART), HIV persists in long lived latently infected cells in the blood and tissue, and treatment is required lifelong. Recent clinical studies have trialed latency-reversing agents (LRA) as a method to eliminate latently infected cells; however, the effects of LRA on the central nervous system (CNS), a well-known site of virus persistence on cART, are unknown. In this study, we evaluated the toxicity and potency of a panel of commonly used and well-known LRA (panobinostat, romidepsin, vorinostat, chaetocin, disulfiram, hexamethylene bisacetamide [HMBA], and JQ-1) in primary fetal astrocytes (PFA) as well as monocyte-derived macrophages as a cellular model for brain perivascular macrophages. We show that most LRA are non-toxic in these cells at therapeutic concentrations. Additionally, romidepsin, JQ-1, and panobinostat were the most potent at inducing viral transcription, with greater magnitude observed in PFA. In contrast, vorinostat, chaetocin, disulfiram, and HMBA all demonstrated little or no induction of viral transcription. Together, these data suggest that some LRA could potentially activate transcription in latently infected cells in the CNS. We recommend that future trials of LRA also examine the effects of these agents on the CNS via examination of cerebrospinal fluid.

Topics: Acetamides; Astrocytes; Azepines; Cell Line; Cell Survival; Depsipeptides; Disulfiram; Fetus; Histone Deacetylase Inhibitors; HIV-1; Humans; Hydroxamic Acids; Indoles; Macrophages; Neurons; Panobinostat; Piperazines; Primary Cell Culture; Transcription, Genetic; Triazoles; Virus Activation; Virus Latency; Virus Replication; Vorinostat

Cessation of highly active antiretroviral therapy (HAART) in HIV-infected individual leads to a rebound of viral replication due to reactivation of a viral reservoir composed largely of latently infected memory CD4(+) T cells. Efforts to deplete this reservoir have focused on reactivation of transcriptionally silent latent proviruses. HIV provirus transcription depends critically on the positive transcription elongation factor b (P-TEFb), whose core components are cyclin-dependent kinase 9 (CDK9) and cyclin T1. In resting CD4(+) cells, the functional levels of P-TEFb are extremely low. Cellular activation upregulates cyclin T1 protein levels and CDK9 T-loop (T186) phosphorylation. The broad-spectrum histone deacetylase inhibitors (HDACis) vorinostat and panobinostat have been shown to reactivate latent virus in vivo in HAART-treated individuals. In this study, we have found that vorinostat and panobinostat activate P-TEFb in resting primary CD4(+) T cells through induction of CDK9 T-loop phosphorylation. In contrast, tacedinaline and romidepsin, HDAC 1 and 2 inhibitors, were unable to activate CDK9 T-loop phosphorylation. We used a CCL19 primary CD4(+) T-cell model HIV latency to assess the correlation between induction of CDK9 T-loop phosphorylation and reactivation of latent HIV virus by HDACis. Vorinostat and panobinostat treatment of cells harboring latent HIV increased CDK9 T-loop phosphorylation and reactivation of latent virus, whereas tacedinaline and romidepsin failed to induce T-loop phosphorylation or reactivate latent virus. We conclude that the ability of vorinostat and panobinostat to induce latent HIV is, in part, likely due to the ability of the broad-spectrum HDACis to upregulate P-TEFb through increased CDK9 T-loop phosphorylation.

Topics: Antiretroviral Therapy, Highly Active; Benzamides; CD4-Positive T-Lymphocytes; Cells, Cultured; Cyclin T; Cyclin-Dependent Kinase 9; Depsipeptides; Enzyme Activation; Gene Expression Regulation, Viral; Histone Deacetylase Inhibitors; HIV Infections; HIV-1; Humans; Hydroxamic Acids; Indoles; Panobinostat; Phenylenediamines; Phosphorylation; Positive Transcriptional Elongation Factor B; Proviruses; Virus Activation; Virus Latency; Virus Replication; Vorinostat

HDAC inhibitors, DNA alkylators and nucleoside analogs are effective components of combination chemotherapy. To determine a possible mechanism of their synergism, we analyzed the effects of HDAC inhibitors on the expression of drug transporters which export DNA alkylators. Exposure of PEER lymphoma T-cells to 15 nM romidepsin (Rom) resulted in 40%-50% reduction in mRNA for the drug transporter MRP1 and up to ~500-fold increase in the MDR1 mRNA within 32-48 hrs. MRP1 protein levels concomitantly decreased while MDR1 increased. Other HDAC inhibitors - panobinostat, belinostat and suberoylanilide hydroxamic acid (SAHA) - had similar effects on these transporters. The protein level of MRP1 correlated with cellular resistance to busulfan and chlorambucil, and Rom exposure sensitized cells to these DNA alkylators. The decrease in MRP1 correlated with decreased cellular drug export activity, and increased level of MDR1 correlated with increased export of daunorubicin. A similar decrease in the level of MRP1 protein, and increase in MDR1, were observed when mononuclear cells derived from patients with T-cell malignancies were exposed to Rom. Decreased MRP1 and increased MDR1 expressions were also observed in blood mononuclear cells from lymphoma patients who received SAHA-containing chemotherapy in a clinical trial. This inhibitory effect of HDAC inhibitors on the expression of MRP1 suggests that their synergism with DNA alkylating agents is partly due to decreased efflux of these alkylators. Our results further imply the possibility of antagonistic effects when HDAC inhibitors are combined with anthracyclines and other MDR1 drug ligands in chemotherapy.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; Cell Death; Cell Line, Tumor; Cell Proliferation; Depsipeptides; DNA Methylation; Drug Synergism; Epigenesis, Genetic; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Lymphoma; Multidrug Resistance-Associated Proteins; Panobinostat; RNA, Messenger; Sulfonamides; Up-Regulation; Vorinostat

Antiretroviral therapy (ART) is unable to cure HIV infection. The ability of HIV to establish a subset of latent infected CD4(+) T cells, which remain undetectable to the immune system, becomes a major roadblock to achieve viral eradication. Histone deacetylase inhibitors (HDACi) have been shown to potently induce the reactivation of latent HIV. Here, we show that a new thiol-based HDACi, the thioacetate-ω(γ-lactam carboxamide) derivative ST7612AA1, is a potent inducer of HIV reactivation. We evaluated HIV reactivation activity of ST7612AA1 compared to panobinostat (PNB), romidepsin (RMD) and vorinostat (VOR) in cell culture models of HIV-1 latency, in latently infected primary CD4(+) T lymphocytes and in PBMCs from HIV(+) patients. ST7612AA1 potently induced HIV-1 reactivation at submicromolar concentrations with comparable potency to panobinostat or superior to vorinostat. The presence of known antiretrovirals did not affect ST7612AA1-induced reactivation and their activity was not affected by ST7612AA1. Cell proliferation and cell activation were not affected by ST7612AA1, or any other HDACi used. In conclusion, our results indicate that ST7612AA1 is a potent activator of latent HIV and that reactivation activity of ST7612AA1 is exerted without activation or proliferation of CD4(+) T cells. ST7612AA1 is a suitable candidate for further studies of HIV reactivation strategies and potential new therapies to eradicate the viral reservoirs.

Topics: Anilides; Anti-Retroviral Agents; Cell Proliferation; Cells, Cultured; Depsipeptides; Drug Interactions; Histone Deacetylase Inhibitors; HIV-1; Humans; Hydroxamic Acids; Indoles; Leukocytes, Mononuclear; Male; Panobinostat; Pyrrolidinones; Virus Activation; Virus Latency; Vorinostat

Viral reactivation from latently infected cells has become a promising therapeutic approach to eradicate HIV. Due to the complexity of the viral latency, combinations of efficient and available drugs targeting different pathways of latency are needed. In this work, we evaluated the effect of various combinations of bryostatin-1 (BRY) and novel histone deacetylase inhibitors (HDACIs) on HIV-reactivation and on cellular phenotype. The lymphocyte (J89GFP) or monocyte/macrophage (THP89GFP) latently infected cell lines were treated with BRY, panobinostat (PNB) and romidepsin (RMD) either alone or in combination. Thus, the effect on the viral reactivation was evaluated. We calculated the combination index for each drug combination; the BRY/HDACIs showed a synergistic HIV-reactivation profile in the majority of the combinations tested, whereas non-synergistic effects were observed when PNB was mixed with RMD. Indeed, the 75% effective concentrations of BRY, PNB and RMD were reduced in these combinations. Moreover, primary CD4 T cells treated with such drug combinations presented similar activation and proliferation profiles in comparison with single drug treated cells. Summing up, combinations between BRY, PNB and/or RMD presented a synergistic profile by inducing virus expression in HIV-latently infected cells, rendering these combinations an attractive novel and safe option for future clinical trials.

Topics: Antibiotics, Antineoplastic; Bryostatins; Cell Line; Cell Survival; Depsipeptides; Dose-Response Relationship, Drug; Drug Synergism; Histone Deacetylase Inhibitors; HIV-1; Host-Pathogen Interactions; Humans; Hydroxamic Acids; Indoles; Lymphocytes; Macrophages; Monocytes; Panobinostat; Time Factors; Virus Activation; Virus Latency

HIV-1 persists in a latent reservoir despite antiretroviral therapy (ART). This reservoir is the major barrier to HIV-1 eradication. Current approaches to purging the latent reservoir involve pharmacologic induction of HIV-1 transcription and subsequent killing of infected cells by cytolytic T lymphocytes (CTLs) or viral cytopathic effects. Agents that reverse latency without activating T cells have been identified using in vitro models of latency. However, their effects on latently infected cells from infected individuals remain largely unknown. Using a new ex vivo assay, we demonstrate that none of the latency-reversing agents (LRAs) tested induced outgrowth of HIV-1 from the latent reservoir of patients on ART. Using a quantitative reverse transcription PCR assay specific for all HIV-1 mRNAs, we demonstrate that LRAs that do not cause T cell activation do not induce substantial increases in intracellular HIV-1 mRNA in patient cells; only the protein kinase C agonist bryostatin-1 caused significant increases. These findings demonstrate that current in vitro models do not fully recapitulate mechanisms governing HIV-1 latency in vivo. Further, our data indicate that non-activating LRAs are unlikely to drive the elimination of the latent reservoir in vivo when administered individually.

Topics: Anti-HIV Agents; Azepines; Bryostatins; CD4-Positive T-Lymphocytes; Cell Cycle Proteins; Depsipeptides; Disulfiram; Histone Deacetylase Inhibitors; HIV Infections; HIV-1; Humans; Hydroxamic Acids; Indoles; Ionomycin; Lymphocyte Activation; Nuclear Proteins; Panobinostat; Tetradecanoylphorbol Acetate; Transcription Factors; Triazoles; Virus Latency; Vorinostat

Resting memory CD4+ T-cells harboring latent HIV proviruses represent a critical barrier to viral eradication. Histone deacetylase inhibitors (HDACis), such as suberanilohydroxamic acid (SAHA), romidepsin, and panobinostat have been shown to induce HIV expression in these resting cells. Recently, it has been demonstrated that the low levels of viral gene expression induced by a candidate HDACi may be insufficient to cause the death of infected cells by viral cytopathic effects, necessitating their elimination by immune effectors, such as cytotoxic T-lymphocytes (CTL). Here, we study the impact of three HDACis in clinical development on T-cell effector functions. We report two modes of HDACi-induced functional impairment: i) the rapid suppression of cytokine production from viable T-cells induced by all three HDACis ii) the selective death of activated T-cells occurring at later time-points following transient exposures to romidepsin or, to a lesser extent, panobinostat. As a net result of these factors, HDACis impaired CTL-mediated IFN-γ production, as well as the elimination of HIV-infected or peptide-pulsed target cells, both in liquid culture and in collagen matrices. Romidepsin exerted greater inhibition of antiviral function than SAHA or panobinostat over the dose ranges tested. These data suggest that treatment with HDACis to mobilize the latent reservoir could have unintended negative impacts on the effector functions of CTL. This could influence the effectiveness of HDACi-based eradication strategies, by impairing elimination of infected cells, and is a critical consideration for trials where therapeutic interruptions are being contemplated, given the importance of CTL in containing rebound viremia.

Topics: Cell Proliferation; Cell Survival; Cytotoxicity, Immunologic; Depsipeptides; Histone Deacetylase Inhibitors; HIV Infections; Humans; Hydroxamic Acids; Indoles; Panobinostat; T-Lymphocytes, Cytotoxic; Virus Replication

Topics: Anti-HIV Agents; Depsipeptides; Histone Deacetylase Inhibitors; HIV-1; Humans; Hydroxamic Acids; Indoles; Panobinostat; Virus Activation; Virus Latency; Vorinostat

Platelet Glycoprotein (GP)VI is a member of the immunoglobulin superfamily expressed only on platelets, and is the major signalling receptor for collagen. Histone deacetylase inhibitors (HDACi) are anti-cancer agents used for the treatment of haematological malignancies, and we examined the effects of administration of HDACi to mice on platelet function including responses to agonists including collagen related peptide (CRP).. C57BL/6 mice were injected with two structurally different HDACi, panobinostat and romidepsin, for three days and platelet receptor levels and responses to agonists were assessed by flow cytometry and western blot.. Platelets from mice treated with either HDACi were impaired in their ability to respond to CRP, but not thrombin or adenosine diphosphate (ADP). HDACi treatment increased acetylation of megakaryocytic GPVI, resulting in loss of intact (~60-65-kDa) GPVI and formation of ~10-kDa remnant GPVI. Circulating platelets had reduced surface and total expression of GPVI. Platelets from mice treated with HDACi had impaired GPVI signalling following treatment with CRP, resulting in inhibition of Syk phosphorylation and activation, and the final common pathways of platelet activation.. Administration of HDACi in vivo may ablate platelet responses to agonists and platelet function.

Topics: Acetylation; Animals; Blood Platelets; Carrier Proteins; Cells, Cultured; Depsipeptides; Down-Regulation; Histone Deacetylase Inhibitors; Hydroxamic Acids; Indoles; Megakaryocytes; Mice; Mice, Inbred C57BL; Panobinostat; Peptides; Platelet Aggregation; Platelet Membrane Glycoproteins; Signal Transduction

Topics: Acetylation; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Depsipeptides; Drug Screening Assays, Antitumor; Histone Deacetylase Inhibitors; Histones; Humans; Hydroxamic Acids; Indoles; Multiple Myeloma; Neoplasm Proteins; Panobinostat; Protein Processing, Post-Translational; Pyrimidines; Tubulin; Tumor Cells, Cultured

Histone deacetylase (HDAC) inhibitors such as vorinostat (suberoylanilide hydroxamic acid), valproic acid, romidepsin (FK-228), and LBH589 comprise a relatively new class of potent anticancer agents. This study provides evidence for the potential of vorinostat to cause acquisition of multidrug resistance protein-independent resistance in HCT116 colon tumor cells. This acquired resistance is moderate (two-fold to three-fold), is nonreversible, and correlates with the loss of responses typically seen with HDAC inhibitors, that is the loss of acetylation of the histones H2A, H2B, H3, and H4, the loss of the G2/M checkpoint activation, and the loss of caspase 3-dependent and caspase 7-dependent apoptosis. This acquired resistance also associates with cross-resistance to the hydroxamate-class (LBH589 and JNJ26481585) and to the aliphatic acid-class (valproic acid) HDAC inhibitors but not to the benzamide-class (MGCD0103) and the cyclic peptide-class (romidepsin) HDAC inhibitors. The acquired HDAC inhibitor resistance described hereis not a result of altered HDAC and histone acetyltransferase activities and differs from that previously reported for romidepsin.

Topics: Acetylation; Adenocarcinoma; Antineoplastic Agents; Apoptosis; Benzamides; Cell Line, Tumor; Colorectal Neoplasms; Depsipeptides; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Genes, MDR; HeLa Cells; Histone Acetyltransferases; Histone Deacetylase Inhibitors; Histone Deacetylases; Histones; Humans; Hydroxamic Acids; Indoles; Inhibitory Concentration 50; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Panobinostat; Protein Processing, Post-Translational; Pyrimidines; Tumor Stem Cell Assay; Vorinostat