The emerging role of histone deacetylase inhibitors in treating T-cell lymphomas

Targeted Deep Sequencing of Mycosis Fungoides Reveals Intracellular Signaling Pathways Associated with Aggressiveness and Large Cell Transformation

INTRODUCTION

Large-cell transformation (LCT) of mycosis fungoides (MF) has been associated with a higher risk of relapse and progression and, consequently, restricted prognosis. Its molecular pathogenesis has not been elucidated yet.

MATERIALS AND METHODS

In order to address molecular mechanisms of LCT, we performed hybrid capture panel-based sequencing of skin biopsies from 10 patients suffering from MF with LCT versus 17 patients without LCT including follow-up biopsies during clinical course, respectively (51 samples in total). The analyzed patients were attributed to three different groups based on the presence of LCT and clinical behavior.

RESULTS

While indolent MF cases without LCT did not show pathogenic driver mutations, a high rate of oncogenic alterations was detected in patients with LCT and aggressive clinical courses. Various genes of different oncogenic signaling pathways, including the MAPK and JAK-STAT signaling pathways, as well as epigenetic modifiers were affected. A high inter-individual and distinctive intra-individual mutation diversity was observed. Oncogenic RAS mutations were exclusively detected in patients with LCT.

CONCLUSION

Our data demonstrate that LCT transition of MF is associated with increased frequency of somatic mutations in cancer-associated genes. In particular, the activation of RAS signaling-together with epigenetic dysregulation-may crucially contribute to the molecular pathogenesis of the LCT phenotype, thus conveying its adverse clinical behavior.

Histone deacetylase 4 increases progressive epithelial ovarian cancer cells via repression of p21 on fibrillar collagen matrices

Histone deacetylase (HDAC) 4 is an emerging target in cancer therapeutics, but little is known about the function of HDAC4 in gynecologic malignancies. Therefore we investigated the mechanism of HDAC4 promoting the proliferation of epithelial ovarian cancer cells (OV). In this study, we observed that the proliferation of cells with HDAC4 inhibitor Trichostatin A (TSA) treatment was markedly decreased, Further, we showed that epithelial ovarian cancer tissues with stage III/IV had higher HDAC4 expression, compared to that with stage I/II. We examined first that the HDAC4 expression was increased in response to fibrillar collagen matrices. In addition, we found that HDAC4 was retained in the nucleus by regulation of PP1α, which regulated HDAC4 cellular fraction via phosphorylation of HDAC4. In addition, we found that HDAC4 bound to Sp1 in epithelial ovarian cancer cells. Finally, ovarian cancer cell line OVCAR3 was evaluated via gain/loss-of-function of HDAC4 by either overexpression of HDCA4 or knock-down of HDAC4 with shRNA. We examined both protein and mRNA of p21 by western blotting and qPCR. We performed analysis of colony formation in matrigel and migration by ECIS. Our results suggest that the accumulation of HDAC4 induced by fibrillar collagen matrices in the nucleus via co-localization of PP1α, leads to repression of the mRNA/protein of p21 and in turn promotes the proliferation and migration of epithelial ovarian cancer cells.

Belinostat in Patients With Relapsed or Refractory Peripheral T-Cell Lymphoma: Results of the Pivotal Phase II BELIEF (CLN-19) Study

PURPOSE

Peripheral T-cell lymphomas (PTCLs) represent a diverse group of non-Hodgkin lymphomas with a poor prognosis and no accepted standard of care for patients with relapsed or refractory disease. This study evaluated the efficacy and tolerability of belinostat, a novel histone deacetylase inhibitor, as a single agent in relapsed or refractory PTCL.

PATIENTS AND METHODS

Patients with confirmed PTCL who experienced progression after ≥ one prior therapy received belinostat 1,000 mg/m(2) as daily 30-minute infusions on days 1 to 5 every 21 days. Central assessment of response used International Working Group criteria. Primary end point was overall response rate. Secondary end points included duration of response (DoR) and progression-free and overall survival.

RESULTS

A total of 129 patients were enrolled, with a median of two prior systemic therapies. Overall response rate in the 120 evaluable patients was 25.8% (31 of 120), including 13 complete (10.8%) and 18 partial responses (15%). Median DoR by International Working Group criteria was 13.6 months, with the longest ongoing patient at ≥ 36 months. Median progression-free and overall survival were 1.6 and 7.9 months, respectively. Twelve of the enrolled patients underwent stem-cell transplantation after belinostat monotherapy. The most common grade 3 to 4 adverse events were anemia (10.8%), thrombocytopenia (7%), dyspnea (6.2%), and neutropenia (6.2%).

CONCLUSION

Monotherapy with belinostat produced complete and durable responses with manageable toxicity in patients with relapsed or refractory PTCL across the major subtypes, irrespective of number or type of prior therapies. These results have led to US Food and Drug Administration approval of belinostat for this indication.

Syntheses and discovery of a novel class of cinnamic hydroxamates as histone deacetylase inhibitors by multimodality molecular imaging in living subjects

Histone deacetylases (HDAC) that regulate gene expression are being explored as cancer therapeutic targets. In this study, we focused on HDAC6 based on its ability to inhibit cancerous Hsp90 chaperone activities by disrupting Hsp90/p23 interactions. To identify novel HDAC6 inhibitors, we used a dual-luciferase reporter system in cell culture and living mice by bioluminescence imaging (BLI). On the basis of existing knowledge, a library of hydrazone compounds was generated for screening by coupling cinnamic hydroxamates with aldehydes and ketones. Potency and selectivity were determined by in vitro HDAC profiling assays, with further evaluation to inhibit Hsp90(α/β)/p23 interactions by BLI. In this manner, we identified compound 1A12 as a dose-dependent inhibitor of Hsp90(α/β)/p23 interactions, UKE-1 myeloid cell proliferation, p21(waf1) upregulation, and acetylated histone H3 levels. 1A12 was efficacious in tumor xenografts expressing Hsp90(α)/p23 reporters relative to carrier control-treated mice as determined by BLI. Small animal (18)F-FDG PET/CT imaging on the same cohort showed that 1A12 also inhibited glucose metabolism relative to control subjects. Ex vivo analyses of tumor lysates showed that 1A12 administration upregulated acetylated-H3 by approximately 3.5-fold. Taken together, our results describe the discovery and initial preclinical validation of a novel selective HDAC inhibitor.

Expression of histone deacetylases in diffuse large B-cell lymphoma and its clinical significance

BACKGROUND

Histone deacetylase inhibitors are a new class of drugs used in treatment of malignant tumors. Diffuse large B-cell lymphoma (DLBCL) is the most common type of B-cell lymphoma, and it accounts for more than 40% of all B-cell lymphomas. In this study, we aimed to determine the expression patterns of histone deacetylases (HDACs) in DLBCL, to examine whether HDAC expression patterns differ among cases, and to assess whether these findings have clinical significance.

MATERIALS AND METHODS

We selected 91 cases of DLBCL diagnosed at St. Vincent Hospital, The Catholic University of Korea, from 2001-2012. We performed a pathology slide review and collected clinical data including age, sex, tumor site, survival time, and mortality. Immunohistochemical analysis was performed using primary antibodies for HDACs, including HDAC1 and 2 of class I, HDAC4 and 5 of class IIa, and HDAC6 of class IIb. Expression site was determined to be nuclear, cytoplasmic, or both. Staining intensities were graded as low and high. We assessed correlations between HDAC expression levels and clinical data and survival analysis.

RESULTS

Of the 91 cases examined, 46 (50.5%) were men and 45 (49.5%) were women. Most of the patients were elderly, and 74 (81.3%) cases were older than 46 y. Forty-six (50.5%) cases showed lymph node involvement, and 45 (49.5%) cases showed lymphoma at extranodal sites. In nodal lymphoma, staining was strongly positive for HDAC2, whereas staining was weak or negative for HDAC4; however, there was no significant correlation with survival. But nodal lymphoma cases with high nuclear expression of HDAC2 and nodal lymphoma cases with high nuclear expression of HDAC2 and low nuclear expression of HDAC4 showed significantly shorter survival times compared with other cases.

CONCLUSIONS

High nuclear expression of HDAC2 may play an important role in survival of DLBCL patients, especially in those with nodal lymphoma, which is associated with a shorter survival time. Our results may have important implications for treatment of DLBCL by epigenetic regulation.

Romidepsin: A Histone Deacetylase Inhibitor for Refractory Cutaneous T-Cell Lymphoma

Objective:

To evaluate the efficacy and safety of romidepsin in refractory cutaneous T-cell lymphoma (CTCL).

Data Sources:

An English-language literature search of PubMed and MEDLINE (Nov 2011–April 2012) was performed using the terms romidepsin, CTCL, and depsipeptide (FK228). The National Comprehensive Cancer Network guidelines, American Society of Clinical Oncology abstracts, American Society of Hematology abstracts, clinical trial registry, and prescribing information from the manufacturer were reviewed for additional information.

Study Selection and Data Extraction:

Phase 1 and 2 trials evaluating the efficacy and safety of romidepsin were reviewed with a specific focus on its use in cutaneous T-cell lymphoma. All peer-reviewed articles with clinically relevant information were evaluated for inclusion.

Data Synthesis:

In advanced stage CTCL, single or combination chemotherapy regimen responses are variable and lack durability. Romidepsin is a histone deacetylase inhibitor approved for refractory cutaneous T-cell lymphoma, Romidepsin has shown an improvement in duration of response and pruritus over traditional therapy. In 2 independent Phase 2 trials, romidepsin showed an overall response rate of 34% and durable response of 13–15 months in patients with refractory CTCL. The most frequent toxicities of romidepsin include nausea. vomiting, fatigue, or myelosuppresston. Clinically insignificant QT interval changes have been observed but did not correlate with a decrease in left ventricular ejection fraction, or elevated laboratory markers of myocardial damage.

Conclusions:

Romidepsin is an effective, durable, and well-tolerated single-agent therapy in patients with refractory CTCL and should be considered for formulary addition in this population.

Histone deacetylases inhibitor Trichostatin A ameliorates DNFB-induced allergic contact dermatitis and reduces epidermal Langerhans cells in mice

BACKGROUND

Histone deacetylases (HDACs) influence chromatin organization, representing a key epigenetic regulatory mechanism in cells. Trichostatin A (TSA), a potent HDAC inhibitor, has anti-tumor and anti-inflammatory effects. Allergic contact dermatitis (ACD) is a T-cell-mediated inflammatory reaction in skin and is regulated by epidermal Langerhans cells (LCs).

OBJECTIVE

The aim of this study was to investigate if TSA treatment prevents 2,4-dinitrofluorobenzene (DNFB)-induced ACD in mice and regulates epidermal LCs and other immune cells during ACD development.

METHODS

ACD was induced by sensitizing and challenging with DNFB topically. Mice were treated intraperitoneally with TSA or vehicle DMSO as a control every other day before and during induction of ACD. The ear swelling response was measured and skin biopsies from sensitized skin areas were obtained for histology. Epidermal cells, thymus, spleen and skin draining lymph nodes were collected for immune staining.

RESULTS

TSA treatment ameliorated skin lesion severity of DNFB-induced ACD. The percentages of epidermal LCs and splenic DCs as well as LC maturation were significantly reduced in TSA-treated mice. However, TSA treatment did not significantly affect the homeostasis of conventional CD4(+) and CD8(+) T cells, Foxp3(+)CD4(+) regulatory T cells, iNKT cells, and γδ T cells in thymus, spleen and draining lymph nodes (dLNs). Furthermore, there were no significant differences in IL-4 and IFN-γ-producing T cells and iNKT cells between TSA- and DMSO-treated mice.

CONCLUSION

Our findings suggest that TSA may ameliorate ACD through the regulation of epidermal LCs and HDACs could serve as potential therapeutic targets for ACD and other LCs-related skin diseases.

Cardiac HDAC6 catalytic activity is induced in response to chronic hypertension

Small molecule histone deacetylase (HDAC) inhibitors block adverse cardiac remodeling in animal models of heart failure. The efficacious compounds target class I, class IIb and, to a lesser extent, class IIa HDACs. It is hypothesized that a selective inhibitor of a specific HDAC class (or an isoform within that class) will provide a favorable therapeutic window for the treatment of heart failure, although the optimal selectivity profile for such a compound remains unknown. Genetic studies have suggested that class I HDACs promote pathological cardiac remodeling, while class IIa HDACs are protective. In contrast, nothing is known about the function or regulation of class IIb HDACs in the heart. We developed assays to quantify catalytic activity of distinct HDAC classes in left and right ventricular cardiac tissue from animal models of hypertensive heart disease. Class I and IIa HDAC activity was elevated in some but not all diseased tissues. In contrast, catalytic activity of the class IIb HDAC, HDAC6, was consistently increased in stressed myocardium, but not in a model of physiologic hypertrophy. HDAC6 catalytic activity was also induced by diverse extracellular stimuli in cultured cardiac myocytes and fibroblasts. These findings suggest an unforeseen role for HDAC6 in the heart, and highlight the need for pre-clinical evaluation of HDAC6-selective inhibitors to determine whether this HDAC isoform is pathological or protective in the setting of cardiovascular disease.