Development of posaconazole-based analogues as hedgehog signaling pathway inhibitors

Palladium-Catalyzed [2+3] Cycloaddition/Cross-Coupling Reaction: Z/E and Diastereoselective Synthesis of Dendralene-Functionalized Dihydrofurans

Herein, we describe a Pd-catalyzed [2+3] cycloaddition/cross-coupling reaction of allenyl acetates for the Z/E selective and diastereoselective synthesis of dendralene-functionalized dihydrofurans. Remarkably, mechanistic studies show the formation of an epoxide from a carbonyl bond via cycloaddition, which is practically and mechanistically significant for the construction of other bioactive heterocyclic epoxides. This research also revealed the utility and potential of allenic esters as C2 synthons and 1,2-biselectrophiles in cycloaddition reactions.

Molecular Mechanisms Involving the Sonic Hedgehog Pathway in Lung Cancer Therapy: Recent Advances

According to the latest statistics from the International Agency for Research on Cancer (IARC), lung cancer is one of the most lethal malignancies in the world, accounting for approximately 18% of all cancer-associated deaths. Yet, even with aggressive interventions for advanced lung cancer, the five-year survival rate remains low, at around 15%. The hedgehog signaling pathway is highly conserved during embryonic development and is involved in tissue homeostasis as well as organ development. However, studies have documented an increasing prevalence of aberrant activation of HH signaling in lung cancer patients, promoting malignant lung cancer progression with poor prognostic outcomes. Inhibitors targeting the HH pathway have been widely used in tumor therapy, however, they still cannot avoid the occurrence of drug resistance. Interestingly, natural products, either alone or in combination with chemotherapy, have greatly improved overall survival outcomes for lung cancer patients by acting on the HH signaling pathway because of its unique and excellent pharmacological properties. In this review, we elucidate on the underlying molecular mechanisms through which the HH pathway promotes malignant biological behaviors in lung cancer, as well as the potential of inhibitors or natural compounds in targeting HH signaling for clinical applications in lung cancer therapy.

Repurposing of posaconazole as a hedgehog/SMO signaling inhibitor for embryonal rhabdomyosarcoma therapy

Posaconazole (POS) is a novel antifungal agent, which has been repurposed as an anti-tumor drug for its potential inhibition of Hedgehog signaling pathway. Hedgehog pathway is reported to be abnormally activated in embryonal rhabdomyosarcoma (ERMS), this study aimed to reveal whether POS could inhibit Hedgehog signaling pathway in ERMS. Following POS treatment, XTT viability assay was used to determine the cell proliferation of ERMS cell lines. Protein changes related to Hedgehog signaling, cell cycle and autophagy were detected by Western blot. The cell cycle distribution was analyzed by flow cytometry. Moreover, a subcutaneous tumor mouse model of ERMS was established to assess the anti-tumor effect of POS. POS was found to inhibit tumor progression by inducing G0/G1 arrest and autophagy of RD, RMS-YM, and KYM-1 cells dose-dependently. Western blot demonstrated that POS downregulated the expressions of SMO, Gli1, c-Myc, CDK4, and CDK6, while upregulated the expressions of autophagy-related proteins. Immunofluorescence microscopy revealed a significant increase of LC3B puncta in POS-treated ERMS cells. Furthermore, POS treatment led to a significant inhibition of tumor growth in mice bearing ERMS. Our findings could provide a theoretical basis and have important clinical implications in developing POS as a promising agent against ERMS by targeting Hedgehog pathway.

Growing Preferences towards Analog-based Drug Discovery

BACKGROUND

The major concern of today's time is the developing resistance in most of the clinically derived pathogenic micro-organisms for available drugs through several mechanisms. Therefore, there is a dire need to develop novel molecules with drug-like properties that can be effective against the otherwise resistant micro-organisms.

METHODS

New drugs can be developed using several methods like structure-based drug design, ligandbased drug design, or by developing analogs of the available drugs to further improve their effects. However, the smartness is to opt for the techniques that have comparatively less expenditure, lower failure rates, and faster discovery rates.

RESULTS

Analog-Based Drug Design (ABDD) is one such technique that researchers worldwide are opting to develop new drug-like molecules with comparatively lower market values. They start by first designing the analogs sharing structural and pharmacological similarities to the existing drugs. This method embarks on scaffold structures of available drugs already approved by the clinical trials, but are left ineffective because of resistance developed by the pathogens.

CONCLUSION

In this review, we have discussed some recent examples of anti-fungal and anti-bacterial (antimicrobial) drugs that were designed based on the ABDD technique. Also, we have tried to focus on the in silico tools and techniques that can contribute to the designing and computational screening of the analogs, so that these can be further considered for in vitro screening to validate their better biological activities against the pathogens with comparatively reduced rates of failure.

Voriconazole and the Risk of Keratinocyte Carcinomas Among Lung Transplant Recipients in the United States

Question

What is the association between voriconazole, an antifungal used to treat aspergillosis infections, and the risk of keratinocyte carcinomas among recipients of lung transplants?

Findings

In a population-based cohort study of 9599 non-Hispanic white recipients of 9793 lung transplants in the United States (2007-2016) with linkage to pharmacy claims, increasing cumulative voriconazole exposure was associated with an increased risk of cutaneous squamous cell carcinoma.

Meaning

These findings suggest that physicians caring for lung transplant recipients at high risk for aggressive keratinocyte carcinomas should limit voriconazole exposure when possible and encourage skin protection behaviors and more frequent cancer screenings.

Importance

The antifungal medication voriconazole is used to prevent and treat aspergillosis, a major cause of mortality among recipients of lung transplants (hereinafter referred to as lung recipients). Small studies suggest that voriconazole increases risk of cutaneous squamous cell carcinoma (SCC).

Objective

To examine associations of voriconazole and other antifungal medications with risk of keratinocyte carcinomas (SCC and cutaneous basal cell carcinoma [BCC]) in lung recipients.

Design, Setting, and Participants

This population-based cohort study included non-Hispanic white patients (n = 9599) who underwent lung transplant in the United States from January 1, 2007, to December 31, 2016, identified through the national Scientific Registry of Transplant Recipients with data linkable to pharmacy claims. Data were analyzed from March 1, 2018, to February 13, 2019.

Exposures

Antifungal medication use, including voriconazole, itraconazole, posaconazole, and other antifungals, was ascertained from pharmacy claims and treated as a time-varying exposure (assessed every 30 days). Cumulative antifungal exposure was calculated as the total number of exposed months.

Main Outcomes and Measures

Primary outcomes were the first SCC or BCC reported to the transplant registry by transplant centers. Follow-up began at transplant and ended at SCC or BCC diagnosis, transplant failure or retransplant, death, loss to follow-up, or December 31, 2016. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (AHRs) for each antifungal medication.

Results

Among the 9793 lung transplants in 9599 recipients included in the analysis, median age at transplant was 59 (interquartile range [IQR], 48-65) years, 5824 (59.5%) were male, and 5721 (58.4%) reported ever smoking. During a median follow-up of 3.0 (IQR, 1.4-5.0) years after transplant, 1031 SCCs (incidence, 322 per 10 000 person-years) and 347 BCCs (incidence, 101 per 10 000 person-years) were reported. Compared with lung recipients with no observed voriconazole use, those with 1 to 3 months of voriconazole use experienced increased AHR for SCC of 1.09 (95% CI, 0.90-1.31); 4 to 7 months, 1.42 (95% CI, 1.16-1.73); 8 to 15 months, 2.04 (95% CI, 1.67-2.50); and more than 15 months, 3.05 (95% CI, 2.37-3.91). Ever itraconazole exposure was associated with increased SCC risk (AHR, 1.20; 95% CI, 1.00-1.45). For BCC, risk was not associated with voriconazole use but was increased with itraconazole use (AHR, 1.74; 95% CI, 1.27-2.37) or posaconazole use (AHR, 1.55; 95% CI, 1.00-2.41).

Conclusions and Relevance

In this study, voriconazole use was associated with increased SCC risk among lung recipients, especially after prolonged exposure. Further research evaluating the risk-benefit ratio of shorter courses or alternative medications in transplant recipients at high risk for SCC should be considered.

Rh-Catalyzed oxidative homo-coupling cyclization of 2,3-allenols to conjugated furylenones

An unexpected rhodium-catalyzed highly regio- and stereo-selective bimolecular nucleophilic oxyrhodation/insertion/1,4-Rh migration/β-H elimination reaction of 2,3-allenols affording (2,5-dihydrofuran-3-yl)but-2(E)-en-1-one derivatives is reported.

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.

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.

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.

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.