A phase I study of the safety and pharmacokinetics of the histone deacetylase inhibitor belinostat administered in combination with carboplatin and/or paclitaxel in patients with solid tumours

Electrocardiographic studies of romidepsin demonstrate its safety and identify a potential role for K(ATP) channel

PURPOSE

Romidepsin is a histone deacetylase inhibitor (HDI) approved for the treatment of both cutaneous and peripheral T-cell lymphoma (CTCL and PTCL). During development, a thorough assessment of cardiac toxicity was conducted.

EXPERIMENTAL DESIGN

A phase II single-agent nonrandomized study of romidepsin was conducted in patients with CTCL or PTCL who had progressed after at least 1 prior systemic therapy.

RESULTS

Results for the first 42 patients enrolled on the NCI 1312 phase II study of romidepsin in CTCL or PTCL showed no cardiac toxicity based on serial electrocardiograms (ECG), troponins, and MUGA scans/echocardiograms. The cardiac assessments reported herein confirm the safety of romidepsin among 131 enrolled patients, while supporting a role for electrolyte replacement. Heart rate increased an average 11 bpm following romidepsin infusion; there was no evidence of increased arrhythmia. Criteria for potassium/magnesium replacement were met before 55% of 1365 romidepsin doses; an association with hypoalbuminemia was confirmed. We propose a mechanism for ST segment flattening and depression, the most common ECG abnormalities observed: HDI-induced alteration of the activity or expression of KATP channels. In addition, examination of the variants of the active transporter of romidepsin, ABCB1, showed a trend toward smaller heart rate changes in the peri-infusion period among wild-type than variant diplotypes.

CONCLUSIONS

We conclude that in the context of appropriate attention to electrolyte levels, the data support the cardiac safety of romidepsin.

[18F]FDG and [18F]FLT positron emission tomography imaging following treatment with belinostat in human ovary cancer xenografts in mice

BACKGROUND

Belinostat is a histone deacetylase inhibitor with anti-tumor effect in several pre-clinical tumor models and clinical trials. The aim of the study was to evaluate changes in cell proliferation and glucose uptake by use of 3'-deoxy-3'-[(18)F]fluorothymidine ([18F]FLT) and 2-deoxy-2-[(18)F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET) following treatment with belinostat in ovarian cancer in vivo models.

METHODS

In vivo uptake of [18F]FLT and [18F]FDG in human ovary cancer xenografts in mice (A2780) were studied after treatment with belinostat. Mice were divided in 2 groups receiving either belinostat (40 mg/kg ip twice daily Day 0-4 and 6-10) or vehicle. Baseline [18F]FLT or [18F]FDG scans were made before treatment (Day 0) and repeated at Day 3, 6 and 10. Tracer uptake was quantified using small animal PET/CT.

RESULTS

Tumors in the belinostat group had volumes that were 462 ± 62% (640 mm(3)) at Day 10 relative to baseline which was significantly different (P = 0.011) from the control group 769 ± 74% (926 mm(3)). [18F]FLT SUVmax increased from baseline to Day 10 (+30 ± 9%; P = 0.048) in the control group. No increase was observed in the treatment group. [18F]FDG SUVmean was significantly different in the treatment group compared to the control group (P = 0.0023) at Day 10. Within treatment groups [18F]FDG uptake and to a lesser extent [18F]FLT uptake at Day 3 were significantly correlated with tumor growth at Day 10.

CONCLUSIONS

[18F]FDG uptake early following treatment initiation predicted tumor sizes at Day 10, suggesting that [18F]FDG may be a valuable biomarker for non-invasive assessment of anti-tumor activity of belinostat.

Growth inhibition of pancreatic cancer cells by histone deacetylase inhibitor belinostat through suppression of multiple pathways including HIF, NFkB, and mTOR signaling in vitro and in vivo

Pancreatic ductal adenocarcinoma is a devastating disease with few therapeutic options. Histone deacetylase inhibitors are a novel therapeutic approach to cancer treatment; and two new pan-histone deacetylase inhibitors (HDACi), belinostat and panobinostat, are undergoing clinical trials for advanced hematologic malignancies, non-small cell lung cancers and advanced ovarian epithelial cancers. We found that belinostat and panobinostat potently inhibited, in a dose-dependent manner, the growth of six (AsPc1, BxPc3, Panc0327, Panc0403, Panc1005, MiaPaCa2) of 14 human pancreatic cancer cell lines. Belinostat increased the percentage of apoptotic pancreatic cancer cells and caused prominent G2 /M growth arrest of most pancreatic cancer cells. Belinostat prominently inhibited PI3K-mTOR-4EBP1 signaling with a 50% suppression of phorphorylated 4EBP1 (AsPc1, BxPc3, Panc0327, Panc1005 cells). Surprisingly, belinostat profoundly blocked hypoxia signaling including the suppression of hypoxia response element reporter activity; as well as an approximately 10-fold decreased transcriptional expression of VEGF, adrenomedullin, and HIF1α at 1% compared to 20% O2 . Treatment with this HDACi decreased levels of thioredoxin mRNA associated with increased levels of its endogenous inhibitor thioredoxin binding protein-2. Also, belinostat alone and synergistically with gemcitabine significantly (P = 0.0044) decreased the size of human pancreatic tumors grown in immunodeficiency mice. Taken together, HDACi decreases growth, increases apoptosis, and is associated with blocking the AKT/mTOR pathway. Surprisingly, it blocked hypoxic growth related signals. Our studies of belinostat suggest it may be an effective drug for the treatment of pancreatic cancers when used in combination with other drugs such as gemcitabine.

Histone deacetylase inhibitors and pancreatic cancer: Are there any promising clinical trials?

Pancreatic cancer, although not very frequent, has an exceptionally high mortality rate, making it one of the most common causes of cancer mortality in developed countries. Pancreatic cancer is difficult to diagnose, allowing few patients to have the necessary treatment at a relatively early stage. Despite a marginal benefit in survival, the overall response of pancreatic cancer to current systemic therapy continues to be poor, and new therapies are desperately needed. Histone deacetylase (HDAC) enzymes play an important role in the development and progression of cancer and HDAC inhibitors (HDACIs) have been shown to induce differentiation and cell cycle arrest, activate the extrinsic or intrinsic pathways of apoptosis, and inhibit invasion, migration and angiogenesis in different cancer cell lines. As a result of promising preclinical data, various HDACIs are being tested as either monotherapeutic agents or in combination regimens for both solid and hematological malignancies. Vorinostat was the first HDACI approved by the Food and Drug Administration for patients with cutaneous T-cell lymphoma. The use of HDACIs in clinical trials, in pretreated and relapsed patients suffering from advanced pancreatic cancer is discussed. Unfortunately, clinical data for HDACIs in patients with pancreatic cancer are inadequate, because only a few studies have included patients suffering from this type of neoplasm and the number of pancreatic cancer patients that entered HDACIs phase II/III trials, among others with advanced solid tumors, is very limited. More studies recruiting patients with pancreatic cancer remain to determine the efficiency of these therapies.

Low dosed interferon alpha augments the anti-tumor potential of histone deacetylase inhibition on prostate cancer cell growth and invasion

We evaluated whether low-dosed interferon alpha (IFNa) may augment the anti-tumor potential of the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on prostate cancer cells in vitro and in vivo. PC-3, DU-145, or LNCaP prostate cancer cells were treated with VPA (1 mM), IFNa (200 U/ml), or with the VPA-IFNa combination. Tumor cell growth, cell cycle progression, and cell cycle regulating proteins were then investigated by the MTT assay, flow cytometry, and western blotting. Tumor cell adhesion to endothelium or to immobilized extracellular matrix proteins, as well as migratory properties of the cells, were evaluated. Integrin α and β adhesion molecules and alterations of cell signaling pathways were analyzed. Finally, effects of the drug treatment on prostate cancer growth in vivo were determined in the NOD/SCID mouse model. VPA reduced tumor cell adhesion, migration, and growth in vitro. A much stronger anti-cancer potential was evoked by the VPA-IFNa combination, although IFNa in itself did not block growth or adhesion. The same effect was seen when tumor growth was evaluated in vivo. Molecular analysis revealed distinct elevation of histone H3 acetylation caused by VPA which was further up-regulated by VPA-IFNa, whereas IFNa alone did not alter H3 acetylation. The combinatorial benefit became obvious in Akt phosphorylation, p21 and p27 and integrin α1, α3, and β1 expression. Application of low-dosed IFNa to a VPA based regimen profoundly boosts the anti-tumor properties of VPA. The combined use of VPA and low-dosed IFNa may therefore be an innovative option in treating advanced prostate cancer.

Phase II activity of belinostat (PXD-101), carboplatin, and paclitaxel in women with previously treated ovarian cancer

BACKGROUND

Preclinical data show that belinostat (Bel) is synergistic with carboplatin and paclitaxel in ovarian cancer. To further evaluate the clinical activity of belinostat, carboplatin, and paclitaxel (BelCaP), a phase 1b/2 study was performed, with an exploratory phase 2 expansion planned specifically for women with recurrent epithelial ovarian cancer (EOC).

METHODS

Thirty-five women were treated on the phase 2 expansion cohort. BelCap was given as follows: belinostat, 1000 mg/m² daily for 5 days with carboplatin, AUC 5; and paclitaxel, 175 mg/m² given on day 3 of a 21-day cycle. The primary end point was overall response rate (ORR), using a Simon 2 stage design.

RESULTS

The median age was 60 years (range, 39-80 years), and patients had received a median of 3 prior regimens (range, 1-4). Fifty-four percent had received more than two prior platinum-based combinations, sixteen patients (46%) had primary platinum-resistant disease, whereas 19 patients (54%) recurred within 6 months of their most recent platinum treatment. The median number of cycles of BelCaP administered was 6 (range, 1-23). Three patients had a complete response, and 12 had a partial response, for an ORR of 43% (95% confidence interval, 26%-61%). When stratified by primary platinum status, the ORR was 44% among resistant patients and 63% among sensitive patients. The most common drug-related adverse events related to BelCaP were nausea (83%), fatigue (74%), vomiting (63%), alopecia (57%), and diarrhea (37%). With a median follow-up of 4 months (range, 0-23.3 months), 6-month progression-free survival is 48% (95% confidence interval, 31%-66%). Median overall survival was not reached during study follow-up.

CONCLUSIONS

Belinostat, carboplatin, and paclitaxel combined was reasonably well tolerated and demonstrated clinical benefit in heavily-pretreated patients with EOC. The addition of belinostat to this platinum-based regimen represents a novel approach to EOC therapy and warrants further exploration.

HDAC inhibitors for the treatment of cutaneous T-cell lymphomas

Epigenetic modification by small-molecule histone deacetylase inhibitors (HDAC-Is) has been a promising new antineoplastic approach for various solid and hematological malignancies, particularly for cutaneous T-cell lymphoma (CTCL). Vorinostat, a pan-HDAC-I and, most recently, romidepsin, a bicyclic pan-HDAC-I, have been US FDA approved for treatment of relapsed or refractory CTCL. However, because many patients do not reach the 50% partial response mark and response is not always sustainable, overcoming HDAC-I resistance by adding other agents or finding more selective molecules is an important clinical problem in realizing the full clinical potential of HDAC-Is. In this review, we discuss the molecular basis for HDAC-I function in cancer, the clinical response and side-effect profile experienced by CTCL patients, and the progress made in attempting to identify biomarkers of response and resistance, as well as synergistic combination therapies.

Developing histone deacetylase inhibitors in the therapeutic armamentarium of pancreatic adenocarcinoma

INTRODUCTION

Histone deacetylases (HDACs) are commonly dysregulated in pancreatic adenocarcinoma (PA) and have a central role in the development and progression of the disease. HDAC is a family of enzymes involved in deacetylation of lysine residues on histone and non-histone proteins. Deacetylation of histone proteins leads to compaction of the DNA/histone complex resulting in inhibition of gene expression. Deacetylation of non-histone proteins can affect the stability and function of key proteins leading to dysregulation of cellular signaling pathways. HDAC inhibitors have been shown to potentiate the antiproliferative and proapoptotic effects of several cytotoxic agents, in vitro and in vivo PA xenograft models.

AREAS COVERED

The areas covered include the biology and function of the HDAC isoenzymes and their significant role in multiple oncogenic pathways in PA. Preclinical and clinical trials evaluating HDAC inhibitors are also reviewed.

EXPERT OPINION

Despite discouraging early phase clinical trials evaluating HDAC inhibitors in PA, this strategy deserves further evaluation guided by better preclinical studies in identifying the role of specific HDAC isoenzyme inhibitors in PA. Evaluation of the effects of HDAC inhibitors on PA stem cell function and epithelial to mesenchymal transformation is also an evolving area that holds future potential for these agents. Such preclinical studies will yield insight into the functionality of HDAC isoenzymes, which can then be translated into rationally designed clinical trials. One such strategy could focus on HDAC inhibition employed in combination with proteasome inhibition targeting the aggresome pathway in PA.

Synergistic interaction between the novel histone deacetylase inhibitor ST2782 and the proteasome inhibitor bortezomib in platinum-sensitive and resistant ovarian carcinoma cells

The ability of histone deacetylase inhibitors to modulate the expression of genes relevant for growth or apoptotis regulation supports their interest in combination treatments of resistant tumors. We explored the effect of the combination of the histone deacetylase inhibitor ST2782 and the proteasome inhibitor bortezomib in ovarian carcinoma cell lines, including the IGROV-1 cell line and two p53 mutant platinum-resistant sublines (IGROV-1/OHP and IGROV-1/Pt1). We found a synergistic interaction between the two drugs, more evident in the p53-mutant resistant sublines, which was associated with increa sed apoptosis. The treatment with ST2782 resulted in early induction of Bax as well as in cleavage of caspase 3 and poly (ADP-ribose) polymerase only in the resistant cell lines. The inhibition of p53-transcriptional transactivation by pifithrin alpha in IGROV-1 cells enhanced the synergism. Conversely, knockdown of endogenous wild-type p53 in IGROV-1 cells determined synergism reduction. These opposite effects support the relevance of the transactivation-deficient mutant p53 as a synergism determinant. Moreover, in vivo studies indicated that tumor growth inhibition tended to be more evident in mice receiving the drug combination than in those treated with bortezomib alone. Overall, our study supports the potential effectiveness of the combination in platinum drug-resistant ovarian cancer carrying mutant p53.

A phase II evaluation of belinostat and carboplatin in the treatment of recurrent or persistent platinum-resistant ovarian, fallopian tube, or primary peritoneal carcinoma: a Gynecologic Oncology Group study

BACKGROUND

Patients with recurrent ovarian cancer have limited options, especially in the context of relapse less than six months from primary platinum-based therapy. This Gynecologic Oncology Group (GOG) study was conducted to evaluate the impact of the histone deacetylase inhibitor, belinostat, in combination with carboplatin in women with platinum-resistant ovarian cancer.

METHODS

Eligible patients had measurable, recurrent disease within six months of their last dose of a platinum-based combination. Belinostat was dosed at 1000 mg/m(2) daily for five days with carboplatin AUC 5 on day three of 21-day cycles. The primary endpoint was overall response rate (ORR), using a two-stage design.

RESULTS

Twenty-nine women enrolled on study and 27 were evaluable. The median number of cycles given was two (range 1-10). One patient had a complete response and one had a partial response, for an ORR of 7.4% (95% CI, .9%-24.3%). Twelve patients had stable disease while eight had increasing disease. Response could not be assessed in five (18.5%). Grade 3 and 4 events occurring in more than 10% of treated patients were uncommon and limited to neutropenia (22.2%), thrombocytopenia (14.8%), and vomiting (11.1%). The median progression-free survival (PFS) was 3.3 months and overall survival was 13.7 months. PFS of at least six months was noted in 29.6% of patients. Due to the lack of drug activity, the study was closed after the first-stage.

CONCLUSIONS

The addition of belinostat to carboplatin had little activity in a population with platinum-resistant ovarian cancer.

Mechanisms of resistance to histone deacetylase inhibitors

Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents. HDAC inhibitors induce acetylation of histones and nonhistone proteins which are involved in regulation of gene expression and in various cellular pathways including cell growth arrest, differentiation, DNA damage and repair, redox signaling, and apoptosis (Marks, 2010). The U.S. Food and Drug Administration has approved two HDAC inhibitors, vorinostat and romidepsin, for the treatment of cutaneous T-cell lymphoma (Duvic & Vu, 2007; Grant et al., 2010; Marks & Breslow, 2007). Over 20 chemically different HDAC inhibitors are in clinical trials for hematological malignancies and solid tumors. This review considers the mechanisms of resistance to HDAC inhibitors that have been identified which account for the selective effects of these agents in inducing cancer but not normal cell death. These mechanisms, such as functioning Chk1, high levels of thioredoxin, or the prosurvival BCL-2, may also contribute to resistance of cancer cells to HDAC inhibitors.

Belinostat: clinical applications in solid tumors and lymphoma

INTRODUCTION

Histone deacetylase (HDAC) inhibitors have recently emerged as a novel and active class of anticancer agents. Belinostat is one member of the class that has been tested as a single agent and in combination with other chemotherapies and biological agents in the treatment of solid tumors and lymphoma.

AREAS COVERED

A literature search of pre-clinical and clinical studies of belinostat was performed. The data from these studies were analysed to summarise the progress of belinostat from Phase I to a current pivotal trial in peripheral T-cell lymphoma. The parallel development of appropriate biomarker analysis is also discussed.

EXPERT OPINION

Belinostat has demonstrated significant clinical activity in T-cell lymphomas. Although its activity as a single agent in solid tumors has been less compelling, the emerging results from combination trials are promising. However, the basis for the activity of belinostat, like that of other HDAC inhibitors, remains to be truly defined and the identification of predictive and prognostic biomarkers of activity should be established to further progress the development of this compound.

Romidepsin: a novel histone deacetylase inhibitor for cancer

INTRODUCTION

Romidepsin is a novel histone deacetylase (HDAC) inhibitor, with a recent approval for treatment of cutaneous T-cell lymphoma (CTCL). HDAC inhibitors represent a novel approach to anti-tumor therapy. In contrast to traditional cytotoxic chemotherapy, HDAC inhibitors target underlying epigenetic changes leading to malignant transformation. Further study of romidepsin and similar agents in solid and hematologic malignancies is ongoing.

AREAS COVERED

This review discusses the development of romidepsin, its mechanism of action, pivotal clinical trials, drug toxicity and its recent approval for CTCL treatment. Key clinical trials covered include Phase I/II testing of romidepsin in solid and hematologic malignancies. In addition, the Phase II trial in CTCL leading to FDA approval of romidepsin is reviewed in detail. Literature search was performed using PubMed; keywords and concepts used included romidepsin, T-cell lymphoma and HDAC inhibitors.

EXPERT OPINION

Romidepsin is a potent HDAC inhibitor with demonstrable activity in T-cell lymphoma. In contrast to vorinostat, romidepsin is approved as second-line therapy. Current approval only includes CTCL; promising results have been demonstrated in Phase II testing of peripheral T-cell lymphoma subtypes. Future directions include expanded indications in T-cell lymphomas as well as novel combinations with other HDAC inhibitors and other therapeutic agents.

Zinc-chelation contributes to the anti-angiogenic effect of ellagic acid on inhibiting MMP-2 activity, cell migration and tube formation

Background

Ellagic acid (EA), a dietary polyphenolic compound, has been demonstrated to exert anti-angiogenic effect but the detailed mechanism is not yet fully understood. The aim of this study was to investigate whether the zinc chelating activity of EA contributed to its anti-angiogenic effect.

Methods and Principal Findings

The matrix metalloproteinases-2 (MMP-2) activity, a zinc-required reaction, was directly inhibited by EA as examined by gelatin zymography, which was reversed dose-dependently by adding zinc chloride. In addition, EA was demonstrated to inhibit the secretion of MMP-2 from human umbilical vein endothelial cells (HUVECs) as analyzed by Western blot method, which was also reversed by the addition of zinc chloride. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), known to down-regulate the MMP-2 activity, was induced by EA at both the mRNA and protein levels which was correlated well with the inhibition of MMP-2 activity. Interestingly, zinc chloride could also abolish the increase of EA-induced RECK expression. The anti-angiogenic effect of EA was further confirmed to inhibit matrix-induced tube formation of endothelial cells. The migration of endothelial cells as analyzed by transwell filter assay was suppressed markedly by EA dose-dependently as well. Zinc chloride could reverse these two effects of EA also in a dose-dependent manner. Since magnesium chloride or calcium chloride could not reverse the inhibitory effect of EA, zinc was found to be involved in tube formation and migration of vascular endothelial cells.

Conclusions/Significance

Together these results demonstrated that the zinc chelation of EA is involved in its anti-angiogenic effects by inhibiting MMP-2 activity, tube formation and cell migration of vascular endothelial cells. The role of zinc was confirmed to be important in the process of angiogenesis.

Rational therapeutic combinations with histone deacetylase inhibitors for the treatment of cancer

Histone deacetylases (HDACs) regulate the acetylation of a variety of histone and nonhistone proteins, controlling the transcription and regulation of genes involved in cell cycle control, proliferation, survival, DNA repair and differentiation. Unsurprisingly, HDAC expression is frequently altered in hematologic and solid tumor malignancies. Two HDAC inhibitors (vorinostat and romidepsin) have been approved by the US FDA for the treatment of cutaneous T-cell lymphoma. As single agents, treatment with HDAC inhibitors has demonstrated limited clinical benefit for patients with solid tumors, prompting the investigation of novel treatment combinations with other cancer therapeutics. In this article, the rationales and clinical progress of several combinations with HDAC inhibitors are presented, including DNA-damaging chemotherapeutic agents, radiotherapy, hormonal therapies, DNA methyltransferase inhibitors and various small-molecule inhibitors. The future application of HDAC inhibitors as a treatment for cancer is discussed, examining current hurdles to overcome before realizing the potential of this new approach.