Epothilones as Natural Compounds for Novel Anticancer Drugs Development

Harnessing bacterial metabolites for enhanced cancer chemotherapy: unveiling unique therapeutic potentials

Cancer poses a serious threat to health globally, with millions diagnosed every year. According to Global Cancer Statistics 2024, about 20 million new cases were reported in 2022, and 9.7 million people worldwide died of this condition. Advanced therapies include combination of one or more treatment procedures, depending on the type, stage, and particular genetic constitution of the cancer, which may include surgery, radiotherapy, chemotherapy, immunotherapy, hormone therapy, targeted therapy, and stem cell transplant. Also, awareness about lifestyle changes, preventive measures and screening at early stages has reduced the incidence of the disease; still, there is a major failure in controlling the incidence of cancer because of its complex and multifaceted nature. With increasing interest in bacterial metabolites as possible novel and effective treatment options in cancer therapy, their main benefits include not only direct anticancer effects but also the modulation of the immune system and potential for targeted and combination therapies. They can therefore be used in combination with chemotherapy, radiotherapy, or immunotherapy to improve outcomes or reduce side effects. Furthermore, nanoparticle-based delivery systems have the potential to enhance the potency and safety of anticancer drugs by providing improved stability, targeted release, and controlled delivery.

Combining culture optimization and synthetic biology to improve production and detection of secondary metabolites in Myxococcus xanthus: application to myxoprincomide

Microbial secondary metabolites play crucial ecological roles in governing species interactions and contributing to their defense strategies. Their unique structures and potent bioactivities have been key in discovering antibiotics and anticancer drugs. Genome sequencing has undoubtedly revealed that myxobacteria constitute a huge reservoir of secondary metabolites as the well-known producers, actinomycetes. However, because most secondary metabolites are not produced in the laboratory context, the natural products from myxobacteria characterized to date represent only the tip of the iceberg. By combining the engineering of a dedicated Myxococcus xanthus DZ2 chassis strain with a two-step growth medium protocol, we provide a new approach called two-step Protocol for Resource Integration and Maximization-Biomolecules Overproduction and Optimal Screening Therapeutics (2PRIM-BOOST) for the production of non-ribosomal peptides synthetases (NRPS)/polyketides synthases (PKS) secondary metabolites from myxobacteria. We further show that the 2PRIM-BOOST strategy will facilitate the screening of secondary metabolites for biological activities of medical interest. As proof of concept, using a constitutive strong promoter, the myxoprincomide from M. xanthus DZ2 has been efficiently produced and its biosynthesis has been enhanced using the 2PRIM-BOOST approach, allowing the identification of new features of myxoprincomide. This strategy should allow the chances to produce and discover new NRPS, PKS, and mixed NRPS/PKS hybrid natural metabolites that are currently considered as cryptic and are the most represented in myxobacteria.IMPORTANCEMicrobial secondary metabolites are important in species interactions and are also a prolific source of drugs. Myxobacteria are ubiquitous soil-dwelling bacteria constituting a huge reservoir of secondary metabolites. However, because most of these molecules are not produced in the laboratory context, one can estimate that only one-tenth have been characterized to date. Here, we developed a new strategy called two-step Protocol for Resource Integration and Maximization-Biomolecules Overproduction and Optimal Screening Therapeutics (2PRIM-BOOST) that combines the engineering of a dedicated Myxococcus xanthus chassis strain together with growth medium optimization. By combining these strategies with the insertion of a constitutive promoter upstream the biosynthetic gene cluster (BGC), the production of myxoprincomide, a characterized low-produced secondary metabolite, was successfully and significantly increased. The 2PRIM-BOOST enriches the toolbox used to produce previously cryptic metabolites, unveil their ecological role, and provide new molecules of medical interest.

Synthesis and Evaluation of Thiazolyl-indole-2-carboxamide Derivatives as Potent Multitarget Anticancer Agents

Cancer is a complex disease driven by the dysregulation of multiple signaling pathways and cellular processes. The development of compounds capable of exerting multitarget actions against these key pathways involved in cancer progression is a promising therapeutic approach. Here, a series of novel (E/Z)-N-(4-(2-(2-(substituted)hydrazineyl)-2-oxoethyl)thiazol-2-yl)-1H-indole-2-carboxamide derivatives (6a-6z) were designed, synthesized, and evaluated for their biological activity. Compounds 6e, 6i, 6q, 6v, 7a, and 7b exhibited exceptional cytotoxicity against various cancer cell lines, particularly 6i (IC50 = 6.10 ± 0.4 μM against MCF-7 cell lines) and 6v (IC50 = 6.49 ± 0.3 μM against MCF-7 cell lines). These potent compounds inhibited key protein kinases like EGFR, HER2, VEGFR-2, and CDK2, induced cell cycle arrest at the G2/M phase, and promoted apoptosis. Docking studies revealed improved binding affinity of 6i and 6v with target proteins compared to reference drugs. These findings highlight the promising potential of 6i and 6v as multitarget cancer therapeutics deserving further development.

Total Synthesis of an Epothilone Analogue Based on the Amide-Triazole Bioisosterism

Epothilones are 16-membered macrolides that act as microtubule-targeting agents to tackle cancer. Many synthetic analogues have been investigated for their activity, yet often based on macrolide structures. A notable exception is Ixabepilone, an azalide whose metabolic stability and pharmacokinetics are significantly improved. Exploiting the amide-triazole bioisosterism, in this work we report the synthesis of the first generation of epothilones lacking the macrolide or azalide structure, with the ester or amide linkage replaced by a triazole unit. Together with the synthesis of this new analogue, computational and biological evaluations have been performed too.

Utidelone-based therapy in advanced or metastatic solid tumors after failure of standard therapies: a prospective, multicenter, single-arm trial

Treatment options are limited for tumors after failure of standard therapies. Utidelone (UTD1), a novel microtubule stabilizer, given via 5 days intermittent infusion, has demonstrated high activity in heavily pretreated metastatic breast cancer, while its efficacy in other cancers was unclear. Peripheral neuropathy is a common and severe adverse event (AE) of UTD1. We performed a prospective, multicenter, single-arm trial (ChiCTR2300074299) to evaluate the efficacy and safety of UTD1 with a changed administration mode in patients with advanced or metastatic solid tumors after failure of standard therapies. UTD1 (150 mg/m2, alone or in combination with other anticancer agents) was administrated via 120 h continuous intravenous infusion every 21 days until disease progression or intolerable toxicity. A total of 50 patients were enrolled and analyzed, including 20 breast cancer patients, 11 gynecological cancer patients, 8 gastrointestinal cancer patients, 6 lung cancer patients, and 5 patients with other solid tumors. The overall median progression-free survival (PFS) was 4 months, the overall objective response rate and disease control rate were 20% and 66%, respectively, and the median overall survival was not reached. Most of the AEs were grade 1 or 2 and were manageable and reversible, the rate of grade ≥3 AEs including peripheral neuropathy was 4%. This study demonstrated a promising anti-tumor activity of UTD1 in patients with advanced or metastatic solid tumors after failure of the standard therapies. Moreover, 120 h continuous intravenous infusion was a more tolerable administration mode than 5 days intermittent infusion, and worthy of further study.

In Vivo and Clinical Studies of Natural Products Targeting the Hallmarks of Cancer

Despite more than 200 approved anticancer agents, cancer remains a leading cause of death worldwide due to disease complexity, tumour heterogeneity, drug toxicity, and the emergence of drug resistance. Accordingly, the development of chemotherapeutic agents with higher efficacy, a better safety profile, and the capability of bypassing drug resistance would be a cornerstone in cancer therapy. Natural products have played a pivotal role in the field of drug discovery, especially for the pharmacotherapy of cancer, infectious, and chronic diseases. Owing to their distinctive structures and multiple mechanistic activities, natural products and their derivatives have been utilized for decades in cancer treatment protocols. In this review, we delve into the potential of natural products as anticancer agents by targeting cancer's hallmarks, including sustained proliferative signalling, evading growth suppression, resisting apoptosis and cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. We highlight the molecular mechanisms of some natural products, in vivo studies, and promising clinical trials. This review emphasizes the significance of natural products in fighting cancer and the need for further studies to uncover their fully therapeutic potential.

The genetic basis of predation by myxobacteria

Myxobacteria (phylum Myxococcota) are abundant and virtually ubiquitous microbial predators. Facultatively multicellular organisms, they are able to form multicellular fruiting bodies and swarm across surfaces, cooperatively hunting for prey. Myxobacterial communities are able to kill a wide range of prey microbes, assimilating their biomass to fuel population growth. Their mechanism of predation is exobiotic - hydrolytic enzymes and toxic metabolites are secreted into the extracellular environment, killing and digesting prey cells from without. However, recent observations of single-cell predation and contact-dependent prey killing challenge the dogma of myxobacterial predation being obligately cooperative. Regardless of their predatory mechanisms, myxobacteria have a broad prey range, which includes Gram-negative bacteria, Gram-positive bacteria and fungi. Pangenome analyses have shown that their extremely large genomes are mainly composed of accessory genes, which are not shared by all members of their species. It seems that the diversity of accessory genes in different strains provides the breadth of activity required to prey upon such a smorgasbord of microbes, and also explains the considerable strain-to-strain variation in predatory efficiency against specific prey. After providing a short introduction to general features of myxobacterial biology which are relevant to predation, this review brings together a rapidly growing body of work into the molecular mechanisms and genetic basis of predation, presenting a summary of current knowledge, highlighting trends in research and suggesting strategies by which we can potentially exploit myxobacterial predation in the future.

Macrocycles and macrocyclization in anticancer drug discovery: Important pieces of the puzzle

Increasing disease-related proteins have been identified as novel therapeutic targets. Macrocycles are emerging as potential solutions, bridging the gap between conventional small molecules and biomacromolecules in drug discovery. Inspired by successful macrocyclic drugs of natural origins, macrocycles are attracting more attention for enhanced binding affinity and target selectivity. Due to the conformation constraint and structure preorganization, macrocycles can reach bioactive conformations more easily than parent acyclic compounds. Also, rational macrocyclization combined with sequent structural modification will help improve oral bioavailability and combat drug resistance. This review introduces various strategies to enhance membrane permeability in macrocyclization and subsequent modification, such as N-methylation, intramolecular hydrogen bonding modulation, isomerization, and reversible bicyclization. Several case studies highlight macrocyclic inhibitors targeting kinases, HDAC, and protein-protein interactions. Finally, some macrocyclic agents targeting tumor microenvironments are illustrated.

An update on the development on tubulin inhibitors for the treatment of solid tumors

INTRODUCTION

Microtubules play a vital role in cancer therapeutics. They are implicated in tumorigenesis, thus inhibiting tubulin polymerization in cancer cells, and have now become a significant target for anticancer drug development. A plethora of drug molecules has been crafted to influence microtubule dynamics and presently, numerous tubulin inhibitors are being investigated. This review discusses the recently developed inhibitors including natural products, and also examines the preclinical and clinical data of some potential molecules.

AREA COVERED

The current review article summarizes the development of tubulin inhibitors while detailing their specific binding sites. It also discusses the newly designed inhibitors that may be useful in the treatment of solid tumors.

EXPERT OPINION

Microtubules play a crucial role in cellular processes, especially in cancer therapy where inhibiting tubulin polymerization holds promise. Ongoing trials signify a commitment to revolutionizing cancer treatment and exploring targeted therapies. Challenges in microtubule modulation, like resistance and off-target effects, demand focused efforts, emphasizing combination therapies and personalized treatments. Beyond microtubules, promising avenues in cancer research include immunotherapy, genomic medicine, CRISPR gene editing, liquid biopsies, AI diagnostics, and stem cell therapy, showcasing a holistic approach for future advancements.

Bioprocessing of Epothilone B from Aspergillus fumigatus under solid state fermentation: Antiproliferative activity, tubulin polymerization and cell cycle analysis

Epothilone derivatives have been recognized as one of the most powerful anticancer drugs towards solid tumors, for their unique affinity to bind with β-tubulin microtubule arrays, stabilizing their disassembly, causing cell death. Sornagium cellulosum is the main source for Epothilone, however, the fermentation bioprocessing of this myxobacteria is the main challenge for commercial production of Epothilone. The metabolic biosynthetic potency of epothilone by Aspergillus fumigatus, an endophyte of Catharanthus roseus, raises the hope for commercial epothilone production, for their fast growth rate and feasibility of manipulating their secondary metabolites. Thus, nutritional optimization of A. fumigatus for maximizing their epothilone productivity under solid state fermentation process is the objective. The highest yield of epothilone was obtained by growing A. fumigatus on orange peels under solid state fermentation (2.2 μg/g), bioprocessed by the Plackett-Burman design. The chemical structure of the extracted epothilone was resolved from the HPLC and LC-MS/MS analysis, with molecular mass 507.2 m/z and identical molecular fragmentation pattern of epothilone B of S. cellulosum. The purified A. fumigatus epothilone had a significant activity towards HepG2 (IC50 0.98 μg/ml), Pancl (IC50 1.5 μg/ml), MCF7 (IC50 3.7 μg/ml) and WI38 (IC50 4.6 μg/ml), as well as a strong anti-tubulin polymerization activity (IC50 0.52 μg/ml) compared to Paclitaxel (2.0 μg/ml). The effect of A. fumigatus epothilone on the immigration ability of HepG2 cells was assessed, as revealed from the wound closure of the monolayer cells that was estimated by ~ 63.7 and 72.5%, in response to the sample and doxorubicin, respectively, compared to negative control. From the Annexin V-PI flow cytometry results, a significant shift of the normal cells to the apoptosis was observed in response to A. fumigatus epothilone by ~ 20 folds compared to control cells, with the highest growth arrest of the HepG2 cells at the G0-G1 stage.

Efficacy and safety of utidelone plus capecitabine in advanced first-line therapy for metastatic breast cancer: A multicenter real-world study

Background

The purpose of this study was to compare the efficacy and safety of utidelone plus capecitabine for advanced first-line versus second-line or above therapy in metastatic breast cancer patients who had previously received anthracycline and taxane. At the same time, we compared the efficacy of utidelone plus capecitabine and vinorelbine plus cisplatin in advanced first-line treatment of metastatic breast cancer.

Patients and methods

A retrospective cohort of 11 patients with metastatic breast cancer previously treated with anthracycline and taxane (including neoadjuvant and adjuvant therapies) for advanced first-line with utidelone plus capecitabine, 32 patients treated with second-line or above, and 60 patients with vinorelbine plus cisplatin between October 2011 and August 2022 was collected. The first and second groups were treated with utidelone plus capecitabine, and the third group was treated with vinorelbine plus cisplatin. The primary endpoint was progression-free survival (PFS), and secondary endpoints were overall survival (OS), objective response rate (ORR), and treatment safety.

Results

By 03/31/2023, median PFS reached 11.70 months (95 % CI 0.093-0.141) in utidelone plus capecitabine group in the advanced first-line therapy, compared to 5.60 months (95 % CI 0.025-0.079) in the second-line or above therapy [HR 0.42, (95 % CI 0.226-0.787), P = 0.0077]. In utidelone plus capecitabine, the median OS was not reached in the advanced first-line therapy, with a mean overall survival of 23.16 months (95 % CI 0.198-0.265); whereas the median OS in the second-line or above therapy was 19.50 months (95 % CI 0.083-0.307), with a mean overall survival of 16.89 months (95 % CI 0.136-0.202) [HR 0.26, (95 % CI 0.098-0.678), P = 0.0495]. The ORR for advanced first-line therapy was 27.27 % (95%CI 0.060, 0.610) compared with 15.63 % (95%CI 0.053, 0.328) for second-line or above. In advanced first-line therapy, utidelone plus capecitabine was superior to vinorelbine plus cisplatin with a median PFS of 6.12 months (95 % CI 0.051-0.072) [HR 0.49, (95 % CI 0.286-0.839), P = 0.0291]. Compared with utidelone plus capecitabine, the median OS in vinorelbine plus cisplatin advanced first-line therapy group was 35.37 months (95 % CI 0.258-0.449), and the mean overall survival was 40.79 months (95 % CI 0.315-0.501) [HR 0.54, (95 % CI 0.188-1.568), P = 0.2587]. The ORR for vinorelbine plus cisplatin was 18.33 % (95 % CI 0.095, 0.304). The most common adverse events in our study were neurological toxicity, hand-foot syndrome, hematological toxicity, gastrointestinal toxicity, and hepatic and renal function abnormalities. There were no deaths due to adverse effects during the utidelone plus capecitabine treatment period.

Conclusions

In MBC, advanced first-line therapy with utidelone plus capecitabine resulted in more favorable PFS, OS, and ORR than second-line or above therapy. In advanced first-line therapy, utidelone plus capecitabine had superior PFS, and ORR compared with vinorelbine plus cisplatin. This study concludes that utidelone plus capecitabine is a more valuable chemotherapy option in advanced first-line MBC.

Tumor selective self-assembled nanomicelles of carbohydrate-epothilone B conjugate for targeted chemotherapy

Epothilone B (Epo B) is a potent antitumor natural product with sub-nanomolar anti-proliferation action against several human cancer cells. However, poor selectivity to tumor cells and unacceptable therapeutic windows of Epo B and its analogs are the major obstacles to their development into clinical drugs. Herein, we present self-assembled nanomicelles based on an amphiphilic carbohydrate-Epo B conjugate that is inactive until converted to active Epo B within the tumor. Four Epo B-Rhamnose conjugates linked via two linkers containing a disulfide bond that is sensitive to GSH were synthesized. Conjugate 34 can self-assemble into nanomicelles with a high concentration of Rha on the surface, allowing for better tumor targeting. After internalization by cancer cells, the disulfide bond can be cleaved in the presence of high levels of GSH to release active Epo B, thereby exhibiting significant anticancer efficiency and selectivity in vitro and in vivo.