The histone deacetylase inhibitor vorinostat selectively sensitizes fibrosarcoma cells to chemotherapy

Systemic Treatment of Ewing Sarcoma: Current Options and Future Perspectives

Ewing sarcoma (ES) is an uncommon malignant neoplasm, mostly affecting young adults and adolescents. Surgical excision, irradiation, and combinations of multiple chemotherapeutic agents are currently used as a multimodal strategy for the treatment of local and oligometastatic disease. Although ES usually responds to the primary treatment, relapsed and primarily refractory disease remains a difficult therapeutic challenge. The growing understanding of cancer biology and the subsequent development of new therapeutic strategies have been put at the service of research in recurrent and refractory ES, generating a great number of ongoing studies with compounds that could find superior clinical outcomes in the years to come. This review gathers the current available information on the treatment and clinical investigation of ES and aims to be a point of support for future research.

Vulnerability of IDH1-Mutant Cancers to Histone Deacetylase Inhibition via Orthogonal Suppression of DNA Repair

Exploitation of DNA repair defects has enabled major advances in treating specific cancers. Recent work discovered that the oncometabolite 2-hydroxyglutarate (2-HG), produced by neomorphic isocitrate dehydrogenase 1/2 (IDH1/2) mutations, confers a homology-directed repair (HDR) defect through 2-HG-induced histone hypermethylation masking HDR signaling. Here, we report that IDH1-mutant cancer cells are profoundly sensitive to the histone deacetylase inhibitor (HDACi) vorinostat, by further suppressing the residual HDR in 2-HG-producing cells. Vorinostat downregulates repair factors BRCA1 and RAD51 via disrupted E2F-factor regulation, causing increased DNA double-strand breaks, reduced DNA repair factor foci, and functional HDR deficiency even beyond 2-HG's effects. This results in greater cell death of IDH1-mutant cells and confers synergy with radiation and PARPi, both against cells in culture and patient-derived tumor xenografts. Our work identifies HDACi's utility against IDH1-mutant cancers, and presents IDH1/2 mutations as potential biomarkers to guide trials testing HDACi in gliomas and other malignancies. IMPLICATIONS: IDH1-mutant cells show profound vulnerability to HDACi treatment, alone and with PARPi and radiation, via HDR suppression, presenting IDH1/2 mutations as biomarkers for HDACi use in gliomas and other malignancies.

Ferroptosis: A Trusted Ally in Combating Drug Resistance in Cancer

Ferroptosis, which is an iron-dependent, non-apoptotic cell death mechanism, has recently been proposed as a novel approach in cancer treatment. Bearing distinctive features and its exclusive mechanism have put forward the potential therapeutic benefit of triggering this newly discovered form of cell death. Numerous studies have indicated that apoptotic pathways are often deactivated in resistant cells, leading to a failure in therapy. Hence, alternative strategies to promote cell death are required. Mounting evidence suggests that drug-resistant cancer cells are particularly sensitive to ferroptosis. Given that cancer cells consume a higher amount of iron than healthy ones, ferroptosis not only stands as an excellent alternative to trigger cell death and reverse drug-resistance, but also provides selectivity in therapy. This review focuses specifically on overcoming drug-resistance in cancer through activating ferroptotic pathways and brings together the relevant chemotherapeutics-based and nanotherapeutics-based studies to offer a perspective for researchers regarding the potential use of this mechanism in developing novel therapeutic strategies.

Recent Advances in Multi-target Drugs Targeting Protein Kinases and Histone Deacetylases in Cancer Therapy

Protein Kinase Inhibitors (PKIs) and Histone Deacetylase Inhibitors (HDACIs) are two important classes of anticancer agents and have provided a variety of small molecule drugs for the treatment of various types of human cancers. However, malignant tumors are of a multifactorial nature that can hardly be "cured" by targeting a single target, and treatment of cancers hence requires modulation of multiple biological targets to restore the physiological balance and generate sufficient therapeutic efficacy. Multi-target drugs have attracted great interest because of their advantages in the treatment of complex cancers by simultaneously targeting multiple signaling pathways and possibly leading to synergistic effects. Synergistic effects have been observed in the combination of kinase inhibitors, such as imatinib, dasatinib, or sorafenib, with an array of HDACIs including vorinostat, romidepsin, or panobinostat. A considerable number of multi-target agents based on PKIs and HDACIs have been developed. In this review, we summarize the recent literature on the development of multi-target kinase-HDAC inhibitors and provide our view on the challenges and future directions on this topic.

Assessment of Synergistic Contribution of Histone Deacetylases in Prognosis and Therapeutic Management of Sarcoma

Sarcomas are a rare group of neoplasms with a mesenchymal origin that are mainly characterized by the abnormal growth of connective tissue cells. The standard treatment for local control of sarcomas includes surgery and radiation, while for adjuvant and palliative therapy, chemotherapy has been strongly recommended. Despite the availability of multimodal therapies, the survival rate for patients with sarcoma is still not satisfactory. In recent decades, there has been a considerable effort to overcome chemotherapy resistance in sarcoma cells. This has led to the investigation of more cellular compounds implicated in gene expression and transcription processes. Furthermore, it has been discovered that histone acetylation/deacetylation equilibrium is affected in carcinogenesis, leading to a modified chromatin structure and therefore changes in gene expression. In addition, histone deacetylase inhibition is found to play a key role in limiting the tumor burden in sarcomas, as histone deacetylase inhibitors act on well-described oncogenic signaling pathways. Histone deacetylase inhibitors disrupt the increased cell motility and invasiveness of sarcoma cells, undermining their metastatic potential. Moreover, their activity on evoking cell arrest has been extensively described, with histone deacetylase inhibitors regulating the reactivation of tumor suppressor genes and induction of apoptosis. Promoting autophagy and increasing cellular reactive oxygen species are also included in the antitumor activity of histone deacetylase inhibitors. It should be noted that many studies revealed the synergy between histone deacetylase inhibitors and other drugs, leading to the enhancement of an antitumor effect in sarcomas. Therefore, there is an urgent need for therapeutic interventions modulated according to the distinct clinical and molecular characteristics of each sarcoma subtype. It is concluded that a better understanding of histone deacetylase and histone deacetylase inhibitors could provide patients with sarcoma with more targeted and efficient therapies, which may contribute to significant improvement of their survival potential.

SARC018_SPORE02: Phase II Study of Mocetinostat Administered with Gemcitabine for Patients with Metastatic Leiomyosarcoma with Progression or Relapse following Prior Treatment with Gemcitabine-Containing Therapy

Histone deacetylase inhibitors (HDACi) can reverse chemoresistance, enhance chemotherapy-induced cytotoxicity, and reduce sarcoma proliferation in cell lines and animal models. We sought to determine the safety and toxicity of mocetinostat and its ability to reverse chemoresistance when administered with gemcitabine in patients with metastatic leiomyosarcoma resistant to prior gemcitabine-containing therapy. Participants with metastatic leiomyosarcoma received mocetinostat orally, 70 mg per day, three days per week, increasing to 90 mg after three weeks if well tolerated. Gemcitabine was administered at 1,000 mg/m² intravenously at 10 mg/m²/minute on days five and 12 of every 21-day cycle. Disease response was evaluated with CT or MRI. Twenty participants with leiomyosarcoma were evaluated for toxicity. Median time to disease progression was 2.0 months (95% CI 1.54–3.12). Eighteen participants were evaluated for radiologic response by RECIST 1.1. Best responses included one PR and 12 SD. Tumor size reduced in 3 patients. Most common toxicities were fatigue, thrombocytopenia, anemia, nausea, and anorexia. One patient experienced a significant pericardial adverse event. No study-related deaths were observed. Rechallenging with gemcitabine by adding mocetinostat was feasible and demonstrated modest activity in patients with leiomyosarcoma. Further studies are needed to better define the role of HDAC inhibitors in patients with metastatic leiomyosarcoma.

Supramolecularly self-assembled nano-twin drug for reversing multidrug resistance

A new approach to reverse the multidrug resistance for cancer therapy.

Mocetinostat combined with gemcitabine for the treatment of leiomyosarcoma: Preclinical correlates

Leiomyosarcoma (LMS) is a malignant soft tissue sarcoma (STS) with a dismal prognosis following metastatic disease. Chemotherapeutic intervention has demonstrated to have modest clinical efficacy with no curative potential in LMS patients. Previously, we demonstrated pan-HDAC inhibition to have a superior effect in various complex karyotypic sarcomas. In this study, our goal is to evaluate the therapeutic efficacy of mocetinostat alone and in combination with gemcitabine in LMS. Human leiomyosarcoma (LMS) cell lines were used for in vitro and in vivo studies. Compounds tested included the class I HDAC inhibitor, mocetinostat, and nucleoside analog, gemcitabine. MTS and clonogenic assays were used to evaluate the effect of mocetinostat on LMS cell growth. Cleaved caspase 3/7 analysis was used to determine the effects of mocetinostat on apoptosis. Compusyn software was used to determine in vitro synergy studies for the combination of mocetinostat plus gemcitabine. A LMS xenograft model in SCID mice was used to test the impact of mocetinostat alone, gemcitabine alone and the combination of mocetinostat plus gemcitabine. Mocetinostat abrogated LMS cell growth and clonogenic potential, and enhanced apoptosis in LMS cell lines. The combination of mocetinostat plus gemcitabine exhibited a synergistic effect in LMS cells in vitro. Similarly, mocetinostat combined with gemcitabine resulted in superior anti-LMS effects in vivo. Mocetinostat reduced the expression of gemcitabine-resistance markers RRM1, RRM2, and increased the expression of gemcitabine-sensitivity marker, hENT1, in LMS cells. LMS are aggressive, metastatic tumors with poor prognosis where effective therapeutic interventions are wanting. Our studies demonstrate the potential utility of mocetinostat combined with gemcitabine for the treatment of LMS.

Therapeutic applications of histone deacetylase inhibitors in sarcoma

Sarcomas are a rare group of malignant tumors originating from mesenchymal stem cells. Surgery, radiation and chemotherapy are currently the only standard treatments for sarcoma. However, their response rates to chemotherapy are quite low. Toxic side effects and multi-drug chemoresistance make treatment even more challenging. Therefore, better drugs to treat sarcomas are needed. Histone deacetylase inhibitors (HDAC inhibitors, HDACi, HDIs) are epigenetic modifying agents that can inhibit sarcoma growth in vitro and in vivo through a variety of pathways, including inducing tumor cell apoptosis, causing cell cycle arrest, impairing tumor invasion and preventing metastasis. Importantly, preclinical studies have revealed that HDIs can not only sensitize sarcomas to chemotherapy and radiotherapy, but also increase treatment responses when combined with other chemotherapeutic drugs. Several phase I and II clinical trials have been conducted to assess the efficacy of HDIs either as monotherapy or in combination with standard chemotherapeutic agents or targeted therapeutic drugs for sarcomas. Combination regimen for sarcomas appear to be more promising than monotherapy when using HDIs. This review summarizes our current understanding and therapeutic applications of HDIs in sarcomas.

Evaluating the Effect of HDAC8 Inhibition in Malignant Peripheral Nerve Sheath Tumors

Malignant peripheral nerve sheath tumor (MPNST) is a highly aggressive disease with a dismal prognosis. The disease can occur sporadically or in patients with inherited neurofibromatosis (NF-1). MPNST is typically resistant to therapeutic intervention. Hence, the need for improved therapies is warranted. Several broad spectrum histone deacetylase (HDAC) inhibitors have a high affinity for class I HDAC isoforms. Inhibition of multiple HDAC isoforms often results in undesirable side effects, while inhibiting a single isoform could possibly improve the therapeutic window and limit toxicity. Recently, HDAC8 inhibitors have been developed and in initial preclinical studies, they demonstrate anticancer efficacy. Little is known about the role of HDAC8 in MPNST. We recently revealed an anticancer effect of HDAC8 inhibition in human and murine MPNST models. The goal of our previous study was to determine the potential therapeutic efficacy of HDAC8 inhibition in MPNST. In this chapter, we briefly describe the methods for determining the role of pharmacological HDAC inhibition in MPNST.

Vorinostat in refractory soft tissue sarcomas - Results of a multi-centre phase II trial of the German Soft Tissue Sarcoma and Bone Tumour Working Group (AIO)

INTRODUCTION

New treatment options for patients with metastatic Soft Tissue Sarcoma are urgently needed. Preclinical studies suggested activity of vorinostat, a histone deacetylase inhibitor.

METHODS

A multi-centre, open-label, non-randomised phase II trial to investigate the efficacy and safety of vorinostat in patients with locally advanced or metastatic Soft Tissue Sarcoma failing 1st-line anthracycline-based chemotherapy was initiated. Patients were treated with vorinostat 400 mg po qd for 28 d followed by a treatment-free period of 7 d, representing a treatment cycle of 5 weeks. Restaging was performed every three cycles or at clinical progression.

RESULTS

Between 06/10 and 09/13, 40 Soft Tissue Sarcoma patients were treated with vorinostat at seven participating centres. Patients had received 1 (n=8, 20%), 2 (n=10, 25%) or ≥3 (n=22, 55%) previous lines of chemotherapy. Best response after three cycles of treatment was stable disease (n=9, 23%). Median progression-free survival and overall survival were 3.2 and 12.3 months, respectively. Six patients showed long-lasting disease stabilisation for up to ten cycles. Statistical analyses failed to identify baseline predictive markers in this subgroup. Major toxicities (grade ≥III) included haematological toxicity (n=6, 15%) gastrointestinal disorders (n=5, 13%), fatigue (n=4, 10%), musculoskeletal pain (n=4, 10%), and pneumonia (n=2, 5%).

CONCLUSION

In a heavily pre-treated patient population, objective response to vorinostat was low. However, a small subgroup of patients had long-lasting disease stabilisation. Further studies aiming to identify predictive markers for treatment response as well as exploration of combination regimens are warranted.

TRIAL REGISTRATION

NCT00918489 (ClinicalTrials.gov) EudraCT-number: 2008-008513-19.

A phase I trial of panobinostat and epirubicin in solid tumors with a dose expansion in patients with sarcoma

BACKGROUND

Treatment options for sarcoma are limited. Histone deacetylase inhibitors increase the efficacy of topoisomerase II inhibitors by promoting access to chromatin and by down-regulating DNA repair. Thus, combined panobinostat and epirubicin therapy was evaluated to treat refractory sarcoma.

PATIENTS AND METHODS

Patients with advanced solid tumors were enrolled in a 3 + 3 dose-escalation phase I trial of panobinostat given on days 1, 3, and 5 followed by 75 mg/m(2) of epirubicin on day 5 in 21-day cycles, with a dose expansion at maximum tolerated dose (MTD) in 20 sarcoma patients. Peripheral blood mononucleocyte histone acetylation was also evaluated.

RESULTS

Forty patients received 20-60 mg panobinostat. Dose-limiting toxicities included thrombocytopenia, febrile neutropenia, and fatigue at 60 mg, defining a panobinostat MTD at 50 mg. Four responses were seen in 37 assessable patients, all after progression on prior topoisomerase II inhibitors. For those with sarcoma, 12 of 20 derived clinical benefit (1 partial response and 11 stable disease, median overall survival 8.3 months), including 8 of 14 previously progressed on topoisomerase II therapy. Treatment benefits correlated with increased histone acetylation and decreased neutrophil count on day 5.

CONCLUSIONS

Panobinostat and epirubicin treatment is well tolerated and may reverse anthracycline resistance. Changes in histone acetylation and associated decrease in neutrophil count correlated with clinical benefit and warrant investigation as predictive biomarkers.

CLINICAL TRIAL

This trial is registered at www.Clinicaltrials.gov, Identifier: NCT00878904.

The Therapeutic Potential of AN-7, a Novel Histone Deacetylase Inhibitor, for Treatment of Mycosis Fungoides/Sezary Syndrome Alone or with Doxorubicin

The 2 histone deacetylase inhibitors (HDACIs) approved for the treatment of cutaneous T-cell lymphoma (CTCL) including mycosis fungoides/sezary syndrome (MF/SS), suberoylanilide hydroxamic acid (SAHA) and romidepsin, are associated with low rates of overall response and high rates of adverse effects. Data regarding combination treatments with HDACIs is sparse. Butyroyloxymethyl diethylphosphate (AN-7) is a novel HDACI, which was found to have selective anticancer activity in several cell lines and animal models. The aim of this study was to compare the anticancer effects of AN-7 and SAHA, either alone or combined with doxorubicin, on MF/SS cell lines and peripheral blood lymphocytes (PBL) from patients with Sezary syndrome (SPBL). MyLa cells, Hut78 cells, SPBL, and PBL from healthy normal individuals (NPBL) were exposed to the test drugs, and the findings were analyzed by a viability assay, an apoptosis assay, and Western blot. AN-7 was more selectively toxic to MyLa cells, Hut78 cells, and SPBL (relative to NPBL) than SAHA and also acted more rapidly. Both drugs induced apoptosis in MF/SS cell lines, SAHA had a greater effect on MyLa cell line, while AN-7 induced greater apoptosis in SPBL; both caused an accumulation of acetylated histone H₃, but AN-7 was associated with earlier kinetics; and both caused a downregulation of the HDAC1 protein in MF/SS cell lines. AN-7 acted synergistically with doxorubicin in both MF/SS cell lines and SPBL, and antagonistically with doxorubicin in NPBL. By contrast, SAHA acted antagonistically with doxorubicin on MF/SS cell lines, SPBL, and NPBL, leaving <50% viable cells. In conclusion, AN-7 holds promise as a therapeutic agent in MF/SS and has several advantages over SAHA. Our data provide a rationale for combining AN-7, but not SAHA, with doxorubicin to induce the cell death in MF/SS.

Phase 1 study of oral abexinostat, a histone deacetylase inhibitor, in combination with doxorubicin in patients with metastatic sarcoma

BACKGROUND

It has been demonstrated that several inhibitors of histone deacetylase (HDAC) can enhance chemotherapy-induced apoptosis and reduce sarcoma tumor volume in preclinical models. The authors sought to determine the maximum tolerated dose, pharmacokinetics/pharmacodynamics, safety, and toxicity of the HDAC inhibitor abexinostat (PCI-24781) when administered with doxorubicin to patients with metastatic sarcomas.

METHODS

Participants were enrolled in a standard, phase 1, 3 + 3, dose-escalation study design. Abexinostat was administered on days 1 through 5 with 75 mg/m(2) of doxorubicin administered on day 4 of every 21-day cycle until patients developed disease progression or drug intolerance or reached a cumulative lifetime doxorubicin dose of 450 mg/m(2). Granulocyte-colony-stimulating factor (G-CSF) support was provided at physician discretion on arm A and was provided to all participants in arm B. From 3 to 6 participants initially received abexinostat 30 mg/m(2) twice daily, and subsequent cohorts were administered doses of 15 mg/m(2), 45 mg/m(2), or 60 mg/m(2) twice daily. All patients without progressive disease after receiving a cumulative lifetime doxorubicin dose of 450 mg/m(2) were given the option to continue with abexinostat as a single agent until they developed disease progression.

RESULTS

In total, 22 participants (10 who had previously experienced tumor growth after doxorubicin therapy) were enrolled (6 in arm A, 14 in arm B), 20 were evaluable for dose-limiting toxicity (DLT), and 17 were evaluable for radiologic response. In arm A, participants received abexinostat 15 mg/m(2) or 30 mg/m(2) twice daily. DLTs of grade 3 and 4 neutropenia were observed in 2 of 3 participants who received abexinostat 30 mg/m(2) twice daily. Neither of those patients received G-CSF prophylaxis. In arm B, participants received abexinostat at doses of 30 mg/m(2), 45 mg/m(2), or 60 mg/m(2) twice daily, all with mandated G-CSF support. Two DLTs were observed at the 60 mg/m(2) twice-daily dose (grade 3 infection, grade 4 thrombocytopenia). The pharmacokinetics of abexinostat were not affected by doxorubicin. HDAC activity, as measured by histone acetylation in peripheral blood mononuclear cells, was maximally inhibited at the abexinostat 30 mg/m(2) twice-daily dose. Of the 17 participants who were evaluable for radiologic response, 1 patient had a partial response, 9 patients had stable disease, and 7 patients had progressive disease as their best response; and 8 patients completed ≥ 5 cycles. Three of those participants had stable disease as their most recent disease status when the current report was written. Four participants who continued on monotherapy remained in stable disease for a median of 9.8 weeks after completing doxorubicin. The most common toxicities were fatigue, thrombocytopenia, and anemia. No study-related deaths were observed.

CONCLUSIONS

The maximum tolerated dose for abexinostat was 45 mg/m(2) twice daily administered on days 1 through 5 when patients received doxorubicin 75 mg/m(2) on day 4 of a 3-week cycle and G-CSF support was mandated. Toxicities were manageable, and tumor responses were observed. Additional studies are needed to further define the specific contributions of HDAC inhibition in patients who receive doxorubicin for the treatment of metastatic sarcoma.

The histone deacetylase inhibitor vorinostat prevents TNFα-induced necroptosis by regulating multiple signaling pathways

Histone deacetylase (HDAC) inhibitors are novel anticancer reagents that have recently been reported to have anti-inflammatory and neuroprotective effects; however, the mechanisms underlying their activities are largely undefined. The data from this study show that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) can protect L929 cells from TNFα-induced necroptosis. This effect involves multiple mechanisms, including the upregulation of cFLIPL expression, the enhanced activation of NFκB and p38 MAPK, and the inactivation of JNK. In addition, SAHA could initiate cell autophagy by inhibiting Akt and mTOR, which also play important roles in protecting cells from necroptosis. Because cell necroptosis is important for inflammation-related deterioration and neurodegenerative disease, our results indicate that preventing cell necrosis may be an important mechanism through which HDAC inhibitor compounds exert their anti-inflammatory or neuroprotective effects.

Trend of histone deacetylase inhibitors in cancer therapy: isoform selectivity or multitargeted strategy

Pharmacological inhibition of histone deacetylases (HDACs) has been successfully applied in the treatment of a wide range of disorders, including Parkinson's disease, infection, cardiac diseases, inflammation, and especially cancer. HDAC inhibitors (HDACIs) have been proved to be effective antitumor agents by various stages of investigation. At present, there are two opposite focuses of HDACI design in the cancer therapy, highly selective inhibitor strategy and dual- or multitargeted inhibitors. The former method, which is supposed to elucidate the function of individual HDAC and provide candidate inhibitors with fewer side effects, has been widely accepted by the inhibitor developer. The latter approach, though less practiced, has promising potential for the antitumor therapy based on HDACIs. Effective HDACIs, some of which are in clinic anticancer research, have been developed by both methods. In order to gain insight into HDACI design, the strategies and achievements of the two diverse methods are reviewed.

Vorinostat with sustained exposure and high solubility in poly(ethylene glycol)-b-poly(DL-lactic acid) micelle nanocarriers: characterization and effects on pharmacokinetics in rat serum and urine

The histone deacetylase inhibitor suberoylanilide hydroxamic acid, known as vorinostat, is a promising anticancer drug with a unique mode of action; however, it is plagued by low water solubility, low permeability, and suboptimal pharmacokinetics. In this study, poly(ethylene glycol)-b-poly(DL-lactic acid) (PEG-b-PLA) micelles of vorinostat were developed. Vorinostat's pharmacokinetics in rats was investigated after intravenous (i.v.) (10 mg/kg) and oral (p.o.) (50 mg/kg) micellar administrations and compared with a conventional polyethylene glycol 400 solution and methylcellulose suspension. The micelles increased the aqueous solubility of vorinostat from 0.2 to 8.15 ± 0.60 and 10.24 ± 0.92 mg/mL at drug to nanocarrier ratios of 1:10 and 1:15, respectively. Micelles had nanoscopic mean diameters of 75.67 ± 7.57 and 87.33 ± 8.62 nm for 1:10 and 1:15 micelles, respectively, with drug loading capacities of 9.93 ± 0.21% and 6.91 ± 1.19%, and encapsulation efficiencies of 42.74 ± 1.67% and 73.29 ± 4.78%, respectively. The micelles provided sustained exposure and improved pharmacokinetics characterized by a significant increase in serum half-life, area under curve, and mean residence time. The micelles reduced vorinostat clearance particularly after i.v. dosing. Thus, PEG-b-PLA micelles significantly improved the p.o. and i.v. pharmacokinetics and bioavailability of vorinostat, which warrants further investigation.

Targeted therapies in sarcomas: challenging the challenge

Sarcomas are a heterogeneous group of mesenchymal malignancies that very often lead to death. Nowadays, chemotherapy is the only available treatment for most sarcomas but there are few active drugs and clinical results still remain very poor. Thus, there is an imperious need to find new therapeutic alternatives in order to improve sarcoma patient's outcome. During the last years, there have been described a number of new molecular pathways that have allowed us to know more about cancer biology and tumorigenesis. Sarcomas are one of the tumors in which more advances have been made. Identification of specific chromosomal translocations, some important pathways characterization such as mTOR pathway or the insulin-like growth factor pathway, the stunning development in angiogenesis knowledge, and brand new agents like viruses have lead to the development of new therapeutic options with promising results. This paper makes an exhaustive review of preclinical and clinical evidence of the most recent targeted therapies in sarcomas and provides a future view of treatments that may lead to improve prognosis of patients affected with this disease.

New therapeutic targets in soft tissue sarcoma

Soft tissue sarcomas are an uncommon and diverse group of more than 50 mesenchymal malignancies. The pathogenesis of many of these is poorly understood, but others have begun to reveal the secrets of their underlying mechanisms. With considerable effort over recent years, soft tissue sarcomas have increasingly been classified on the basis of underlying molecular alterations. In turn, this has allowed the development and application of targeted agents in several specific, molecularly defined, sarcoma subtypes. This review will focus on the rationale for targeted therapy in sarcoma, with emphasis on the relevance of specific molecular factors and pathways in both translocation-associated sarcomas and in genetically complex tumors. In addition, we will address some of the early successes in sarcoma-targeted therapy as well as a few challenges and disappointments in this field. Finally, we will discuss several possible opportunities represented by poorly understood, but potentially promising new therapeutic targets, as well as several novel biological agents currently in preclinical and early phase I/II trials. This will provide the reader with the context for understanding the current state of this field and a sense of where it may be headed in the coming years.

Overview of the Classical Histone Deacetylase Enzymes and Histone Deacetylase Inhibitors

The important role of histone deacetylase enzymes in regulating gene expression, cellular proliferation, and survival has made them attractive targets for the development of histone deacetylase inhibitors as anticancer drugs. Suberoylanilide hydroxamic acid (Vorinostat, Zolinza), a structural analogue of the prototypical Trichostatin A, was approved by the US Food and Drug Administration for the treatment of advanced cutaneous T-cell lymphoma in 2006. This was followed by approval of the cyclic peptide, depsipeptide (Romidepsin, Istodax) for the same disease in 2009. Currently numerous histone deacetylase inhibitors are undergoing preclinical and clinical trials for the treatment of hematological and solid malignancies. Most of these studies are focused on combinations of histone deacetylase inhibitors with other therapeutic modalities, particularly conventional chemotherapeutics and radiotherapy. The aim of this paper is to provide an overview of the classical histone deacetylase enzymes and histone deacetylase inhibitors with an emphasis on potential combination therapies.

Epigenetic regulation in neural crest development

The neural crest (NC) is a multipotent, migratory cell population that arises from the developing dorsal neural fold of vertebrate embryos. Once their fates are specified, neural crest cells (NCCs) migrate along defined routes and differentiate into a variety of tissues, including bone and cartilage of the craniofacial skeleton, peripheral neurons, glia, pigment cells, endocrine cells, and mesenchymal precursor cells (Santagati and Rijli,2003; Dupin et al.,2006; Hall,2009). Abnormal development of NCCs causes a number of human diseases, including ear abnormalities (including deafness), heart anomalies, neuroblastomas, and mandibulofacial dysostosis (Hall,2009). For more than a century, NCCs have attracted the attention of geneticists and developmental biologists for their stem cell-like properties, including self-renewal and multipotent differentiation potential. However, we have only begun to understand the underlying mechanisms responsible for their formation and behavior. Recent studies have demonstrated that epigenetic regulation plays important roles in NC development. In this review, we focused on some of the most recent findings on chromatin-mediated mechanisms for vertebrate NCC development.