Phase IIb multicenter trial of vorinostat in patients with persistent, progressive, or treatment refractory cutaneous T-cell lymphoma

Therapeutic prospects for epigenetic modulation

INTRODUCTION

Epigenetics describes the phenomenon of heritable changes in gene regulation governed by non-Mendelian processes, primarily through biochemical modifications to chromatin that occur during cell differentiation and development. Abnormal levels of DNA and/or histone modifications are observed in patients with a wide variety of chronic diseases. Drugs that target the proteins controlling these chromatin modifications can modulate the expression of clusters of genes, potentially offering higher therapeutic efficacy than classical agents with single target pharmacologies that are susceptible to biochemical pathway degeneracy.

AREAS COVERED

This article reviews research characterizing dysregulation of epigenetic processes in cancer, immuno-inflammatory, psychiatric, neurological, metabolic and virology disease areas, and summarizes recent developments in identifying small molecule modulators that are being used to inform target discovery and initiate drug discovery projects.

EXPERT OPINION

There are numerous potential opportunities for epigenetic modulators in treating a wide range of chronic diseases; however, the field is complex, involving > 300 proteins, and much work is still required to provide tools to unravel the functions of individual proteins, particularly in vivo. This groundwork is essential to allow the drug discovery community to focus on those epigenetic proteins most likely to be suitable targets for safe, efficacious new therapies.

Aberrations of EZH2 in cancer

Control of gene expression is exerted at a number of different levels, one of which is the accessibility of genes and their controlling elements to the transcriptional machinery. Accessibility is dictated broadly by the degree of chromatin compaction, which is influenced in part by polycomb group proteins. EZH2, together with SUZ12 and EED, forms the polycomb repressive complex 2 (PRC2), which catalyzes trimethylation of histone H3 lysine 27 (H3K27me3). PRC2 may recruit other polycomb complexes, DNA methyltransferases, and histone deacetylases, resulting in additional transcriptional repressive marks and chromatin compaction at key developmental loci. Overexpression of EZH2 is a marker of advanced and metastatic disease in many solid tumors, including prostate and breast cancer. Mutation of EZH2 Y641 is described in lymphoma and results in enhanced activity, whereas inactivating mutations are seen in poor prognosis myeloid neoplasms. No histone demethylating agents are currently available for treatment of patients, but 3-deazaneplanocin (DZNep) reduces EZH2 levels and H3K27 trimethylation, resulting in reduced cell proliferation in breast and prostate cancer cells in vitro. Furthermore, synergistic effects are seen for combined treatment with DNA demethylating agents and histone deacetylation inhibitors, opening up the possibility of refined epigenetic treatments in the future.

Lung cancer: New biological insights and recent therapeutic advances

Approximately 1.6 million new cases of lung cancer are diagnosed each year throughout the world. In many countries, the mortality related to lung cancer continues to rise. The outcomes for patients with all stages of lung cancer have improved in recent years. The use of systemic therapy in conjunction with local therapy has led to improved cure rates in both resectable and unresectable patient groups. For patients with advanced stage disease, modest but real improvements in overall survival and quality of life have been achieved with systemic chemotherapy. A major focus of research has been the development of molecularly targeted agents and the identification of biomarkers for patient selection. Patients with non-small cell lung cancer with mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain achieve response rates of greater than 70% and superior progression-free survival when treated with an EGFR tyrosine kinase inhibitor compared with standard chemotherapy. This has now emerged as the preferred therapeutic approach for the subset of patients with a mutation in exons 19 or 21 of the EGFR. Another promising targeted approach involves the use of an anaplastic lymphoma kinase (ALK) inhibitor in patients with a translocation involving the echinoderm microtubule-associated protein-like 4 (EML4) and -ALK genes. Finally, a paradigm shift in favor of maintenance therapy for patients with advanced stage disease has gained strength from recent data. All of these advances have been made possible by developing a greater understanding of the biology, the discovery of novel anticancer agents, and improved supportive care measures. This article reviews the major strides made in the treatment of lung cancer in the recent past.

Phase 2 trial of romidepsin in patients with peripheral T-cell lymphoma

Romidepsin (depsipeptide or FK228) is a histone deacetylase inhibitor, one of a new class of agents active in T-cell lymphoma. A phase 2 trial was conducted in cutaneous (CTCL) and peripheral (PTCL) T-cell lymphoma. Major and durable responses in CTCL supported the approval of romidepsin for CTCL. Forty-seven patients with PTCL of various subtypes including PTCL NOS, angioimmunoblastic, ALK-negative anaplastic large cell lymphoma, and enteropathy-associated T-cell lymphoma were enrolled. All patients had received prior therapy with a median of 3 previous treatments (range 1-11); 18 (38%) had undergone stem-cell transplant. All patients were evaluated for toxicity; 2 patients discovered to be ineligible were excluded from response assessment. Common toxicities were nausea, fatigue, and transient thrombocytopenia and granulocytopenia. Complete responses were observed in 8 and partial responses in 9 of 45 patients, for an overall response rate of 38% (95% confidence interval 24%-53%). The median duration of overall response was 8.9 months (range 2-74). Responses were observed in various subtypes, with 6 responses among the 18 patients with prior stem-cell transplant. The histone deacetylase inhibitor romidepsin has single agent clinical activity associated with durable responses in patients with relapsed PTCL.

DNA hypermethylation as a chemotherapy target

Epigenetics refers to partially reversible, somatically inheritable, but DNA sequence-independent traits that modulate gene expression, chromatin structure, and cell functions such as cell cycle and apoptosis. DNA methylation is an example of a crucial epigenetic event; aberrant DNA methylation patterns are frequently found in human malignancies. DNA hypermethylation and the associated expression silencing of tumor suppressor genes represent a hallmark of neoplastic cells. The cancer methylome is highly disrupted, making DNA methylation an excellent target for anti-cancer therapies. Several small synthetic and natural molecules, are able to reverse the DNA hypermethylation through inhibition of DNA methyltransferase (DNMT). DNMT is the enzyme catalyzing the transfer of methyl groups to cytosines in genomic DNA. These reagents are studied intensively in cell cultures, animal models, and clinical trials for potential anti-cancer activities. It was found that accompanying DNA demethylation is a dramatic reactivation of the silenced genes and inhibition of cancer cell proliferation, promotion of cell apoptosis, or sensitization of cells to other chemotherapeutic reagents. During the last few decades, an increasing number of DNMT inhibitors (DNMTi) targeting DNA methylation have been developed to increase efficacy with reduced toxicity. This review provides an update on new findings on cancer epigenetic mechanisms, the development of new DNMTi, and their application in the clinical setting. Current challenges, potential solutions, and future directions concerning the development of DNMTi are also discussed in this review.

Changing therapeutic landscape--the last decade

Undoubtedly the most important event in the previous decade in lymphoma treatment was the establishment of immunotherapy as a prime modality. Addition of rituximab improves survival in almost every group of patients with CD20+ tumors. This has led to the appearance of a number of "me too" monoclonal antibodies (MoAbs) as well as MoAbs directed against other antigens whose usefulness remains to be proven during the next decade. We have also seen the raise and, probably unwarranted, fall of radioimmunotherapy. Conventional radiotherapy is losing ground. Regarding chemotherapy, the success of attempts to supplant R-CHOP-21 for front-line treatment of DLBCL with more dose-dense or dose-intense regimens remains doubtful and this issue is still unresolved. Bendamustine appeared as possibly the most effective cytotoxic agent for treatment of indolent lymphomas, while treatment of HL is becoming more tailored to prognostic features. This decade has also seen the advent of targeted drugs for lymphoma treatment. Their real impact will become known in the years to come. Finally, we may hope that advances in understanding the biology of lymphomas, made in the last decade, will help resolve remaining critical issues, treatment of T-NHLs and high-risk DLBCLs, being probably the most prominent.

Addition of a histone deacetylase inhibitor redirects tamoxifen-treated breast cancer cells into apoptosis, which is opposed by the induction of autophagy

Modulation of estrogen signaling is one of the most successful modalities for the treatment of estrogen receptor (ER)-positive breast cancer, yet de novo and acquired resistance are frequent. Recent data suggests that the induction of autophagy may play a considerable role in promoting tumor cell survival and resistance to anti-estrogen therapy. Hence, bypassing autophagy may offer a novel strategy to enhance the anti-tumor efficacy of anti-estrogens. Histone deacetylases (HDAC) are involved in the regulation of steroid hormone receptor mediated cell signaling and their inhibition potentiates the anti-tumor effects of anti-estrogens. However, the mechanism underlying this anti-tumor activity is poorly understood. In this report, we show that the addition of an HDAC inhibitor redirects the response of ER-positive breast cancer cells when treated with tamoxifen from growth arrest to apoptotic cell death. This redirection requires functional ER signaling and is mediated by a depletion of Bcl-2 and an induction of Bax and Bak, manifesting in cytochrome C release and PARP cleavage. With combined treatment, a subpopulation of cells is refractory to apoptosis and exhibit a strong induction of autophagy. Inhibition of autophagy in these cells, using siRNA directed against Beclin-1 or treatment with chloroquine, further promotes the induction of apoptosis. Thus, supporting prior reports that autophagy acts as a survival mechanism, our findings demonstrate that HDAC and autophagy inhibition directs autophagy-protected cells into apoptotic cell death, which may impair development of tamoxifen resistance.

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.

Investigational histone deacetylase inhibitors for non-Hodgkin lymphomas

IMPORTANCE OF THE FIELD

Histone deacetylase inhibitors (HDIs) have been shown effective as single agents for cutaneous T-cell lymphomas, peripheral T-cell lymphomas, and B-cell lymphomas, such as follicular lymphoma and mantle cell lymphoma. Of interest, HDIs in combination with other drugs can be a treatment for Epstein-Barr virus-associated lymphoproliferative disorders. Our data of gene expression profiles in PBMCs of responders to vorinostat was discussed.

AREAS COVERED IN THIS REVIEW

This review summarizes recent clinical trials of HDIs in non-Hodgkin lymphomas, the effects of HDIs in in vitro and mouse models, and the possibility of future combination treatments.

WHAT THE READER WILL GAIN

The HDI dosing schedule is crucial to optimize outcomes and avoid irreversible adverse effects. Responses to HDIs are slow, highlighting the need to continue treatment until the maximum response is achieved. HDIs cause hyperacetylation of histone and nonhistone proteins, resulting in various effects on neoplastic cells and immune responses in their microenvironment.

TAKE HOME MESSAGE

Even though HDIs are not potent as single agents, they are likely to provide promising therapeutic options when combined with other agents, i.e., BCL2/BCL-XL antagonists and proteasome inhibitors. Future studies should seek to identify biomarkers that predict patient responses to HDIs.

Enhancement of vaccinia virus based oncolysis with histone deacetylase inhibitors

Histone deacetylase inhibitors (HDI) dampen cellular innate immune response by decreasing interferon production and have been shown to increase the growth of vesicular stomatitis virus and HSV. As attenuated tumour-selective oncolytic vaccinia viruses (VV) are already undergoing clinical evaluation, the goal of this study is to determine whether HDI can also enhance the potency of these poxviruses in infection-resistant cancer cell lines. Multiple HDIs were tested and Trichostatin A (TSA) was found to potently enhance the spread and replication of a tumour selective vaccinia virus in several infection-resistant cancer cell lines. TSA significantly decreased the number of lung metastases in a syngeneic B16F10LacZ lung metastasis model yet did not increase the replication of vaccinia in normal tissues. The combination of TSA and VV increased survival of mice harbouring human HCT116 colon tumour xenografts as compared to mice treated with either agent alone. We conclude that TSA can selectively and effectively enhance the replication and spread of oncolytic vaccinia virus in cancer cells.

Peripheral T-cell lymphoma: review and updates of current management strategies

The classification of T-cell and natural-killer- (NK-) cell lymphomas has been updated in the 4th edition of the World Health Organization (WHO) classification of tumors of the haematopoietic and lymphoid tissue published in 2008. Based on recent epidemiological studies, NK-cell lymphomas occur almost exclusively in Asia and South America, although T-cell lymphomas appear to occur in the East as commonly as in the West. Due to the low prevalence of this disease, diagnosis and optimal treatment of patients have not been studied prospectively in large randomized trials. Nevertheless, there has been development in the understanding of T-cell lymphomas and how they should be managed; FDG-PET emerges as an increasingly important tool in diagnosis, gene-expression signatures may aid with prognostication in the future, and novel therapies are currently being studied to improve outcomes in T-cell lymphomas. More work, however, needs to be done, and international collaboration will be pertinent to deriving meaningful results from future clinical studies.

Romidepsin: evidence for its potential use to manage previously treated cutaneous T cell lymphoma

Introduction:

Cutaneous T cell lymphoma (CTCL) encompasses a heterogeneous group of neoplasms of skin-homing T cells, which includes mycosis fungoides, the most common form, and Sézary syndrome, the leukemia equivalent of mycosis fungoides. Histone deacetylase inhibitors are currently under investigation for their therapeutic value in a variety of conditions. Through multiple mechanisms, they induce apoptosis or inhibition of tumor cell growth. Some studies have also shown histone deacetylase inhibitors to have synergistic activity with existing therapeutic agents in selected conditions. Romidepsin is a histone deacetylase inhibitor with a promising efficacy and safety profile that may represent a valuable treatment alternative for patients with treatment-resistant mycosis fungoides and Sézary syndrome.

Aims:

To review emerging evidence regarding the use of romidepsin in the management of treatment-resistant CTCL.

Evidence review:

There is evidence that romidepsin can induce significant and durable responses in patients with refractory CTCL. In two independent Phase II trials including a total of 167 patients with CTCL, there was an overall response rate of 34% with a partial response of 28% and complete response rate of 6%. The most frequent toxicities reported from the Phase II trials were nausea, vomiting, fatigue, anorexia, and dysgeusia.

Clinical potential:

Romidepsin may be an effective therapeutic option for patients with CTCL who have had treatment failure with multiple standard treatment modalities.

Exciting new targets in lung cancer therapy: ALK, IGF-1R, HDAC, and Hh

The anaplastic lymphoma kinase (ALK) inhibitor crizotinib will become an integral addition to the treatment of patients with non-small cell lung cancer (NSCLC) harboring genetic ALK translocations. The insulin-like growth factor receptor (IGF-1R) monoclonal antibody figitumumab, while initially promising, appears to increase toxicity and death in combination with chemotherapy in the treatment of patients with NSCLC of squamous histology; therefore, clinical development of this class of agents will need to proceed with caution. The histone deacetylation (HDAC) inhibitor vorinostat did not demonstrate an improvement in overall survival (OS) compared with placebo in a large randomized trial, but other agents in this class may have greater selectivity and efficacy. Inhibitors of the hedgehog (Hh) signaling pathways have some early clinical promise in both NSCLC and small cell lung cancer (SCLC), and larger studies using these agents are eagerly anticipated.

Histone deacetylase inhibitors in the treatment of hematological malignancies and solid tumors

The human genome is epigenetically organized through a series of modifications to the histone proteins that interact with the DNA. In cancer, many of the proteins that regulate these modifications can be altered in both function and expression. One example of this is the family of histone deacetylases (HDACs), which as their name implies remove acetyl groups from the histone proteins, allowing for more condensed nucleosomal structure. HDACs have increased expression in cancer and are also believed to promote carcinogenesis through the acetylation and interaction with key transcriptional regulators. Given this, small molecule histone deacetylases inhibitors have been identified and developed, which not only inhibit HDACs, but can also lead to growth arrest, differentiation, and/or apoptosis in tumors both in vitro and in vivo. Here, we will discuss some of the recent developments in clinical trials utilizing HDACs inhibitors for the treatment of both hematological malignancies as well as solid tumors.

Targeting histone deacetyalses in the treatment of B- and T-cell malignancies

HDAC inhibitors (HDACI) are now emerging as one of the most promising new classes of drugs for the treatment of select forms of non-Hodgkin’s lymphoma (NHL). They are particularly active in T-cell lymphomas, possibly hodgkin’s lymphoma and indolent B cell lymphomas. Presently, two of these agents, vorinostat and romidepsin, have been approved in the US for the treatment of relapsed and refractory cutaneous T cell lymphomas (CTCL). Initially, these agents were developed with the idea that they affected transcriptional activation and thus gene expression, by modulating chromatin condensation and decondensation. It is now clear that their effects go beyond chromatin and by affecting the acetylation status of histones and other intra-cellular proteins, they modify gene expression and cellular function via multiple pathways. Gene expression profiles and functional genetic analysis has led to further understanding of the various molecular pathways that are affected by these agents including cell cycle regulation, pathways of cellular proliferation, apoptosis and angiogenesis all important in lymphomagenesis. There is also increasing data to support the effects of these agents on T cell receptor and immune function which may explain the high level of activity of these agents in T cell lymphomas and hodgkin’s lymphoma. There is ample evidence of epigenetic dysregulation in lymphomas which may underlie the mechanisms of action of these agents but how these agents work is still not clear. Current HDAC inhibitors can be divided into at least four classes based on their chemical structure. At present several of these HDAC inhibitors are in clinical trials both as single agents and in combination with chemotherapy or other biological agents. They are easy to administer and are generally well tolerated with minimal side effects. Different dosing levels and schedules and the use of isospecific HDAC inhibitors are some of the strategies that are being employed to increase the therapeutic effect of these agents in the treatment of lymphomas. There may also be class differences that translate into specific activity against different lymphoma. HDAC inhibitors will likely be incorporated into combinations of targeted therapies both in the upfront and relapsed setting for lymphomas.

New strategies in peripheral T-cell lymphoma: understanding tumor biology and developing novel therapies

Peripheral T-cell lymphomas (PTCL) constitute a group of heterogeneous diseases that are uncommon, representing, in Western countries, only approximately 10% of all non-Hodgkin lymphomas. They are typically associated with a poor prognosis compared with their B-cell counterparts and are much less well understood with respect to tumor biology, owing to their rarity and biologic heterogeneity, and to the fact that characteristic cytogenetic abnormalities are few compared with B-cell lymphomas. Although the outcome for patients with anaplastic large cell lymphoma (ALCL), particularly anaplastic lymphoma kinase (ALK)-positive ALCL, is good, other types of PTCLs are associated with a poor prognosis, even with aggressive anthracycline-based chemotherapy. In this respect, there is a need for new approaches in these diseases, and this review focuses on and explores recent experience with novel therapies in PTCL.

Cardio-oncology/onco-cardiology

An understanding of onco-cardiology or cardio-oncology is critical for the effective care of cancer patients. Virtually all antineoplastic agents are associated with cardiotoxicity, which can be divided into 5 categories: direct cytotoxic effects of chemotherapy and associated cardiac systolic dysfunction, cardiac ischemia, arrhythmias, pericarditis, and chemotherapy-induced repolarization abnormalities. Radiation therapy can also lead to coronary artery disease and fibrotic changes to the valves, pericardium, and myocardium. All patients being considered for chemotherapy, especially those who have prior cardiac history, should undergo detailed cardiovascular evaluation to optimize the treatment. Serial assessment of left ventricular systolic function and cardiac biomarkers might also be considered in selected patient populations. Cardiotoxic effects of chemotherapy might be decreased by the concurrent use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers. Antiplatelet or anticoagulation therapy might be considered in patients with a potential hypercoagulable state associated with chemotherapy or cancer. Open dialogue between both cardiologists and oncologists will be required for optimal patient care.

Emerging therapies for the treatment of relapsed or refractory multiple myeloma

Encouraging progress has been made in the treatment of patients with relapsed/refractory multiple myeloma (MM). The rapidly evolving understanding of key pathways responsible for tumor growth and survival has led to the development of novel agents (including immunomodulatory drugs, proteasome inhibitors, histone deacetylase inhibitors, and other targeted agents) with the potential to provide significant improvements in response and survival, and influence treatment guidelines. This review summarizes recent advances in understanding of the biology of relapsed/refractory MM and clinical trials with novel targeted agents that are currently under investigation for patients with this disease.

Romidepsin: a new therapy for cutaneous T-cell lymphoma and a potential therapy for solid tumors

Romidepsin is a histone deacetylase inhibitor (HDI), approved by the US FDA for the treatment of cutaneous T-cell lymphoma (CTCL). Although various mechanisms have been proposed for the activity of HDIs, including induction of genes controlling cell cycle, acetylation of cytoplasmic proteins and direct induction of apoptosis, the mechanism underlying activity of romidepsin and other HDIs in CTCL is not known. Romidepsin induces long-lasting responses. The side-effect profile is similar to that of other HDIs, causing fatigue, nausea and thrombocytopenia. Management of the CTCL population requires vigilence to prevent infection with skin contaminants, and monitoring of potassium and magnesium, electrolytes found to be low in a large proportion of patients. Electrocardiographic (ECG) changes are common but are not associated with myocardial damage. When molecular end points were evaluated in 61 patients enrolled on a Phase II trial with romidepsin, response was associated with persistence of acetylated histone H3, suggesting that drug exposure is important in effective therapy with romidepsin. Future studies will endeavor to identify combination strategies to increase the efficacy both in resistant CTCL and in solid tumors and to identify biomarkers of response that will allow selection of patients most likely to benefit from the therapy.

Overcoming resistance to histone deacetylase inhibitors in human leukemia with the redox modulating compound β-phenylethyl isothiocyanate

Mechanisms of action and resistance of histone deacetylase inhibitors (HDACIs) are not well understood. A gene expression analysis performed in a phase 1 trial of vorinostat in leukemia indicated that overexpression of genes involved in antioxidant defense was associated with clinical resistance. We hypothesized that nonepigenetic mechanisms may be involved in resistance to HDACI therapy in leukemia. Here we confirmed up-regulation of a series of antioxidants in a pan-HDACI-resistant leukemia cell line HL60/LR. Vorinostat induced reactive oxygen species (ROS) through nicotinamide adenine dinucleotide phosphate oxidase in leukemia cells. An increase in ROS resulted in translocation of nuclear factor E2-related factor 2 from cytosol to nucleus, leading to up-regulation of antioxidant genes, including a majority of glutathione-associated enzymes as a cellular protective mechanism. Addition of β-phenylethyl isothiocyanate, a natural compound capable of depleting cellular glutathione, significantly enhanced the cytotoxicity of vorinostat in leukemia cell lines and primary leukemia cells by inhibiting the cytoprotective antioxidant response. These results suggest that ROS plays an important role in action of vorinostat and that combination with a redox-modulating compound increases sensitivity to HDACIs and also overcomes vorinostat resistance. Such a combination strategy may be an effective therapeutic regimen and have potential clinical application in leukemia.

Final Results From a Multicenter, International, Pivotal Study of Romidepsin in Refractory Cutaneous T-Cell Lymphoma

Purpose

The primary objective of this study was to confirm the efficacy of romidepsin in patients with treatment refractory cutaneous T-cell lymphoma (CTCL).

Patients and Methods

This international, pivotal, single-arm, open-label, phase II study was conducted in patients with stage IB to IVA CTCL who had received one or more prior systemic therapies. Patients received romidepsin as an intravenous infusion at a dose of 14 mg/m2on days 1, 8, and 15 every 28 days. Response was determined by a composite assessment of total tumor burden including cutaneous disease, lymph node involvement, and blood (Sézary cells).

Results

Ninety-six patients were enrolled and received one or more doses of romidepsin. Most patients (71%) had advanced stage disease (≥ IIB). The response rate was 34% (primary end point), including six patients with complete response (CR). Twenty-six of 68 patients (38%) with advanced disease achieved a response, including five CRs. The median time to response was 2 months, and the median duration of response was 15 months. A clinically meaningful improvement in pruritus was observed in 28 (43%) of 65 patients, including patients who did not achieve an objective response. Median duration of reduction in pruritus was 6 months. Drug-related adverse events were generally mild and consisted mainly of GI disturbances and asthenic conditions. Nonspecific, reversible ECG changes were noted in some patients.

Conclusion

Romidepsin has significant and sustainable single-agent activity (including improvement in pruritus) and an acceptable safety profile, making it an important therapeutic option for treatment refractory CTCL.

[Histone deacetylase inhibitors: highlight on epigenetic regulation]

HDAC, by modifiing relations between DNA and histones, are major proteins of the epigenetic regulation. They play part in the signal transduction and in many cellular processes: cell cycle control, apoptosis, protein degradation, angiogenesis, invasion and cell motility. In several models of cancer HDAC inhibitors (HDACIs) are able to up regulate tumor suppressing gene (p53, p21, pRB...) and to down regulate oncogenes (SRC, HIF-Ialpha,HER2...). Many inhibitors are currently in clinical development and promising results have been reported in cutaneous T cell lymphoma, Hodgkin's disease and non-hodgkin lymphoma. Combination with chemotherapy and molecular targeted agents seem to be effective in myeloma, lung cancer and myeloïd neoplasms. In this review, we focus on recent biologic and clinical data that highlitght the anti-neoplastic role of HDACIs.

Vorinostat: A novel therapy for the treatment of cutaneous T-cell lymphoma

PURPOSE

The pharmacology, pharmacokinetics, clinical efficacy, safety, adverse effects, dosage and administration, and role in therapy of vorinostat in the treatment of cutaneous T-cell lymphoma (CTCL) are reviewed.

SUMMARY

Vorinostat is a novel histone deacetylase (HDAC) inhibitor approved for the treatment of advanced CTCL. Its primary biochemical mechanism is to correct an aberrant balance between acetylated and deacetylated histones, the proteins involved in chromatin structure and organization. Vorinostat is metabolized and excreted following glucuronidation by the uridine diphosphate glucuronosyl-transferase (UGT) enzyme system. Polymorphisms in the gene encoding for this enzyme system, UGT1A1, may be an important predictor of vorinostat toxicity and response levels in individual patients. Vorinostat is not metabolized by and does not inhibit the cytochrome P-450 isoenzyme system, and only two drug interactions have been noted with vorinostat: warfarin and valproic acid or other HDAC inhibitors. In two Phase II studies, patients with CTCL treated with oral vorinostat demonstrated significant reductions in skin lesions and decreased disease progression. The overall response rate was approximately 30%, including one complete response and a time to response of approximately 10 weeks. At the approved 400-mg, once-daily dose, vorinostat was well tolerated, with the most common grade 1 or 2 adverse events being fatigue, nausea, and diarrhea. More-severe toxicities included thrombocytopenia, fatigue, and nausea and occurred in less than 6% of patients.

CONCLUSION

Vorinostat, a novel HDAC inhibitor, is efficacious and well tolerated in patients with CTCL and is being investigated for its efficacy and safety in other types of cancers and as a part of combination therapy.

Clinical Toxicities of Histone Deacetylase Inhibitors

The HDAC inhibitors are a new family of antineoplastic agents. Since the entry of these agents into our therapeutic armamentarium, there has been increasing interest in their use. Although this family comprises chemical compounds from unrelated chemical classes that have different HDAC isoform specificities, they surprisingly have very similar toxicity profiles. In contrast, the observed toxicity profile is somewhat different from that of traditional cytotoxic chemotherapeutic agents and from other epigenetic agents. While some of the side effects may be familiar to the oncologist, others are less commonly seen. As some patients remain on therapy for a prolonged period of time, the long-term sequelae need to be characterized. In addition, since preclinical models suggest promising activity when used in combination with other antineoplastic agents, combination trials are being pursued. It will thus be important to distinguish the relative toxicity attributed to these agents and be alert to the exacerbation of toxicities observed in single agent studies. Notably, few of the agents in this class have completed phase 2 testing. Consequently, more clinical experience is needed to determine the relative frequency of the observed side effects, and to identify and develop approaches to mitigate potential clinical sequelae.

Combinations of DNA methyltransferase and histone deacetylase inhibitors induce DNA damage in small cell lung cancer cells: correlation of resistance with IFN-stimulated gene expression

Because epigenetic inhibitors can reduce cancer cell proliferation, we tested the hypothesis that concurrent inhibition of histone acetylation and DNA methylation could synergistically reduce the viability of small cell lung cancer (SCLC) cells. Sub-IC(50) concentrations of the DNA methyltransferase (DNMT) inhibitor decitabine (5-AZA-dC) and the histone deacetylase (HDAC) inhibitors (LBH589 or MGCD0103) synergistically reduced the proliferation of five of nine SCLC cell lines. Loss of viability of sensitive SCLC cells did not correlate with the inhibition of either DNMT1 or HDACs, suggesting nonepigenetic mechanisms for synergy between these two classes of epigenetic modulators. Because combinations of 5-AZA-dC and HDAC inhibitors had marginal effects on the apoptosis index, Comet assay was undertaken to assess DNA damage. MGCD0103 and 5AZA-dC cotreatment augmented DNA damage in SCLC cells, resulting in increased tail length and moment in Comet assays by 24 hours in sensitive cell lines (P < 0.01). Consistent with augmented DNA damage, combination of a DNMT and HDAC inhibitor markedly increased the levels of phospho-H2A.X in sensitive cells but not in resistant ones. Comparison of basal gene expression between resistant and sensitive cells identified markedly higher basal expression of IFN-stimulated genes in the resistant cell lines, suggesting that IFN-stimulated gene expression may determine SCLC cell sensitivity to epigenetic modulators or other DNA damaging agents.

Histone deacetylase inhibitors: clinical implications for hematological malignancies

Histone modifications have widely been implicated in cancer development and progression and are potentially reversible by drug treatments. The N-terminal tails of each histone extend outward through the DNA strand containing amino acid residues modified by posttranslational acetylation, methylation, and phosphorylation. These modifications change the secondary structure of the histone protein tails in relation to the DNA strands, increasing the distance between DNA and histones, and thus allowing accessibility of transcription factors to gene promoter regions. A large number of HDAC inhibitors have been synthesized in the last few years, most being effective in vitro, inducing cancer cells differentiation or cell death. The majority of the inhibitors are in clinical trials, unlike the suberoylanilide hydroxamic acid, a pan-HDACi, and Romidepsin (FK 228), a class I-selective HDACi, which are only approved in the second line treatment of refractory, persistent or relapsed cutaneous T-cell lymphoma, and active in approximately 150 clinical trials, in monotherapy or in association. Preclinical studies investigated the use of these drugs in clinical practice, as single agents and in combination with chemotherapy, hypomethylating agents, proteasome inhibitors, and MTOR inhibitors, showing a significant effect mostly in hematological malignancies. The aim of this review is to focus on the biological features of these drugs, analyzing the possible mechanism(s) of action and outline an overview on the current use in the clinical practice.

Novel agents in development for peripheral T-cell lymphoma

Though peripheral T-cell lymphoma (PTCL) is an area of significant unmet therapeutic need, a number of new treatment options are available for patients, especially those with relapsed or refractory disease. A plethora of drugs are now in development for PTCL, but drugs that truly target novel disease biology are noticeably absent. Combinations of T-cell centric agents could produce novel platforms of therapy to replace the relatively ineffective CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone)-based regimens. Among agents with T-cell activity are the folate analog pralatrexate, histone deacetylase inhibitors (HDACi) like romidepsin, the proteasome inhibitor bortezomib, the immunomodulatory agent lenalidomide, the purine nucleoside phosphorylase (PNP) inhibitor forodesine, the nucleoside analog gemcitabine, and BH3-only mimetics like ABT-263 and ABT-737.

Vorinostat plus bortezomib for the treatment of relapsed/refractory multiple myeloma: a case series illustrating utility in clinical practice

INTRODUCTION

Increasing numbers of patients are presenting with relapsed/refractory multiple myeloma (MM) following treatment with bortezomib. Therefore, there is a need for effective and well-tolerated treatment strategies after failure of bortezomib-based regimens. Vorinostat, a histone deacetylase inhibitor, has demonstrated antiproliferative and proapoptotic activity alone and in combination with bortezomib in preclinical models of MM. Preliminary results from ongoing phase I trials have demonstrated the clinical activity of vorinostat in combination with bortezomib in patients with MM. This case series reports our experience of combined vorinostat and bortezomib in 6 patients with relapsed/refractory MM after previous bortezomib.

MATERIALS AND METHODS

Patients received oral vorinostat 300 mg or 400 mg once daily (days 1-14) and bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 in a 21-day cycle.

RESULTS

All patients derived clinical benefit from combined vorinostat and bortezomib, with objective response observed in 5 of the 6 patients (> or = minimal response), including 1 very good partial response; stable disease was observed in the remaining patient. Patients remained on therapy until disease progression. Combined vorinostat and bortezomib therapy was well tolerated: grade 2 nausea and diarrhea were the only adverse events reported. No patients discontinued therapy because of toxicity, and no dose adjustments were required for either agent.

CONCLUSION

These results suggest that combined vorinostat and bortezomib therapy is effective in patients with relapsed/refractory MM after failure of previous bortezomib-based regimens and support further evaluation of this combination in randomized trials.

Pediatric phase I trial and pharmacokinetic study of vorinostat: a Children's Oncology Group phase I consortium report

PURPOSE

The purpose of this study was to determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), and pharmacokinetics of vorinostat administered as a single agent and in combination 13-cis retinoic acid (13cRA) in children with refractory solid tumors; to evaluate the tolerability of the solid tumor MTD in children with refractory leukemias; and to characterize the pharmacokinetics of a vorinostat suspension in children.

PATIENTS AND METHODS

Vorinostat was administered orally daily starting at 180 mg/m(2)/d with escalations planned in 30% increments. Pharmacokinetic studies were performed with the initial dose. Acetyl-histone (H3) accumulation was assessed by Western blotting of peripheral blood mononuclear cells (PBMC).

RESULTS

Sixty-four patients were enrolled on this multipart trial. In patients with solid tumors, the MTD was 230 mg/m(2)/d with dose-limiting neutropenia, thrombocytopenia, and hypokalemia at 300 mg/m(2)/d. DLTs observed with the combination of 13cRA and vorinostat included thrombocytopenia, neutropenia, anorexia, and hypertriglyceridemia, resulting in a MTD of vorinostat 180 mg/m(2)/d 4 times per week and 13cRA 80 mg/m(2)/dose twice per day, days 1 through 14 every 28 days. Wide interpatient variability was noted in vorinostat disposition, with area under the concentration-time curves at 230 mg/m(2)/d for the capsule (range, 1,415 to 9,291 ng/mL x hr) and oral suspension (range, 1,186 to 4,780 ng/mL x hr). Significant accumulation of acetylated H3 histone in PBMC was observed after administration of vorinostat, particularly at higher doses. One patient with neuroblastoma experienced a complete response to the combination.

CONCLUSION

In children with recurrent solid tumors, vorinostat is well-tolerated at 230 mg/m(2)/d, with a modest dose reduction being required when combining vorinostat with 13cRA. Drug disposition is similar to that observed in adults.

Reversion of epigenetically mediated BIM silencing overcomes chemoresistance in Burkitt lymphoma

In Burkitt lymphoma/leukemia (BL), achievement of complete remission with first-line chemotherapy remains a challenging issue, as most patients who respond remain disease-free, whereas those refractory have few options of being rescued with salvage therapies. The mechanisms underlying BL chemoresistance and how it can be circumvented remain undetermined. We previously reported the frequent inactivation of the proapoptotic BIM gene in B-cell lymphomas. Here we show that BIM epigenetic silencing by concurrent promoter hypermethylation and deacetylation occurs frequently in primary BL samples and BL-derived cell lines. Remarkably, patients with BL with hypermethylated BIM presented lower complete remission rate (24% vs 79%; P = .002) and shorter overall survival (P = .007) than those with BIM-expressing lymphomas, indicating that BIM transcriptional repression may mediate tumor chemoresistance. Accordingly, by combining in vitro and in vivo studies of human BL-xenografts grown in immunodeficient RAG2(-/-)γc(-/-) mice and of murine B220(+)IgM(+) B-cell lymphomas generated in Eμ-MYC and Eμ-MYC-BIM(+/-) transgenes, we demonstrate that lymphoma chemoresistance is dictated by BIM gene dosage and is reversible on BIM reactivation by genetic manipulation or after treatment with histone-deacetylase inhibitors. We suggest that the combination of histone-deacetylase inhibitors and high-dose chemotherapy may overcome chemoresistance, achieve durable remission, and improve survival of patients with BL.

New targets of therapy in T-cell lymphomas

T-cell lymphomas (TCL) are characterized by poor response to chemotherapy and generally poor outcome. While molecular profiling has identified distinct biological subsets and therapeutic targets in B-cell lymphomas, the molecular characterization of TCL has been slower. Surface markers expressed on malignant T-cells, such as CD2, CD3, CD4, CD25, and CD52 were the first TCL-specific therapeutic targets to be discovered. However, the presence of these receptors on normal T-cells means that monoclonal antibody (mAb)- or immunotoxin (IT)-based therapy in TCL inevitably results in variable degrees of immunosuppression. Thus, although some mAbs/IT have significant activity in selected subsets of TCL, more specific agents that target signaling pathways preferentially activated in malignant T-cells are needed. One such novel class of agents is represented by the histone deacetylase (HDAC) inhibitors. These molecules selectively induce apoptosis in a variety of transformed cells, including malignant T-cells, both in vitro and in vivo. Several HDAC inhibitors have been studied in TCL with promising results, and have recently been approved for clinical use. Immunomodulatory drugs, such as interferons and Toll Receptor (TLR) agonists have significant clinical activity in TCL, and are particularly important in the treatment of primary cutaneous subtypes (CTCL). Although most classical cytotoxic drugs have limited efficacy against TCL, agents that inhibit purine and pyrimidine metabolism, known as nucleoside analogues, and novel antifolate drugs, such as pralatrexate, are highly active in TCL. With improved molecular profiling of TCL novel pharmacological agents with activity in TCL are now being discovered at an increasingly rapid pace. Clinical trials are in progress and these agents are being integrated in combination therapies for TCL, both in the relapsed/refractory setting as well as front line.

The novel deacetylase inhibitor AR-42 demonstrates pre-clinical activity in B-cell malignancies in vitro and in vivo

Background

While deacetylase (DAC) inhibitors show promise for the treatment of B-cell malignancies, those introduced to date are weak inhibitors of class I and II DACs or potent inhibitors of class I DAC only, and have shown suboptimal activity or unacceptable toxicities. We therefore investigated the novel DAC inhibitor AR-42 to determine its efficacy in B-cell malignancies.

Principal Findings

In mantle cell lymphoma (JeKo-1), Burkitt's lymphoma (Raji), and acute lymphoblastic leukemia (697) cell lines, the 48-hr IC₅₀ (50% growth inhibitory concentration) of AR-42 is 0.61 µM or less. In chronic lymphocytic leukemia (CLL) patient cells, the 48-hr LC₅₀ (concentration lethal to 50%) of AR-42 is 0.76 µM. AR-42 produces dose- and time-dependent acetylation both of histones and tubulin, and induces caspase-dependent apoptosis that is not reduced in the presence of stromal cells. AR-42 also sensitizes CLL cells to TNF-Related Apoptosis Inducing Ligand (TRAIL), potentially through reduction of c-FLIP. AR-42 significantly reduced leukocyte counts and/or prolonged survival in three separate mouse models of B-cell malignancy without evidence of toxicity.

Conclusions/Significance

Together, these data demonstrate that AR-42 has in vitro and in vivo efficacy at tolerable doses. These results strongly support upcoming phase I testing of AR-42 in B-cell malignancies.

A phase I, pharmacokinetic, and pharmacodynamic study of two schedules of vorinostat in combination with 5-fluorouracil and leucovorin in patients with refractory solid tumors

PURPOSE

We conducted a phase I clinical trial to determine the maximum tolerated dose (MTD) of daily or twice daily vorinostat x 3 days when combined with fixed doses of 5-fluorouracil (FU) and leucovorin every 2 weeks.

EXPERIMENTAL DESIGN

Vorinostat doses were escalated in a standard 3 x 3 phase I design. FU/leucovorin was started on day 2 of vorinostat and consisted of leucovorin 400 mg/m(2) i.v. over 2 hours followed by FU 400 mg/m(2) i.v. bolus and 2,400 mg/m(2) over 46 hours (sLV5FU2).

RESULTS

Forty-three patients were enrolled. Grade 3 fatigue, and hand and foot syndrome were the dose-limiting toxicities (DLT) at the 2,000 mg vorinostat once-daily dose level. Grade 3 fatigue and mucositis were DLTs at the 800 mg vorinostat twice-daily dose level. None of six patients at the 1,700 mg once daily or six patients at the 600 mg twice daily dose levels had a DLT; those dose levels represent the MTD. Twenty-one of 38 patients with FU-refractory colorectal cancer had stable disease, and one had a partial response. Vorinostat maximum serum concentrations at the MTD exceeded concentrations associated with thymidylate synthase downregulation in vitro. No pharmacokinetic interactions were noted between vorinostat and FU.

CONCLUSIONS

The MTD of vorinostat in combination with sLV5FU2 is 1,700 mg orally once daily x 3 or 600 mg orally twice daily x 3 days every 2 weeks. Clinical activity in refractory colorectal cancer supports further clinical development of this combination.

Current and emerging treatment strategies for cutaneous T-cell lymphoma

Cutaneous T-cell lymphomas (CTCLs) are a rare group of mature T-cell lymphomas presenting primarily in the skin. The most common subtypes of CTCL are mycosis fungoides and its leukaemic variant Sézary's syndrome. Patients with early-stage disease frequently have an indolent clinical course; however, those with advanced stages have a shortened survival. For the treating physician, the question of how to choose a particular therapy in the management of CTCL is important. These diseases span the disciplines of dermatology, medical oncology and radiation oncology. Other than an allogeneic stem cell transplant, there are no curative therapies for this disease. Hence, many treatment modalities need to be offered to the patient over the course of their life. An accepted treatment approach has been to delay traditional chemotherapy, which can cause excessive toxicity without durable benefit. More conservative treatment strategies in the initial management of CTCL have led to the development of newer biological and targeted therapies. These therapies include biological immune enhancers such as interferon alpha and extracorporeal photopheresis that exert their effect by stimulating an immune response to the tumour cells. Retinoids such as bexarotene have been shown to be effective and well tolerated with predictable adverse effects. The fusion toxin denileukin diftitox targets the interleukin-2 receptor expressed on malignant T cells. Histone deacetylase inhibitors such as vorinostat and romidepsin (depsipeptide) may reverse the epigenetic states associated with cancer. Forodesine is a novel inhibitor of purine nucleoside phosphorylase and leads to apoptosis of malignant T cells. Pralatrexate is a novel targeted antifolate that targets the reduced folate carrier in cancer cells. Lastly, systemic chemotherapy including transplantation is used when rapid disease control is needed or if all other biological therapies have failed. As response rates to most of the biological agents used to treat CTCL are 25-30%, it is also reasonable to consider clinical trials with novel agents if one or two front-line therapies have failed, especially before considering chemotherapy. CTCL is largely an incurable disease with significant morbidity and more active agents are needed.

Novel targeted therapeutics for metastatic castration-resistant prostate cancer

Virtually all patients that succumb to prostate cancer die of metastatic castration-resistant disease. Although docetaxel is the standard of care for these patients and is associated with a modest prolongation of survival, there is an urgent need for novel treatment strategies for metastatic prostate cancer. In the last several years, great strides have been made in our understanding of the biological and molecular mechanisms driving prostate cancer growth and progression, and this has resulted in widespread clinical testing of numerous new targeted therapies. This review discusses some of the key therapeutic agents that have emerged for the treatment of metastatic castration-resistant prostate cancer in the last 5years, with an emphasis on both molecular targets and clinical trial design. These agents include mammalian target of rapamycin (mTOR) pathway inhibitors, anti-angiogenic drugs, epidermal growth factor receptor (EGFR) inhibitors, insulin-like growth factor (IGF) pathway inhibitors, apoptosis-inducing drugs, endothelin receptor antagonists, receptor activator of nuclear factor kappaB (RANK) ligand inhibitors, vitamin D analogues, cytochrome P17 enzyme inhibitors, androgen receptor modulators, epigenetic therapies, vaccine therapies, and cytotoxic T lymphocyte-associated antigen (CTLA)-4 blocking agents.

A phase I study of vorinostat in combination with idarubicin in relapsed or refractory leukaemia

Histone deacetylase inhibitors (HDACi) affect chromatin remodelling and modulate the expression of aberrantly silenced genes. HDACi have single-agent clinical activity in haematological malignancies and have synergistic anti-leukaemia activity when combined with anthracyclines in vitro. We conducted a two-arm, parallel Phase I trial to investigate two schedules of escalating doses of vorinostat (Schedule A: thrice daily (TID) for 14 d; B: TID for 3 d) in combination with a fixed dose of idarubicin in patients with refractory leukaemia. Of the 41 patients enrolled, 90% had acute myeloid leukaemia, with a median of 3 prior therapies. Seven responses (17%) were documented (two complete response (5%), one complete response without platelet recovery (2.5%), and four marrow responses). The 3-d schedule of vorinostat was better tolerated than the 14-d schedule. The maximum tolerated dose for vorinostat was defined as 400 mg TID for 3 d. The most common grade 3 and 4 toxicities included mucositis, fatigue and diarrhoea. Correlative studies demonstrated histone acetylation in patients on therapy and modulation of CDKN1A and TOP2A (topoisomerase II) gene expression. Pharmacokinetic analysis confirmed a dose-related elevation in plasma vorinostat concentrations. The combination of vorinostat and idarubicin is generally tolerable and active in patients with advanced leukaemia and should be studied in the front-line setting.

Epigenetic causes of apoptosis resistance in cutaneous T-cell lymphomas

In cutaneous T-cell lymphomas (CTCLs) defects in Fas-mediated apoptosis have been suggested to be involved in disease pathogenesis. Decreased or absent Fas expression has been reported in a significant proportion of CTCL patients, but the molecular mechanisms of such impaired Fas expression have hardly been investigated to date. In this issue, Jones et al. show that defective Fas expression is attributable to positional methylation of the Fas gene.

Histone deacetylase inhibitors and 15-deoxy-Delta12,14-prostaglandin J2 synergistically induce apoptosis

PURPOSE

The clinically relevant histone deacetylase inhibitors (HDI) valproic acid (VPA) and suberoylanilide hydroxamic acid exert variable antitumor activities but increase therapeutic efficacy when combined with other agents. The natural endogenous ligand of peroxisome proliferator-activated receptor gamma 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is a potent antineoplastic agent. Therefore, we investigated whether these HDIs in combination with 15d-PGJ(2) could show synergistic antitumor activity in colon cancer DLD-1 cells.

EXPERIMENTAL DESIGN

Cell viability was determined using a Cell Counting Kit-8 assay. Apoptosis and reactive oxygen species (ROS) generation were determined using flow cytometry analysis. Western blotting and real-time reverse transcription-PCR analysis were carried out to investigate the expression of apoptosis-related molecules. Mice bearing DLD-1 xenograft were divided into four groups (n = 5) and injected everyday (i.p.) with diluent, VPA (100 mg/kg), 15d-PGJ(2) (5 mg/kg), or a combination for 25 days.

RESULTS

HDI/15d-PGJ(2) cotreatments synergistically induced cell death through caspase-dependent apoptosis in DLD-1 cells. Moreover, HDIs/15d-PGJ(2) caused histone deacetylase inhibition, leading to subsequent ROS generation and endoplasmic reticulum stress to decrease the expression of antiapoptotic molecules Bcl-X(L) and XIAP and to increase that of proapoptotic molecules CAAT/enhancer binding protein homologous protein and death receptor 5. Additionally, VPA/15d-PGJ(2) cotreatment induced ROS-dependent apoptosis in other malignant tumor cells and was more effective than a VPA or 15d-PGJ(2) monotherapy in vivo.

CONCLUSIONS

Cotreatments with the clinically relevant HDIs and the endogenous peroxisome proliferator-activated receptor gamma ligand 15d-PGJ(2) are promising for the treatment of a broad spectrum of malignant tumors.

Total skin electron beam and non-myeloablative allogeneic hematopoietic stem-cell transplantation in advanced mycosis fungoides and Sezary syndrome

PURPOSE

Transformed mycosis fungoides (MF) and Sézary syndrome (SS) are currently incurable. We studied the safety and efficacy of total skin electron beam with allogeneic hematopoietic stem-cell transplantation (HSCT) in patients with cutaneous T-cell lymphoma (CTCL).

PATIENTS AND METHODS

Nineteen patients with advanced CTCL (median age, 50 years; four prior therapies) underwent total skin electron beam radiation followed by allogeneic HSCT between July 2001 and July 2008. Sixteen patients were conditioned with fludarabine (125 mg/m(2)) and melphalan (140 mg/m(2)) plus thymoglobulin (for mismatched donors). Graft-versus-host disease (GVHD) prophylaxis was with tacrolimus/mini methotrexate.

RESULTS

Eighteen patients experienced engraftment, and one died as a result of sepsis on day 16. Median time to recovery of absolute neutrophil count (ANC) was 12 days. Fifteen achieved full donor chimerism, 12 had acute GVHD, and 12 were treated for chronic GVHD. The overall intent-to-treat response was 68%, and the complete response rate was 58%. Four of six patients died in complete remission as a result of bacterial sepsis (n = 2), chronic GVHD and fungal infection (n = 1), or lung cancer (n = 1); only two died as a result of progressive disease. Eight experienced relapse in skin; five regained complete response with reduced immunosuppression or donor lymphocyte infusions. Eleven of 13 are currently in complete remissions, with median follow-up of 19 months (range, 1.3 to 8.3 years). Median overall survival has not been reached.

CONCLUSION

Total skin electron beam followed by allogeneic stem-cell transplantation merits additional evaluation for a selected group of patients with refractory, advanced, cutaneous T-cell lymphoma with evidence for graft-versus-tumor effect.