Repurposing the Clinically Efficacious Antifungal Agent Itraconazole as an Anticancer Chemotherapeutic

An update on the global treatment of invasive fungal infections

Fungal infections are a serious problem affecting many people worldwide, creating critical economic and medical consequences. Fungi are ubiquitous and can cause invasive diseases in individuals mostly living in developing countries or with weakened immune systems, and antifungal drugs currently available have important limitations in tolerability and efficacy. In an effort to counteract the high morbidity and mortality rates associated with invasive fungal infections, various approaches are being utilized to discover and develop new antifungal agents. This review discusses the challenges posed by fungal infections, outlines different methods for developing antifungal drugs and reports on the status of drugs currently in clinical trials, which offer hope for combating this serious global problem.

Repurposing antifungal drugs for cancer therapy

BACKGROUND

Repurposing antifungal drugs in cancer therapy has attracted unprecedented attention in both preclinical and clinical research due to specific advantages, such as safety, high-cost effectiveness and time savings compared with cancer drug discovery. The surprising and encouraging efficacy of antifungal drugs in cancer therapy, mechanistically, is attributed to the overlapping targets or molecular pathways between fungal and cancer pathogenesis. Advancements in omics, informatics and analytical technology have led to the discovery of increasing "off-site" targets from antifungal drugs involved in cancerogenesis, such as smoothened (D477G) inhibition from itraconazole in basal cell carcinoma.

AIM OF REVIEW

This review illustrates several antifungal drugs repurposed for cancer therapy and reveals the underlying mechanism based on their original target and "off-site" target. Furthermore, the challenges and perspectives for the future development and clinical applications of antifungal drugs for cancer therapy are also discussed, providing a refresh understanding of drug repurposing.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review may provide a basic understanding of repurposed antifungal drugs for clinical cancer management, thereby helping antifungal drugs broaden new indications and promote clinical translation.

8-Hydroxyquinoline derivatives suppress GLI1-mediated transcription through multiple mechanisms

Aberrant activation of the Hedgehog (Hh) signaling pathway has been observed in various human malignancies. Glioma-associated oncogene transcription factor 1 (GLI1) is the ultimate effector of the canonical Hh pathway and has also been identified as a common regulator of several tumorigenic pathways prevalent in Hh-independent cancers. The anti-cancer potential of GLI1 antagonism with small molecule inhibitors has demonstrated initial promise; however, the continued development of GLI1 inhibitors is still needed. We previously identified a scaffold containing an 8-hydroxyquinoline as a promising lead GLI1 inhibitor (compound 1). To further develop this scaffold, we performed a systematic structure-activity relationship study to map the structural requirements of GLI1 inhibition by this chemotype. A series of biophysical and cellular experiments identified compound 39 as an enhanced GLI1 inhibitor with improved activity. In addition, our studies on this scaffold suggest a potential role for SRC family kinases in regulating oncogenic GLI1 transcriptional activity.

Repurposed itraconazole for use in the treatment of malignancies as a promising therapeutic strategy

Understanding cancer biology and the development of novel agents for cancer treatment has always been the goal of cancer researchers. However, the research and development of new drugs is hindered by its long development time, exorbitant cost, high regulatory hurdles, and staggering failure rates. Given the challenges involved drug development for cancer therapies, alternative strategies, in particular the repurposing of 'old' drugs that have been approved for other indications, are attractive. Itraconazole is an FDA-approved anti-fungal drug of the triazole class, and has been used clinically for more than 30 years. Recent drug repurposing screens revealed itraconazole exerts anti-cancer activity via inhibiting angiogenesis and multiple oncogenic signaling pathways. To explore the potential utilization of itraconazole in different types of malignancies, we retrieved the published literature relating to itraconazole in cancer and reviewed the mechanisms of itraconazole in preclinical and clinical cancer studies. Current research predicts the hedgehog signaling pathway as the main target by which itraconazole inhibits a variety of solid and hematological cancers. As clinical trial results become available, itraconazole could emerge as a new antitumor drug that can be used in combination with first-line antitumor drugs.

N-Phenacyldibromobenzimidazoles—Synthesis Optimization and Evaluation of Their Cytotoxic Activity

Antifungal N-phenacyl derivatives of 4,6- and 5,6-dibromobenzimidazoles are interesting substrates in the synthesis of new antimycotics. Unfortunately, their application is limited by the low synthesis yields and time-consuming separation procedure. In this paper, we present the optimization of the synthesis conditions and purification methods of N-phenacyldibromobenzimidazoles. The reactions were carried out in various base solvent-systems including K₂CO₃, NaH, KOH, t-BuOK, MeONa, NaHCO₃, Et₃N, Cs₂CO₃, DBU, DIPEA, or DABCO as a base, and MeCN, DMF, THF, DMSO, or dioxane as a solvent. The progress of the reaction was monitored using HPLC analysis. The best results were reached when the reactions were carried out in an NaHCO₃–MeCN system at reflux for 24 h. Additionally, the cytotoxic activity of the synthesized compounds against MCF-7 (breast adenocarcinoma), A-549 (lung adenocarcinoma), CCRF-CEM (acute lymphoblastic leukemia), and MRC-5 (normal lung fibroblasts) was evaluated. We observed that the studied cell lines differed in sensitivity to the tested compounds with MCF-7 cells being the most sensitive, while A-549 cells were the least sensitive. Moreover, the cytotoxicity of the tested derivatives towards CCRF-CEM cells increased with the number of chlorine or fluorine substituents. Furthermore, some of the active compounds, i.e., 2-(5,6-dibromo-1H-benzimidazol-1-yl)-1-(3,4-dichlorophenyl)ethanone (4f), 2-(4,6-dibromo-1H-benzimidazol-1-yl)-1-(2,4,6-trichlorophenyl)ethanone (5g), and 2-(4,6-dibromo-1H-benzimidazol-1-yl)-1-(2,4,6-trifluorophenyl)ethanone (5j) demonstrated pro-apoptotic properties against leukemic cells with derivative 5g being the most effective.

A global picture: therapeutic perspectives for COVID-19

The COVID-19 pandemic is a lethal virus outbreak by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has severely affected human lives and the global economy. The most vital part of the research and development of therapeutic agents is to design drug products to manage COVID-19 efficiently. Numerous attempts have been in place to determine the optimal drug dose and combination of drugs to treat the disease on a global scale. This article documents the information available on SARS-CoV-2 and its life cycle, which will aid in the development of the potential treatment options. A consolidated summary of several natural and repurposed drugs to manage COVID-19 is depicted with summary of current vaccine development. People with high age, comorbity and concomitant illnesses such as overweight, metabolic disorders, pulmonary disease, coronary heart disease, renal failure, fatty liver and neoplastic disorders are more prone to create serious COVID-19 and its consequences. This article also presents an overview of post-COVID-19 complications in patients.

A global picture: therapeutic perspectives for COVID-19

The COVID-19 pandemic is a lethal virus outbreak by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has severely affected human lives and the global economy. The most vital part of the research and development of therapeutic agents is to design drug products to manage COVID-19 efficiently. Numerous attempts have been in place to determine the optimal drug dose and combination of drugs to treat the disease on a global scale. This article documents the information available on SARS-CoV-2 and its life cycle, which will aid in the development of the potential treatment options. A consolidated summary of several natural and repurposed drugs to manage COVID-19 is depicted with summary of current vaccine development. People with high age, comorbity and concomitant illnesses such as overweight, metabolic disorders, pulmonary disease, coronary heart disease, renal failure, fatty liver and neoplastic disorders are more prone to create serious COVID-19 and its consequences. This article also presents an overview of post-COVID-19 complications in patients.

Recent advances in synthesis and anticancer potential of triazole containing scaffolds

Cancer is the most lethal disease that may be found anywhere on the globe. Approximately 10% of individuals die as a result of cancer of various types, with 19.3 million new cancer cases and 10 million deaths expected in 2020. More than 100 medications are commercially available for the treatment of cancer, but only a few candidates have high specificity, resulting in several side effects. The scientific community has spent the past decades focusing on drug discovery. Natural resources are used to isolate pharmaceutically active candidates, which are then synthesized in laboratories. More than 60% of all prescribed drugs are made from natural ingredients. Unique five-membered heteroaromatic center motifs with sulfur, oxygen and nitrogen atoms are found in heterocyclic compounds such as indazole, thiazole, triazole, triazole, and oxazole, and are used as a core scaffold in many medicinally important therapies. Triazole possesses a wide range of pharmacological activities including anticancer, antibacterial, antifungal, antibiotic antiviral, analgesic, anti-inflammatory, anti-HIV, antidiabetic, and antiprotozoal activities. Novel Triazole motifs with a variety of biological characteristics have been successfully synthesized using versatile synthetic methods. We intend here to facilitate the rational design and development of innovative triazole-based anti-cancer medicines with increased selectivity for various cancer cell lines by providing insight into various ligand-receptor interactions.

Repurposing of Antimicrobial Agents for Cancer Therapy: What Do We Know?

The substantial costs of clinical trials, the lengthy timelines of new drug discovery and development, along the high attrition rates underscore the need for alternative strategies for finding quickly suitable therapeutics agents. Given that most approved drugs possess more than one target tightly linked to other diseases, it encourages promptly testing these drugs in patients. Over the past decades, this has led to considerable attention for drug repurposing, which relies on identifying new uses for approved or investigational drugs outside the scope of the original medical indication. The known safety of approved drugs minimizes the possibility of failure for adverse toxicology, making them attractive de-risked compounds for new applications with potentially lower overall development costs and shorter development timelines. This latter case is an exciting opportunity, specifically in oncology, due to increased resistance towards the current therapies. Indeed, a large body of evidence shows that a wealth of non-cancer drugs has beneficial effects against cancer. Interestingly, 335 drugs are currently being evaluated in different clinical trials for their potential activities against various cancers (Redo database). This review aims to provide an extensive discussion about the anti-cancer activities exerted by antimicrobial agents and presents information about their mechanism(s) of action and stage of development/evaluation.

Itraconazole synergistically increases therapeutic effect of paclitaxel and 99mTc-MIBI accumulation, as a probe of P-gp activity, in HT-29 tumor-bearing nude mice

P-glycoprotein (P-gp), is an important efflux pump involved in chemotherapy resistance in human colon cancer. We investigated the efficacy of itraconazole as a P-gp inhibitor and its therapeutic synergistic relationship to paclitaxel through 99mTc-MIBI accumulation in HT-29 tumor-bearing nude mice. Histopathological screening along with in vitro experiments was done for further assessment. Itraconazole successfully inhibited P-gp mediated 99mTc-MIBI efflux, increasing its in vitro accumulation in itraconazole-receiving dishes. Notably, the co-administration of itraconazole with paclitaxel significantly enhanced the in vitro cytotoxicity effect of paclitaxel in itraconazole + paclitaxel wells containing HT-29 cells. Compared to the control, tumor volume in mice treated with itraconazole, paclitaxel and itraconazole +paclitaxel showed growth suppression approximately by 36.21, 60.02, and 73.3% respectively. And compared to paclitaxel group, the nude mice co-treated with paclitaxel and itraconazole showed suppression of tumor growth by about 33.31 % at the end of the treatment period. Also the biodistribution result showed that the co-administration of itraconazole with paclitaxel raised the mean tumor radioactivity accumulation compared to control and paclitaxel group. When given paclitaxel alone, the ID% of hepatic and cardiac tissue was reduced while co-administration of itraconazole with paclitaxel increased 99mTc-MIBI accumulation in these organs. Furthermore, the histopathological findings confirmed the biodistribution results. These results demonstrate that although monotherapy with itraconazole or paclitaxel has anti-tumor activity against HT-29 human colorectal cancer, a synergistic anti-tumor activity can be achieved when itraconazole is co-administered with paclitaxel. Also, 99mTc-MIBI is an effective radiotracer for monitoring response to treatment in MDR tumors.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.

An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease

Filarial worms cause multiple debilitating diseases in millions of people worldwide, including river blindness. Currently available drugs reduce transmission by killing larvae (microfilariae), but there are no effective cures targeting the adult parasites (macrofilaricides) which survive and reproduce in the host for very long periods. To identify effective macrofilaricides, we carried out phenotypic screening of a library of 2121 approved drugs for clinical use against adult Brugia pahangi and prioritized the hits for further studies by integrating those results with a computational prioritization of drugs and associated targets. This resulted in the identification of 18 hits with anti-macrofilaricidal activity, of which two classes, azoles and aspartic protease inhibitors, were further expanded upon. Follow up screening against Onchocerca spp. (adult Onchocerca ochengi and pre-adult O. volvulus) confirmed activity for 13 drugs (the majority having IC50 < 10 μM), and a counter screen of a subset against L. loa microfilariae showed the potential to identify selective drugs that prevent adverse events when co-infected individuals are treated. Stage specific activity was also observed. Many of these drugs are amenable to structural optimization, and also have known canonical targets, making them promising candidates for further optimization that can lead to identifying and characterizing novel anti-macrofilarial drugs.

Hydrophobically modified PEGylated glycol chitosan nanoparticles: synthesis, characterisation and anticancer properties

A novel palmitoylated glycol chitosan polymer grafted with PEG (PGC-PEG) was successfully developed to form amphiphilic micelles in aqueous solution.

Drug targets for COVID-19 therapeutics: Ongoing global efforts

The current global pandemic COVID-19 caused by the SARS-CoV-2 virus has already inflicted insurmountable damage both to the human lives and global economy. There is an immediate need for identification of effective drugs to contain the disastrous virus outbreak. Global efforts are already underway at a war footing to identify the best drug combination to address the disease. In this review, an attempt has been made to understand the SARS-CoV-2 life cycle, and based on this information potential druggable targets against SARS-CoV-2 are summarized. Also, the strategies for ongoing and future drug discovery against the SARS-CoV-2 virus are outlined. Given the urgency to find a definitive cure, ongoing drug repurposing efforts being carried out by various organizations are also described. The unprecedented crisis requires extraordinary efforts from the scientific community to effectively address the issue and prevent further loss of human lives and health.

Design and Synthesis of Tetrazole- and Pyridine-Containing Itraconazole Analogs as Potent Angiogenesis Inhibitors

Itraconazole, a widely used antifungal drug, was found to possess antiangiogenic activity and is currently undergoing multiple clinical trials for the treatment of different types of cancer. However, it suffers from extremely low solubility and strong interactions with many drugs through inhibition of CYP3A4, limiting its potential as a new antiangiogenic and anticancer drug. To address these issues, a series of analogs in which the phenyl group is replaced with pyridine or fluorine-substituted benzene was synthesized. Among them the pyridine- and tetrazole-containing compound 24 has significantly improved solubility and reduced CYP3A4 inhibition compared to itraconazole. Similar to itraconazole, compound 24 inhibited the AMPK/mTOR signaling axis and the glycosylation of VEGFR2. It also induced cholesterol accumulation in the endolysosome and demonstrated binding to the sterol-sensing domain of NPC1 in a simulation study. These results suggested that compound 24 may serve as an attractive candidate for the development of a new generation of antiangiogenic drug.

A comprehensive overview of the medicinal chemistry of antifungal drugs: perspectives and promise

The emergence of new fungal pathogens makes the development of new antifungal drugs a medical imperative that in recent years motivates the talents of numerous investigators across the world. Understanding not only the structural families of these drugs but also their biological targets provides a rational means for evaluating the merits and selectivity of new agents for fungal pathogens and normal cells. An equally important aspect of modern antifungal drug development takes a balanced look at the problems of drug potency and drug resistance. The future development of new antifungal agents will rest with those who employ synthetic and semisynthetic methodology as well as natural product isolation to tackle these problems and with those who possess a clear understanding of fungal cell architecture and drug resistance mechanisms. This review endeavors to provide an introduction to a growing and increasingly important literature, including coverage of the new developments in medicinal chemistry since 2015, and also endeavors to spark the curiosity of investigators who might enter this fascinatingly complex fungal landscape.

Hedgehog signaling pathway inhibitors: an updated patent review (2015-present)

Introduction: Hedgehog (Hh) signaling plays a pivotal role in tissue development and stemness, and its deregulation is found in many different tumors. Several efforts have been devoted to discovery of Hh inhibitors, including three drugs approved by the Food and Drug Administration (FDA), targeting the upstream receptor smoothened (SMO). However, SMO mutations or SMO-independent Hh pathway activation raise the need for novel Hh inhibitors.Areas covered: This review describes Hh inhibitors with anticancer potential patented in the period 2015-present.Expert opinion: Despite the initial enthusiasm in SMO antagonists, drug-resistant mutations, and SMO-independent Hh activation limited their clinical application. A growing number of therapeutic strategies are currently focusing on downstream Hh effectors (i.e. glioma-associate oncogenes (GLI) proteins) or other signaling pathways related to Hh, in addition to drug repositioning. Given the heterogenic nature of cancers, a terrific clinical impact is expected by multi-targeting approaches able to modulate simultaneously SMO and GLI, and/or additional targets that act as regulators of Hh signaling. It is expected that these alternative strategies might be investigated in clinical trials in the next years against a wide variety of tumor types, and that they provide improved outcomes compared to current SMO antagonists or other single-agent anticancer drugs.

"Hedgehog pathway": a potential target of itraconazole in the treatment of cancer

PURPOSE

Itraconazole is an antifungal drug that has been clinically used for over 30 years. In recent years, scholars have discovered that it possesses an anticancer effect. Moreover, its mechanism has been clarified to some degree. What deserves to be mentioned is that itraconazole acting on the Hedgehog pathway has made a new progress in the treatment of cancers. While interestingly, studies have demonstrated that the Hedgehog pathway is largely activated in different cancer cells.

RESULT

This review tries to highlight the effect of itraconazole on smoothened receptor (SMO) in the Hedgehog pathway, thereby reducing the glioma-associated oncogene homolog (GLI) release and finally exhibiting a range of anticancer effects, promoting apoptosis of cancer cells, and inhibiting proliferation by indirect inhibition of NF-κB pathway and inflammation, moreover, promoting the expression of cyclin-dependent kinase inhibitors, inhibiting the expression of target genes transcribed by GLI such as BCL-2 and Cyclin-D1. Besides, itraconazole increases the number of Bnip3, subsequently, inducing the dissociation of the Beclin-1/BCL-2 binding complex, as a result of ultimately promoting autophagy of cancer cells.

CONCLUSION

As a new anticancer drug, whether itraconazole eventually entering clinical application requires the joint eforts of all scholars. In any case, an in-depth study on itraconazole will bring new hope for cancer patients in the near future.

Inhibition of hedgehog signaling by stereochemically defined des-triazole itraconazole analogues

Dysregulation of the hedgehog (Hh) signaling pathway is associated with cancer occurrence and development in various malignancies. Previous structure-activity relationships (SAR) studies have provided potent Itraconazole (ITZ) analogues as Hh pathway antagonists. To further expand on our SAR for the ITZ scaffold, we synthesized and evaluated a series of compounds focused on replacing the triazole. Our results demonstrate that the triazole region is amenable to modification to a variety of different moieties; with a single methyl group representing the most favorable substituent. In addition, nonpolar substituents were more active than polar substituents. These SAR results provide valuable insight into the continued exploration of ITZ analogues as Hh pathway antagonists.

Investigation of the Detailed Internal Structure and Dynamics of Itraconazole by Solid-State NMR Measurements

The structure and dynamics of itraconazole were investigated by ¹³C 2DPASS MAS SSNMR and spin-lattice relaxation time measurement to get an insight into its multiple biological activities, e.g., antifungal, antiviral, anticancer activities, etc. The molecular correlation time at chemically different sites of carbon nuclei was calculated by considering that the spin-lattice relaxation mechanism is mainly dominated by chemical shift anisotropy interaction and heteronuclear dipole-dipole interaction. The spin-lattice relaxation time is long for C35, C6, C5, and C34 carbon nuclei that participated in the 1, 2, 4-triazole ring. On the contrary, it is comparatively shorter for C1, C2, C3, and C4 carbon nuclei associated with the sec-butyl group in the triazolane side-chain region. Chemical shift anisotropy (CSA) parameters of C5, C6, C34, and C35 nuclei are much higher than those of C1, C2, C3, C4 nuclei, indicating that the relaxation mechanism at a high value of magnetic field is predominated by chemical shift anisotropy interaction. The molecular correlation time of carbon nuclei residing at the side-chain region is 2-3 orders of magnitude lesser than that of those participated in the 1,2,4-triazole ring. The spin-lattice relaxation time is very long for carbon nuclei C28 and C30 bonded with chlorine. Asymmetry and anisotropy parameters are also very high for the spinning CSA sideband pattern corresponding to the C28 and C30 nuclei. The molecular correlation time is on the order of 10^-3 s for C28 and 10^-4 s for C30, whereas for side-chain carbon nuclei, it is on the order of 10^-6 s. This suggests that the effective magnetic field experienced by C28 and C30 nuclei is affected by the polarization of the chemical bond. A huge variation in molecular correlation time is observed for chemically different sites of carbon nuclei of the itraconazole molecule. These investigations vividly portrayed how the structure is correlated with the dynamics of a valuable drug, itraconazole, with multiple biological activities. This study will enlighten the way of inventing advance medicine for multiple biological activities in the pharmaceutical industry.

Synthesis of 3-(tri/difluoromethyl)-1H-1,2,4-triazol-5(4H)-ones via the cyclization of hydrazinecarboxamides with tri/difluoroacetic anhydride

An efficient method for the synthesis of structurally diverse 4-aryl-3-(tri/difluoromethyl)-1H-1,2,4-triazol-5(4H)-ones through the cyclization of hydrazinecarboxamides with tri/difluoroacetic anhydride is presented. The method is simple and environmentally benign, providing tri/difluoromethylated 1,2,4-triazol-5(4H)-ones in moderate-to-good yields. A mechanism is proposed to proceed via a tandem reaction of tri/difluoroacetylation, nucleophilic addition and water elimination. Some of these compounds exhibit promising insecticidal activities.

Formulation and evaluation of itraconazole liposomes for Hedgehog pathway inhibition

Itraconazole (ITZ) is an FDA-approved antifungal agent that has recently been explored for novel biological properties. In particular, ITZ was identified as a potent inhibitor of the hedgehog (Hh) pathway, a cell signalling pathway that has been linked to a variety of cancers and accounts for ∼25% of paediatric medulloblastoma (MB) cases. To date, there is not a targeted therapeutic option for paediatric MB, resulting in long-term side effects such as hormone deficiency, organ damage and secondary cancers. A primary obstacle for developing targeted therapy for brain ailments is the presence of the blood-brain barrier (BBB), which protects the brain from potentially harmful substances. Due to its size and hydrophobicity, ITZ does not penetrate the BBB. Alternatively, liposomes are being increasingly used within the clinic to increase drug bioavailability, target specificity and BBB permeability. With this in mind, we have successfully developed ITZ-containing liposomes with an optimal size for BBB penetration (<100 nm) and encapsulation efficiency (∼95%) by utilizing a continuous manufacturing approach-turbulent coaxial jet in co-flow. Our preliminary in vitro data demonstrate that these liposomes inhibit the Hh pathway, albeit at a reduced level in comparison to free ITZ. (196/250 words).

Truncated Itraconazole Analogues Exhibiting Potent Anti-Hedgehog Activity and Improved Drug-like Properties

We conducted a structure-activity relationship study to explore simplified analogues of the itraconazole (ITZ) scaffold for their ability to inhibit the hedgehog (Hh) signaling pathway. These analogues were based on exploring the effects of chemical modifications to the linker and triazolone/side chain region of ITZ. Analogue 11 was identified as the most potent compound in our first generation, with an IC₅₀ value of 81 nM in a murine Hh-dependent basal cell carcinoma. Metabolic identification studies led us to identify truncated piperazine (26) as the major metabolite in human liver microsomes (HLMs) and an improved Hh pathway inhibitor (IC₅₀ = 22 nM). This work verifies that continued truncation of the ITZ scaffold is a practical method to maintain potent anti-Hh activity while also reducing the molecular weight for the ITZ scaffold and achieving improved pharmacokinetic properties.

Inhibition of the hedgehog pathway for the treatment of cancer using Itraconazole

Itraconazole (ITZ) is an anti-fungal drug that has been used in clinical practice for nearly 35 years. Recently, numerous experiments have shown that ITZ possesses anti-cancer properties. The Hedgehog (Hh) pathway plays a pivotal role in fundamental processes, including embryogenesis, structure, morphology and proliferation in various species. This pathway is typically silent in adult cells, and inappropriate activity is linked to various tumor types. The most important mechanism of ITZ in the treatment of cancer is inhibition of the Hh pathway through the inhibition of smoothened receptors (SMO), glioma-associated oncogene homologs (GLI), and their downstream targets. In this review, we discuss the mechanisms of ITZ in the treatment of cancer through inhibition of the Hh pathway, which includes anti-inflammation, prevention of tumor growth, induction of cell cycle arrest, induction of apoptosis and autophagy, prevention of angiogenesis, and drug resistance. We also discuss the clinical use of ITZ in many types of cancers. We hope this review will provide more information to support future studies on ITZ in the treatment of various cancers.

Physicochemical and pathohistological changes in experimental fibrosarcoma tumors of hamsters treated with metformin and itraconazole

The anticancer effects of metformin (an antihyperglycaemic agent) and itraconazole (an antifungal agent), which are established non-oncologic drugs, were investigated in the present study. The weight, diameter, volume, density, surface, surface to volume ratio and immunohistochemistry of experimental fibrosarcoma tumors were investigated in hamsters treated with metformin and itraconazole. Briefly, the hamsters were injected with BHK-21/C13 cells in order to induce fibrosarcoma, and the animals were treated daily with metformin, itraconazole or a combination of the two drugs. Subsequently, blood samples were obtained for biochemical analyses and the tumors were excised, weighed and measured. The tumor samples were pathohistologically and immunohistochemically assessed for proliferation marker protein Ki-67, hematopoietic progenitor cell antigen CD34, cytochrome c oxidase subunit 4 (COX4), glucose transporter 1 (GLUT1) and inducible nitric oxide synthase (iNOS), and vital organs were toxicologically tested. Ki-67-positivity and cytoplasmic marker (CD34, COX4, GLUT1, iNOS) immunoexpression in the tumor samples were quantified. The results revealed that the combination of metformin and itraconazole significantly altered the physicochemical and pathohistological characteristics of the hamster fibrosarcoma tumors, including absolute and relative weight, volume, density, length, surface area, surface to volume ratio, Ki-67-positivity and the immunoexpression of cytoplasmic markers, without indications of toxicity. Furthermore, metformin with itraconazole demonstrated antiproliferative functions in cervical carcinoma HeLa, colon carcinoma HT-29, lung carcinoma A549 and fibrosarcoma BHK-21/C13 cells, with markedly lower cytotoxicity in the normal fetal lung MRC-5 cells. In conclusion, the administration of metformin in combination with itraconazole may inhibit the growth of fibrosarcoma tumors in vivo and the proliferation of various malignant cell lines in vitro, suggesting that this may be an effective and safe approach as a nontoxic anticancer adjuvant and relapse prevention therapy.

Overview of Recent Strategic Advances in Medicinal Chemistry

Introducing novel strategies, concepts, and technologies that speed up drug discovery and the drug development cycle is of great importance both in the highly competitive pharmaceutical industry as well as in academia. This Perspective aims to present a "big-picture" overview of recent strategic innovations in medicinal chemistry and drug discovery.

Structure-Activity Relationships for Itraconazole-Based Triazolone Analogues as Hedgehog Pathway Inhibitors

The Food and Drug Administration-approved antifungal agent, itraconazole (ITZ), has been increasingly studied for its novel biological properties. In particular, ITZ inhibits the hedgehog (Hh) signaling pathway and has the potential to serve as an anticancer chemotherapeutic against several Hh-dependent malignancies. We have extended our studies on ITZ analogues as Hh pathway inhibitors through the design, synthesis, and evaluation of novel des-triazole ITZ analogues that incorporate modifications to the triazolone/side chain region of the scaffold. Our overall results suggest that the triazolone/side chain region can be replaced with various functionalities (hydrazine carboxamides and meta-substituted amides) resulting in improved potency when compared to ITZ. Our studies also indicate that the stereochemical orientation of the dioxolane ring is important for both potent Hh pathway inhibition and compound stability. Finally, our studies suggest that the ITZ scaffold can be successfully modified in terms of functionality and stereochemistry to further improve its anti-Hh potency and physicochemical properties.

Development of posaconazole-based analogues as hedgehog signaling pathway inhibitors

Inhibition of the hedgehog (Hh) signaling pathway has been validated as a therapeutic strategy to treat basal cell carcinoma and holds potential for several other forms of human cancer. Itraconazole and posaconazole are clinically useful triazole anti-fungals that are being repurposed as anti-cancer agents based on their ability to inhibit the Hh pathway. We have previously demonstrated that removal of the triazole from itraconazole does not affect its ability to inhibit the Hh pathway while abolishing its primary side effect, potent inhibition of Cyp3A4. To develop structure-activity relationships for the related posaconazole scaffold, we synthesized and evaluated a series of des-triazole analogues designed through both ligand- and structure-based methods. These compounds demonstrated improved anti-Hh properties compared to posaconazole and enhanced stability without inhibiting Cyp3A4. In addition, we utilized a series of molecular dynamics and binding energy studies to probe specific interactions between the compounds and their proposed binding site on Smoothened. These studies strongly suggest that the tetrahydrofuran region of the scaffold projects out of the binding site and that π-π interactions between the compound and Smoothened play a key role in stabilizing the bound analogues.

Repurposing Drugs Based on Evolutionary Relationships Between Targets of Approved Drugs and Proteins of Interest

Drug repurposing has garnered much interest as an effective method for drug development among biopharmaceutical companies. The availability of information on complete sequences of genomes and their associated biological data, genotype-phenotype-disease relationships, and properties of small molecules offers opportunities to explore the repurpose-able potential of existing pharmacopoeia. This method gains further importance, especially, in the context of development of drugs against infectious diseases, some of which pose serious complications due to emergence of drug-resistant pathogens. In this article, we describe computational means to achieve potential repurpose-able drug candidates that may be used against infectious diseases by exploring evolutionary relationships between established targets of FDA-approved drugs and proteins of pathogen of interest.

Novel Tetrazole-Containing Analogues of Itraconazole as Potent Antiangiogenic Agents with Reduced Cytochrome P450 3A4 Inhibition

Itraconazole has been found to possess potent antiangiogenic activity, exhibiting promising antitumor activity in several human clinical studies. The wider use of itraconazole in the treatment of cancer, however, has been limited by its potent inhibition of the drug metabolizing enzyme cytochrome P450 3A4 (CYP3A4). In an effort to eliminate the CYP3A4 inhibition while retaining its antiangiogenic activity, we designed and synthesized a series of derivatives in which the 1,2,4-triazole ring is replaced with various azoles and nonazoles. Among these analogues, 15n with tetrazole in place of 1,2,4-triazole exhibited optimal inhibition of human umbilical vein endothelial cell proliferation with an IC₅₀ of 73 nM without a significant effect on CYP3A4 (EC₅₀ > 20 μM). Similar to itraconazole, 15n induced Niemann-Pick C phenotype (NPC phenotype) and blocked AMPK/mechanistic target of rapamycin signaling. These results suggest that 15n is a promising angiogenesis inhibitor that can be used in combination with most other known anticancer drugs.

Design of Hedgehog pathway inhibitors for cancer treatment

Hedgehog (Hh) signaling is involved in the initiation and progression of various cancers and is essential for embryonic and postnatal development. This pathway remains in the quiescent state in adult tissues but gets activated upon inflammation and injuries. Inhibition of Hh signaling pathway using natural and synthetic compounds has provided an attractive approach for treating cancer and inflammatory diseases. While the majority of Hh pathway inhibitors target the transmembrane protein Smoothened (SMO), some small molecules that target the signaling cascade downstream of SMO are of particular interest. Substantial efforts are being made to develop new molecules targeting various components of the Hh signaling pathway. Here, we have discussed the discovery of small molecules as Hh inhibitors from the diverse chemical background. Also, some of the recently identified natural products have been included as a separate section. Extensive structure-activity relationship (SAR) of each chemical class is the focus of this review. Also, clinically advanced molecules are discussed from the last 5 to 7 years. Nanomedicine-based delivery approaches for Hh pathway inhibitors are also discussed concisely.

New N,C-Diaryl-1,2,4-triazol-3-ones: Synthesis and Evaluation as Anticancer Agents

BACKGROUND

A set of 2,5-diaryl-1,2,4-triazol-3-ones was synthesized in two steps and evaluated as regards their activity in some relevant biological targets related to cancer.

OBJECTIVE

This study is focused on the synthesis and the biological evaluation of 2,5-diaryl-1,2,4- triazol-3-ones. In this sense, the effect of the synthetic triazolones on the proliferation of HT-29 and A549 cancer cells and on HEK non-cancer cells has been measured. In addition, the effects of triazolones on the expression of hTERT, c-Myc and PD-L1 genes and on the production of c-Myc and PD-L1 proteins have also been evaluated.

METHOD

A set of 2,5-diaryl-1,2,4-triazol-3-ones was synthesized in two steps. Firstly, N- (aminocarbonyl)-3-methoxybenzamide was prepared by coupling 3-methoxybenzoic acid and cyanamide followed by aqueous HCl hydrolysis. Then, the 2,5-diaryl-1,2,4-triazol-3-ones were obtained upon reaction of N-(aminocarbonyl)-3-methoxybenzamide with arylhydrazines in decaline at 170ºC. The ability of the triazolones to inhibit cell proliferation was measured against two human carcinoma cell lines (colorectal HT-29 and lung A549), and one non-tumor cell line (HEK- 293) by MTT assay. The downregulation of the synthetic triazolones on the expression of the hTERT, c-Myc and PD-L1 genes was measured by an RT-qPCR analysis. Their ability to regulate the expression of the c-Myc and PD-L1 proteins, as well as their direct interaction with c-Myc protein, was determined by the ELISA method. Finally, the direct interaction of triazolones with PD-L1 protein was assessed by the thermal shift assay.

RESULTS

Ten 2,5-diaryl-1,2,4-triazol-3-ones were synthesized and characterized by spectroscopic methods. A thorough study by 1H, 13C, 15N and 19F NMR spectroscopy showed that all the synthetic compounds exist as 4H-triazolones and not as hydroxytriazoles or 1H-triazolones. Some triazolones showed relatively high activities together with very poor toxicity in non-tumor cell line HEK-293. 2-(2-fluorophenyl)-5-(3-methoxyphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (4) was particularly active in downregulating c-Myc and PD-L1 gene expression although 2-(4- chloro-2-fluorophenyl)-5-(3-methoxyphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (8) is the one that combines the best downregulatory activities in the three genes studied. Considering protein expression, the most active compounds are 2-(4-fluorophenyl)-5-(3-methoxyphenyl)-2,4-dihydro- 3H-1,2,4-triazol-3-one (5) and 2-(2,4,6-trifluorophenyl)-5-(3-methoxyphenyl)-2,4-dihydro-3H- 1,2,4-triazol-3-one (10) (c-Myc expression) and 2-(2,3,5,6-tetrafluorophenyl)-5-(3-methoxyphenyl)- 2,4-dihydro-3H-1,2,4-triazol-3-one (11) and (8) (PD-L1 expression).

CONCLUSION

Some of the triazolones studied have shown relevant activities in the inhibition of the hTERT, c-Myc and PD-L1 genes, and in the inhibition of c-Myc and PD-L1 protein secretion, the 2-(4-chloro-2-fluorophenyl)-5-(3-methoxyphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (8) was found to be a particularly promising lead compound.

The potential to treat lung cancer via inhalation of repurposed drugs

Lung cancer is a highly invasive and prevalent disease with ineffective first-line treatment and remains the leading cause of cancer death in men and women. Despite the improvements in diagnosis and therapy, the prognosis and outcome of lung cancer patients is still poor. This could be associated with the lack of effective first-line oncology drugs, formation of resistant tumors and non-optimal administration route. Therefore, the repurposing of existing drugs currently used for different indications and the introduction of a different method of drug administration could be investigated as an alternative to improve lung cancer therapy. This review describes the rationale and development of repositioning of drugs for lung cancer treatment with emphasis on inhalation. The review includes the current progress of repurposing non-cancer drugs, as well as current chemotherapeutics for lung malignancies via inhalation. Several potential non-cancer drugs such as statins, itraconazole and clarithromycin, that have demonstrated preclinical anti-cancer activity, are also presented. Furthermore, the potential challenges and limitations that might hamper the clinical translation of repurposed oncology drugs are described.

Posaconazole-Induced Pseudohyperaldosteronism

A woman in her late 60s with disseminated histoplasmosis was treated with posaconazole because first-line therapies were not tolerated. She subsequently presented with decompensated heart failure, hypertension, and hypokalemia. Laboratory tests revealed low renin and aldosterone levels. A potential mechanism is inhibition of the enzyme 11β-hydroxysteroid dehydrogenase 2, with resultant apparent mineralocorticoid excess.

Repurposing itraconazole to the benefit of skin cancer treatment: A combined azole-DDAB nanoencapsulation strategy

In this work, we aimed at developing an improved topical SLN formulation combining itraconazole delivery with a coating layer of didodecyldimethylammonium bromide, thus repurposing the drug effectiveness by synergistic skin anticancer effectiveness. In order to obtain a stable SLN formulation with small homogeneously dispersed particles, a deep formulative study was developed screening three different solid lipids (Suppocire NB, Cetyl Palmitate and Dynasan 114) for the SLN preparation by the phase inversion temperature. A bluishcolored shade formulation, with homogeneous small particles size (<50 nm) was obtained only using Suppocire NB. The cytotoxicity of all SLN was tested after 24 h exposure against three adherent skin cell lines (A431, HaCaT and SK-MEL-5). Results demonstrate that both unloaded and drugloaded SLN did not significantly affect the cell viability of the non-tumoral HaCaT cell line, thus confirming the safe potential topical application of these formulations. A dose-dependent decrease in cell viability was observed for the tumoral cell lines, A431 and SK-MEL-5, with a significant reduction of the A431 cancer cell line viability. The drug molecule addition to the uncoated nanoparticles was able to increase of almost 20% the reduction of the viability of the cancer cells treated. Ours results demonstrate the potentiality of repurposing itraconazole activity by using the combined nanoencapsulation strategy with the positively charged coating layer on SLN, which can be further investigated as a promising stable and safe approach to significantly reduce the viability of skin cancer cells.

Structure-Activity Relationship Studies of Vitamin D3 Analogues Containing an Ether or Thioether Linker as Hedgehog Pathway Inhibitors

The Hedgehog (Hh) signaling pathway is critical for embryonic patterning and postembryonic tissue regeneration. Constitutive pathway activation has also been linked to human malignancies such as basal cell carcinoma (BCC) and medulloblastoma; therefore, multiple small-molecule scaffolds that inhibit Hh signaling are in development. Previously, Grundmann's alcohol, also known as the "northern region" of vitamin D3 (VD3), has been identified as a moderate Hh pathway inhibitor. In this study, isomers of Grundmann's alcohol with different orientations of the C4 hydroxy group and C3α proton were investigated to determine the optimal configuration for this hexahydroindane scaffold with respect to Hh inhibition. A series of analogues containing Grundmann's alcohol linked to a substituted phenyl or benzyl ring through an ether or thioether linker were synthesized and evaluated for their anti-Hh activity. Of these, analogue 17 ((1R,3aR,4R,7aR)-1-[(R)-1,5-dimethylhexyl]-4-(4-aminophenoxy)-7a-methyloctahydro-1H-indene) demonstrated potent anti-Hh activity in Hh-dependent BCC cells and did not activate canonical vitamin D receptor signaling, demonstrating its selective nature for the Hh signaling pathway.

Strategies to target the Hedgehog signaling pathway for cancer therapy

Hedgehog (Hh) signaling is an essential pathway in the human body, and plays a major role in embryo development and tissue patterning. Constitutive activation of the Hh signaling pathway through sporadic mutations or other mechanisms is explicitly associated with cancer development and progression in various solid malignancies. Therefore, targeted inhibition of the Hh signaling pathway has emerged as an attractive and validated therapeutic strategy for the treatment of a wide range of cancers. Vismodegib, a first-in-class Hh signaling pathway inhibitor was approved by the US Food and Drug Administration in 2012, and sonidegib, another potent Hh pathway inhibitor, received FDA's approval in 2015 as a new treatment of locally advanced or metastatic basal cell carcinoma. The clinical success of vismodegib and sonidegib provided strong support for the development of Hh signaling pathway inhibitors via targeting the smoothened (Smo) receptor. Moreover, Hh signaling pathway inhibitors aimed to target proteins, which are downstream or upstream of Smo, have also been pursued based on the identification of additional therapeutic benefits. Recently, much progress has been made in Hh singling and inhibitors of this pathway. Herein, medicinal chemistry strategies, especially the structural optimization process of different classes of Hh inhibitors, are comprehensively summarized. Further therapeutic potentials and challenges are also discussed.

Co-delivery of doxorubicin and itraconazole by Pluronic® P123 coated liposomes to enhance the anticancer effect in breast cancers

A Pluronic® P123 modified liposome-based co-delivery system of hydrophilic doxorubicin and hydrophobic itraconazole for enhanced anticancer effect in breast cancers.

Novel Cell-Killing Mechanisms of Hydroxyurea and the Implication toward Combination Therapy for the Treatment of Fungal Infections

We have previously reported that an erg11 mutation affecting ergosterol synthesis and a hem13 mutation in the heme synthesis pathway significantly sensitize the fission yeast Schizosaccharomyces pombe to hydroxyurea (HU) (1, 2). Here we show that treatment with inhibitors of Erg11 and heme biosynthesis phenocopies the two mutations in sensitizing wild-type cells to HU. Importantly, HU synergistically interacts with the heme biosynthesis inhibitor sampangine and several Erg11 inhibitors, the antifungal azoles, in causing cell lethality. Since the synergistic drug interactions are also observed in the phylogenetically divergent Saccharomyces cerevisiae and the opportunistic fungal pathogen Candida albicans, the synergism is likely conserved in eukaryotes. Interestingly, our genetic data for S. pombe has also led to the discovery of a robust synergism between sampangine and the azoles in C. albicans Thus, combinations of HU, sampangine, and the azoles can be further studied as a new method for the treatment of fungal infections.

Repurposing itraconazole for the treatment of cancer

The repurposing of drugs is becoming increasingly attractive as it avoids the lengthy process and cost implications associated with bringing a novel drug to market. Itraconazole is a broad-spectrum anti-fungal agent. An emerging body of in vivo, in vitro and clinical evidence have confirmed that it also possesses antineoplastic activities and has a synergistic action when combined with other chemotherapeutic agents. It acts via several mechanisms to prevent tumour growth, including inhibition of the Hedgehog pathway, prevention of angiogenesis, decreased endothelial cell proliferation, cell cycle arrest and induction of auto-phagocytosis. These allow itraconazole, either alone or in combination with other cytotoxic agents, to increase drug efficacy and overcome drug resistance. This study reviews the reported literature on the use of itraconazole in a variety of malignancies and highlights the recent insights into the critical pathways acted upon to prevent tumour growth.

Blocking epithelial-to-mesenchymal transition in glioblastoma with a sextet of repurposed drugs: the EIS regimen

This paper outlines a treatment protocol to run alongside of standard current treatment of glioblastoma- resection, temozolomide and radiation. The epithelial to mesenchymal transition (EMT) inhibiting sextet, EIS Regimen, uses the ancillary attributes of six older medicines to impede EMT during glioblastoma. EMT is an actively motile, therapy-resisting, low proliferation, transient state that is an integral feature of cancers’ lethality generally and of glioblastoma specifically. It is believed to be during the EMT state that glioblastoma’s centrifugal migration occurs. EMT is also a feature of untreated glioblastoma but is enhanced by chemotherapy, by radiation and by surgical trauma. EIS Regimen uses the antifungal drug itraconazole to block Hedgehog signaling, the antidiabetes drug metformin to block AMP kinase (AMPK), the analgesic drug naproxen to block Rac1, the anti-fibrosis drug pirfenidone to block transforming growth factor-beta (TGF-beta), the psychiatric drug quetiapine to block receptor activator NFkB ligand (RANKL) and the antibiotic rifampin to block Wnt- all by their previously established ancillary attributes. All these systems have been identified as triggers of EMT and worthy targets to inhibit. The EIS Regimen drugs have a good safety profile when used individually. They are not expected to have any new side effects when combined. Further studies of the EIS Regimen are needed.

The antifungal pipeline: a reality check

Invasive fungal infections continue to appear in record numbers as the immunocompromised population of the world increases, owing partially to the increased number of individuals who are infected with HIV and partially to the successful treatment of serious underlying diseases. The effectiveness of current antifungal therapies - polyenes, flucytosine, azoles and echinocandins (as monotherapies or in combinations for prophylaxis, or as empiric, pre-emptive or specific therapies) - in the management of these infections has plateaued. Although these drugs are clinically useful, they have several limitations, such as off-target toxicity, and drug-resistant fungi are now emerging. New antifungals are therefore needed. In this Review, I discuss the robust and dynamic antifungal pipeline, including results from preclinical academic efforts through to pharmaceutical industry products, and describe the targets, strategies, compounds and potential outcomes.

Inhibition of 11β-hydroxysteroid dehydrogenase 2 by the fungicides itraconazole and posaconazole

Impaired 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)-dependent cortisol inactivation can lead to electrolyte dysbalance, hypertension and cardiometabolic disease. Furthermore, placental 11β-HSD2 essentially protects the fetus from high maternal glucocorticoid levels, and its impaired function has been associated with altered fetal growth and a higher risk for cardio-metabolic diseases in later life. Despite its important role, 11β-HSD2 is not included in current off-target screening approaches. To identify potential 11β-HSD inhibitors among approved drugs, a pharmacophore model was used for virtual screening, followed by biological assessment of selected hits. This led to the identification of several azole fungicides as 11β-HSD inhibitors, showing a significant structure-activity relationship between azole scaffold size, 11β-HSD enzyme selectivity and inhibitory potency. A hydrophobic linker connecting the azole ring to the other, more polar end of the molecule was observed to be favorable for 11β-HSD2 inhibition and selectivity over 11β-HSD1. The most potent 11β-HSD2 inhibition, using cell lysates expressing recombinant human 11β-HSD2, was obtained for itraconazole (IC₅₀ 139±14nM), its active metabolite hydroxyitraconazole (IC₅₀ 223±31nM) and posaconazole (IC₅₀ 460±98nM). Interestingly, experiments with mouse and rat kidney homogenates showed considerably lower inhibitory activity of these compounds towards 11β-HSD2, indicating important species-specific differences. Thus, 11β-HSD2 inhibition by these compounds is likely to be overlooked in preclinical rodent studies. Inhibition of placental 11β-HSD2 by these compounds, in addition to the known inhibition of cytochrome P450 enzymes and P-glycoprotein efflux transport, might contribute to elevated local cortisol levels, thereby affecting fetal programming.