Sphingosine signaling and atherogenesis

INTRODUCTIONSphingosine-1-phosphate (S1P), converted fromsphingosine by sphingosine kinase (SphK) (Fig 1), is akey cell signalling molecule that acts both extracellu-larly and intracellularly with specific effects on cells ofthe vessel wall. Serum contains S1P that is mainly re-leased from activated platelets[1], while other blood cellssuch as erythrocytes, neutrophils, and mononuclear cellsrelease constitutively a small percentage of circulatingS1P[2]. Circulating S1P is mainly pre…     

Checkpoint kinase inhibitors: a review of the patent literature

Background: The checkpoint kinases, Chk1 and Chk2 are Ser/Thr protein kinases, which function as key regulatory kinases in cellular DNA damage response pathways limiting cell-cycle progression in the presence of DNA damage. The development of checkpoint kinase inhibitors for the treatment of cancer has been a major objective in drug discovery over the past decade, as evidenced by three checkpoint kinase inhibitors entering clinic trials since late 2005. Objectives: This review describes and discusses the most recent inhibitors of checkpoint kinases Chk1 and Chk2, as reported in the patent literature, including an evaluation of chemical structure and biological activity. Methods: Using a variety of approaches, we searched and analyzed all patent applications claiming chemical matter in which Chk1 or Chk2 were stated as targets of inhibition from January 2006 through August 2008. Conclusions: A large number of chemically diverse Chk1 and Chk2 kinase inhibitors have appeared in the recent patent literature. Common structural motifs of the checkpoint kinase inhibitors were identified. There are currently three checkpoint kinase inhibitors in clinical development, a continuing effort by the pharmaceutical industry to identify novel scaffolds for checkpoint kinase inhibition.     

Glycogen phosphorylase inhibitors: a patent review (2013 - 2015)

Introduction: Control of glycemia is crucial in the treatment of type 2 diabetes complications. Glycogen phosphorylase (GP) releases glucose from the liver into the blood stream. Design of potent GP inhibitors is a therapeutic strategy in the context of type 2 diabetes.

Areas covered: Glucose-based inhibitors have found potential applications since they now reach low nanomolar K_i values. Another set of patents disclose cholic acid/7-aza-indole conjugates for targeted drug delivery to the liver. A series of benzazepinones have also been reported as potent GP inhibitors. In vitro data are reported for GP inhibition but the in vivo biological data at the cellular or animal levels are often missing, even though the literature reported for these molecules is also discussed.

Expert opinion: A structural analogy between glucose-based GP inhibitors and C-glucosides targeting sodium glucose co-transporter 2 (SGLT2) is intriguing. Cholic acid/7-aza-indole conjugates are promising in vivo drug delivery systems to the liver. Benzazepinones were very recently described and no associated literature is available, making it very difficult to comment at present. While industry has slowed down on GP inhibitors design, academic groups are pursuing investigations and have provided potential drug candidates which will resuscitate the interest for GP, including its potential for targeting cancer.     

Sphingosine kinase signalling in immune cells

1. Sphingolipids are potent second messengers modulating biochemical intracellular events and acting as ligands to mediate extracellular systems. Sphingosine kinase (SPHK) is the enzyme that phosphorylates sphingosine into sphingosine-1-phosphate (S1P), a potent bioactive sphingolipid. 2. The fact that SPHK is highly conserved from protozoa to mammals and is ubiquitous in living tissues reveals important roles of the SPHK pathway for the maintenance of health maintenance. This is also supported by comprehensive reviews on features of its main product, S1P, as having intracellular as well as extracellular roles, inducing a wide range of physiological responses from triggering Ca2+ release from internal stores to promoting growth and cell motility. 3. Immune cell activities have been shown to be modulated by the dynamic balance between ceramide, sphingosine and S1P, conceptualized as a rheostat. Cell proliferation, differentiation, motility and survival have been attributed to the regulatory actions of S1P. The properties of SPHK activity in immune cells are linked to the functions of triggered growth and survival factors, phorbol esters, hormones, cytokines and chemokines, as well as antigen receptors, such as FcgammaRI and FcepsilonRI. 4. Mechanisms of the SPHK signalling pathway are explored as new targets for drug development to suppress inflammation and other pathological conditions.     

Leucine-rich repeat kinase 2 inhibitors: a patent review (2014-2016)

Introduction: Leucine-rich repeat kinase 2 (LRRK2) is a member of the Tyrosine Kinase-Like (TKL) branch of the kinome tree and is a multi-domain protein that includes GTPase and kinase activity. While genome-wide association studies (GWAS) has linked LRRK2 with Crohn’s disease and leprosy, it has received the greatest attention due to it being implicated as one of the genetic loci associated with autosomal dominant inheritance in Parkinson’s disease (PD).

Areas covered: In this review, the small molecule patent literature from 2014–2016 with a focus on composition of matter and use patents was surveyed. Scifinder was primarily searched using ‘LRRK2? as the query to identify all relevant literature and then triaged for small molecule patents.

Expert opinion: The patent landscape around LRRK2 continues to develop. The early patents covered using existing kinase inhibitors for use against LRRK2. This evolved to compounds specifically designed for selectivity against LRRK2, but key exemplified compounds lacked sufficient brain exposure to affect sufficient efficacy. More recent compounds have addressed this deficiency and show greater potential for treating PD. While potency will be necessary to generate medicines with low human daily doses, brain penetration and safety will be the key differentiators for ultimately determining the most effective LRRK2 disease-modifying treatment for PD.     

Gamma secretase inhibitors: a patent review (2013 - 2015)

Introduction: Gamma secretase (GS) is an intricate and multi-subunits complex, and it can cut various transmembrane proteins. Now it is a therapeutic target for a number of diseases. However, due to some side effects, the clinical development of GSI is not successful. Therefore, searching for effective GSIs has become a key point in drug discovery.

Areas covered: This review discusses the structure and function of GS and various types of GSIs. And this article seeks to give an overview of the patents or applications published from 2013 to 2015 in which novel chemical classes are claimed to inhibit the GS.

Expert opinion: Firstly, further understanding the structure and function of GS to elucidate the disease mechanism and develop AD therapies is urgent. Secondly, if the bioequivalence, pharmacokinetics and selectivity can be improved greatly, some failed clinical inhibitors still can become the promising compounds for clinical trials. Thirdly, some weaknesses are exposed during the development of GSI, especially the insufficient potency, low brain penetration and poor selectivity. Finally, to find potent and selective GSI is the major direction in future. Moreover, to find new indications and dosing regimens in a trial of GSIs also can be seen as new ways.     

FMS-like tyrosine kinase 3 inhibitors: a patent review

Introduction: Flt3 (FMS-like tyrosine kinase 3) has been presented as a target for novel anti-leukemic drugs because Flt3 mutations have been observed in acute myeloid leukemia (AML) cells. Due to both the poor efficacy and high toxicity of current standard AML therapies, there is an unmet need for new, improved therapies. Flt3 inhibitors have great potential to address this with mutated Flt3.

Areas covered: This paper provides a comprehensive review of the Flt3 inhibitor patents currently available. Information from original research articles in peer-reviewed journals and current clinical developments from several resources is also described.

Expert opinion: Our understanding of Flt3 inhibitors has been increased by findings from recent preclinical and clinical trials. Some Flt3 inhibitors show good efficacy in AML patients, but relapse and resistance to these inhibitors are still unavoidable. To address these problems, structurally diverse inhibitors, which exhibit inhibitory activities against both wild type and mutated Flt3, should be explored.     

Cyclin-dependent kinase inhibitors: a survey of the recent patent literature

Since the mid-1990s cyclin-dependent kinase (CDK) inhibition has been the subject of an intense drug discovery effort in the pharmaceutical industry and in some academic institutions. Although only few compounds have at present progressed into human clinical trials, the prospect of finding safe agents useful in therapy, particularly in the cancer setting, is still positive. Some trends can be observed that witness the impact of recent findings in CDK basic biological research and technology advancements on the evolution of the patent literature on CDK inhibition. A patent literature review of small organic molecules as CDK inhibitors comprising the years 2001 – 2004 is presented here, as many of the major pharmaceutical companies have shown a continued effort in the field.     

c-Met kinase inhibitors: an update patent review (2014-2017)

Introduction: The receptor tyrosine kinase c-Met is involved in the formation, metastasis and invasion of various malignant tumors thus it has been an attractive target for anti-tumor drug designing. Many compositions targeting c-Met have been developed in pharmaceutical industry for cancer therapy and some of them are in clinical study now. Among them, Crizotinib was the first small molecular inhibitor approved by FDA in 2011.

Areas covered: This review briefly summarizes the signal transduction pathway about c-Met, its role in oncogenesis, most recent patents of small-molecule inhibitors and antibodies of c-Met from 2014 to 2017.

Expert opinion: To date, some c-Met inhibitors have been launched in the market. In addition, their clinical performances have shown encouraging value in cancer therapy. Many potential agents are still in preclinical or clinical study now and achieve some promising progressions. Some patients have developed resistance to c-Met inhibitors which results in the need to develop inhibitors with novel structures. Development of several potent drugs also tends to be pharmacodynamically active against multiple targets.     

Sulfonamide inhibitors: a patent review 2013-present

Introduction: Sulfonamide compounds are significant class of synthetic bacteriostatic antibiotics still which used today for the therapy of bacterial infections and those caused by other microorganisms. They are also known as sulfa drugs and were the main source of therapy against bacterial infections before the introduction of penicillin in 1941. Additionally, The first sulfonamide section is present inmany clinically used drugs such as diuretics, carbonic anhydrase inhibitors and antiepileptics.

Areas covered in this review: The article presents the main classes of sulfonamide inhibitors investigated between 2013 and present. Specifically, the authors review the scientific and patent literature on tyrosine kinase, human immunodeficieny virus protease-1 (HIV?1), histone deacetylase 6, protein tyrosine phosphatase 1B, sphingosine kinase, phosphatidyl inositol 3-kinase, angiogenesis, pyrazole kinase, tyrosyl DNA phosphodiesterase inhibitors were evaluated.

Expert opinion: Sulfonamides are utilized as the antiviral HIV protease inhibitor amprenavir, as an anticancer agent, and in Alzheimer’s disease drugs. All these data show that although known for more than 100 years, the primary sulfonamides constitute an important class of compounds which leads to highly valuable drugs and drug candidates for many conditions, such as cancer, glaucoma, inflammation, dandruff, just to mention the most investigated ones.     

Immune checkpoint inhibitors: a patent review (2010-2015)

Introduction: Immune checkpoint inhibitors, like anti-PD-1/PD-L1 antibodies, are revolutionizing therapeutic concepts in the treatment of cancer. Said class of drugs will represent a multi-billion dollar market over the coming decade. Many companies have therefore developed important patent activities in the field.

Areas covered: The present review gives an overview of the patent literature during the period 2010-2015 in the field of immune checkpoint inhibitors. In particular, the review presents a selection of international patent applications related to inhibitors of PD-1/PD-L1, CTLA-4, IDO, TIM3, LAG3, TIGIT, BTLA, VISTA, ICOS, KIRs and CD39.

Expert opinion: Immune checkpoint inhibitors are now widely accepted as a key component of the therapeutic strategies in cancer. This fervent activity creates a maze of third-party patents that pose considerable risks for both newcomers and established companies. We can thus anticipate that the number of patent conflicts and disputes will increase in the near future. Treatments will involve combination therapy comprising at least one immune checkpoint inhibitor and companies will multiply patent filings in this field. Finally, we can expect that patents related to biomarkers that will render a patient eligible to a treatment with an immune checkpoint inhibitor will have tremendous commercial value.     

检测生物样品中SphK1活性的LC-MS/MS分析方法的建立

目的建立并确证一种快速、灵敏、高效的测定生物样品中SphK1活性的液质联用（LC-MS/MS）分析方法。方法采用C17-Sph作为底物,通过测定产物C17-S1P的生成量来评价SphK1的活性进行体外酶促反应。终止反应后,生物样品经液-液萃取,真空干燥,复溶,进行LC-MS/MS分析。通过测定产物C17-S1P的生成量来评价SphK1的活性。结果 C17-S1P标准曲线的线性范围为10～1 000 ng mL-1,相关系数r2〉0.998,最低检测限（LLOQ）为10 ng mL-1。HEK293细胞转染了野生型SphK（SphKWT）后,SphK1活性显著增加。相反HEK293细胞转染了突变型SphK（SphKG82D）后,SphK1活性接近正常水平。结论该方法能够灵敏快速地测量SphK1活性,为研究SphK1信号通路及其相应靶标药物提供了有效的分析手段。     

Protein kinase CK2 inhibitors: a patent review

Introduction: CK2 is a pleiotropic, ubiquitous and constitutively active protein kinase, localized in both cytosolic and nuclear compartments, where it catalyzes the phosphorylation of hundreds of proteins. CK2 is generally described as a tetramer composed of two catalytic (α and/or α′) and two regulatory subunits (β), however, the free α/α′ subunits are catalytically active by themselves. CK2 plays a key role in several physiological and pathological processes and has been connected to many neoplastic, inflammatory, autoimmune and infectious disorders. In the last 20 years, several inhibitors of CK2 have been discovered though only one of these, CX-4945, has recently entered into Phase II clinical trials as potential anticancer drug.

Areas covered: The main objective of the present review is to describe the development of CK2 activity modulators over the years according to the timeline of their patent registration.

Expert opinion: CK2 was discovered in 1954, but the first patent on CK2 modulators was deposited only 50 years later, in 2004. However, in the last 5 years an increasing number of patents on CK2 inhibitors have been registered, reflecting an increased interest in this kind of drug candidates and their possible therapeutic applications.     

Sphingosine kinase 1 is critically involved in nitric oxide-mediated human endothelial cell migration and tube formation

Background and purpose:

Sphingosine kinases (SKs) convert sphingosine to sphingosine 1-phosphate (S1P), which is a bioactive lipid that regulates a variety of cellular processes including proliferation, differentiation and migration.

Experimental approach:

We used the human endothelial cell line EA.hy926 to investigate the effect of nitric oxide (NO) donors on SK-1 expression, and on cell migration and tube formation.

Key results:

We showed that exposure of EA.hy926 cells to Deta-NO (125–1000 µM) resulted in a time- and concentration-dependent up-regulation of SK-1 mRNA and protein expression, and activity with a first significant effect at 250 µM of Deta-NO. The increased SK-1 mRNA expression resulted from an enhanced SK-1 promoter activity. A similar effect was also seen with various other NO donors. In mechanistic terms, the NO-triggered effect occurred independently of cGMP, but involved the classical mitogen-activated protein kinase cascade because the MEK inhibitor U0126 abolished the NO-induced SK-1 expression. The effect of NO was also markedly reduced by the thiol-reducing agent N-acetylcysteine, suggesting a redox-dependent mechanism. Functionally, Deta-NO triggered an increase in the migration of endothelial cells in an adapted Boyden chamber assay, and also increased endothelial tube formation in a Matrigel assay. These responses were both abolished in cells depleted of SK-1.

Conclusions and implications:

These data show that NO donors up-regulate specifically SK-1 expression and activity in human endothelial cells, and SK-1 in turn critically contributes to the migratory capability and tube formation of endothelial cells. Thus, SK-1 may be considered an attractive novel target to interfere with pathological processes involving angiogenesis.     

Inhibitors of interleukin-1 receptor-associated kinase 4 (IRAK4): a patent review (2012-2015)

Introduction: IRAK4 is located proximal to TLR/IL-1 receptors, and in preclinical studies, inhibits downstream signaling from these receptors. The development of novel small molecule inhibitors of this kinase has the potential to lead to new therapeutics to treat diseases such as rheumatoid arthritis, lupus, and lymphomas.

Areas covered: The aim of this review is to summarize the recent patent literature (2012–2015) surrounding small molecule inhibitors of IRAK4. Specific examples of the chemical matter from each patent will be discussed, including any data that are presented for the examples highlighted.

Expert opinion: There are currently many examples of highly potent and kinase selective IRAK4 inhibitors and some have been tested in various in vivo disease models, demonstrating robust pre-clinical efficacy. Several compounds appear to have the ‘drug-like’ properties to advance to the clinic, with Pfizer having already initiated several phase I studies.     

Sphingosine 1-phosphate receptor 1 agonists: a patent review (2013-2015)

Introduction: The sphingosine-1-phosphate (S1P) regulates diverse biological functions including cell proliferation, endothelial cell chemotaxis, angiogenesis, immune cell trafficking, mitogenesis, heart rate. The first-in-class S1P_1,3–5-R pan-agonist fingolimod (FTY720) was approved by the FDA and EMEA for the treatment of relapsing-remitting multiple sclerosis, though the most common adverse effect is bradycardia which occurs in the early stage of treatment and resolves within the first 24 h despite continuing treatment. The underlying mechanism of the cardiovascular effects is the activation of G-protein-gated inwardly rectifying potassium (GIRK) channel by the S1P₁-R. Several second generation S1P₁-R agonists with distinct selectivity, pharmacokinetics and safety profile from FTY720 are under development for the treatment of autoimmune and chronic inflammatory diseases.

Areas covered: This review provides a summary of the patent literature from 2013 up to November 2015 on the S1P₁-R agonist molecules and their relevant biological/pharmacological properties.

Expert opinion: The molecules reviewed are S1P₁-R agonists with a promising clinical outlook in particular in inflammation and autoimmune diseases. Clinical and preclinical studies of second generation S1P₁-R agonists have been generating interesting results and may finally provide pharmacological agents with improved therapeutic profile than FTY720, particularly in terms of cardiovascular and pulmonary liabilities.     

LSD1 inhibitors: a patent review (2010-2015)

Introduction: Lysine demethylase 1 (LSD1) plays an important role in mediating the expression of genes involved in cancer and non-cancer diseases such as viral infections, cardiovascular and neurodegenerative disorders. It is involved in a number of processes from adipogenesis to cell adhesion to viral latency, regulating several cell pathways related with proliferation, development, and cell cycle control. Numerous chemical entities have been studied in recent years and some of them entered the clinical arena.

Areas covered: This review summarizes recent efforts in the drug development of LSD1 inhibitors reported in the patent literature covering the 2010-2015 period, including their potential use as therapeutics in cancerous, neurological, inflammatory, cardiovascular, and viral diseases.

Expert opinion: The development of novel potent and selective LSD1 inhibitors is ongoing, in order to improve their potency and selectivity against specific types of cancer or non-cancer diseases. More in-depth studies are required to assess the role of LSD1 inhibitors in the expression of LSD1 target genes, for a better assessment of the biochemistry underlying their efficacy, and to provide evidence for any possible side effects. Furthermore, an interesting therapeutic approach is the use of LSD1 inhibitors in conjunction with other epidrugs to combine their therapeutic potential, leading to innovative, personalized treatments.     

Small-molecule BACE1 inhibitors: a patent literature review (2006 - 2011)

INTRODUCTION: Alzheimer's disease is a devastating neurodegenerative disorder for which no disease-modifying therapy exists. The amyloid hypothesis, which implicates Aβ as the toxin initiating a biological cascade leading to neurodegeneration, is the most prominent theory concerning the underlying cause of the disease. BACE1 is one of two aspartyl proteinases that generate Aβ, thus inhibition of BACE1 has the potential to ameliorate the progression of Alzheimer's disease by abating the production of Aβ. AREAS COVERED: This review chronicles small-molecule BACE1 inhibitors as described in the patent literature between 2006 and 2011 and their potential use as disease-modifying treatments for Alzheimer's disease. Over the past half a dozen years, numerous BACE1 inhibitors have been published in the patent applications, but often these contain a paltry amount of pertinent biological data (e.g. potency, selectivity, and efficacy). Fortunately, numerous relevant publications containing important data have appeared in the journal literature during this period. The goal in this effort was to create an amalgam of the two records to add value to this review. EXPERT OPINION: The pharmaceutical industry has made tremendous progress in the development of small-molecule BACE1 inhibitors that lower Aβ in the central nervous system. Assuming the amyloid hypothesis is veracious, we anticipate a disease-modifying therapy to combat Alzheimer's disease is near.