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Ramatroban-Based Analogues Containing Fluorine Group as Potential 18F-Labeled Positron Emission Tomography (PET) G-Protein Coupled Receptor 44 (GPR44) Tracers.
Huang, LA, Huang, KX, Tu, J, Kandeel, F, Li, J
Molecules (Basel, Switzerland). 2021;(5)
Abstract
Diabetes remains one of the fastest growing chronic diseases and is a leading source of morbidity and accelerated mortality in the world. Loss of beta cell mass (BCM) and decreased sensitivity to insulin underlie diabetes pathogenesis. Yet, the ability to safely and directly assess BCM in individuals with diabetes does not exist. Measures such as blood glucose provide only a crude indirect picture of beta cell health. PET imaging could, in theory, allow for safe, direct, and precise characterization of BCM. However, identification of beta cell-specific radiolabeled tracers remains elusive. G-protein coupled receptor 44 (GPR44) is a transmembrane protein that was characterized in 2012 as highly beta cell-specific within the insulin-positive islets of Langerhans. Accordingly, radiolabeling of existing GPR44 antagonists could be a viable method to accelerate PET tracer development. The present study aims to evaluate and summarize published analogues of the GPR44 antagonist ramatroban to develop 18F-labeled PET tracers for BCM analysis. The 77 corresponding ramatroban analogues containing a fluorine nuclide were characterized for properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile, and 32 compounds with favorable properties were identified. This review illustrates the potential of GPR44 analogues for the development of PET tracers.
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Difluoromethylthiolator: A Toolbox of Reagents for Difluoromethylthiolation.
Wu, J, Shen, Q
Accounts of chemical research. 2021;(14):2946-2958
Abstract
Recently, the strategic installation of a fluorine atom or a fluoroalkyl group site-selectively at the specific position of the target molecule has become a routine approach and daily practice for medicinal chemists in their endeavor to fine tune the structure of the lead compound to improve its physicochemical properties such as the cell membrane permeability and metabolic stability. Among many fluoroalkyl groups, the difluoromethylthio group (-SCF2H) has attracted recent intense attention. Largely due to the weak acidity of the proton in the difluoromethylthio group, the difluoromethylthio group is generally considered to be a lipophilic hydrogen-bonding donor and a bioisostere of the hydroxy/thio group that might interact with the heteroatom of the enzyme via a hydrogen bond to improve the binding selectivity of the drug molecule. Besides, the difluoromethylthio group is less lipophilic, less electron-withdrawing, and less stable to the acidic or basic environment than its analogue trifluoromethylthio group (-SCF3), making it easier to regulate the metabolic stability of drug molecules. These beneficial effects render the difluoromethylthio group one of the most favorable functional groups in drug design; consequently, there is an urgent need to develop new strategies for the efficient introduction of the difluoromethylthio group into small molecules under mild conditions. Over the last few decades, several different approaches to the preparation of difluoromethylthiolated compounds have been developed, including the difluoromethylation of thiolated substrates with an electrophilic/nucleophilic difluoromethylating reagent or the insertion of a difluoromethyl carbene into the S-H bond of the thiols. In contrast, we adopt an alternative approach to the preparation of difluoromethylthiolated compounds by late-stage direct difluoromethylthiolation of the specific substrates with a difluoromethylthiolating reagent. With this aim in mind, in the last 6 years we have successfully developed a toolbox of reagents that are capable of the direct introduction of the difluoromethylthio group into the target molecules, including nucleophilic difluoromethylthiolating reagent [(SIPr)AgSCF2H] I, electrophilic difluoromethylthiolating reagent PhthSCF2H II, three optically pure difluoromethylthiolating reagents camphorsultam-SCF2H III, radical difluoromethylthiolating reagent PhSO2SCF2H IV, and reagent PhSO2SCFClH V that could be used for the preparation of 18F-labeled [18F]ArSCF2H. These reagents reacted with a broad range of substrates to get access to difluoromethylthiolated compounds efficiently, thus providing medicinal chemists a powerful weapon for the direct introduction of the difluoromethylthio group into promising molecules during the search for new drugs.
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A Highlight on the Inhibition of Fungal Carbonic Anhydrases as Drug Targets for the Antifungal Armamentarium.
Supuran, CT, Capasso, C
International journal of molecular sciences. 2021;(9)
Abstract
Carbon dioxide (CO2), a vital molecule of the carbon cycle, is a critical component in living organisms' metabolism, performing functions that lead to the building of compounds fundamental for the life cycle. In all living organisms, the CO2/bicarbonate (HCO3-) balancing is governed by a superfamily of enzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1). CAs catalyze the pivotal physiological reaction, consisting of the reversible hydration of the CO2 to HCO3- and protons. Opportunistic and pathogenic fungi can sense the environmental CO2 levels, which influence their virulence or environmental subsistence traits. The fungal CO2-sensing is directly stimulated by HCO3- produced in a CA-dependent manner, which directly activates adenylyl cyclase (AC) involved in the fungal spore formation. The interference with CA activity may impair fungal growth and virulence, making this approach interesting for designing antifungal drugs with a novel mechanism of action: the inhibition of CAs linked to the CO2/HCO3-/pH chemosensing and signaling. This review reports that sulfonamides and their bioisosteres as well as inorganic anions can inhibit in vitro the β- and α-CAs from the fungi, suggesting how CAs may be considered as a novel "pathogen protein" target of many opportunistic, pathogenic fungi.
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4.
How we manage adults with myelodysplastic syndrome.
Fenaux, P, Platzbecker, U, Ades, L
British journal of haematology. 2020;(6):1016-1027
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Abstract
The prognosis in Myelodysplastic syndromes (MDS), although recently refined by molecular studies, remains largely based on conventional prognostic scores [International Prognostic Scoring System (IPSS), revised IPSS], classifying patients into "lower risk" MDS (LR-MDS) and "higher risk" MDS (HR-MDS). In LR-MDS, treatment mainly aims at improving cytopenias, principally anaemia, while in HR-MDS it aims at delaying disease progression and prolonging survival. In LR-MDS without deletion 5q, anaemia is generally treated first by erythropoietic stimulating factors, while second line treatments are currently not approved [lenalidomide, hypomethylating agents (HMA), luspatercept] or rarely indicated (antithymocyte globulin). Lenalidomide has major efficacy in LR-MDS with deletion 5q. Allogeneic stem cell transplantation (allo-SCT) is sometimes considered in LR-MDS, and iron chelation can be considered when multiple red blood cell transfusions are required. Allo-SCT is the only potentially curative treatment for HR-MDS; however, it is rarely applicable. It is generally preceded by intensive chemotherapy (IC) or HMA in patients with excess of marrow blasts (especially if >10%). In other patients, HMA can improve survival. The role of new drugs, including venetoclax or, in case of specific mutations, IDH1 or IDH2 inhibitors, is investigated. IC is mainly indicated as a bridge to allo-SCT, in the absence of unfavourable karyotype.
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Tenapanor for constipation-predominant irritable bowel syndrome.
Siddiqui, S, Cash, BD
Drugs of today (Barcelona, Spain : 1998). 2020;(3):203-210
Abstract
Irritable bowel syndrome (IBS) is among the most common gastrointestinal disorders encountered in primary and secondary care and is associated with impaired quality of life, increased healthcare utilization, and significant costs to patients and society. There are three primary phenotypes of IBS, categorized according to stool pattern: IBS with diarrhea (IBS-D), IBS with constipation (IBS-C) and IBS with a mixed bowel pattern (IBS-M). The treatment approach to all forms of IBS is typically hierarchal, with initial therapies consisting of dietary and lifestyle modifications. When these interventions are impractical or ineffective, pharmacotherapy with over-the-counter and prescription therapies is often employed. Tenapanor is a locally acting, minimally absorbed, selective small-molecule inhibitor of the intestinal sodium/hydrogen exchanger 3 (NHE3) that was approved in September 2019 by the U.S. Food and Drug Administration (FDA) for IBS-C. This agent works by increasing the sodium level in the intestinal lumen and promoting the efflux of fluid into the gut lumen to maintain osmotic balance in addition to having an antinociceptive effect. Tenapanor has been shown to improve bowel movement frequency/form and abdominal pain in patients with IBS-C. This article will elaborate on the clinical development program for tenapanor for this indication.
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Successful treatment of chronic hepatitis C virus infection with crushed glecaprevir/pibrentasvir administered via a percutaneous endoscopic gastrostomy tube: case report and review of the literature.
Tanaka, Y, Tateishi, R, Koike, K
Clinical journal of gastroenterology. 2019;(6):588-591
Abstract
Glecaprevir (GLE)/pibrentasvir (PIB) is a direct-acting antiviral regimen approved for patients infected with hepatitis C virus. No data are available on the safety and efficacy of this regimen when crushed and administered through a percutaneous endoscopic gastrostomy (PEG) tube. Here, we report a patient who successfully achieved a sustained viral response after treatment with GLE/PIB administered via a PEG tube. A 41-year-old female with chronic hepatitis C viral infection was referred to our department for treatment. She had a history of spina bifida and hydrocephalus, and she received a PEG tube for nutrition and medication due to an aftereffect of hydrocephalus. She received crushed GLE/PIB treatment through a PEG tube for 8 weeks and achieved a sustained viral response 12, without any treatment-related severe adverse events. This is the first documented case treated with GLE/PIB administered through a PEG tube. Based on this case report and a review of the literature, we discuss the safety and efficacy of direct-acting antiviral treatment via a PEG tube.
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Can we selectively target AML stem cells?
Jordan, CT
Best practice & research. Clinical haematology. 2019;(4):101100
Abstract
De novo acute myeloid leukemia (AML) leukemia stem cell (LSC) populations are uniquely dependent on amino acid metabolism to drive the TCA cycle and oxidative phosphorylation. Oxidative phosphorylation can be selectively downregulated in de novo AML LSC populations by perturbing amino acid metabolism via BCL2 inhibition with venetoclax. While venetoclax-based therapies have shown high response rates, not all patients achieve remission. It may be possible to prospectively identify the patients who will most likely respond to venetoclax-based treatment by analyzing the metabolic properties of individual patients. Specifically, it appears that patients who are likely to be resistant to venetoclax-based therapy are able to employ alternate metabolic pathways to drive oxidative phosphorylation.
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[What is recommended in the treatment of acute myeloid leukemia?].
Thol, F
Der Internist. 2019;(12):1240-1250
Abstract
Acute myeloid leukemia (AML) is characterized by a malignant transformation and proliferation of myeloid progenitor cells that cause a replacement of normal hematopoiesis. Diagnostic workup for AML includes cytogenetic analysis and mutational screening covering frequently mutated genes in AML. The genetic analysis is required for risk stratification and treatment decisions. Very recently, three novel drugs have been approved for patients who can be intensively treated: a tyrosine kinase inhibitor (midostaurin) for patients with FLT3 mutations, a liposomal formulation of chemotherapy (CPX) for patients with features of secondary AML, and a CD33 antibody-drug conjugate (gemtuzumab-ozogamicin) for AML with CD33 expression. Allogeneic stem cell transplantation remains an important treatment strategy for patients with intermediate- or high-risk AML and for patients with relapsed AML. For elderly patients who cannot undergo intensive treatment, demethylating agents are the treatment of choice. The aim is to prolong life expectancy with acceptable quality of life. In recent clinical trials, novel drugs have shown promising results in this patient population. Some of these drugs have already been approved in the US. Among these drugs are the Bcl‑2 inhibitor venetoclax, which is already approved in Germany for chronic lymphatic leukemia, as well as IDH1/IDH2 inhibitors (the latter for patients with IDH1/IDH2 mutated AML). Acute promyelocytic leukemia represents a special type of AML that should be treated with a combination of all-trans retinoic acid and arsenic trioxide leading to excellent outcome.
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9.
Tenapanor: First Approval.
Markham, A
Drugs. 2019;(17):1897-1903
Abstract
The selective sodium hydrogen exchanger 3 (NHE3) inhibitor tenapanor is being developed by Ardelyx Inc. for the treatment of constipation-predominant irritable bowel syndrome (IBS-C) [under the tradename IBSRELA®] and for hyperphosphataemia in patients with chronic kidney disease (CKD) on dialysis or with end stage renal disease (ESRD). Based on positive results from the phase III T3MPO trial program, tenapanor was recently approved in the USA for the treatment of IBS-C in adults. This article summarises the milestones in the development of tenapanor leading to this first approval.
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10.
Lipid profile and effect of statin treatment in pooled phase II and phase III baricitinib studies.
Taylor, PC, Kremer, JM, Emery, P, Zuckerman, SH, Ruotolo, G, Zhong, J, Chen, L, Witt, S, Saifan, C, Kurzawa, M, et al
Annals of the rheumatic diseases. 2018;(7):988-995
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Abstract
OBJECTIVES Lipid profiles are altered by active disease in patients with rheumatoid arthritis (RA) and may be further modified by treatment with Janus kinase inhibitors and other disease-modifying antirheumatic drugs. METHODS Lipid data were analysed from phase II and III studies of 4 mg (n=997) and 2 mg (n=479) oral baricitinib administered once daily in patients with moderate-to-severe active RA. Lipoprotein particle size and number and GlycA were evaluated with nuclear magnetic resonance in one phase III study. The effect of statin therapy on lipid levels was evaluated in patients on statins at baseline and in patients who initiated statins during the study. RESULTS Treatment with baricitinib was associated with increased levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides, but no significant change in LDL-C:HDL-C ratio. Lipid levels plateaued after 12 weeks of treatment. Baricitinib treatment increased large LDL and decreased small, dense LDL particle numbers and GlycA. Lipid changes from baseline were not significantly different between baseline statin users and non-users. In patients who initiated statin therapy during the study, LDL-C, triglycerides (baricitinib 4 mg only) and apolipoprotein B decreased to pre-baricitinib levels; HDL-C and apolipoprotein A-I levels remained elevated. CONCLUSIONS Baricitinib was associated with increased LDL-C, HDL-C and triglyceride levels, but did not alter the LDL-C:HDL-C ratio. Evaluation of cardiovascular event rates during long-term treatment is warranted to further characterise these findings and their possible clinical implications. TRIAL REGISTRATION NUMBER NCT00902486, NCT01469013, NCT01185353, NCT01721044, NCT01721057, NCT01711359, NCT01710358, NCT01885078.