Vorinostat as a radiosensitizer for brain metastasis: a phase I clinical trial. J Neurooncol. 2014;118:313-319. [PMID: 24728831 DOI: 10.1007/s11060-014-1433-2]

Advances in the Delivery and Development of Epigenetic Therapeutics for the Treatment of Cancer

Gene expression at the transcriptional level is altered by epigenetic modifications such as DNA methylation, histone methylation, and acetylation, which can upregulate, downregulate, or entirely silence genes. Pathological dysregulation of epigenetic processes can result in the development of cancer, neurological problems, metabolic disorders, and cardiovascular diseases. It is of promising therapeutic interest to find medications that target these epigenetic alterations. Despite the enormous amount of work that has been done in this area, very few molecules have been approved for clinical purposes. This article provides a comprehensive review of recent advances in epigenetic therapeutics for cancer, with a specific focus on emerging delivery and development strategies. Various delivery systems, including pro-drugs, conjugated molecules, nanoparticles (NPs), and liposomes, as well as remedial strategies such as combination therapies, and epigenetic editing, are being investigated to improve the efficacy and specificity of epigenetic drugs (epi-drugs). Furthermore, the challenges associated with available epi-drugs and the limitations of their translation into clinics have been discussed. Target selection, isoform selectivity, physiochemical properties of synthesized molecules, drug screening, and scalability of epi-drugs from preclinical to clinical fields are the major shortcomings that are addressed. This Review discusses novel strategies for the identification of new biomarkers, exploration of the medicinal chemistry of epigenetic modifiers, optimization of the dosage regimen, and design of proper clinical trials that will lead to better utilization of epigenetic modifiers over conventional therapies. The integration of these approaches holds great potential for improving the efficacy and precision of epigenetic treatments, ultimately benefiting cancer patients.

Epigenetic regulation of radioresistance: insights from preclinical and clinical studies

INTRODUCTION

Oftentimes, radiation therapy (RT) is ineffective due to the development of radioresistance (RR). However, studies have shown that targeting epigenetic modifiers to enhance radiosensitivity represents a promising direction of clinical investigation.

AREAS COVERED

This review discusses the mechanisms by which epigenetic modifiers alter radiosensitivity through dysregulation of MAPK-ERK and AKT-mTOR signaling. Finally, we discuss the clinical directions for targeting epigenetic modifiers and current radiology techniques used in the clinic.

METHODOLOGY

We searched PubMed and ScienceDirect databases from April 4^th, 2022 to October 18^th, 2022. We examined 226 papers related to radioresistance, epigenetics, MAPK, and PI3K/AKT/mTOR signaling. 194 papers were selected for this review. Keywords used for this search include, 'radioresistance,' 'radiosensitivity,' 'radiation,' 'radiotherapy,' 'particle radiation,' 'photon radiation,' 'epigenetic modifiers,' 'MAPK,' 'AKT,' 'mTOR,' 'cancer,' and 'PI3K.' We examined 41 papers related to clinical trials on the aforementioned topics. Outcomes of interest were safety, overall survival (OS), dose-limiting toxicities (DLT), progression-free survival (PFS), and maximum tolerated dose (MTD).

EXPERT OPINION

Current studies focusing on epigenetic mechanisms of RR strongly support the use of targeting epigenetic modifiers as adjuvants to standard cancer therapies. To further the success of such treatments and their clinical benefit , both preclinical and clinical studies are needed to broaden the scope of known radioresistant mechanisms.

Radiosensitization to γ-Ray by Functional Inhibition of APOBEC3G

The radiosensitization of tumor cells is one of the promising approaches for enhancing radiation damage to cancer cells and limiting radiation effects on normal tissue. In this study, we performed a comprehensive screening of radiosensitization targets in human lung cancer cell line A549 using an shRNA library and identified apolipoprotein B mRNA editing enzyme catalytic subunit 3G (APOBEC3G: A3G) as a candidate target. APOBEC3G is an innate restriction factor that inhibits HIV-1 infection as a cytidine deaminase. APOBEC3G knockdown with siRNA showed an increased radiosensitivity in several cancer cell lines, including pancreatic cancer MIAPaCa2 cells and lung cancer A549 cells. Cell cycle analysis revealed that APOBEC3G knockdown increased S-phase arrest in MIAPaCa2 and G2/M arrest in A549 cells after γ-irradiation. DNA double-strand break marker γH2AX level was increased in APOBEC3G-knocked-down MIAPaCa2 cells after γ-irradiation. Using a xenograft model of A549 in mice, enhanced radiosensitivity by a combination of X-ray irradiation and APOBEC3G knockdown was observed. These results suggest that the functional inhibition of APOBEC3G sensitizes cancer cells to radiation by attenuating the activation of the DNA repair pathway, suggesting that APOBEC3G could be useful as a target for the radiosensitization of cancer therapy.

Randomized Phase II Trial of MIBG Versus MIBG, Vincristine, and Irinotecan Versus MIBG and Vorinostat for Patients With Relapsed or Refractory Neuroblastoma: A Report From NANT Consortium

PURPOSE

131I-metaiodobenzylguanidine (MIBG) is an active radiotherapeutic for neuroblastoma. The primary aim of this trial was to identify which of three MIBG regimens was likely associated with the highest true response rate.

PATIENTS AND METHODS

Patients 1-30 years were eligible if they had relapsed or refractory neuroblastoma, at least one MIBG-avid site, and adequate autologous stem cells. Patients received MIBG 18 mCi/kg on day 1 and autologous stem cell on day 15. Patients randomly assigned to arm A received only MIBG; patients randomly assigned to arm B received intravenous vincristine on day 0 and irinotecan daily on days 0-4; patients randomly assigned to arm C received vorinostat (180 mg/m2/dose) orally once daily on days 1 to 12. The primary end point was response after one course by New Approaches to Neuroblastoma Therapy criteria. The trial was designed with 105 patients to ensure an 80% chance that the arm with highest response rate was selected.

RESULTS

One hundred fourteen patients were enrolled, with three ineligible and six unevaluable, leaving 105 eligible and evaluable patients (36 in arm A, 35 in arm B, and 34 in arm C; 55 boys; and median age 6.5 years). After one course, the response rates (partial response or better) on arms A, B, and C were 14% (95% CI, 5 to 30), 14% (5 to 31), and 32% (18 to 51). An additional five, five, and four patients met New Approaches to Neuroblastoma Therapy Minor Response criteria on arms A, B, and C, respectively. On arms A, B, and C, rates of any grade 3+ nonhematologic toxicity after first course were 19%, 49%, and 35%.

CONCLUSION

Vorinostat and MIBG is likely the arm with the highest true response rate, with manageable toxicity. Vincristine and irinotecan do not appear to improve the response rate to MIBG and are associated with increased toxicity.

Non-Hydroxamate Zinc-Binding Groups as Warheads for Histone Deacetylases

Histone deacetylases (HDACs) remove acetyl groups from acetylated lysine residues and have a large variety of substrates and interaction partners. Therefore, it is not surprising that HDACs are involved in many diseases. Most inhibitors of zinc-dependent HDACs (HDACis) including approved drugs contain a hydroxamate as a zinc-binding group (ZBG), which is by far the biggest contributor to affinity, while chemical variation of the residual molecule is exploited to create more or less selectivity against HDAC isozymes or other metalloproteins. Hydroxamates have a propensity for nonspecificity and have recently come under considerable suspicion because of potential mutagenicity. Therefore, there are significant concerns when applying hydroxamate-containing compounds as therapeutics in chronic diseases beyond oncology due to unwanted toxic side effects. In the last years, several alternative ZBGs have been developed, which can replace the critical hydroxamate group in HDACis, while preserving high potency. Moreover, these compounds can be developed into highly selective inhibitors. This review aims at providing an overview of the progress in the field of non-hydroxamic HDACis in the time period from 2015 to present. Formally, ZBGs are clustered according to their binding mode and structural similarity to provide qualitative assessments and predictions based on available structural information.

Epigenetic mechanisms underlying prostate cancer radioresistance

Radiotherapy (RT) is one of the mainstay treatments for prostate cancer (PCa), a highly prevalent neoplasm among males worldwide. About 30% of newly diagnosed PCa patients receive RT with a curative intent. However, biochemical relapse occurs in 20–40% of advanced PCa treated with RT either alone or in combination with adjuvant-hormonal therapy. Epigenetic alterations, frequently associated with molecular variations in PCa, contribute to the acquisition of a radioresistant phenotype. Increased DNA damage repair and cell cycle deregulation decreases radio-response in PCa patients. Moreover, the interplay between epigenome and cell growth pathways is extensively described in published literature. Importantly, as the clinical pattern of PCa ranges from an indolent tumor to an aggressive disease, discovering specific targetable epigenetic molecules able to overcome and predict PCa radioresistance is urgently needed. Currently, histone-deacetylase and DNA-methyltransferase inhibitors are the most studied classes of chromatin-modifying drugs (so-called ‘epidrugs’) within cancer radiosensitization context. Nonetheless, the lack of reliable validation trials is a foremost drawback. This review summarizes the major epigenetically induced changes in radioresistant-like PCa cells and describes recently reported targeted epigenetic therapies in pre-clinical and clinical settings.

Anticancer Therapy with HDAC Inhibitors: Mechanism-Based Combination Strategies and Future Perspectives

The increasing knowledge of molecular drivers of tumorigenesis has fueled targeted cancer therapies based on specific inhibitors. Beyond "classic" oncogene inhibitors, epigenetic therapy is an emerging field. Epigenetic alterations can occur at any time during cancer progression, altering the structure of the chromatin, the accessibility for transcription factors and thus the transcription of genes. They rely on post-translational histone modifications, particularly the acetylation of histone lysine residues, and are determined by the inverse action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Importantly, HDACs are often aberrantly overexpressed, predominantly leading to the transcriptional repression of tumor suppressor genes. Thus, histone deacetylase inhibitors (HDACis) are powerful drugs, with some already approved for certain hematological cancers. Albeit HDACis show activity in solid tumors as well, further refinement and the development of novel drugs are needed. This review describes the capability of HDACis to influence various pathways and, based on this knowledge, gives a comprehensive overview of various preclinical and clinical studies on solid tumors. A particular focus is placed on strategies for achieving higher efficacy by combination therapies, including phosphoinositide 3-kinase (PI3K)-EGFR inhibitors and hormone- or immunotherapy. This also includes new bifunctional inhibitors as well as novel approaches for HDAC degradation via PROteolysis-TArgeting Chimeras (PROTACs).

Recent Progress in Histone Deacetylase Inhibitors as Anticancer Agents

Histone Deacetylase (HDAC) inhibitors are a relatively new class of anti-cancer agents that play important roles in epigenetic or non-epigenetic regulation, inducing death, apoptosis, and cell cycle arrest in cancer cells. Recently, their use has been clinically validated in cancer patients resulting in the approval by the FDA of four HDAC inhibitors, vorinostat, romidepsin, belinostat and panobinostat, used for the treatment of cutaneous/peripheral T-cell lymphoma and multiple myeloma. Many more HDAC inhibitors are at different stages of clinical development for the treatment of hematological malignancies as well as solid tumors. Also, clinical trials of several HDAC inhibitors for use as anti-cancer drugs (alone or in combination with other anti-cancer therapeutics) are ongoing. In the intensifying efforts to discover new, hopefully, more therapeutically efficacious HDAC inhibitors, molecular modelingbased rational drug design has played an important role. In this review, we summarize four major structural classes of HDAC inhibitors (hydroxamic acid derivatives, aminobenzamide, cyclic peptide and short-chain fatty acids) that are in clinical trials and different computer modeling tools available for their structural modifications as a guide to discover additional HDAC inhibitors with greater therapeutic utility.

The impact of tumour pH on cancer progression: strategies for clinical intervention

Dysregulation of cellular pH is frequent in solid tumours and provides potential opportunities for therapeutic intervention. The acidic microenvironment within a tumour can promote migration, invasion and metastasis of cancer cells through a variety of mechanisms. Pathways associated with the control of intracellular pH that are under consideration for intervention include carbonic anhydrase IX, the monocarboxylate transporters (MCT, MCT1 and MCT4), the vacuolar-type H⁺-ATPase proton pump, and the sodium-hydrogen exchanger 1. This review will describe progress in the development of inhibitors to these targets.

Enhancing the Efficacy of Melanocortin 1 Receptor-Targeted Radiotherapy by Pharmacologically Upregulating the Receptor in Metastatic Melanoma

Melanocortin 1 receptor (MC1R) is under investigation as a target for drug delivery for metastatic melanoma therapy and imaging. The purpose of this study was to determine the potential of using BRAF inhibitors (BRAF_i) and histone deacetylase inhibitors (HDAC_i) to enhance the delivery of MC1R-targeted radiolabeled peptide ([²¹²Pb]DOTA-MC1L) by pharmacologically upregulating the MC1R expression in metastatic melanoma cells and tumors. MC1R expression was analyzed in de-identified melanoma biopsies by immunohistochemical staining. Upregulation of MC1R expression was determined in BRAF^V600E cells (A2058) and BRAF wild-type melanoma cells (MEWO) by quantitative real-time polymerase chain reaction, flow cytometry, and receptor-ligand binding assays. The role of microphthalmia-associated transcription factor (MITF) in the upregulation of MC1R was also examined in A2058 and MEWO cells. The effectiveness of [²¹²Pb]DOTA-MC1L α-particle radiotherapy in combination with BRAF_i and/or HDAC_i was determined in athymic nu/nu mice bearing A2058 and MEWO human melanoma xenografts. High expression of MC1R was observed in situ in clinical melanoma biopsies. BRAF_i and HDAC_i significantly increased the MC1R expression (up to 10-fold in mRNA and 4-fold in protein levels) via MITF-dependent pathways, and this increase led to enhanced ligand binding on the cell surface. Inhibition of MITF expression antagonized the upregulation of MC1R in both BRAF^V600E and BRAF^WT cells. Combining [²¹²Pb]DOTA-MC1L with BRAF_i and/or HDAC_i improved the tumor response by increasing the delivery of ²¹²Pb α-particle emissions to melanoma tumors via augmented MC1R expression. These data suggest that FDA-approved HDAC_i and BRAF_i could improve the effectiveness of MC1R-targeted therapies by enhancing drug delivery via upregulated MC1R.

Combining precision radiotherapy with molecular targeting and immunomodulatory agents: a guideline by the American Society for Radiation Oncology

The practice of radiation oncology is primarily based on precise technical delivery of highly conformal, image-guided external beam radiotherapy or brachytherapy. However, systematic research efforts are being made to facilitate individualised radiation dose prescriptions on the basis of gene-expressssion profiles that reflect the radiosensitivity of tumour and normal tissue. This advance in precision radiotherapy should complement those benefits made in precision cancer medicine that use molecularly targeted agents and immunotherapies. The personalisation of cancer therapy, predicated largely on genomic interrogation, is facilitating the selection of therapies that are directed against driver mutations, aberrant cell signalling, tumour microenvironments, and genetic susceptibilities. With the increasing technical power of radiotherapy to safely increase local tumour control for many solid tumours, it is an opportune time to rigorously explore the potential benefits of combining radiotherapy with molecular targeted agents and immunotherapies to increase cancer survival outcomes. This theme provides the basis and foundation for this American Society for Radiation Oncology guideline on combining radiotherapy with molecular targeting and immunotherapy agents.

Histone deacetylase 8 (HDAC8) and its inhibitors with selectivity to other isoforms: An overview

The histone deacetylases (HDACs) enzymes provided crucial role in transcriptional regulation of cells through deacetylation of nuclear histone proteins. Discoveries related to the HDAC8 enzyme activity signified the importance of HDAC8 isoform in cell proliferation, tumorigenesis, cancer, neuronal disorders, parasitic/viral infections and other epigenetic regulations. The pan-HDAC inhibitors can confront these conditions but have chances to affect epigenetic functions of other HDAC isoforms. Designing of selective HDAC8 inhibitors is a key feature to combat the pathophysiological and diseased conditions involving the HDAC8 activity. This review is concerned about the structural and positional aspects of HDAC8 in the HDAC family. It also covers the contributions of HDAC8 in the pathophysiological conditions, a preliminary discussion about the recent scenario of HDAC8 inhibitors. This review might help to deliver the structural, functional and computational information in order to identify and design potent and selective HDAC8 inhibitors for target specific treatment of diseases involving HDAC8 enzymatic activity.

Epigenetic Therapeutics and Their Impact in Immunotherapy of Lung Cancer

Lung cancer is the leading cause of cancer-related death in the United States and worldwide. Novel therapeutic developments are critically necessary to improve outcomes for this disease. Aberrant epigenetic change plays an important role in lung cancer development and progression. Therefore, drugs targeting the epigenome are being investigated in the treatment of lung cancer. Monotherapy of epigenetic therapeutics such as DNA methyltransferase inhibitors (DNMTi) and histone deacetylase inhibitors (HDACi) have so far not shown any apparent benefit while one of the clinical trials with the combinations of DNMTi and HDACi showed a small positive signal for treating lung cancer. Combinations of DNMTi and HDACi with chemotherapies have some efficacy but are often limited by increased toxicities. Preclinical data and clinical trial results suggest that combining epigenetic therapeutics with targeted therapies might potentially improve outcomes in lung cancer patients. Furthermore, several clinical studies suggest that the HDACi vorinostat could be used as a radiosensitizer in lung cancer patients receiving radiation therapy. Immune checkpoint blockade therapies are revolutionizing lung cancer management. However, only a minority of lung cancer patients experience long-lasting benefits from immunotherapy. The role of epigenetic reprogramming in boosting the effects of immunotherapy is an area of active investigation. Preclinical studies and early clinical trial results support this approach which may improve lung cancer treatment, with potentially prolonged survival and tolerable toxicity. In this review, we discuss the current status of epigenetic therapeutics and their combination with other antineoplastic therapies, including novel immunotherapies, in lung cancer management.

肿瘤表观遗传学治疗研究进展

表观遗传学沉默几乎是人类恶性肿瘤的普遍特征, 其影响涉及从肿瘤起始到进展的所有关键信号通路, 靶向表观遗传学异常具有巨大潜力. 近年来, 表观遗传学治疗药物DNA甲基转移酶抑制剂与组蛋白去乙酰化酶抑制剂单独或与其他治疗相结合, 在一些血源性肿瘤及实体瘤中获得了突出的疗效, 正在实现从实验室到临床的快速转化. 本文就表观遗传学治疗药物单独及与其他治疗相结合在肿瘤基础与临床研究中的相关进展作一综述, 以便发现并确定进一步的研究方向, 加速其向肿瘤临床的转化.

HDACs and HDAC Inhibitors in Cancer Development and Therapy

Over the last several decades, it has become clear that epigenetic abnormalities may be one of the hallmarks of cancer. Posttranslational modifications of histones, for example, may play a crucial role in cancer development and progression by modulating gene transcription, chromatin remodeling, and nuclear architecture. Histone acetylation, a well-studied posttranslational histone modification, is controlled by the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). By removing acetyl groups, HDACs reverse chromatin acetylation and alter transcription of oncogenes and tumor suppressor genes. In addition, HDACs deacetylate numerous nonhistone cellular substrates that govern a wide array of biological processes including cancer initiation and progression. This review will discuss the role of HDACs in cancer and the therapeutic potential of HDAC inhibitors (HDACi) as emerging drugs in cancer treatment.

Inhibition of SRC-3 enhances sensitivity of human cancer cells to histone deacetylase inhibitors

SRC-3 is widely expressed in multiple tumor types and involved in cancer cell proliferation and apoptosis. Histone deacetylase (HDAC) inhibitors are promising antitumor drugs. However, the poor efficacy of HDAC inhibitors in solid tumors has restricted its further clinical application. Here, we reported the novel finding that depletion of SRC-3 enhanced sensitivity of breast and lung cancer cells to HDAC inhibitors (SAHA and romidepsin). In contrast, overexpression of SRC-3 decreased SAHA-induced cancer cell apoptosis. Furthermore, we found that SRC-3 inhibitor bufalin increased cancer cell apoptosis induced by HDAC inhibitors. The combination of bufalin and SAHA was particular efficient in attenuating AKT activation and reducing Bcl-2 levels. Taken together, these accumulating data might guide development of new breast and lung cancer therapies.

Radiotherapy for Hepatocellular Carcinoma: New Indications and Directions for Future Study

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide; its incidence is increasing in the United States. Depending on disease extent and underlying liver status, patients may be treated with local, locoregional, and/or systemic therapy. Recent data indicates that radiotherapy (RT) can play a meaningful role in the management of HCC. Here, we review published experiences using RT for HCC, including the use of radiosensitizers and stereotactic RT. We discuss methods for performing preclinical studies of RT for HCC and biomarkers of response. As a part of the HCC Working Group, an informal committee of the National Cancer Institute's Radiation Research Program, we suggest how RT should be implemented in the management of HCC and identify future directions for the study of RT in HCC.

Cellular Pathways in Response to Ionizing Radiation and Their Targetability for Tumor Radiosensitization

During the last few decades, improvements in the planning and application of radiotherapy in combination with surgery and chemotherapy resulted in increased survival rates of tumor patients. However, the success of radiotherapy is impaired by two reasons: firstly, the radioresistance of tumor cells and, secondly, the radiation-induced damage of normal tissue cells located in the field of ionizing radiation. These limitations demand the development of drugs for either radiosensitization of tumor cells or radioprotection of normal tissue cells. In order to identify potential targets, a detailed understanding of the cellular pathways involved in radiation response is an absolute requirement. This review describes the most important pathways of radioresponse and several key target proteins for radiosensitization.

Mining the epigenetic landscape of tissue polarity in search of new targets for cancer therapy

The epigenetic nature of cancer encourages the development of inhibitors of epigenetic pathways. Yet, the clinical use for solid tumors of approved epigenetic drugs is meager. We argue that this situation might improve upon understanding the coinfluence between epigenetic pathways and tissue architecture. We present emerging information on the epigenetic control of the polarity axis, a central feature of epithelial architecture created by the orderly distribution of multiprotein complexes at cell-cell and cell-extracellular matrix contacts and altered upon cancer onset (with apical polarity loss), invasive progression (with basolateral polarity loss) and metastatic development (with basoapical polarity imbalance). This information combined with the impact of polarity-related proteins on epigenetic mechanisms of cancer enables us to envision how to guide the choice of drugs specific for distinct epigenetic modifiers, in order to halt cancer development and counter the consequences of polarity alterations.

Epigenetic therapy for solid tumors: from bench science to clinical trials

The cancer epigenome is characterized by global DNA methylation and chromatin changes, such as the hypermethylation of specific CpG island promoters. Epigenetic agents like DNA methyltransferase or histone deacetylase inhibitors induce phenotype changes by reactivation of epigenetically silenced tumor suppressor genes. Despite initial promise in hematologic malignancies, epigenetic agents have not shown significant efficacy as monotherapy against solid tumors. Recent trials showed that epigenetic agents exert favorable modifier effects when combined with chemotherapy, hormonal therapy, or other epigenetic agents. Due to the novel nature of their mechanism, it is important to reconsider the optimal patient selection, drug regimen, study design, and outcome measures when pursuing future trials in order to discover the full potential of this new therapeutic modality.

Histone deacetylase inhibitors in clinical studies as templates for new anticancer agents

Histone dacetylases (HDACs) are a group of enzymes that remove acetyl groups from histones and regulate expression of tumor suppressor genes. They are implicated in many human diseases, especially cancer, making them a promising therapeutic target for treatment of the latter by developing a wide variety of inhibitors. HDAC inhibitors interfere with HDAC activity and regulate biological events, such as cell cycle, differentiation and apoptosis in cancer cells. As a result, HDAC inhibitor-based therapies have gained much attention for cancer treatment. To date, the FDA has approved three HDAC inhibitors for cutaneous/peripheral T-cell lymphoma and many more HDAC inhibitors are in different stages of clinical development for the treatment of hematological malignancies as well as solid tumors. In the intensifying efforts to discover new, hopefully more therapeutically efficacious HDAC inhibitors, molecular modeling-based rational drug design has played an important role in identifying potential inhibitors that vary in molecular structures and properties. In this review, we summarize four major structural classes of HDAC inhibitors that are in clinical trials and different computer modeling tools available for their structural modifications as a guide to discover additional HDAC inhibitors with greater therapeutic utility.

Phase I Study of Vorinostat as a Radiation Sensitizer with 131I-Metaiodobenzylguanidine (131I-MIBG) for Patients with Relapsed or Refractory Neuroblastoma

PURPOSE

(131)I-metaiodobenzylguanidine (MIBG) is a radiopharmaceutical with activity in neuroblastoma. Vorinostat is a histone deacetylase inhibitor that has radiosensitizing properties. The goal of this phase I study was to determine the MTDs of vorinostat and MIBG in combination.

EXPERIMENTAL DESIGN

Patients ≤ 30 years with relapsed/refractory MIBG-avid neuroblastoma were eligible. Patients received oral vorinostat (dose levels 180 and 230 mg/m(2)) daily days 1 to 14. MIBG (dose levels 8, 12, 15, and 18 mCi/kg) was given on day 3 and peripheral blood stem cells on day 17. Alternating dose escalation of vorinostat and MIBG was performed using a 3+3 design.

RESULTS

Twenty-seven patients enrolled to six dose levels, with 23 evaluable for dose escalation. No dose-limiting toxicities (DLT) were seen in the first three dose levels. At dose level 4 (15 mCi/kg MIBG/230 mg/m(2) vorinostat), 1 of 6 patients had DLT with grade 4 hypokalemia. At dose level 5 (18 mCi/kg MIBG/230 mg/m(2) vorinostat), 2 patients had dose-limiting bleeding (one grade 3 and one grade 5). At dose level 5a (18 mCi/kg MIBG/180 mg/m(2) vorinostat), 0 of 6 patients had DLT. The most common toxicities were neutropenia and thrombocytopenia. The response rate was 12% across all dose levels and 17% at dose level 5a. Histone acetylation increased from baseline in peripheral blood mononuclear cells collected on days 3 and 12 to 14.

CONCLUSIONS

Vorinostat at 180 mg/m(2)/dose is tolerable with 18 mCi/kg MIBG. A phase II trial comparing this regimen to single-agent MIBG is ongoing.

A Phase I Study of CUDC-101, a Multitarget Inhibitor of HDACs, EGFR, and HER2, in Combination with Chemoradiation in Patients with Head and Neck Squamous Cell Carcinoma

PURPOSE

CUDC-101 is a small molecule that simultaneously inhibits the epidermal growth factor receptor (EGFR), human growth factor receptor 2 (HER2), and histone deacetylase (HDAC) with preclinical activity in head and neck squamous cell cancer (HNSCC). The primary objective of this investigation is to determine the maximum tolerated dose (MTD) of CUDC-101 with cisplatin-radiotherapy in the treatment of HNSCC.

EXPERIMENTAL DESIGN

CUDC-101 monotherapy was administered intravenously three times weekly (Monday, Wednesday, Friday) for a one-week run-in, then continued with concurrent cisplatin (100 mg/m(2) every 3 weeks) and external beam radiation (70 Gy to gross disease) over 7 weeks.

RESULTS

Twelve patients with intermediate or high-risk HNSCC enrolled. Eleven were p16INKa (p16)-negative. The MTD of CUDC-101-based combination therapy was established at 275 mg/m(2)/dose. Five patients discontinued CUDC-101 due to an adverse event (AE); only one was considered a dose-limiting toxicity (DLT), at the MTD. Pharmacokinetic evaluation suggested low accumulation with this dosing regimen. HDAC inhibition was demonstrated by pharmacodynamic analyses in peripheral blood mononuclear cells (PBMC), tumor biopsies, and paired skin biopsies. Paired tumor biopsies demonstrated a trend of EGFR inhibition. At 1.5 years of median follow-up, there has been one recurrence and two patient deaths (neither attributed to CUDC-101). The remaining nine patients are free of progression.

CONCLUSIONS

CUDC-101, cisplatin, and radiation were feasible in intermediate-/high-risk patients with HNSCC, with no unexpected patterns of AE. Although the MTD was identified, a high rate of DLT-independent discontinuation of CUDC-101 suggests a need for alternate schedules or routes of administration.