Detection of influenza A(H1N1)pdm09 virus in a patient travelling from Shanghai to Italy in July 2018: an uncommon clinical presentation in a non-seasonal period.

Influenza is one of the most common infectious diseases in travellers, especially in those returning from subtropical and tropical regions. In late June 2018 an influenza A(H1N1)pdm09 virus infection was diagnosed in a 36-years-old man, returned from a travel in Shanghai and hospitalized at the Ospedale Policlinico San Martino, Genoa, Italy, with a diagnosis of fever and an uncommon clinical presentation characterised by a persistent leukopenia. Phylogenetic analysis revealed a closeness with influenza A(H1N1)pdm09 strains circulating in the US in May-June 2018. Prompt recognition of influenza infection led to a proper case management, demonstrating the crucial role of the continuous influenza surveillance programme.

Click chemistry, a potent tool in medicinal sciences.

This review focuses on the application of click chemistry in medicinal sciences, and particularly on its role in drug discovery. Because of its high modularity, click chemistry helps to accelerate the current drug discovery process, which relies on massive screening of chemical libraries. This article describes examples of click chemistry applications that are aimed at finding new lead candidates against pathologies such as cancer, AIDS and Alzheimer's disease, and explores the impact that the technique could have in therapy and prevention in the near future, through application in drug delivery systems, bioconjugation and diagnostic. An introduction, addressed to researchers who intend to use this methodology, examines the opportunities to perform click reactions according to the most common and best studied techniques, such as synthesis in water, on solid phase, and under microwave or ultrasound irradiation. Every topic is furnished with examples which have appeared in the literature in the last five years and is clarified by schemes and figures.

Hck inhibitors as potential therapeutic agents in cancer and HIV infection.

Hematopoietic cell kinase (Hck) is a member of the Src-family of non-receptor tyrosine kinases, which plays many roles in signalling pathways involved in the regulation of cell processes. Hck is expressed in cells of hematopoietic origin, specifically myelomonocytic cells and B lymphocytes. It participates in phagocytosis, adhesion, migration, regulation of protrusion formation on cell membrane, lysosome exocytosis, podosome formation and actin polymerization. More importantly from a medicinal chemistry point of view, high levels of Hck are involved in chronic myeloid leukemia and other hematologic tumors. Furthermore, Hck activity has been associated with virus infections including HIV-1. In particular, Hck is activated by the HIV-1 accessory protein Nef, a multifunctional HIV-1 protein that accelerates progression to AIDS and enhances the infectivity of progeny viruses. Nef binding to Hck leads to kinase activation which is important in AIDS pathogenesis. For these reasons, Hck represents a potentially good therapeutic target for the treatment of both specific cancers and HIV infection. This article summarizes Hck biological activities connected with malignancies and HIV infection, many of which have been only recently reported, and presents an overview of the compounds endowed with Hck inhibitory activity, especially focusing on the medicinal chemistry aspect.

New pyrazolo[3,4-d]pyrimidine SRC inhibitors induce apoptosis in mesothelioma cell lines through p27 nuclear stabilization.

Malignant mesothelioma (MM) is a highly aggressive tumor of the serous membranes for which there is currently no effective curative modality. Recent data suggest that hyperactivation of the tyrosine kinase SRC has a key role in MM development and therefore this kinase represents an important molecular target for MM therapy. We tested new pyrazolo[3,4-d]pyrimidine SRC inhibitors on a panel of MM cell lines expressing the active form of SRC. These SRC inhibitors exerted a significant proapoptotic effect on MM cells without affecting the normal mesothelial cell line MET-5A, supporting a possible use of these SRC inhibitors for a safe treatment of MM. We also showed that SRC inhibitor-induced apoptosis occurred concomitantly with an increase in the nuclear stability of the cyclin-dependent kinase inhibitor p27. This finding is remarkable considering that loss of nuclear p27 expression is a well-established adverse prognostic factor in MM, and p27 nuclear localization is crucial for its tumor-suppressive function. Consistently, SRC inhibition seems to promote the increase in p27 nuclear level also by inactivating the AKT kinase and downregulating cyclin D1, which would otherwise delay p27 nuclear import and provoke its cytoplasmic accumulation. To determine whether p27 stabilization has a direct role in apoptosis induced by SRC inhibition, we stably silenced the CDKN1B gene, encoding p27, in MSTO-211H and REN mesothelioma cells by transduction with lentiviral vectors expressing short hairpin RNAs against the CDKN1B transcript. Strikingly, p27 silencing was able to suppress the apoptosis induced by these SRC inhibitors in both MM cell lines, suggesting that p27 has a crucial proapoptotic role in MM cells treated with SRC inhibitors. Our findings reveal a new mechanism, dependent on p27 nuclear stabilization, by which SRC inhibition can induce apoptosis in MM cells and provide a new rationale for the use of SRC inhibitors in MM therapy.

SRC kinase inhibitors: an update on patented compounds.

The cytoplasmatic tyrosine in kinase c-Src is involved in the regulation of several cell functions including adhesion, invasion, proliferation, survival and angiogenesis. Src activity is strictly regulated in healthy cells, whereas its overexpression or hyperactivation plays a critical role during tumor development. Recently it has been suggested that the oncogenic potential of Src is linked to its role in the activation of key signalling molecules involved in several cell pathways, rather than its direct activity. For all these reasons Src represents a promising therapeutic target for the treatment of tumors. In this article a number of examples of c-Src inhibitors appeared in selected patents from 2006 to early 2011 will be reported, focusing on their chemical features and, whenever possible, on structure- activity relationships and mechanism of action. Examples of type I or II ATP-competitive inhibitors or substrate competitive inhibitors will be presented. The research in this field is very active and will probably lead to the discovery of therapeutically useful compounds, both c-Src selective and multitargeted inhibitors, that acting on different cell pathways could be more effective in blocking cancer development. However, only the results of clinical trials will show in the near future the most promising compounds.

ATP-competitive inhibitors of mTOR: an update.

mTOR (mammalian target of rapamycin) is a serine-threonine kinase belonging to the PI3K/Akt/mTOR signalling pathway that is involved in several cell functions, including growth, proliferation, apoptosis and autophagy. mTOR hyperactivation has been detected in several human cancers, thus representing, together with its upstream effectors, an important target for cancer therapy. mTOR exists in two different complexes in cells, mTORC1 and mTORC2 which could both be targeted by potential anticancer agents. Rapamycin, the selective and allosteric inhibitor of mTOR, inhibits the enzyme in mTORC1, but not in mTORC2. In the last few years a number of mTOR ATP-competitive inhibitors has been reported acting on mTOR in both complexes and possessing a more complete anticancer activity in comparison with that of rapamycin and its derivatives. mTOR shares high sequence homology in the hinge-region with PI3K that is a lipid kinase upstream to mTOR in the same signaling pathway; for this reason some compounds originally developed as PI3K inhibitors later showed to also target mTOR. As indicated by preclinical and clinical studies, compounds acting on more than one target could result in a better biological response and in enhanced therapeutic potential and also dual PI3K/mTOR inhibitors result of great interest as potential antitumor agents. This review mainly reports the recently discovered mTOR ATP-competitive inhibitors in terms of medicinal chemistry, classified by their chemical structures, focusing on SAR and modelling studies that led to the discovery of very potent and selective agents, such as AZD-8055, OSI-027 and INK128, already entered clinical trials, or WYE-132, Torin1 and others in preclinical studies. Also some examples of dual PI3K/mTOR inhibitors, including PI-103, GNE477, WJD008 and GSK2126458 are reported together with their biological and clinical data.

Fyn kinase in brain diseases and cancer: the search for inhibitors.

Fyn is a non-receptor tyrosine kinase belonging to the Src family kinases. It has been shown to play important roles in neuronal functions, including myelination and oligodendrocytes formation, and in inflammatory processes. It has also demonstrated its involvement in signaling pathways that lead to severe brain pathologies, such as Alzheimer's and Parkinson's diseases. Moreover, Fyn is upregulated in some malignancies. Experimental studies demonstrated that Fyn inhibition could be useful in the disruption of metabolic processes involved in cancer neurodegenerative diseases. Unfortunately, no specific Fyn inhibitor has been discovered till today, active compounds on other members of Src family or on different tyrosine kinases have also been reported. However, multitargeted inhibitors might be endowed with therapeutic potential. Indeed, as increasingly reported, also a not completely selective inhibitor of a specific protein could be therapeutically useful, affecting a number of cell pathways involved especially in cancer development. In this review, we report some examples of small molecule tyrosine kinase inhibitors for which data on Fyn inhibition, both in enzymatic and in cell assays, have been reported, with the aim of giving information as starting point for the researchers working in this field.

New insights into small-molecule inhibitors of Bcr-Abl.

Chronic myelogenous leukemia (CML) is a myeloproliferative disease associated with a defined genetic abnormality, the Bcr-Abl fusion gene on the Philadelphia chromosome that expresses the constitutively activated tyrosine kinase (TK) Bcr-Abl. This enzyme leads to the malignant transformation of primitive hematopoietic cells and to the consequent disease. The central role of Bcr-Abl in the pathogenesis of CML culminated in the discovery of imatinib (an ATP-competitive inhibitor), which is currently the frontline therapy for CML. Unfortunately, the initial enthusiasm generated by its high response rate has been dampened by the development of resistance, especially in the advanced phases of CML. To overcome imatinib resistance, several second-generation ATP-competitive inhibitors endowed with increased potency against imatinib-resistant mutants have been developed: the dual Src/Abl inhibitor dasatinib and the Abl inhibitor nilotinib have been recently approved by US-FDA for the treatment of imatinib-resistant CML, and many other compounds are currently in clinical trial. Although second-generation TK inhibitors have shown to be clinically effective against most of the imatinib-resistant mutants, to date poor results have been obtained in the treatment of the Bcr-Abl T315I mutant. In this review we will report the most interesting second-generation Abl and dual Src/Abl inhibitors recently entered in clinical trial, but also the new ATP-competitive and uncompetitive inhibitors published in the last few years, focusing on their chemical structure, mechanism of action, and structure-activity relationship.

A1 receptors ligands: past, present and future trends.

Adenosine is a neuromodulator that interacting with four receptors, A(1), A(2A), A(2B) and A(3), is involved in the regulation of several biological functions in different organs and tissues, including the central nervous system, the cardiovascular system and the airways; many pathophysiological states are associated with changes of adenosine levels. For these reasons pharmaceutical companies and academicians performed intense efforts to obtain agonists, antagonists and allosteric enhancers selective for each adenosine receptor subtypes as potential clinical candidates. In fact, therapeutic modulation of the adenosine system could offer the possibility of a "soft" treatment of different diseases, but, due to the ubiquitous distribution of adenosine and of its receptors, the challenge in therapy development depends from specificity for the different receptor subtypes. Some A(1) agonists and antagonists, very potent and selective, reached clinical trials for the treatment of different diseases. A(1) agonists are clinical candidates for atrial arrhythmias, angina, type 2 diabetes and in pain management, while A(1) antagonists are in study as potassium-sparing diuretics with kidney-protecting properties and in chronic heart diseases. Several reviews, recently published and herein cited reported in detail the biological and clinical aspects of such molecules. This review focuses on the A(1) adenosine receptor (A(1)AR) ligands, both agonists and antagonists, appeared in the literature in the last few years, together with their potential therapeutic application, pointing the attention on their chemical structures and SAR (Structure Activity Relationship) and also reporting new findings on preclinical or clinical trials of some important A(1)AR ligands synthesized in the past.

New opportunities to treat the T315I-Bcr-Abl mutant in chronic myeloid leukaemia: tyrosine kinase inhibitors and molecules that act by alternative mechanisms.

Resistance to the Bcr-Abl inhibitors approved for the treatment of chronic myeloid leukaemia (CML) may arise from different mechanisms, including Bcr-Abl amino acid mutations, gene amplification and mechanisms independent of Bcr-Abl. The T315I mutation at the gatekeeper residue is very frequent in advanced phases of the disease and is one of the main causes of resistance, disrupting important contact points between the inhibitors and the enzyme. Different strategies have been implemented to overcome this resistance, including the synthesis of new Bcr-Abl ATPcompetitive or non-ATP-competitive inhibitors, dual Aurora/Bcr-Abl inhibitors and multi-targeted kinase inhibitors. An alternative approach is the use of other compounds that do not bind directly to the Bcr-Abl protein; instead, these molecules act on several downstream pathways, regulated by or linked in different ways to Bcr-Abl, that lead to the malignant transformation of the cells. For this reason, farnesyl transferase inhibitors, MAPK inhibitors, Rac guanosine triphosphatase inhibitors, PI3K inhibitors, JAK inhibitors, Hsp90 inhibitors, mTOR inhibitors, PP2A activators and apoptosis inducers have been tested, alone or in combination with ATP-competitive inhibitors, against CML cell lines. This review discusses compounds that act on Bcr-Abl or different cell pathways and reports on the molecules active against the T315I mutation, particularly the most recent findings in this field. New molecules that are claimed by recent patents to be active on this mutation are also reported. When possible, the review will focus on medicinal chemistry in terms of chemical structure, mechanism of action and structure-activity relationships.

Small molecules ATP-competitive inhibitors of FLT3: a chemical overview.

FLT3 is a tyrosine kinase (TK), member of the class III TK receptor family, normally expressed in hematopoietic, immune and neural systems, also playing an important role in the pathogenesis of acute leukemias, particularly acute myeloid leukemia (AML), where it is present in constitutively activated mutated forms, correlated with poor prognosis, in a notable percentage of patients. For these reasons FLT3 soon appeared as a promising target for the therapeutic intervention for this severe and aggressive malignancy; the recent determination of the crystal structure of the autoinhibited form of FLT3 gave new trend for the design and the synthesis of potent inhibitors. Small molecules tyrosine kinase inhibitors represent one of the largest drug family currently targeted by pharmaceutical companies for the treatment of cancer. Exciting examples of such molecules have reached advanced clinical trials and have been recently approved by FDA for the treatment of different solid or haematological tumors. Usually TK inhibitors share common features, namely two hydrophobic/aromatic regions bearing one or more hydrogen bonding substituents. These two regions can be connected by different spacers and almost all the molecules contain a component resembling the ATP purine structure. This review will deal with FLT3 synthetic inhibitors, reporting not only the most important molecules that are in clinical trials, but also the new compounds that have appeared in literature in the last few years. Our attention will be focused on chemical structures, mechanisms of action and structure-activity relationships.

Cytotoxic effects of a novel pyrazolopyrimidine derivative entrapped in liposomes in anaplastic thyroid cancer cells in vitro and in xenograft tumors in vivo.

In this study, we evaluated the activity of two novel pyrazolopyrimidine derivatives (Si 34 and Si 35) against ARO cells, a human anaplastic thyroid cancer cell line. ARO cells exposed to different concentrations of the drugs showed a reduced growth rate and an increase of mortality. After 72 h incubation, doses of 5 and 10 microM Si 34 determined a decrease of cell counts by approximately 25% and approximately 75% compared with those of control cells respectively. Similar findings were observed using Si 35. Treatment with both Si 34 and Si 35 at 10 microM increased cell mortality also ( approximately 29% and approximately 18% respectively). At these concentrations, a decrease in cyclin D1 levels was observed. To improve the biopharmaceutical properties, a liposome formulation was prepared. When entrapped in unilamellar liposomes, Si 34 exerted its cytotoxic effects even at lower doses (maximal inhibition at 5 microM) and after shorter incubation time (48 h) either in ARO or other thyroid cancer cell lines. The effects were associated with weak apoptotic death. Inhibition of epidermal growth factor-stimulated src and ERK phosphorylation, as well as reduction of migration properties of ARO cells was also observed. Moreover, the growth of tumor xenografts induced in severe combined immunodeficiency (SCID) mice was inhibited by i.v. administration of 25-50 mg/kg of the drug liposomal formulation. In conclusion, the liposomal preparation of this novel pyrazolopyrimidine derivative appears to be a promising tool for the treatment of anaplasic thyroid cancer.

Growth inhibition of medullary thyroid carcinoma cells by pyrazolo-pyrimidine derivates.

There is no effective treatment for recurrent or metastatic medullary thyroid carcinoma (MTC), a tumor arising from thyroid C-cells commonly presenting an inherited or acquired RET mutation. In this study we examined the sensitivity of two human MTC cell lines to novel pyrazolopyrimidine derivates, able to inhibit src-family tyrosine kinase activity. In TT cells [carrying the multiple endocrine neoplasia (MEN)2A Ret mutation Cys 634Trp] and MZ-CRC-1 cells (carrying the MEN2B RET mutation Met891Thr), one of these compounds, namely Si 34, determined a significant growth inhibitory effect (approximately 90% vs control for TT, 80% vs control for MZ-CRC-1) mainly due to enhanced cell mortality after a 6-day incubation. At concentrations that increased cell mortality, neither biochemical or morphological characteristics of apoptosis were detected in TT and MZCRC- 1 cells treated with Si 34. These results, when confirmed in other in vivo preclinical models, suggest that this novel tyrosine kinase inhibitor may be useful for the treatment of MTC.

Antiangiogenic agents: an update on small molecule VEGFR inhibitors.

Angiogenesis is a tightly regulated process that leads to the formation of new blood vessels sprouting from pre-existing microvasculature and occurs in limited physiological conditions or under pathological situations such as retinopathies, arthritis, endometriosis and cancer. Blockade of angiogenesis is an attractive approach for the treatment of such diseases. Particularly in malignancies, antiangiogenic therapy should be less toxic in comparison with conventional treatments such as chemotherapy, as angiogenesis is a process relatively restricted to the growing tumor. Vascular endothelial growth factor (VEGF) is one of the most important inducers of angiogenesis and exerts its cellular effects mainly by interacting with two high-affinity transmembrane tyrosine kinase receptors: VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1). It has been proven that inhibition of VEGF receptor activity reduces angiogenesis. For these reasons, the inhibition of VEGF or its receptor signalling system is an attractive target for therapeutic intervention. The most studied and developed inhibitors are monoclonal antibodies that neutralize VEGF, ribozymes, and small molecule VEGFR kinase inhibitors. Many important reviews dealing with VEGF-induced angiogenesis and its inhibition through the block of VEGF receptors have been reported, especially from a biological point of view. Here, we will review small synthetic VEGFR inhibitors that have appeared in literature in the last few years, focusing our attention on their medicinal chemistry in terms of chemical structure, mechanisms of action and structure-activity relationships. In fact, there have been an increased number of tyrosine kinase inhibitors in the most recent literature reports; their biological profile is extremely interesting and could be of great importance to medicinal chemists working in this area in improving their efficacy.

SRC inhibitors and angiogenesis.

Angiogenesis is a tightly regulated process that leads to the formation of new blood vessels in limited physiological conditions, and can also occur under pathological situations as retinopathies, arthritis, endometriosis and cancer. Enhanced angiogenesis is present in tumors that need new blood capillaries to grow, remove metabolic waste and transport the cells to locations distal to the primary tumor, facilitating metastasis formation. For these reasons, blockade of angiogenesis is an attractive approach for the treatment of both solid and haematological malignancies. Antiangiogenic therapy should be less toxic in comparison with conventional treatments such as chemotherapy, being angiogenesis a process relatively restricted to the growing tumor. The Src family of tyrosine kinases has been implicated in the intracellular signaling cascade that acts downstream of cell surface receptors to elicit different cellular functions, including growth, proliferation, adhesion and motility. Src kinases are frequently activated in human malignancies, causing tumor progression, metastasis formation and deregulating expression of proangiogenic molecules. This review reports several studies performed by different authors demonstrating the involvement of Src tyrosine kinases in angiogenesis by regulating different signalling pathways. Moreover, we report selective Src inhibitors for which a direct involvement with angiogenesis has been demonstrated, even if every Src inhibitor could potentially possesses also antiangiogenic properties. Biological data, structures and mechanisms of action of selected molecules, in terms of Src protein-inhibitor interactions, are also reported.

2-Amino/azido/hydrazino-5-alkoxy-5H-[1]benzopyrano[4,3-d]pyrimidines: synthesis and pharmacological evaluation.

New series of 5-alkoxy-benzopyranopyrimidine derivatives were developed from the chemical modulation of the substituent in position 2 of the scaffold, with the aim to produce analgesic/antiphlogistic agents more potent than analogues previously reported. The 2-hydrazino derivatives exhibited a good analgesic activity in writhing test; the analgesic doses of the compounds did not affect mice spontaneous locomotor activity thus any confounding sedative effect could be excluded. These derivatives revealed an aspirin-like profile with a strong inhibition of AA-induced platelet aggregation, probably due to a strong, non selective, inhibition of cyclooxygenases. In spite of the inhibition of COX activity displayed in vitro, the compounds did not cause gastric damage in rats after acute oral administration. A different pharmacological profile was observed for the 2-azido derivatives, particularly in vivo.

Last findings on dual inhibitors of abl and SRC tyrosine-kinases.

Chronic myelogenous leukemia (CML) is a myeloproliferative disease characterized by the presence of the Philadelphia chromosome that expresses the constitutively activated tyrosine kinase Bcr-Abl; this enzyme causes hyperproliferation of the stem cells and the consequent pathology of the disease. Targeted inhibitors of Bcr-Abl have antiproliferative effects on the leukemic cells and induce apoptosis, favouring a regression of the CML chronic phase, but in the successive blast crisis phase cancer cells frequently develop resistance to Bcr-Abl inhibitors. Src is a family of non-receptor tyrosine kinases, fundamental for cell development, growth, replication, adhesion, motility and is overexpressed in a wide number of human cancers. Recently it was demonstrated that Src is increased in hematopoietic cells expressing Bcr-Abl and is involved in the oncogenic pathway that causes CML. For this reason and also for the development of resistance to classical Bcr-Abl inhibitors, various dual Src/Abl inhibitors have been recently synthesized and tested. This mini review will be focused on the latest finding on this matter.

New pyrazolo[3,4-d]pyrimidines endowed with A431 antiproliferative activity and inhibitory properties of Src phosphorylation.

New 4-aminopyrazolo[3,4-d]pyrimidines bearing various substituents at the position 1 and 6, were synthesized. The new compounds showed antiproliferative activity toward A431 cells, were found to be inhibitors of Src phosphorylation, and induced apoptotic cell death. In particular, 2h was a better inhibitor of Src phosphorylation than the reference compound PP2.

N-Acyl-N-phenyl ureas of piperidine and substituted piperidines endowed with anti-inflammatory and anti-proliferative activities.

Six series of N-acyl-N-phenyl ureas 1-6 of piperidine (1), and 2-ethyl- (2), 3-methyl- (3), 4-methyl- (4), 4-phenyl- (5), cis-2,6-dimethyl- (6) piperidine were synthesised and evaluated for their anti-inflammatory, anaesthetic, anti-pyretic properties. Some derivatives of series 1 and 5 were also assayed for anti-proliferative activity. Several compounds showed an anti-inflammatory activity comparable or slighty inferior to that of indomethacin in rats (1c,d, 2a,b,g,h, 3b, 4h, 5d,e). Moreover, an appreciable anti-inflammatory activity was also found in 2c,e, 3e,f,g, 4g, 5a,b,c,f,h, and 6a,b,d. All the compounds were devoid of anti-pyretic activity and only a few of them exhibited a low level of infiltration anaesthesia in mice. Compound 5a showed a broad spectrum anti-cancer activity (at low micromolar concentrations), particulary significant against leukemia subpanel.

Synthesis and biological data of 4-amino-1-(2-chloro-2-phenylethyl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl esters, a new series of A1-adenosine receptor (A1AR) ligands.

The synthesis of a new family of A1-adenosine receptor (A1AR) ligands 3a-n has been performed in a straightforward way. Affinity data at A1AR, A2AAR and A3AR in bovine membranes show that these new compounds bind the A1AR in a selective way over A2AAR and A3AR and one of them (3j) presents a very high affinity, probably due to the phenethylamine substituent at C-4.