Current Pharmaceutical Design - Volume 22, Issue 39, 2016

Receptor tyrosine kinases (RTKs) are a superfamily of transmembrane proteins that mediate intracellular signaling by phosphorylating substrate proteins involved in cell proliferation, survival, differentiation or migration. The Human Epidermal growth factor Receptor (HER) family belongs to the RTKs superfamily, and comprises four members: EGFR (epidermal growth factor receptor), HER2, HER3 and HER4. Physiologically, these receptors are activated by the ligands of the EGF family. In solid tumors other mechanisms of activation, such as overexpression or molecular alterations have been reported, and have been linked to tumour initiation/progression. Because of that, several strategies have been developed to target HER receptors and include i) antibody-based therapies using monoclonal antibodies against the extracellular domain of these receptors, and ii) small molecule tyrosine kinase inhibitors (TKIs) against the intracellular kinase domain. In this review we will provide basic information about biological aspects of HER receptors and their ligands as well as the therapeutic strategies to target them. We also summarize general mechanisms of resistance generated in patients to such anti-HER therapies.

Quinones are among the most studied natural and synthetic products in the literature because they have considerable biological potential. These compounds exhibit activity against many microorganisms and are able to eliminate tumor cells through several mechanisms of action. Some of these compounds have become drugs that are used clinically. However, they also have problems with respect to solubility, stability and toxicity. The alternative of using controlled-release systems has been applied to quinones, with good results in some cases, indicating that these formulations may be a strategy for improving the pharmacological profile of this class of compounds.

Background: Thyroid cancer is the most common type of endocrine neoplasia. Differentiated thyroid carcinoma (DTC) represents 94% of all thyroid cancer types. Approximately 20% experience local recurrence and 10% distant metastasis. The recurrent DTC often becomes less differentiated, loses the iodine uptake capability and consequently loses the radioactive iodine treatment option. Under these circumstances survivability drops below 10% at 10 years. The treatment options for dedifferentiated thyroid cancers are extremely limited. This category sometimes referred to as poorly differentiated thyroid cancer (PDTC), is characterised by a missing response to radioiodine treatment and a remarkably reduced survivability. Therefore, new drugs have been developed to fill this gap in treatment. Methods: The goal of this work is to review the effects and roles of the multikinase inhibitors sorafenib, sunitinb and lenatinib in thyroid cancer. Results: The new tyrosine kinase inhibitors (TKIs) aimed to inhibit tumour angiogenesis. Current clinical trials with novel drugs have shown promising results. A phase III trial (DECISION) of sorafenib in radioiodine (RAI)-refractory thyroid cancer showed a median progression-free survival (PFS) of 10.8 months in the sorafenib group, compared to 5.8 months in the placebo group. Sunitinib, another TKI, exhibited significant antitumour effects in patients with advanced DTC. Nevertheless, treatment with TKIs can lead to the development of resistance against these anti-angiogenic treatments, partly due to compensatory mechanisms. Lenvatinib, the recently approved drug for RAI-refractory thyroid cancer, blocks a different receptor than the currently available drugs. Lenvatinib inhibits fibroblast growth factor receptor (FGFR), as well as other receptors. FGFR plays a key role in the development of resistance against anti-angiogenic drugs. In a phase III trial (SELECT) on RAI-refractory DTC, the lenvatinib group showed a PFS of 18.3 months, compared to 3.6 months in the placebo group. This led to the approval of lenvatinib, the first drug capable of reversing anti-angiogenic mechanisms. Conclusion: The frequently adverse effects seen in TKI treatment require further investigation. A well-adjusted balance between efficacy and adverse effects is desirable. No effects on overall survival were reported. Therefore, further studies are required.

Background: Angiogenesis is a mechanism, which tumors use to recruit oxygen and nutrients in order to maintain growth. The vascular endothelial growth factor family is the primary mediator of this process. For the last couple of decades, inhibition of angiogenesis has been the subject of extensive research, but so far anti-angiogenic drugs have only shown a modest effect. Methods: This paper reviews four relevant anti-angiogenic drugs: bevacizumab, ramucirumab, nintedanib and sunitinib. The primary focus will be recent trials investigating the effects of the drugs in lung, breast and gastrointestinal cancers. Furthermore, there will be a discussion of unsolved problems, such as lack of biomarkers, drug resistance, and adverse events, for which a solution is necessary in order to improve the benefit of anti-angiogenic drugs in the future. Results: Anti-angiogenic therapy is extensively used in the treatment of cancer. There is evidence that drug-induced hypertension serves as a biomarker for a good response to therapy. Currently several possible anti-angiogenic biomarkers are under discussion. Further examples are changes in VEGF or interleukin (IL)-8 polymorphisms, changed plasma levels of VEGF, or tumor microvessel density. To overcome therapyassociated problems, more research for valid biomarkers is necessary. In addition, a strategy to overcome resistance problems and severe adverse events is desirable. Conclusion: Clinical trials evaluating targeted therapies with specificity for resistance mechanisms are necessary. Moreover, biomarker studies in future clinical investigations are important for the development of the next generation of anti-angiogenic drugs.

Histone lysine methylation can be modified by various writers and erasers. Different from other epigenetic modifications, mono-, di, and tri- methylation distinctly modulate chromatin structure and thereby contribute to the regulation of DNA-based nuclear processes such as transcription, replication and repair on their target genes depending on different sites. Modulators with opposing catalytic activities dynamically and precisely control levels of histone lysine methylation, and individual enzymes within these families have become candidate oncology targets in recent years. Until now, plenty of medicinal chemists try to pursue potent and selective inhibitor for KMTs and KDMs in order to have the potential anti-cancer agent, and several of the inhibitors have already enrolled in clinic. Here, we discuss three histone lysine methylation modulators with their inhibitors in clinical trials.

The era of personalized medicine for cancer treatment has just begun opening up novel molecular targets improving cancer therapy. Members of the insulin-like growth factor 2 (IGF2) axis have been described to be altered and to have prognostic relevance in several different tumor identities. IGF2 belongs to the most complexly regulated growth factors known. As an imprinted gene it is controlled by epigenetic alterations. IGF2 mRNA binding proteins (IMPs/IGF2BPs) further regulate its translation. IGF2 activity is contained through IGF binding proteins (IGFBPs) and differential expression of the target receptors. The necessity of such a complex regulation implies pathophysiological effects of a deregulated expression of IGF2. This review attempts to summarize the different levels of IGF2 regulation, especially in the context of cancer. Members of the IGF2 axis are enlightened from the perspective of novel molecular targets for cancer therapy. Preclinical as well as experimental therapeutic interventions targeting IGF2 in cancer will be surveyed.

Prostate cancer remains an increasingly common malignancy worldwide. Many advances in drug development have been achieved for the conventional treatments; however, chemotherapeutic agents are distributed nonspecifically in the body where they affect both prostate cancer and healthy cells. Limited dose achievable within the prostate tumor and suboptimal treatment due to excessive toxicities reveal the importance of the development of more specific mechanisms and ways of drug targeting to prostate tumor. In this context, nanotechnology, molecular biology and biochemistry have been applied in the pharmaceutical area for development of new targeted drug delivery nanosystems in order to improve its pharmacokinetic profile, raise the effectiveness of treatment; reduce side effects due to the preferential accumulation in prostate cancer cells, causing low concentrations in healthy tissues; and/or increase the drug chemical stability for improving the prostate cancer therapeutic. Thus, in this review, we will discuss the molecular and biochemical basis of prostate cancer as well as the advantages and disadvantages of conventional clinical treatments, different types and basic characteristics of nanosystems; how these systems can be targeted to prostate cancer, show successful patent examples of prostate cancer targeted nanosystems and present perspectives for the next 10-20 years in this area.

Affinity-based chromatography assays encompass the use of solid supports containing immobilized biological targets to monitor binding events in the isolation, identification and/or characterization of bioactive compounds. This powerful bioanalytical technique allows the screening of potential binders through fast analyses that can be directly performed using isolated substances or complex matrices. An overview of the recent researches in frontal and zonal affinity-based chromatography screening assays, which has been used as a tool in the identification and characterization of new anti-cancer agents, is discussed. In addition, a critical evaluation of the recently emerged ligands fishing assays in complex mixtures is also discussed.

In recent years, advances in nanotechnology have raised the specter of developing effective agents for the treatment of high-impact diseases, like gastric cancer, which remains one of the major causes of cancer deaths worldwide. This article reviews advances in the treatment of this pathology using several types of nanoparticles. First, we start with an overview of gastric cancer, its prevention, detection and the available treatments. Then, we discuss nanotechnology-based novel strategies using polymeric nanosystems, nanovesicular systems and inorganic nanoparticles. All of these systems are being evaluated in the perspective of improving the targeting of anticancer drugs and reducing their negative side effects.

Recent evidence highlights that energy requirements of cancer cells vary greatly from normal cells and they exhibit different metabolic phenotypes with variable participation of both glycolysis and oxidative phosphorylation (OXPHOS). Interestingly, mitochondrial electron transport chain (ETC) has been identified as an essential component in bioenergetics, biosynthesis and redox control during proliferation and metastasis of cancer cells. This dependence converts ETC of cancer cells in a promising target to design small molecules with anti-cancer actions. Several small molecules have been described as ETC inhibitors with different consequences on mitochondrial bioenergetics, viability and proliferation of cancer cells, when the substrate availability is controlled to favor either the glycolytic or OXPHOS pathway. These ETC inhibitors can be grouped as 1) inhibitors of a respiratory complex (e.g. rotenoids, vanilloids, alkaloids, biguanides and polyphenols), 2) inhibitors of several respiratory complexes (e.g. capsaicin, ME-344 and epigallocatechin-3 gallate) and 3) inhibitors of ETC activity (e.g. elesclomol and VLX600). Although pharmacological ETC inhibition may produce cell death and a decrease of proliferation of cancer cells, factors such as degree of inhibition of ETC activity by small molecules, bioenergetic profile and metabolic flexibility of different cancer types or subpopulations of cells in a particular cancer type, can affect the impact of the anti-cancer actions. Particularly interesting are the adaptive mechanisms induced by ETC inhibition, such as induction of glutamine-dependent reductive carboxylation, which may offer a strategy to sensitize cancer cells to inhibitors of glutamine metabolism.

Quinolones have a large bio-dynamicity. Although they are well known as antibacterials, another important activity has been investigated – quinolones are able to inhibit cancer cell proliferation. In view of the great versatility associated with the synthesis of quinolones, many researchers have spent time and resources on the development of new structurally diversified quinolone derivatives with the purpose of finding new possibilities for cancer treatment. In this review some of the most recent advances in the search for new quinolone anticancer agents are highlighted, with focus on naturally occurring substances, bioactive metal complexes, molecular hybrids, photosensitizers and heterocycle condensed quinolones.

This review highlights recent advances in the preparation of silica nanoparticles (SNPs) functionalized with porphyrins and phthalocyanines for application in cancer photodiagnostic and photodynamic therapy (PDT). The use of photosensitizer-SNP formulations has emerged recently as a new nanomedicine for cancer research owing to their unique physicochemical properties, which make them useful for photo-biomedical applications. In order to study their photobiological properties, diverse chemical strategies involving covalent and non-covalent bonding have been used to load photosensitizers in/on SNPs.

Background: PIK3CA gene was found in generation of p110 alpha (p110α) protein through an instruction process. p110 alpha acts as a catalytic subunit of phosphatidylinositol 3-kinase (PI3K) proceed phosphorylation of signal molecules through PI3K pathway. This PI3K involved in regulation of cellular growth, transformation, adhesion, apoptosis, survival and motility. In some situations the PI3K/Akt pathway get altered due to mutation in PIK3CA gene produced oncogenic event in human malignancy. Methods: The goal of this work is to describe the PI3K signaling pathway including mutational activation of PIK3CA gene and inhibitors have been developed or under clinical trials for the targeting of PI3K or PI3KR kinases. Results: Various inhibitors such as Morpholine, pyrimidines, benzenesulfonamide, pyridopyrimidinone, imidazo[1,5]naphthyridine, benzeneacylhydrazones, thienopyrimidine, aminopyridopyrimidine, imidazopyridine, imidazo[1,2-a]pyridine, thiazolopyrimidinone, quinolines and quinoxalines, thieno[3,2-b]pyran-7-one, morpholino-1,3-benzoxazines, quinalozinones, pyrido [3,2-d]pyrimidines, benzo[d]thiazol-2-yl)acetamide, aminopyrimidines, chalcone , azaindole, pyrazolopyrimidine and pyridine, thienobenzoxepin, phenylquinazolines , pyrazolo[1,5-a]pyridines , imidazolo-pyrimidine etc. were investigated under laboratory level as PI3K inhibitors in which few having PI3K and mTOR dual inhibitory activities. Conclusion: After a long term of prognostic standpoint, PIK3CA mutations discussed as a major target for various cancers. These PIK3CA mutations were found in various exon including 1,2,4,6,7,9,13,18 and 20 which may be a cause of different cancers such as breast, colon, ovarian, gastric, brain, lung etc. In clinical trials these mutations still remain question marks for presence or absence to the scientist regarding future perspective. The opinion of these studies is to development of more specific inhibitors of PI3K pathway which produce tremendous impact on various cancers developed due to PIK3CA mutations.