Approaches to optimal dosing of hexamethylene bisacetamide

HMBA ameliorates obesity by MYH9- and ACTG1-dependent regulation of hypothalamic neuropeptides

The global epidemic of obesity remains a daunting problem. Here, we report hexamethylene bisacetamide (HMBA) as a potent anti-obesity compound. Peripheral and central administration of HMBA to diet-induced obese mice regulated the expression of hypothalamic neuropeptides critical for energy balance, leading to beneficial metabolic effects such as anorexia and weight loss. We found that HMBA bound to MYH9 and ACTG1, which were required for the anti-obesity effects of HMBA in both NPY-expressing and POMC-expressing neurons. The binding of HMBA to MYH9 and ACTG1 elevated the expression of HEXIM1 and enhanced its interaction with MDM2, resulting in the dissociation of the HEXIM1-p53 complex in hypothalamic cells. Subsequently, the free HEXIM1 and p53 translocated to the nucleus, where they downregulated the transcription of orexigenic NPY, but p53 and acetylated histone 3 upregulated that of anorexigenic POMC. Our study points to a previously unappreciated efficacy of HMBA and reveals its mechanism of action in metabolic regulation, which may propose HMBA as a potential therapeutic strategy for obesity.

HMBA is a putative HSP70 activator stimulating HEXIM1 expression that is down-regulated by estrogen

Hexamethylene bis-acetamide inducible protein 1 (HEXIM1) is identified as a novel inhibitor of estrogen stimulated breast cell growth, and it suppresses estrogen receptor-α transcriptional activity. HEXIM1 protein level has been found to be downregulated by estrogens. Recently, HEXIM1 has been found to inhibit androgen receptor transcriptional activity as well. Researchers have used Hexamethylene bis-acetamide (HMBA) for decades to stimulate HEXIM1 expression, which also inhibit estrogen stimulated breast cancer cell gene activation and androgen stimulated prostate cancer gene activation. However, the direct molecular targets of HMBA that modulate the induction of HEXIM1 expression in mammalian cells have not been identified. Based on HMBA and its more potent analog 4a1, we designed molecular probes to pull down the binding proteins of these compounds. Via proteomic approach and biological assays, we demonstrate that HMBA and 4a1 are actually heat shock protein 70 (HSP70) binders. The known HSP70 activator showed similar activity as HMBA and 4a1 to induce HEXIM1 expression, suggesting that HMBA and 4a1 might be putative HSP70 activators. Molecular target identification of HMBA and 4a1 could lead to further structural optimization of the parental compound to generate more potent derivatives to stimulate HEXIM1 expression, which could be a novel approach for hormone dependent breast cancer and prostate cancer treatment.

Cancer Differentiating Agent Hexamethylene Bisacetamide Inhibits BET Bromodomain Proteins

Agents that trigger cell differentiation are highly efficacious in treating certain cancers, but such approaches are not generally effective in most malignancies. Compounds such as DMSO and hexamethylene bisacetamide (HMBA) have been used to induce differentiation in experimental systems, but their mechanisms of action and potential range of uses on that basis have not been developed. Here, we show that HMBA, a compound first tested in the oncology clinic over 25 years ago, acts as a selective bromodomain inhibitor. Biochemical and structural studies revealed an affinity of HMBA for the second bromodomain of BET proteins. Accordingly, both HMBA and the prototype BET inhibitor JQ1 induced differentiation of mouse erythroleukemia cells. As expected of a BET inhibitor, HMBA displaced BET proteins from chromatin, caused massive transcriptional changes, and triggered cell-cycle arrest and apoptosis in Myc-induced B-cell lymphoma cells. Furthermore, HMBA exerted anticancer effects in vivo in mouse models of Myc-driven B-cell lymphoma. This study illuminates the function of an early anticancer agent and suggests an intersection with ongoing clinical trials of BET inhibitor, with several implications for predicting patient selection and response rates to this therapy and starting points for generating BD2-selective BET inhibitors. Cancer Res; 76(8); 2376-83. ©2016 AACR.

Amide exchange reaction: a simple and efficient CuO catalyst for diacetamide synthesis

Synthesis of hexamethylenebisacetamide (HMBA) from hexamethylenediamine (HDA), CH₃CN and H₂O catalyzed by CuO without an organic solvent and gas protection.

Lead optimization of HMBA to develop potent HEXIM1 inducers

The potency of a series of Hexamethylene bis-acetamide (HMBA) derivatives inducing Hexamethylene bis-acetamide inducible protein 1 (HEXIM1) was determined in LNCaP prostate cancer cells. Several compounds with unsymmetrical structures showed significantly improved activity. Distinct from HMBA, these analogs have increased hydrophobicity and can improve the short half-life of HMBA, which is one of the factors that have limited the application of HMBA in clinics. The unsymmetrical scaffolds of the new analogs provide the basis for further lead optimization of the compounds using combinatorial chemistry strategy.

Enhancement of baicalin by hexamethylene bisacetamide on the induction of apoptosis contributes to simultaneous activation of the intrinsic and extrinsic apoptotic pathways in human leukemia cells

Hexamethylene bisacetamide (HMBA) and natural flavanoid baicalin both exert potent antileukemic activity. However, there is currently no data on the anti-leukemic effects of baicalin in combination with HMBA. In the present study, we demonstrated that the combination of baicalin and HMBA synergistically inhibited the proliferation of acute myeloid leukemia (AML) cell lines. In addition, a slight G0/G1 phase arrest and significant apoptosis were observed. The combination treatment triggered apoptosis through the intrinsic pathway, which involved loss of MMP, decreased Bcl‑2/Bax ratio and Bcl‑XL/Bax ratio, caspase‑9 activation, as well as through the extrinsic pathway mediated by Fas and caspase‑8 activation. On the other hand, combination of baicalin and HMBA showed little toxic effect on peripheral blood mononuclear cells from healthy volunteers. Our results raise the possibility that the novel combination of baicalin and HMBA may be a promising regimen for the treatment of AML.

Model-based neutrophil-guided dose adaptation in chemotherapy: evaluation of predicted outcome with different types and amounts of information

One of the most employed approaches to reduce severe neutropenia following anticancer drug regimens is to reduce the consecutive dose in fixed steps, commonly by 25%. Another approach has been to use pharmacokinetic (PK) sampling to tailor dosing, but only rarely have model-based computer approaches utilizing collected PK and/or pharmacodynamic (PD) data been used. A semi-mechanistic model for myelosuppression that can characterize the interindividual and interoccasion variability in the time-course of neutrophils following administration of a wide range of anticancer drugs may be used in a clinical setting for model-based dose individualization. The aim of this study was to compare current stepwise procedures to model-based dose adaptation by simulations, and investigate if the overall dose intensity in the population could be increased without increasing the risk of severe toxicity. The value of various amounts of PK- and/or PD-information was compared to standard dosing strategies using a maximum a posteriori procedure in NONMEM. The results showed that when information on neutrophil counts was available, the additional improvement from PK sampling was negligible. Using neutrophil sampling at baseline and an observation near the predicted nadir increased the number of patients in the target range by 27% in comparison with a one-sided 25% dose adjustment schedule, while keeping the number of patients experiencing severe toxicity at a comparable low level after five courses of treatment. High interindividual variability did not limit the benefit of model-based dose adaptation, whereas high interoccasion variability was predicted to make any dose adaptation method less successful. This study indicates that for successful model-based dose adaptation clinically, there is no need for drug concentration sampling, and that one extra neutrophil measurement in addition to the pre-treatment value is sufficient to limit severe neutropenia while increasing dose intensity.

Individualised Cancer Chemotherapy: Strategies and Performance of Prospective Studies on Therapeutic Drug Monitoring with Dose Adaptation

Therapeutic drug monitoring (TDM) is increasingly used in clinical practice for the optimisation of drug treatment. Although pharmacokinetic variability is an established factor involved in the variation of therapeutic outcome of many chemotherapeutic agents, the use of TDM in the field of oncology has been limited thus far. An important reason for this is that a therapeutic index for most anticancer agents has not been established; however, in the last 20 years, relationships between plasma drug concentrations and clinical outcome have been defined for various chemotherapeutic agents. Several attempts have been made to use these relationships for optimising the administration of chemotherapeutics by applying pharmacokinetically guided dosage. These prospective studies, individualising chemotherapy dose during therapy based on measured drug concentrations, are discussed in this review. We focus on the way a target value is defined, the methodologies used for dose adaptation and the way the performance of the dose-adaptation approach is evaluated. Furthermore, attention is paid to the results of the studies and the applicability of the strategies in clinical practice. It can be concluded that TDM may contribute to improving cancer chemotherapy in terms of patient outcome and survival and should therefore be further investigated.

HMBA induces cell death and potentiates doxorubicin toxicity in malignant mesothelioma cells

PURPOSE

Malignant pleural mesothelioma(MM), a rare tumor characterized by high local invasiveness and low metastatic efficiency, is poorly responsive to current therapeutic approaches. The aim of the present study was to evaluate the cytotoxic efficacy of the hybrid polar compound hexamethylene bisacetamide(HMBA), either as a single agent or in combination with the anthracycline doxorubicin (DOX), against MM cells.

METHODS

The MM cell lines MM-B1 and MM-El were treated with HMBA, DOX or with combinations of the two drugs. Cell survival and death were assessed by the MTS assay and trypan blue staining/TUNEL, respectively. The interactions between drugs were evaluated by the method of Kern et al. Western blot analysis was used to investigate the expression of Bcl-2 family proteins.

RESULTS

When administered alone, HMBA dose-dependently decreased the number of viable cells and increased the death rate of MM-B1 and MM-E1 cultures. Combinations of HMBA and DOX achieved a synergistic inhibition of MM cell survival, and the simultaneous administration of HMBA counteracted the resistance induced by DOX in MM-El cells. HMBA,used at cytostatic concentrations, reduced the ratio be-tween antiapoptotic (Bcl-2, Bcl-XL) and proapoptotic(Bax) members of the Bcl-2 family of proteins, thus lowering the threshold for MM cell death commitment.

CONCLUSIONS

HMBA has therapeutic potential in MM both as a single agent and through potentiation of DOX toxicity. These results support future investigations on the feasibility of intrapleural chemotherapy with this hybrid polar compound.

The relevance of therapeutic drug monitoring in plasma and erythrocytes in anti-cancer drug treatment

Therapeutic drug monitoring generally focuses on the plasma compartment only. Differentiation between the total plasma concentration and the free fraction (plasma water) has been described for a number of limited drugs. Besides the plasma compartment, blood has also a cellular fraction which has by far the largest theoretical surface and volume for drug transport. It is with anti-cancer drugs that major progress has been made in the study of partition between the largest cellular blood compartment, i.e., erythrocytes, and the plasma compartment. The aim of the present review is to detail the progress made in predicting what a drug does in the body, i.e., pharmacodynamics including toxicity and plasma and/or red blood cell concentration monitoring. Furthermore, techniques generally used in anti-cancer drug monitoring are highlighted. Data for complex Bayesian statistical approaches and population kinetics studies are beyond the scope of this review, since this is generally limited to the plasma compartment only.

Pharmacokinetically guided administration of chemotherapeutic agents

The current practice for the dose calculation of most anticancer agents is based on body surface area in m2, although lower interpatient variation in pharmacokinetic parameters has been reported with pharmacokinetically guided administration. As chemotherapeutic agents have a narrow therapeutic window, pharmacokinetically guided administration may lead to less toxicity and higher efficacy than administration on the basis of body surface area. Pharmacokinetically guided administration, using parameters such as area under the plasma concentration-time curve (AUC), steady-state plasma drug concentration and drug exposure time above a certain plasma concentration, has been studied for many antineoplastic agents. Assessment of pharmacokinetic profiles allows the characterisation of relationships between pharmacokinetic parameters and efficacy and toxicity. AUC appears to be more closely correlated with pharmacodynamics than does the dose per unit of body surface area. In particular, the AUC-guided administration of carboplatin has been extensively studied, based on the close relationship between the renal clearance of the drug and glomerular filtration rate. Several formulae and limited sampling models have been derived to predict the AUC of carboplatin. The relationship between AUC and pharmacodynamics has also been studied for other anticancer agents, for example fluorouracil, topotecan, etoposide, cisplatin and busulfan, but all less extensively than for carboplatin. The pharmacokinetically guided administration of these agents needs to be investigated further before the use of alternative administration formulae can become standard clinical practice. Prospective studies of pharmacokinetically guided versus surface area-based administration should be performed to validate pharmacokinetic-pharmacodynamic relationships and to facilitate optimal dosage of anticancer agents in the clinic.

Key role of the cyclin-dependent kinase inhibitor p27kip1 for embryonal carcinoma cell survival and differentiation

Hexamethylen-bisacetamide (HMBA) represents the prototype of a group of hybrid polar compounds, which induce differentiation in a variety of transformed cells including human embryonal carcinoma cells. Therefore, HMBA has been used in the differentiation therapy of cancer for patients with both hematological and solid malignancies. Upon HMBA treatment, the embryonal carcinoma cell line NTERA-2 clone D1 (NT2/D1) accumulates in G1 and undergoes terminal differentiation. Here we demonstrate that growth arrest and differentiation of NT2/D1 cells induced by HMBA involve increased expression of the cyclin-dependent kinase inhibitor p27, enhanced association of p27 with cyclin E/CDK2 complexes and suppression of kinase activity associated to cyclin E/CDK2 (but not to cyclin D3/CDK4). When HMBA differentiation was induced in the presence of p27 antisense oligonucleotides, NT2/D1 cells failed to arrest growth properly and, in parallel with the reduction of the anti-apoptotic Bcl-2 gene expression, cells underwent massive programmed cell death. Conversely, constitutive expression of p27 into NT2/D1 cells induced a marked reduction in the growth potential of these cells and partially reproduced HMBA-induced modification of surface antigen expression (down-regulation of SSEA-3 expression and up-regulation of VINIS-53 expression). Expression of p21 induced growth arrest but not differentiation. Likewise, inhibition of CDK2 by transfection of a dominant negative CDK2 in NT2/D1 cells or treatment with the kinase inhibitor olomucine induced growth arrest but not differentiation. Therefore, we propose that p27 represents a crucial molecule in HMBA signaling that cannot be replaced by p21. Furthermore, the results obtained with CDK2 inhibitors demonstrate that the block of CDK2 activity is sufficient for growth arrest but not for cell differentiation and suggest that, at least in these cells, growth arrest and differentiation are regulated by two overlapping but different pathways.

Simultaneous measurement of the cell-differentiating agent hexamethylene bisacetamide and its metabolites by gas chromatography

Hexamethylene bisacetamide (HMBA) is a potent in vitro differentiating agent that has clinical potential as an anticancer drug both as a single agent and as a component of combination therapy. A sensitive and efficient GC method for the isolation, derivatization, and measurement of both HMBA and its two major metabolites in plasma and urine in a single analysis is described. In situ carbamylation of the biological sample with diethylpyrocarbonate forms the urethane derivative of the basic N-acetyl diaminohexane metabolite and allows analyte isolation and concentration by solid-phase extraction. Subsequent formation of the n-butyl ester of 6-acetamidohexanoic acid, the major metabolite, provides a derivatized biological extract that can be rapidly analyzed by temperature-programmed GC. The quantitative extraction and the efficient derivatization steps provide a limit of quantitation of 0.05 mM (10 micrograms/ml) for all analytes with a precision better than 8% for the range of in vitro activity (0.1-2.0 mM). This method is amenable to automation and is well-suited for the analysis of clinical samples.