Current Medicinal Chemistry - Volume 27, Issue 8, 2020

Background: Peptide-based pharmaceuticals have recently experienced a renaissance due to their ability to fill the gap between the two main classes of available drugs, small molecules and biologics. Peptides combine the high potency and selectivity typical of large proteins with some of the characteristic advantages of small molecules such as synthetic accessibility, stability and the potential of oral bioavailability. Methods: In the present manuscript we review the recent literature on selected peptide-based approaches for cancer treatment, emphasizing recent advances, advantages and challenges of each strategy. Results: One of the applications in which peptide-based approaches have grown rapidly is cancer therapy, with a focus on new and established targets. We describe, with selected examples, some of the novel peptide-based methods for cancer treatment that have been developed in the last few years, ranging from naturally-occurring and modified peptides to peptidedrug conjugates, peptide nanomaterials and peptide-based vaccines. Conclusion: This review brings out the emerging role of peptide-based strategies in oncology research, critically analyzing the advantages and limitations of these approaches and the potential for their development as effective anti-cancer therapies.

Cancer, one of the most devastating degenerative diseases nowadays, is one of the main targets in Medicinal Chemistry and Pharmaceutical industry. Due to the significant increase in the incidence of cancer within world population, together with the complexity of such disease, featured with a multifactorial nature, access to new drugs targeting different biological targets connected to cancer is highly necessary. Among the vast arsenal of compounds exhibiting antitumor activities, this review will cover the use of carbohydrate derivatives as privileged scaffolds. Their hydrophilic nature, together with their capacity of establishing selective interactions with biological receptors located on cell surface, involved in cell-to-cell communication processes, has allowed the development of an ample number of new templates useful in cancer treatment. Their intrinsic water solubility has allowed their use as of pro-drug carriers for accessing more efficiently the pharmaceutical targets. The preparation of glycoconjugates in which the carbohydrate is tethered to a pharmacophore has also allowed a better permeation of the drug through cellular membranes, in which selective interactions with the carbohydrate motifs are involved. In this context, the design of multivalent structures (e.g. gold nanoparticles) has been demonstrated to enhance crucial interactions with biological receptors like lectins, glycoproteins that can be involved in cancer progression. Moreover, the modification of the carbohydrate structural motif, by incorporation of metal complexes, or by replacing their endocyclic oxygen, or carbon atoms with heteroatoms has led to new antitumor agents. Such diversity of sugar-based templates with relevant antitumor activity will be covered in this review.

This review covers recent literature from 2012-2019 concerning 170 marine natural products and their semisynthetic analogues with strong anticancer biological activities. Reports that shed light on cellular and molecular mechanisms and biological functions of these compounds, thus advancing the understanding in cancer biology are also included. Biosynthetic studies and total syntheses, which have provided access to derivatives and have contributed to the proper structure or stereochemistry elucidation or revision are mentioned. The natural compounds isolated from marine organisms are divided into nine groups, namely: alkaloids, sterols and steroids, glycosides, terpenes and terpenoids, macrolides, polypeptides, quinones, phenols and polyphenols, and miscellaneous products. An emphasis is placed on several drugs originating from marine natural products that have already been marketed or are currently in clinical trials.

Birch-bark triterpenoids and their semi-synthetic derivatives possess a wide range of biological activities including cytotoxic effects on various tumor cell lines. However, due to the low solubility and bioavailability, their medicinal applications are rather limited. The use of various nanotechnology-based drug delivery systems is a rapidly developing approach to the solubilization of insufficiently bioavailable pharmaceuticals. Herein, the drug delivery systems deemed to be applicable for birch-bark triterpenoid structures are reviewed. The aforementioned disadvantages of birch-bark triterpenoids and their semi-synthetic derivatives can be overcome through their incorporation into organic nanoparticles, which include various dendrimeric systems, as well as embedding the active compounds into polymer matrices or complexation with carbohydrate nanoparticles without covalent bonding. Some of the known triterpenoid delivery systems consist of nanoparticles featuring inorganic cores covered with carbohydrates or other polymers. Methods for delivering the title compounds through encapsulation and emulsification into lipophilic media are also suitable. Besides, the birch-bark triterpenoids can form self-assembling systems with increased bio-availability. Even more, the self-assembling systems are used as carriers for delivering other chemotherapeutic agents. Another advantage besides increased bioavailability and anticancer activity is the reduced overall systemic toxicity in most of the cases, when triterpenoids are delivered with any of the carriers.

Preclinical drug development is an essential step in the drug development process where the evaluation of new chemical entities occurs. In particular, preclinical drug development phases include deep analysis of drug candidates’ interactions with biomolecules/targets, their safety, toxicity, pharmacokinetics, metabolism by use of assays in vitro and in vivo animal assays. Legal aspects of the required procedures are well-established. Herein, we present a comprehensive summary of current state-of-the art approaches and techniques used in preclinical studies. In particular, we will review the potential of new, -omics methods and platforms for mechanistic evaluation of drug candidates and speed-up of the preclinical evaluation steps.

Uveal melanoma is the most prevalent primary intraocular tumour in adults with the incidence between five and six cases per million people in the United States and Europe. The prognosis of patients with uveal melanoma is unfavourable with a 5-year survival rate of 50-70% despite significant advances in local tumour treatment using radiotherapy or surgical resection. Approximately 50% of the patients develop metastases within 15 years from initial diagnosis, mostly in the liver. The median survival rate after the onset of metastases is 6 months. Potential treatment options for metastatic uveal melanoma are chemotherapy, targeted therapy, and immunotherapy but no method showed satisfactory results. Immunotherapy with checkpoint inhibition showed promising results in the treatment of cutaneous melanoma; however, it did not appear to be equally effective with uveal melanoma. This may be due to differences in mutational burden, expression of neoantigens between these two types of tumour, immunosuppressive tumour microenvironment, and low immunogenicity and immune privilege of uveal melanoma. Considering the disappointing results of treatment with anti-CTLA-4 and PD-1/PD-L1 blockade in patients with advanced uveal melanoma several new forms of therapies are being developed. This may include immunotherapy with IMCgp100, glembatumumab vedotin and the infusion of autologous TILs, targeted therapy with selective MEK inhibitors, epigenetic therapy, and nanotherapy. Better insight into the molecular and genetic profile of uveal melanoma will facilitate detection of new prognostic biomarkers and thus enable a better modification of the existing immunotherapy methods and development of new forms of treatment specifically designed for uveal melanoma patients.

The metastatic process has still not been completely elucidated, probably due to insufficient knowledge of the underlying mechanisms. Here, we provide an overview of the current findings that shed light on specific molecular alterations associated with metastasis and present novel concepts in the treatment of the metastatic process. In particular, we discuss novel pharmacological approaches in the clinical setting that target metastatic progression. New insights into the process of metastasis allow optimisation and design of new treatment strategies, especially in view of the fact that metastatic cells share common features with stem cells. Nano- and micro-technologies are herein elaborated in details as a promising therapeutic concept in targeted drug delivery for metastatic cancer. Progression in the field could provide a more efficient way to tackle metastasis and thus bring about advancements in the treatment and management of patients with advanced cancer.