Cancer drug discovery by repurposing: teaching new tricks to old dogs

Flubendazole induces mitotic catastrophe and senescence in colon cancer cells in vitro

Objectives

Flubendazole (FLU), a member of benzimidazole family of anthelmintic drugs, is able to inhibit proliferation of various cancer cells. The aim of present study was to elucidate the mechanisms of antiproliferative effect of FLU on colorectal cancer cells in vitro.

Methods

The effect of FLU on proliferation, microtubular network, DNA content, caspase activation and senescence induction was studied in SW480 and SW620 cell lines.

Key findings

Flubendazole significantly affected cell proliferation in a pattern typical for mitotic inhibitor. This was accompanied by decrease in cyclin D1 levels, increase in cyclin B1 levels, activation of caspase 2 and caspase 3/7 and PARP cleavage. Morphological observations revealed disruption of microtubular network, irregular mitotic spindles, formation of giant multinucleated cells and increase in nuclear area and DNA content. In SW620 cell line, 37.5% giant multinucleated cells induced by FLU treatment showed positivity for SA-β-galactosidase staining. Cell lines were able to recover from the treatment and this process was faster in SW480 cells.

Conclusion

Flubendazole in low concentration temporarily inhibits cell proliferation and induces mitotic catastrophe and premature senescence in human colon cancer cells in vitro.

Pharmacological Modulation of Lung Carcinogenesis in Smokers: Preclinical and Clinical Evidence

Many drugs in common use possess pleiotropic properties that make them capable of interfering with carcinogenesis mechanisms. We discuss here the ability of pharmacological agents to mitigate the pulmonary carcinogenicity of mainstream cigarette smoke. The evaluated agents include anti-inflammatory drugs (budesonide, celecoxib, aspirin, naproxen, licofelone), antidiabetic drugs (metformin, pioglitazone), antineoplastic agents (lapatinib, bexarotene, vorinostat), and other drugs and supplements (phenethyl isothiocyanate, myo-inositol, N-acetylcysteine, ascorbic acid, berry extracts). These drugs have been evaluated in mouse models mimicking interventions either in current smokers or in ex-smokers, or in prenatal chemoprevention. They display a broad spectrum of activities by attenuating either smoke-induced preneoplastic lesions or benign tumors and/or malignant tumors. Together with epidemiological data, these findings provide useful information to predict the potential effects of pharmacological agents in smokers.

Antibiotic monensin synergizes with EGFR inhibitors and oxaliplatin to suppress the proliferation of human ovarian cancer cells

Ovarian cancer is the most lethal gynecologic malignancy with an overall cure rate of merely 30%. Most patients experience recurrence within 12–24 months of cure and die of progressively chemotherapy-resistant disease. Thus, more effective anti-ovarian cancer therapies are needed. Here, we investigate the possibility of repurposing antibiotic monensin as an anti-ovarian cancer agent. We demonstrate that monensin effectively inhibits cell proliferation, migration and cell cycle progression, and induces apoptosis of human ovarian cancer cells. Monensin suppresses multiple cancer-related pathways including Elk1/SRF, AP1, NFκB and STAT, and reduces EGFR expression in ovarian cancer cells. Monensin acts synergistically with EGFR inhibitors and oxaliplatin to inhibit cell proliferation and induce apoptosis of ovarian cancer cells. Xenograft studies confirm that monensin effectively inhibits tumor growth by suppressing cell proliferation through targeting EGFR signaling. Our results suggest monensin may be repurposed as an anti-ovarian cancer agent although further preclinical and clinical studies are needed.

New concepts and challenges in the clinical translation of cancer preventive therapies: the role of pharmacodynamic biomarkers

Implementation of therapeutic cancer prevention strategies has enormous potential for reducing cancer incidence and related mortality. Trials of drugs including tamoxifen and aspirin have led the way in demonstrating proof-of-principle that prevention of breast and colorectal cancer is feasible. Many other compounds ranging from drugs in widespread use for various indications, including metformin, bisphosphonates, and vitamin D, to dietary agents such as the phytochemicals resveratrol and curcumin, show preventive activity against several cancers in preclinical models. Notwithstanding the wealth of opportunities, major challenges have hindered the development process and only a handful of therapies are currently approved for cancer risk reduction. One of the major obstacles to successful clinical translation of promising preventive agents is a lack of pharmacodynamic biomarkers to provide an early read out of biological activity in humans and for optimising doses to take into large scale randomised clinical trials. A further confounding factor is a lack of consideration of clinical pharmacokinetics in the design of preclinical experiments, meaning results are frequently reported from studies that use irrelevant or unachievable concentrations. This article focuses on recent findings from investigations with dietary-derived agents to illustrate how a thorough understanding of the mechanisms of action, using models that mimic the clinical scenario, together with the development of compound-specific accompanying pharmacodynamic biomarkers could accelerate the developmental pipeline for preventive agents and maximise the chances of success in future clinical trials. Moreover, the concept of a bell-shaped dose-response curve for therapeutic cancer prevention is discussed, along with the need to rethink the traditional ‘more is better’ approach for dose selection.

A novel NHE1-centered signaling cassette drives epidermal growth factor receptor-dependent pancreatic tumor metastasis and is a target for combination therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers principally because of early invasion and metastasis. The epidermal growth factor receptor (EGFR) is essential for PDAC development even in the presence of Kras, but its inhibition with erlotinib gives only a modest clinical response, making the discovery of novel EGFR targets of critical interest. Here, we revealed by mining a human pancreatic gene expression database that the metastasis promoter Na⁺/H⁺ exchanger (NHE1) associates with the EGFR in PDAC. In human PDAC cell lines, we confirmed that NHE1 drives both basal and EGF-stimulated three-dimensional growth and early invasion via invadopodial extracellular matrix digestion. EGF promoted the complexing of EGFR with NHE1 via the scaffolding protein Na +/H + exchanger regulatory factor 1, engaging EGFR in a negative transregulatory loop that controls the extent and duration of EGFR oncogenic signaling and stimulates NHE1. The specificity of NHE1 for growth or invasion depends on the segregation of the transient EGFR/Na +/H + exchanger regulatory factor 1/NHE1 signaling complex into dimeric subcomplexes in different lipid raftlike membrane domains. This signaling complex was also found in tumors developed in orthotopic mice. Importantly, the specific NHE1 inhibitor cariporide reduced both three-dimensional growth and invasion independently of PDAC subtype and synergistically sensitized these behaviors to low doses of erlotinib.

Feedback Activation of STAT3 as a Cancer Drug-Resistance Mechanism

Signal transducer and activator of transcription 3 (STAT3) plays crucial roles in several cellular processes such as cell proliferation and survival, and has been found to be aberrantly activated in many cancers. Much research has explored the leading mechanisms for regulating the STAT3 pathway and its role in promoting tumorigenesis. We focus here on recent evidence suggesting that feedback activation of STAT3 plays a prominent role in mediating drug resistance to a broad spectrum of targeted cancer therapies and chemotherapies. We highlight the potential of co-targeting STAT3 and its primary target to overcome drug resistance, and provide perspective on repurposing clinically approved drugs as STAT3 pathway inhibitors, in combination with the FDA-approved receptor tyrosine kinase (RTK) inhibitors, to improve clinical outcome of cancer treatment.

Pharmacogenetics of cancer therapy: breakthroughs from beyond?

‘Pharmacogenetics or Pharmacogenomics’ (PG) is one of the most practiced cancer therapeutic strategies, tailored for individualized patients. Despite its popularity and rapid advancements in the field, many obstacles for cancer therapy PG still need to be overcome. By borrowing scientific systems from other disciplines such as cancer diagnosis, and therapeutic information from the diversity of tumor origins, categories and stages, cancer therapy PG may hopefully be improved. Furthermore, to quickly acquire genetic and pathologic information and seek therapeutic interventions, possible breakthroughs may come from beyond – changing the cancer therapeutic landscapes. The next generations of PG protocols and hospital routines for searching deadly cancer pathogenic pathways versus drug-targeting predictions are of great clinical significance for the future. Yet, progress of cancer therapy PG is entering into a bottleneck stage owing to simple model of relevant techniques and routines. Promoting or even innovating present PG modular is very necessary. This perspective highlights this issue by introducing new initiatives and ideas.

Drug-repositioning opportunities for cancer therapy: novel molecular targets for known compounds

Drug repositioning is gaining increasing attention in drug discovery because it represents a smart way to exploit new molecular targets of a known drug or target promiscuity among diverse diseases, for medical uses different from the one originally considered. In this review, we focus on known non-oncological drugs with new therapeutic applications in oncology, explaining the rationale behind this approach and providing practical evidence. Moving from incompleteness of the knowledge of drug-target interactions, particularly for older molecules, we highlight opportunities for repurposing compounds as cancer therapeutics, underling the biologically and clinically relevant affinities for new targets. Ideal candidates for repositioning can contribute to the therapeutically unmet need for more-efficient anticancer agents, including drugs that selectively target cancer stem cells.

Anti-malarials are anti-cancers and vice versa - one arrow two sparrows

Repurposing is the novel means of drug discovery in modern science due to its affordability, safety and availability. Here, we systematically discussed the efficacy and mode of action of multiple bioactive, synthetic compounds and their potential derivatives which are used to treat/prevent malaria and cancer. We have also discussed the detailed molecular pathway involved in anti-cancer potentiality of an anti-malarial drug and vice versa. Although the causative agents, pathophysiology and manifestation of both the diseases are different but special emphasis has been given on similar pathways governing disease manifestation and the drugs which act through deregulating those pathways. Finally, a future direction has been speculated to combat these two diseases by a single agent developed using nanotechnology. Extended combination and new formulation of existing drugs for one disease may lead to the discovery of drug for other diseases like an arrow for two sparrows.

Repositioning Potential of PAK4 to Osteoclastic Bone Resorption

Drug repositioning is a rational approach for expanding the use of existing drugs or candidate drugs to treat additional disorders. Here we investigated the possibility of using the anticancer p21-activated kinase 4 (PAK4)-targeted inhibitor PF-3758309 to treat osteoclast-mediated disorders. PAK4 was highly expressed in bone marrow cells and was phosphorylated during their differentiation into osteoclasts, and osteoclast differentiation was significantly inhibited by the dominant negative form of PAK4 and by PF-3758309. Specifically, PF-3758309 significantly inhibited the fusion of preosteoclasts, the podosome formation, and the migration of preosteoclasts. PF-3758309 also had in vivo antiresorptive activity in a lipopolysaccharide-induced bone erosion model and in vitro antiosteoclastogenic activity in the differentiation of human bone marrow-derived cells and peripheral blood mononuclear cells into osteoclasts. These data demonstrate the relevance of PAK4 in osteoclast differentiation and the potential of PAK4 inhibitors for treating osteoclast-related disorders.

Activity Profile of an FDA-Approved Compound Library against Schistosoma mansoni

BACKGROUND

As plans to expand mass drug treatment campaigns to fight schistosomiasis form, worries about reliance on praziquantel as the sole available treatment motivate the investigation for novel antischistosomal compounds. Drug repurposing might be an inexpensive and effective source of novel antischistosomal leads.

METHODOLOGY

1600 FDA approved compounds were first assayed against Schistosoma mansoni schistosomula at a concentration of 10 µM. Active compounds identified from this screen were advanced to the adult worm screen at 33.33 µM, followed by hit characterization. Leads with complementary pharmacokinetic and toxicity profiles were then selected for in vivo studies.

PRINCIPAL FINDINGS

The in vitro screen identified 121 and 36 compounds active against the schistosomula and adult stage, respectively. Further, in vitro characterization and comparison with already available pharmacokinetic and toxicity data identified 11 in vivo candidates. Doramectin (10 mg/kg) and clofazimine (400 mg/kg) were found to be active in vivo with worm burden reductions of 60.1% and 82.7%, respectively.

CONCLUSIONS/SIGNIFICANCE

The work presented here expands the knowledge of antischistosomal properties of already approved compounds and underscores variations observed between target-based and phenotypic approaches and among laboratories. The two in vivo-active drugs identified in this study, doramectin and clofazimine are widely available and present as novel drug classes as starting points for further investigation.

Therapeutic Effects of Repurposed Therapies in Non-Small Cell Lung Cancer: What Is Old Is New Again

The recent emergence of targeted and immunotherapeutic agents has dramatically changed the management for patients with non-small cell lung cancer (NSCLC). Despite these advances, lung cancer is not exempt from the challenges facing oncology drug development, including the huge financial cost and the time required for drug implementation. Repositioning noncancer therapies with potential antineoplastic properties into new therapeutic niches is an alternative treatment strategy offering the possibility of saving money and time and improving outcomes. The goal of such a strategy is to deliver an effective drug with a favorable toxicity profile at a reduced cost. Preclinical models and observational data have demonstrated promising activity for many of these agents, and they are now being studied in prospective trials. We review the relevant published data regarding the therapeutic effects of metformin, statins, nonsteroidal anti-inflammatory drugs, β-blockers, and itraconazole in NSCLC, with a focus on the putative mechanisms of action and clinical data. As these drugs are increasingly being tested in clinical trials, we aim to highlight the salient challenges and future strategies to optimize this approach.

In vitro anti-osteoclastogenic activity of p38 inhibitor doramapimod via inhibiting migration of pre-osteoclasts and NFATc1 activity

The mitogen activated protein kinase p38 plays a role in the receptor activator of NF-ĸB ligand (RANKL)-induced osteoclast differentiation. In this study, we investigated the effect of p38 inhibitor doramapimod on the osteoclast differentiation. Doramapimod significantly inhibited the osteoclastogenesis of bone marrow macrophages (BMMs) via attenuating the activation of p38 induced by M-CSF and RANKL. Importantly, doramapimod blocked the migration and fusion in pre-osteoclasts via the down-regulating NFATc1. The inhibitory effect of doramapimod on the migration/fusion of pre-osteoclasts via inhibiting NFATc1 activity were confirmed by measuring NFATc1 luciferase activity and evaluating the mRNA expression of NFATc1-responsive genes related to the osteoclastic migration/fusion. These results suggested anti-osteoclastogenic activity of doramapimod via inhibiting migration/fusion of pre-osteoclasts and NFATc1 activity.

Challenges and perspective of drug repurposing strategies in early phase clinical trials

Despite significant investments in the development of new agents only 5% of cancer drugs entering Phase I clinical trials are ultimately approved for routine clinical cancer care. Drug repurposing strategies using novel combinations of previously tested anticancer agents could reduce the cost and improve treatment outcomes. At MD Anderson Cancer Center, early phase clinical trials with drug repurposing strategies demonstrated promising outcomes in patients with both rare and common treatment refractory advanced cancers. Despite clinical efficacy advancing drug repurposing strategies in the clinical trial trajectory beyond early phase studies has been challenging mainly due to lack of funding and interest from the pharmaceutical industry. In this review, we delineate our experience and challenges with drug repurposing strategies.

The purchasable chemical space: a detailed picture

The screening of a reduced yet diverse and synthesizable region of the chemical space is a critical step in drug discovery. The ZINC database is nowadays routinely used to freely access and screen millions of commercially available compounds. We collected ∼125 million compounds from chemical catalogs and the ZINC database, yielding more than 68 million unique molecules, including a large portion of described natural products (NPs) and drugs. The data set was filtered using advanced medicinal chemistry rules to remove potentially toxic, promiscuous, metabolically labile, or reactive compounds. We studied the physicochemical properties of this compilation and identified millions of NP-like, fragment-like, inhibitors of protein-protein interactions (i-PPIs) like, and drug-like compounds. The related focused libraries were subjected to a detailed scaffold diversity analysis and compared to reference NPs and marketed drugs. This study revealed thousands of diverse chemotypes with distinct representations of building block combinations among the data sets. An analysis of the stereogenic and shape complexity properties of the libraries also showed that they present well-defined levels of complexity, following the tendency: i-PPIs-like < drug-like < fragment-like < NP-like. As the collected compounds have huge interest in drug discovery and particularly virtual screening and library design, we offer a freely available collection comprising over 37 million molecules under: http://pbox.pharmaceutical-bioinformatics.org , as well as the filtering rules used to build the focused libraries described herein.

Survival of patients with stage IV lung cancer with diabetes treated with metformin

RATIONALE

Prior studies have shown an anticancer effect of metformin in patients with breast and colorectal cancer. It is unclear, however, whether metformin has a mortality benefit in lung cancer.

OBJECTIVES

To compare overall survival of patients with diabetes with stage IV non-small cell lung cancer (NSCLC) taking metformin versus those not on metformin.

METHODS

Using data from the Surveillance, Epidemiology, and End Results registry linked to Medicare claims, we identified 750 patients with diabetes 65-80 years of age diagnosed with stage IV NSCLC between 2007 and 2009. We used propensity score methods to assess the association of metformin use with overall survival while controlling for potential confounders.

MEASUREMENTS AND MAIN RESULTS

Overall, 61% of patients were on metformin at the time of lung cancer diagnosis. Median survival in the metformin group was 5 months, compared with 3 months in patients not treated with metformin (P < 0.001). Propensity score analyses showed that metformin use was associated with a statistically significant improvement in survival (hazard ratio, 0.80; 95% confidence interval, 0.71-0.89), after controlling for sociodemographics, diabetes severity, other diabetes medications, cancer characteristics, and treatment.

CONCLUSIONS

Metformin is associated with improved survival among patients with diabetes with stage IV NSCLC, suggesting a potential anticancer effect. Further research should evaluate plausible biologic mechanisms and test the effect of metformin in prospective clinical trials.

Biomechanical effects of microbubbles: from radiosensitization to cell death

ABSTRACT 

Ultrasound-stimulated microbubbles have been demonstrated to mechanically perturb cell membranes, resulting in the activation of biological signaling pathways that significantly enhance the effects of radiation. The underlying mechanism involves augmented ceramide production following both microbubble stimulation and irradiation, leading to rapid and extensive endothelial apoptosis and tumor cell death as a result of vascular collapse. Endothelial cells are particularly sensitive to ceramide-induced cell death due to an enriched presence of sphingomyelinase in their membranes. In tumors, this consequent rapid vascular shutdown translates to an overall increase in tumor responses to radiation treatments. This review summarizes the groundwork behind endothelial-based radiation enhancement with ultrasound-stimulated microbubbles, and presents ongoing research on the use of microbubbles as therapeutic agents in cancer therapy.

In silico prescription of anticancer drugs to cohorts of 28 tumor types reveals targeting opportunities

Large efforts dedicated to detect somatic alterations across tumor genomes/exomes are expected to produce significant improvements in precision cancer medicine. However, high inter-tumor heterogeneity is a major obstacle to developing and applying therapeutic targeted agents to treat most cancer patients. Here, we offer a comprehensive assessment of the scope of targeted therapeutic agents in a large pan-cancer cohort. We developed an in silico prescription strategy based on identification of the driver alterations in each tumor and their druggability options. Although relatively few tumors are tractable by approved agents following clinical guidelines (5.9%), up to 40.2% could benefit from different repurposing options, and up to 73.3% considering treatments currently under clinical investigation. We also identified 80 therapeutically targetable cancer genes.

Prediction of drug indications based on chemical interactions and chemical similarities

Discovering potential indications of novel or approved drugs is a key step in drug development. Previous computational approaches could be categorized into disease-centric and drug-centric based on the starting point of the issues or small-scaled application and large-scale application according to the diversity of the datasets. Here, a classifier has been constructed to predict the indications of a drug based on the assumption that interactive/associated drugs or drugs with similar structures are more likely to target the same diseases using a large drug indication dataset. To examine the classifier, it was conducted on a dataset with 1,573 drugs retrieved from Comprehensive Medicinal Chemistry database for five times, evaluated by 5-fold cross-validation, yielding five 1st order prediction accuracies that were all approximately 51.48%. Meanwhile, the model yielded an accuracy rate of 50.00% for the 1st order prediction by independent test on a dataset with 32 other drugs in which drug repositioning has been confirmed. Interestingly, some clinically repurposed drug indications that were not included in the datasets are successfully identified by our method. These results suggest that our method may become a useful tool to associate novel molecules with new indications or alternative indications with existing drugs.

Nicotinamide sensitizes human breast cancer cells to the cytotoxic effects of radiation and cisplatin

Poly(ADP-ribose) polymerase (PARP) inhibitors enhance the effect of DNA alkylating agents on BRCA1‑ and BRCA2-deficient cell lines. The aim of this study was to analyze the effect of the PARP inhibitor nicotinamide (NAM) on breast cancer cells with different BRCA1 expression or function, such as BRCA1‑deficient MDA-MB-436 cells, low expression BRCA1 MCF-7 cells, and the BRCA1 wild‑type MDA-MB-231 cells, to demonstrate its effects as a chemo‑ or radiosensitizing agent. PARP activity was analyzed in MDA-MB-436, MCF-7 and MDA-MB-231 breast cancer cells subjected or not to NAM. Inhibition of PARP by NAM in the presence of DNA damage was examined by Alexa Fluor 488 immunofluorescence. Crystal violet assays were used to test growth inhibition and the chemo‑ and radiosensitization effects of NAM were investigated using clonogenic assays. Significant differences among data sets were determined using two-tailed ANOVA and Bonferroni tests. We demonstrated that NAM reduces PARP activity in vitro, and in cells subjected or not to DNA damage, it also reduces the viability of breast cancer cell lines and synergyzes the cytotoxicity of cisplatin in MDA-MB-436 and MCF-7 cells. Downregulation of PARP1 with siRNA led to modest growth inhibition, which was further increased by cisplatin. Nicotinamide also induced radiosensitization in MDA-MB-436 and MDA-MB-231 cells. In conclusion, NAM may be used as a chemo‑ or radiosensitizing agent regardless of the BRCA1 status in breast cancer.

Unleashing the power of comparative oncology models in nanomedicine research

The pathway from discovery of novel candidate drugs, including nanomedicine compounds, to FDA approval is lengthy and may be difficult to navigate. Oftentimes, investigational drugs are appropriately abandoned early in the development pathway due to preclinical failure. Other novel compounds may look quite promising in rodent models and preclinical trials, but prove disappointing when tested in human patients. In fact, only 5% of drugs entering Phase I human cancer clinical trials in the US are ultimately approved. Given the enormous cost, in terms of both financial investment and delay in progress toward improved patient outcome, there is a critical need for a more reliable and efficient process. One solution may be to improve translatability of our preclinical data by including trials in cancer-bearing pet dogs in the drug development pathway.

An α1-adrenergic receptor ligand repurposed as a potent antiproliferative agent for head and neck squamous cell carcinoma

In this study we report the anticancer properties of RN5-Me, an α₁-adrenergic receptor ligand.

Potential sonodynamic anticancer activities of artemether and liposome-encapsulated artemether

The potential application of artemether as a novel sonosensitizer for sonodynamic therapy was explored and illustrated for the first time.

The antiparasitic drug, potassium antimony tartrate, inhibits tumor angiogenesis and tumor growth in nonsmall-cell lung cancer

Repurposing existing drugs not only accelerates drug discovery but rapidly advances clinical therapeutic strategies. In this article, we identified potassium antimonyl tartrate (PAT), an antiparasitic drug, as a novel agent to block angiogenesis by screening US Food and Drug Administration-approved chemical drugs. By comparing the cytotoxicity of PAT in various nonsmall-cell lung cancer (NSCLC) cells with that observed in primary cultured human umbilical vein endothelial cells (HUVECs), we found that HUVECs were much more sensitive to the PAT treatment. In in vivo tumor xenograft mouse models established either by PAT-resistant A549 cells or by patient primary tumors, PAT significantly decreased the tumor volume and tumor weight of NSCLC xenografts at dosage of 40 mg/kg (i.p., daily) and, more importantly, augmented the antitumor efficacy of cisplatin chemotherapy. Remarkable loss of vascularization in the treated xenografts indicated the in vivo antiangiogenesis property of PAT, which was well correlated with its tumor growth inhibition in NSCLC cells. Furthermore, in the in vitro angiogenic assays, PAT exhibited dose-dependent inhibition of HUVEC proliferation, migration, and tube formation in response to different stimuli. Consistently, PAT also abolished the vascular endothelial cell growth factor-induced angiogenesis in the Matrigel plugs assay. Mechanistically, we found that PAT inhibited the activities of several receptor tyrosine kinases and specifically blocked the activation of downstream Src and focal adhesion kinases in HUVECs. Taken together, our results characterized the novel antiangiogenic and antitumor function of PAT in NSCLC cells. Further study of PAT in anticancer clinical trials may be warranted.

Repurposing the antipsychotic trifluoperazine as an antimetastasis agent

Because cancer cell invasion is a critical determinant of metastasis, targeting invasion is a viable approach to prevent metastasis. Utilizing a novel three-dimensional high-throughput invasion assay, we screened a National Cancer Institute compound library and discovered compounds demonstrating inhibitory effects on cancer cell invasion. One hit, trifluoperazine, suppresses invasion of human cancer cell lines while displaying a limited cytotoxicity profile. This inhibition is due to the interference with cancer cell migratory ability but not proteolytic activity. Treatment of cancer cells with trifluoperazine significantly reduces angiogenesis and prevents cancer cell invasion through a chorioallantoic basement membrane. Mechanistically, treatment results in decreased phosphorylated AKT (Ser(473) and Thr(308)) and β-catenin (Ser(552)). Lack of phosphorylation of Ser(552) of β-catenin prevents β-catenin nuclear relocation, resulting in decreased expression of vascular endothelial growth factor, likely mediated through dopamine receptor D2. Taken together, we demonstrated that trifluoperazine is responsible for reducing the angiogenic and invasive potential of aggressive cancer cells through dopamine receptor D2 to modulate the β-catenin pathway and propose that trifluoperazine may be used as an antimetastasis chemotherapeutic.

Novel Suppressive Effects of Ketotifen on Migration and Invasion of MDA-MB-231 and HT-1080 Cancer Cells

The high mortality rates associated with cancer reflect the metastatic spread of tumor cells from the site of their origin. Metastasis, in fact, is the cause of 90% of cancer deaths. Therefore, considerable effort is being made to inhibit metastasis. In the present study, we screened ketotifen for anti-migratory and anti-invasive activities against MDA-MB-231 breast cancer and HT-1080 fibrosarcoma cancer cells. Cancer cell migration and invasion were measured using multi-well chambers. Additionally, western blots were used to examine the effects of ketotifen on the expressions of CDC42, Rho, Rac, and matrix metalloproteinase 9 (MMP-9). The results showed that ketotifen dose-dependently suppressed the migration and invasion of MDA-MB-231 and HT-1080 cells. Ketotifen also suppressed the expressions of CDC42, Rac, and Rho, which, significantly, are involved in MDA-MB-231 and HT-1080 cancer cell migration. Moreover, ketotifen suppressed the expression and activity of MMP-9, which is involved in degradation of the extracellular matrix leading to invasion. The overall data suggested that ketotifen suppresses the migration and invasion of MDA-MB-231 and HT-1080 cancer cells via inhibition of CDC42, Rac, Rho, and MMP-9 expression.

Tackling the tumor microenvironment: what challenge does it pose to anticancer therapies?

Cancer is a highly aggressive and devastating disease, and impediments to a cure arise not just from cancer itself. Targeted therapies are difficult to achieve since the majority of cancers are more intricate than ever imagined. Mainstream methodologies including chemotherapy and radiotherapy as routine clinical regimens frequently fail, eventually leading to pathologies that are refractory and incurable. One major cause is the gradual to rapid repopulation of surviving cancer cells during intervals of multiple-dose administration. Novel stress-responsive molecular pathways are increasingly unmasked and show promise as emerging targets for advanced strategies that aim at both de novo and acquired resistance. We highlight recent data reporting that treatments particularly those genotoxic can induce highly conserved damage responses in non-cancerous constituents of the tumor microenvironment (TMEN). Master regulators, including but not limited to NF-kB and C/EBP-β, are implicated and their signal cascades culminate in a robust, chronic and genome-wide secretory program, forming an activated TMEN that releases a myriad of soluble factors. The damage-elicited but essentially off target and cell non-autonomous secretory phenotype of host stroma causes adverse consequences, among which is acquired resistance of cancer cells. Harnessing signals arising from the TMEN, a pathophysiological niche frequently damaged by medical interventions, has the potential to promote overall efficacy and improve clinical outcomes provided that appropriate actions are ingeniously integrated into contemporary therapies. Thereby, anticancer regimens should be well tuned to establish an innovative clinical avenue, and such advancement will allow future oncological treatments to be more specific, accurate, thorough and personalized.

Hydralazine-valproate: a repositioned drug combination for the epigenetic therapy of cancer

INTRODUCTION

DNA methylation (DNMTi) and histone deacetylase inhibitors (HDACi) are in development for cancer therapy. So far, four epigenetic drugs are approved for myelodysplastic syndrome (MDS) and cutaneous T-cell lymphoma (CTCL). The combination of hydralazine-valproate (TRANSKRIP(™)) is being repositioned as an oral DNMT and HDAC inhibitor.

AREAS COVERED

Brief discussion on the current status of epigenetic drugs and studies published on the preclinical and clinical development of the hydralazine-valproate combination.

EXPERT OPINION

Drug repositioning is a strategy for prompt and cost-efficient drug discovery. There is evidence that combining DNMTi with HDACi would be more efficacious than administering each agent on its own. Hydralazine-valproate is safe when used alone or in combination with chemotherapy or chemoradiation. The fact that both drugs are orally administered is another advantage over current epigenetic drugs. This combination is promising but larger studies are needed. Among these, the randomized Phase III trials in advanced and in locally advanced cervical cancer combined with chemotherapy and cisplatin-radiation respectively, would eventually confirm its efficacy. Studies on MDS and CTCL would also eventually prove the efficacy of hydralazine valproate so that in the coming years hydralazine-valproate could have a role in cancer epigenetic therapy.

Nanocarrier for poorly water-soluble anticancer drugs--barriers of translation and solutions

Many existing chemotherapeutic drugs, repurposed drugs and newly developed small-molecule anticancer compounds have high lipophilicity and low water-solubility. Currently, these poorly water-soluble anticancer drugs (PWSAD) are generally solubilized using high concentrations of surfactants and co-solvents, which frequently lead to adverse side effects. In recent years, researchers have been actively exploring the use of nanotechnology as an alternative to the solvent-based drug solubilization approach. Several classes of nanocarrier systems (lipid-based, polymer-based and albumin-based) are widely studied for encapsulation and delivery of the existing and new PWSAD. These nanocarriers were also shown to offer several additional advantages such as enhanced tumour accumulation, reduced systemic toxicity and improved therapeutic effectiveness. In this article, the recent nanotechnological advances in PWSAD delivery will be reviewed. The barriers commonly encountered in the development of PWSAD nanoformulations (e.g. formulation issues and nanotoxicity issues) and the strategies to overcome these barriers will also be discussed. It is our goal to provide the pharmaceutical scientists and clinicians with more in-depth information about the nanodelivery approach, thus, more efficacious and safe PWSAD nanoformulations can be developed with improved translational success.

Praziquantel, mefloquine-praziquantel, and mefloquine-artesunate-praziquantel against Schistosoma haematobium: a randomized, exploratory, open-label trial

Background

Treatment and morbidity control of schistosomiasis relies on a single drug, praziquantel. Hence, there is a pressing need to develop additional therapeutics against schistosomiasis. The antimalarial drug mefloquine shows antischistosomal activity in animal models and clinical trials, which calls for further investigations.

Methodology

We comparatively assessed the efficacy and tolerability of the following treatments against Schistosoma haematobium in school-aged children in Côte d'Ivoire: (i) praziquantel (40 mg/kg; standard treatment); (ii) mefloquine (25 mg/kg) combined with praziquantel (40 mg/kg); and (iii) mefloquine-artesunate (3× (100 mg artesunate +250 mg mefloquine)) combined with praziquantel (40 mg/kg) (treatments administered on subsequent days). Two urine samples were collected before, and on days 21–22 and 78–79 after the first dosing.

Principal Findings

Sixty-one children were present on all examination time points and had complete datasets. No difference in efficacy was observed between the three treatment groups on either follow-up. On the 21–22 day posttreatment follow-up, based on available case analysis, cure rates of 33% (95% confidence interval (CI) 11–55%), 29% (95% CI 8–50%), and 26% (95% CI 5–48%) were observed for praziquantel, mefloquine-artesunate-praziquantel, and mefloquine-praziquantel, respectively. The corresponding egg reduction rates were 94% and above. On the second follow-up, observed cure rates ranged from 19% (praziquantel) to 33% (mefloquine-artesunate-praziquantel), and egg reduction rates were above 90%. Praziquantel monotherapy was the best tolerated treatment. In the mefloquine-artesunate-praziquantel group, adverse events were reported by 91% of the participants, and in the mefloquine-praziquantel group, 95% experienced adverse events. With the exception of abdominal pain at moderate severity, adverse events were mild.

Conclusions/Significance

The addition of mefloquine or mefloquine-artesunate does not increase the efficacy of praziquantel against chronic S. haematobium infection. Additional studies are necessary to elucidate the effect of the combinations against acute schistosomiasis.

The antimalarial drug mefloquine shows activity against blood flukes that cause the disease schistosomiasis. In animal studies it has been found that a mefloquine-praziquantel combination kills blood flukes more effectively than praziquantel alone. Combining praziquantel with another drug might therefore increase efficacy, broaden the spectrum of activity, and delay the development of drug resistance. We designed a study in Ivorian school children to assess the efficacy and tolerability of mefloquine and mefloquine-artesunate combined with praziquantel against the blood fluke Schistosoma haematobium. The administration of the antimalarials and praziquantel was spaced by a day. Treatment outcomes were assessed twice, on days 21–22 and 78–79 after the first dosing to determine the effect against adult and juvenile S. haematobium, respectively. At both follow-ups, high reduction in the intensity of infection (egg reduction rates of 94–96%), but low cure rates (26–33%) were observed in the three treatment groups. Adverse events were common, particularly in children treated with mefloquine-praziquantel and mefloquine-artesunate-praziquantel. Our study suggests that the addition of mefloquine and mefloquine-artesunate to praziquantel has no benefit in the treatment of chronic S. haematobium infection. However, further investigations are warranted to evaluate the effect of combination therapy on juvenile flukes and longer-term morbidity profiles.

New horizons for old drugs and drug leads

There is mounting urgency to find new drugs for the treatment of serious infectious diseases and cancer that are rapidly developing resistance to previously effective drugs. One approach to addressing this need is through drug repurposing, which refers to the discovery of new useful activities for "old" clinically used drugs through screening them against relevant disease targets. A large number of potential drug that, for various reasons, have failed to advance to clinical and commercial use can be added to the candidates available for such purposes. The application of new techniques and methodology developed through the impressive progress made in multidisciplinary, natural product-related research in recent years should aid substantially in expediting the discovery and development process. This review briefly outlines some of these developments as applied to a number of selected natural product examples, which may also include advances in chemical synthesis of derivatives with extended biological activities.

Biomarker-guided repurposing of chemotherapeutic drugs for cancer therapy: a novel strategy in drug development

Cancer is a leading cause of mortality worldwide and matters are only set to worsen as its incidence continues to rise. Traditional approaches to combat cancer include improved prevention, early diagnosis, optimized surgery, development of novel drugs, and honing regimens of existing anti-cancer drugs. Although discovery and development of novel and effective anti-cancer drugs is a major research area, it is well known that oncology drug development is a lengthy process, extremely costly and with high attrition rates. Furthermore, those drugs that do make it through the drug development mill are often quite expensive, laden with severe side-effects and unfortunately, to date, have only demonstrated minimal increases in overall survival. Therefore, a strong interest has emerged to identify approved non-cancer drugs that possess anti-cancer activity, thus shortcutting the development process. This research strategy is commonly known as drug repurposing or drug repositioning and provides a faster path to the clinics. We have developed and implemented a modification of the standard drug repurposing strategy that we review here; rather than investigating target-promiscuous non-cancer drugs for possible anti-cancer activity, we focus on the discovery of novel cancer indications for already approved chemotherapeutic anti-cancer drugs. Clinical implementation of this strategy is normally commenced at clinical phase II trials and includes pre-treated patients. As the response rates to any non-standard chemotherapeutic drug will be relatively low in such a patient cohort it is a pre-requisite that such testing is based on predictive biomarkers. This review describes our strategy of biomarker-guided repurposing of chemotherapeutic drugs for cancer therapy, taking the repurposing of topoisomerase I (Top1) inhibitors and Top1 as a potential predictive biomarker as case in point.

[Sleep and its pharmacologic treatment]

Background

The discovery of novel anticancer drugs is critical for the pharmaceutical research and development, and patient treatment. Repurposing existing drugs that may have unanticipated effects as potential candidates is one way to meet this important goal. Systematic investigation of efficient anticancer drugs could provide valuable insights into trends in the discovery of anticancer drugs, which may contribute to the systematic discovery of new anticancer drugs.

Results

In this study, we collected and analyzed 150 anticancer drugs approved by the US Food and Drug Administration (FDA). Based on drug mechanism of action, these agents are divided into two groups: 61 cytotoxic-based drugs and 89 target-based drugs. We found that in the recent years, the proportion of targeted agents tended to be increasing, and the targeted drugs tended to be delivered as signal drugs. For 89 target-based drugs, we collected 102 effect-mediating drug targets in the human genome and found that most targets located on the plasma membrane and most of them belonged to the enzyme, especially tyrosine kinase. From above 150 drugs, we built a drug-cancer network, which contained 183 nodes (150 drugs and 33 cancer types) and 248 drug-cancer associations. The network indicated that the cytotoxic drugs tended to be used to treat more cancer types than targeted drugs. From 89 targeted drugs, we built a cancer-drug-target network, which contained 214 nodes (23 cancer types, 89 drugs, and 102 targets) and 313 edges (118 drug-cancer associations and 195 drug-target associations). Starting from the network, we discovered 133 novel drug-cancer associations among 52 drugs and 16 cancer types by applying the common target-based approach. Most novel drug-cancer associations (116, 87%) are supported by at least one clinical trial study.

Conclusions

In this study, we provided a comprehensive data source, including anticancer drugs and their targets and performed a detailed analysis in term of historical tendency and networks. Its application to identify novel drug-cancer associations demonstrated that the data collected in this study is promising to serve as a fundamental for anticancer drug repurposing and development.