Novel antifungal agents: a patent review (2011 – present)

Introduction: Invasive fungal infections (IFI) have increased significantly over the past decades. The mortality rate of IFI is alarming, and early and accurate diagnosis is difficult. Most used antifungal drugs are not completely effective due to the development of increasing resistance and undesirable side effects which limit their use. In this scenario, new effective broad spectrum and safer antifungal drugs are urgently needed.

Areas covered: This review summarizes the latest advances in the discovery of new antifungal compounds through the patents granted from 2011 to August 2013. In the 26 patents reviewed here, either derivatives of existing antifungal drugs or novel structures are included. New imidazoles, fluconazole analogs and adducts of azoles with 2,6-di-tert-butyl-4-methylphenol are described. The review also includes chitinases, β-1,3-D-glucan and chitin synthases inhibitors and novel structures.

Expert opinion: In the patents reviewed here, progress has been made to accomplish at least one of the necessary requirements for the development of novel antifungal agents, such as broad spectrum of activity, more favorable pharmacokinetic profile, good bioavailability and low adverse effects. However, in vivo activity, mechanisms of action, drug–drug interactions and other aspects that make a compound a good antifungal agent need further development.     

Cholinesterase inhibitors: a patent review (2007 – 2011)

Introduction: Cholinesterase inhibitors participate in the maintenance of the levels of the neurotransmitter acetylcholine by inhibiting the enzymes implicated in its degradation, namely, butyrylcholinesterase and acetylcholinesterase. This pharmacological action has an important role in several diseases, including neurodegenerative diseases such as Alzheimer's.

Areas covered: This article reviews recent advances in the development of cholinesterase enzyme inhibitors, covering the development of new chemical entities, new pharmaceutical formulations with known inhibitors or treatments in combination with other drug families.

Expert opinion: The development of cholinesterase inhibitors has to face several issues, including the fact that the principal indication for these drugs, Alzheimer's disease, is not currently believed to derivate from a cholinergic deficiency, although most of the drugs clinically used for these disease are cholinesterase inhibitors. Moreover, the adverse effects found when administering cholinesterase inhibitors limit their use in other diseases, such as gastrointestinal diseases, glaucoma, or analgesia.     

Novel monoamine oxidase inhibitors: a patent review (2012 – 2014)

Introduction: Monoamine oxidase (MAO) inhibitors, despite the initial pharmacological interest, are used in clinic for their antidepressant effect and in the management of Parkinson symptoms, due to the established neuroprotective action. Efficacy and tolerability emerged from large-scale and randomized clinical trials.

Areas covered: Thirty-six patents range from April 2012 to September 2014. The number of chemotypes with inhibitory effects on MAO is truly high (40 synthetic compounds, 22 natural products and 6 plant extracts reported and licensed), and the present review is comprehensive of all compounds, which have been patented for their relevance to clinical medicine in this period range (27 patents). Moreover, some of the collected patents deal with new formulations of compounds endowed with MAO inhibitory properties (two patents) and new therapeutic options/drug associations for already known MAO inhibitors (seven patents).

Expert opinion: The patents reported in this review showed that the interest in this field is constant and mainly devoted to the study of selective MAO-B inhibitors, used as drugs for the treatment of neurological disorders. The development of novel human MAO inhibitors took advantage of the discovery of new therapeutic targets (cancer, hair loss, muscle dystrophies, cocaine addiction and inflammation), the recognized role of MAOs as molecular biomarkers and their activity in other tissues.     

Androgen receptor antagonists: a patent review (2008 – 2011)

Introduction: Androgen receptor (AR) antagonists are predominantly used as chemical castration to treat prostate cancer (i.e., in conjunction with androgen deprivation therapy (ADT)). Unfortunately, castration-resistant prostate cancer (CRPC) typically develops that is refractory to targeted therapy. Insights into CRPC biology have led to the emergence of a promising clinical candidate MDV3100 () and a resurgence in this field. A pipeline of preclinical competitive (C-terminally directed) antagonists was discovered using a variety of innovative screening paradigms. Some inhibit nuclear translocation, selectively downregulate or degrade AR (SARD), antagonize wild-type and escape mutant AR (pan-antagonists) and/or antagonize AR target organs in vivo. Separately, the N-terminal domain has emerged as a promising novel target for noncompetitive antagonists.

Areas covered: AR antagonists whose patents published between 2008 and 2011 are reviewed. Antagonists are organized based on the screening paradigm reported as discussed above.

Expert opinion: Novel mechanisms provide a more informed basis for selecting a competitive antagonist; however, high potency and favorable in vivo properties remain paramount. Noncompetitive antagonists have theoretical advantages suggestive of improved clinical efficacy, but no clinical proof of concept as of yet.     

Matrix metalloproteinase inhibitors: a patent review (2011 – 2013)

Introduction: The MMPs are involved in tissue remodeling. An imbalance between the inhibition and activation of MMPs results in excessive degradation of the extracellular matrix, which leads to some diseases including cancer, rheumatoid arthritis, osteoarthritis, heart disease and neurodegenerative diseases such as stroke. In this review, recent advances in the research of MMP inhibitors are reviewed.

Areas covered: This updated review summarized new patents on MMP inhibitors within January 2011 – December 2013.

Expert opinion: This review gives the latest development in the area of MMP inhibitors, which aim to treat disease processes associated with the MMPs. Structure-based design techniques have been used successfully in the search of selective MMP inhibitors, and these inhibitors can also be derived from natural products. Furthermore, imaging ‘in vivo’ technologies have been developed in order to follow the drug distribution to the targeted tissues, and to quantify the drug efficiency.     

Drugs for dengue: a patent review (2010 – 2014)

Introduction: Almost half the global population is estimated to be at risk of contracting dengue infection. Of the 400 million infections estimated to occur annually, 4 million can be potentially life-threatening leading to vascular leakage and shock. The only treatment available to severe dengue patients is fluid replacement therapy and supportive care. A drug for treating dengue is an urgent need.

Areas covered: This article endeavors to provide an overview of the experimental dengue drugs being developed around the world as reflected in the recent patent literature spanning the last few years (2010 – 2014).

Expert opinion: Dengue drug development is essentially in its infancy and currently hobbled by multiple factors including a poor understanding of the molecular mechanism of severe disease and lack of reliable small animal model for preclinical drug evaluation. More intense R&D coupled to setting up product development partnerships to facilitate the efficient movement of a drug molecule from the laboratory to the clinic is needed to make antiviral therapy for dengue a reality in the coming future.     

Liposomes in drug delivery: a patent review (2007 – present)

Introduction: Drug therapy is frequently limited by the widespread biodistribution of the active agents and the little specificity for non-healthy cells. Therefore, inadequate drug concentrations result into the site of action, and severe toxicity may also arise. To address the problem, liposome-based medicines have tried to improve pharmacotherapy.

Areas covered: The review provides an updated revision of the lately published patents covering recent advances in liposome-based drug delivery. They are principally related to the control of drug biodistribution by using stealth, stimuli-sensitive and/or liposomal structures surface modified for ligand-mediated delivery. The contribution further highlights liposome-based theranosis.

Expert opinion: Liposomes have received great attention given their biocompatibility, biodegradability and targetability. From 2007 to present date, patent publications related to their use in drug delivery have shown the move towards more stable structures with optimized drug delivery capabilities, further combining passive and active targeting concepts to gain control of the in vivo fate. However, the introduction of all these liposomal structures in the disease arena is still a challenge. Two key aspects are the difficulty of identifying easy and economic synthesis conditions which can be scaled up in the pharmaceutical industry, and the need for complementary investigations illustrating risks of toxicity/immunogenicity.     

Farnesoid X receptor modulators (2011 – 2014): a patent review

Introduction: Farnesoid-X-receptor (FXR) is the receptor for primary bile acids expressed in enterohepatic tissues where it regulates bile acid uptake, metabolism and disposal. For its role as a bile acid sensor, FXR has been thought to be an important target in the treatment of cholestatic disorders, a family of diseases in which endogenous bile acids accumulate in the body. Cholestasis might occur as a consequence of inborn metabolic errors and three major disorders, intra-hepatic cholestasis in pregnancy, primary biliary cirrhosis (PBC) and primary sclerosing cholangitis account for the vast majority of clinical cholestasis occurring in adulthood. In addition, FXR agonists are gaining attention as potential regulators of lipid and glucose metabolism and therefore as new therapeutical approaches to the treatment of fatty liver disease, type 2 diabetes and obesity.

Areas covered: New chemical entities as FXR modulators and their in vitro and in vivo efficacy are reviewed with particular focus on patents and peer-reviewed publications in the period 2011 – 2014.

Expert opinion: FXR agonists have shown robust therapeutic potential and results from clinical trials have supported their use in the treatment of liver disorders including PBC and fatty liver disease despite side effects.     

Novel diagnostic tools and solutions for multiple sclerosis treatment: a patent review (2009 – 2014)

Introduction: With > 2 million people affected by multiple sclerosis (MS) worldwide, the elucidation of its etiopathogenesis is of highest interest. Ongoing research in medicine, molecular biology, chemistry and physics aims to improve the life of MS patients by increasing efficacy and decreasing adverse side effects of presently available drugs. A precise diagnosis of this complex disease, which can take different courses, is fundamental to finding an efficient treatment strategy.

Areas covered: We present a summary of diagnostic and therapeutic patents granted between 2009 and 2014. Diagnostic inventions use both genetic and proteomic approaches or measure cerebral venous hemodynamics. Instead, new treatments rely on small molecules and/or the active manipulation of proteins that are involved in the pathogenesis of MS.

Expert opinion: There are some promising approaches among recently published patents. In particular, genetic profiling for diagnosis, combination of novel drugs with FDA-approved drugs to reduce side effects, and the personalisation of MS treatments according to a more defined diagnosis are considered as important. In the light of the latest developments, we discuss the complex picture of MS, which we assume to be different events connected by a causal chain consisting of circulatory abnormalities, altered redox processes in CNS immune cells, oligodendropathy, inflammation and finally autoimmunity.     

Lentiviral-mediated gene transfer – a patent review

Background: Lentiviral vectors are at the forefront of gene delivery systems for research and clinical applications. This special position is mainly due to their capacity to transduce slow dividing and non-dividing cells, to insert large genetic constructs in the host chromatin, and to sustain stable long-term transgene expression. Objective: To review the current literature and patents concerning the lentiviral system, the safety improvements, the production and purification of lentiviral vectors, pseudotyping and preclinical and clinical studies to provide expert opinion about the use of lentiviral vectors for gene therapy. Methods: The National Library of Medicine (PubMed) was searched for studies investigating the lentiviral system and the patents were searched at the World Intellectual Property Organization, European Patent Office and US Patent Office websites/databases. Results/conclusion: Based on the literature, several improvements have been performed regarding the safety, pseudotyping, vector production and purification on the lentivirus system. Clinical trials are underway for five different disorders.     

Novel FabH inhibitors: a patent and article literature review (2000 – 2012)

Introduction: The traditional antimicrobial chemotherapy drugs play their effects mostly via bacterial interference with in vivo amino acids, nucleotides, amino sugars and other small molecule synthesis, or interfering the biochemical processes of these small molecules to synthesize nucleic acids, peptidoglycan and other biological macromolecules. In recent years, enzymes with single function in bacterial fatty acid synthetase system have become the genome-driven novel antibacterial drug targets. Among inhibitors of these targets, FabH inhibitors are distinguished, for their target is different from that of existing antibiotics. Therefore, discovery of FabH inhibitors might be a potential orientation to overcome bacterial resistance.

Areas covered: This review summarized new patents and articles published on FabH inhibitors from 2000 to 2012.

Expert opinion: The review gives a brief understanding about the background and development in the area of FabH inhibitors that aims to solve the bacterial resistance problem. This review puts emphasis on some typical small molecules, which participate in the process of FabH inhibition. Overall, the research scopes of antibacterial agents are getting broad. Fatty acid synthase (FAS) pathway has been proved to be a promising target for the therapy. However, claim of novel antibacterial agents with more active and higher specificity is still continued.     

Therapeutic applications of lipoic acid: a patent review (2011 – 2014)

Introduction: Lipoic acid (LA), a naturally occurring 1,2-dithiolane analog that plays an essential role in mitochondrial bioenergetic reactions, has gained unprecedented attention as nutritional supplement and as therapeutic agent. Moreover, LA conjugates with other pharmacophores represent a promising approach toward the development of multifunctional drugs.

Areas covered: The reviewed patent applications from January 2011 to April 2014 include combinations of LA with other bioactive compounds as well as LA conjugates for the treatment of a wide range of clinical conditions. Additionally, some patents disclose methods to overcome the stability problems of LA.

Expert opinion: LA is currently in clinical use for the treatment of diabetic neuropathy, while small clinical trials using combinations of LA with known bioactive agents have been undertaken. The use of the LA is hampered by its instability and its rapid metabolism. Thus, formulations containing LA, in a form ensuring its stability and improving its bioavailability, can have important applications as medicines, nutritional supplements or cosmeceuticals. LA hybrids with other pharmacophores endowed with various activities, possess an enormous potential to promote human health and have been the subject of numerous publications and patent applications. Nevertheless, reliable in vivo data and clinical trials are necessary to prove these beneficial effects.     

Leucine-rich repeat kinase 2 inhibitors: a patent review (2006 – 2011)

Introduction: Leucine-rich repeat kinase 2 (LRRK2) has received considerable attention since the discovery of LRRK2 mutations in families with dominantly inherited Parkinson's disease (PD) in 2004. The missense mutation G2019S is the most common LRRK2 mutation and has been identified in both familial and sporadic PD cases. The G2019S mutation enhances kinase activity suggesting that LRRK2 could be an attractive therapeutic target for PD and small-molecule ATP-competitive LRRK2 kinase inhibitors are one way to investigate this possibility.

Areas covered: Currently, LRRK2 kinase inhibitors are being actively pursued by industry and academia. Herein, patents detailing the discovery of LRRK2 kinase inhibitors from 2006 through 2011 and the corresponding publications from 2006 through July of 2012 are summarized.

Expert opinion: Wild-type and mutant forms of LRRK2 are currently being actively pursued as therapeutic targets for the potential treatment of PD. The increasing number of patent applications being filed for inhibitors of LRRK2 is a testament to this activity. Numerous distinct chemo-types have been reported as LRRK2 inhibitors with some demonstrating exceptional potency and selectivity for LRRK2 relative to other kinases. These compounds are being used as pharmacological ‘tools' to elucidate the physiological and pathophysiological function of LRRK2 and it appears likely that some will be investigated for their potential therapeutic effects for the treatment of PD.     

Sulfonamides: a patent review (2008 – 2012)

Introduction: The primary sulfonamide moiety is present in many clinically used drugs, such as diuretics (furosemide, indapamide, chlorthalidone, thiazides); carbonic anhydrase (CA) inhibitors (CAIs) (including acetazolamide, dichlorophenamide, dorzolamide and brinzolamide); antiepileptics (zonisamide and sulthiame); the antipsychotic sulpiride and the cycloxygenase 2 (COX2) inhibitors celecoxib and valdecoxib. Recently, novel drugs have been launched, such as apricoxib and pazopanib, which also incorporate this group.

Areas covered: The article presents the main classes of sulfonamides investigated between 2008 and 2012. Specifically, the authors review the scientific and patent literature on CAIs, COX2 inhibitors, pazopanib and its congeners, which are multi-targeted receptor tyrosine kinase inhibitor of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-a/β, and c-kit.

Expert opinion: Most patents deal with sulfonamide CAIs incorporating NO-donating moieties as antiglaucoma agents, or with compounds targeting the tumor-associated isoforms CA IX/XII. The antidandruff actions of sulphonamides, which inhibit yeast CAs, were also claimed. Apricoxib (a COX2 inhibitor) and pazopanib, a tyrosine kinase inhibitor, show significant antitumor activity and several patents deal with these drugs. There is a constant need of novel sulfonamides to act as selective antiglaucoma drugs (targeting CA II), as antitumor agents/diagnostic tools (targeting CA IX/XII), and to treat and diagnose other disease. This privileged structural motif is likely to be present in other drugs in the future.     

Novel prostaglandin receptor modulators: a patent review (2002 – 2012) – part I: non-EP receptor modulators

Introduction: Prostaglandins and their G-protein coupled receptors play numerous physiological and pathophysiological roles especially in inflammation and its resolution. The variety of physiological effects mediated by prostanoids makes prostanoid receptors valuable drug targets and the research on prostaglandin receptor modulators is intensive. Prostaglandin receptor targeting drugs might be beneficial for the treatment of inflammatory, allergic, respiratory and cardiovascular disorders as well as treatment of pain but several novel fields of use such as cancer and ophthalmic diseases have also been found apart from these classical indications.

Areas covered: Evaluation of the patent activity over the last decade (2002 – 2012) illustrates many potent and selective modulators of the distinct prostanoid receptors and some novel methods for their use besides the classical indications. By now, some prostaglandin receptor antagonists already have reached clinical development.

Expert opinion: Though the structural diversity of compounds targeting prostanoid receptors is not really large, several highly potent agents with favorable properties have been developed. The clinical potential of FP, IP, TP and DP modulators remains to be investigated, while first very promising clinical results are available as far as CRTH2 is concerned.     

PTP1B inhibitors for type 2 diabetes treatment: a patent review (2011 – 2014)

Introduction: Protein tyrosine phosphatase 1B (PTP1B) plays an important role in the negative regulation of insulin signal transduction pathway and has emerged as novel therapeutic strategy for the treatment of type 2 diabetes. PTP1B inhibitors enhance the sensibility of insulin receptor (IR) and have favorable curing effect for insulin resistance-related diseases. A large number of PTP1B inhibitors, either synthetic or isolated as bioactive agents from natural products, have developed and investigated for their ability to stimulate insulin signaling.

Areas covered: This review includes an updated summary (2011 – 2014) of PTP1B inhibitors that have been published in patent applications, with an emphasis on their chemical structure, mode of action and therapeutic outcomes. The usefulness of PTP1B inhibitors as pharmaceutical agents for the treatment of type 2 diabetes is also discussed.

Expert opinion: PTP1B inhibitors show beneficial effects to enhance sensibility of IR by restricting the activity of enzyme and have favorable curing effects. However, structural homologies in the catalytic domain of PTP1B with other protein tyrosine phosphatases (PTPs) like leukocyte common antigen-related, CD45, SHP-2 and T-cell-PTP present a challenging task of achieving selectivity. Thus, for therapeutic application of PTP1B inhibitors, highly selective molecules exhibiting desired effects without side effects are expected to find clinical application.     

Quinazoline derivatives as potential anticancer agents: a patent review (2007 – 2010)

Introduction : Due to the increase in knowledge about cancer pathways, there is a growing interest in finding novel potential drugs. Quinazoline is one of the most widespread scaffolds amongst bioactive compounds. A number of patents and papers appear in the literature regarding the discovery and development of novel promising quinazoline compounds for cancer chemotherapy. Although there is a progressive decrease in the number of patents filed, there is an increasing number of biochemical targets for quinazoline compounds.

Areas covered : This paper provides a comprehensive review of the quinazolines patented in 2007 – 2010 as potential anticancer agents. Information from articles published in international peer-reviewed journals was also included, to give a more exhaustive overview.

Expert opinion : From about 1995 to 2006, the anticancer quinazolines panorama has been dominated by the 4-anilinoquinazolines as tyrosine kinase inhibitors. The extensive researches conducted in this period could have caused the progressive reduction in the ability to file novel patents as shown in the 2007 – 2010 period. However, the growing knowledge of cancer-related pathways has recently highlighted some novel potential targets for therapy, with quinazolines receiving increasing attention. This is well demonstrated by the number of different targets of the patents considered in this review. The structural heterogeneity in the patented compounds makes it difficult to derive general pharmacophores and make comparisons among claimed compounds. On the other hand, the identification of multi-target compounds seems a reliable goal. Thus, it is reasonable that quinazoline compounds will be studied and developed for multi-target therapies.