Discovery of 2-(Anilino)pyrimidine-4-carboxamides as Highly Potent, Selective, and Orally Active Glycogen Synthase Kinase-3 (GSK-3) Inhibitors.

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that serves as an important regulator of a broad range of cellular functions. It has been linked to Alzheimer's disease as well as various other diseases, including mood disorders, type 2 diabetes, and cancer. There is considerable evidence indicating that GSK-3ß in the central nervous system plays a role in the production of abnormal, hyperphosphorylated, microtubule-associated tau protein found in neurofibrillary tangles associated with Alzheimer's disease. A series of analogues containing a pyrimidine-based hinge-binding heterocycle was synthesized and evaluated, leading to the identification of highly potent GSK-3 inhibitors with excellent kinase selectivity. Further evaluation of 34 and 40 in vivo demonstrated that these compounds are orally bioavailable, brain-penetrant GSK-3 inhibitors that lowered levels of phosphorylated tau in a triple-transgenic mouse Alzheimer's disease model.

Synthesis and biological evaluation of biaryl alkyl ethers as inhibitors of IDO1.

Starting from the dialkylaniline indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor lead 3 (IDO1 HeLa IC50 = 7.0 nM), an iterative process of synthesis and screening led to cyclized analog 21 (IDO1 HeLa IC50 = 3.6 nM) which maintained the high potency of 3 while addressing issues of lipophilicity, cytochrome P450 (CYP) inhibition, hERG (human potassium ion channel Kv11.1) inhibition, Pregnane X Receptor (PXR) transactivation, and oxidative metabolic stability. An x-ray crystal structure of a biaryl alkyl ether 11 bound to IDO1 was obtained. Consistent with our earlier results, compound 11 was shown to bind to the apo form of the enzyme.

Design, Structure-Activity Relationships, and In Vivo Evaluation of Potent and Brain-Penetrant Imidazo[1,2-b]pyridazines as Glycogen Synthase Kinase-3ß (GSK-3ß) Inhibitors.

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that regulates numerous cellular processes, including metabolism, proliferation, and cell survival. Due to its multifaceted role, GSK-3 has been implicated in a variety of diseases, including Alzheimer's disease, type 2 diabetes, cancer, and mood disorders. GSK-3ß has been linked to the formation of the neurofibrillary tangles associated with Alzheimer's disease that arise from the hyperphosphorylation of tau protein. The design and synthesis of a series of imidazo[1,2-b]pyridazine derivatives that were evaluated as GSK-3ß inhibitors are described herein. Structure-activity relationship studies led to the identification of potent GSK-3ß inhibitors. In vivo studies with 47 in a triple-transgenic mouse Alzheimer's disease model showed that this compound is a brain-penetrant, orally bioavailable GSK-3ß inhibitor that significantly lowered levels of phosphorylated tau.

Structure-activity relationship (SAR) studies on substituted N-(pyridin-3-yl)-2-amino-isonicotinamides as highly potent and selective glycogen synthase kinase-3 (GSK-3) inhibitors.

In our continuing efforts to explore structure-activity relationships around the novel class of potent, isonicotinamide-based GSK3 inhibitors described in our previous report, we extensively explored structural variations around both 4/5-pyridine substitutions and the amide group. Some analogs were found to have greatly improved pTau lowering potency while retaining high kinase selectivity. In contrast to previous active compounds 1a-c, a close analog 3h did not show in vivo efficacy in a triple-transgenic mouse Alzheimer's disease model. In general, these 2­pyridinyl amide derivatives were prone to amidase mediated hydrolysis in mouse plasma.

Discovery and Preclinical Profiling of GSK3839919, a Potent HIV-1 Allosteric Integrase Inhibitor.

Allosteric HIV-1 integrase inhibitors (ALLINIs) have been of interest recently because of their novel mechanism of action. Strategic modifications to the C5 moiety of a class of 4-(4,4-dimethylpiperidinyl)-2,6-dimethylpyridinyl ALLINIs led to the identification of a tetrahydroisoquinoline heterocycle as a suitable spacer element to project the distal hydrophobic aryl ring. Subsequent optimization of the aryl substitutions identified 12 as an ALLINI with single-digit nanomolar inhibitory potency and low clearance across preclinical species. In preclinical toxicology studies with 12 in rats, lipid hepatocellular vacuolation was observed. Removal of the C6 methyl group resulted in GSK3839919 (22), which exhibited a reduced incidence and severity of lipid vacuolation in both in vitro assays and in vivo studies while maintaining the potency and pharmacokinetic (PK) properties of the prototype. The virology, PK, and toxicology profiles of 22 are discussed.

Scaffold modifications to the 4-(4,4-dimethylpiperidinyl) 2,6-dimethylpyridinyl class of HIV-1 allosteric integrase inhibitors.

Allosteric integrase inhibitors (ALLINIs) of HIV-1 may hold promise as a novel mechanism for HIV therapeutics and cure. Scaffold modifications to the 4-(4,4-dimethylpiperidinyl) 2,6-dimethylpyridinyl class of ALLINIs provided a series of potent compounds with differentiated 5/6 fused ring systems. Notably, inhibitors containing the 1,2,4-triazolopyridine and imidazopyridine core exhibited single digit nM antiviral potency and low to moderate clearance after intravenous (IV) dosing in rat pharmacokinetic (PK) studies. The 1,2,4-triazolopyridines showed a higher oral exposure when compared to the imidazopyridines. Further modifications to the C5 substituent of the 1,2,4-triazolopyridines resulted in a new lead compound, which had improved rat IV/PO PK compared to the former lead compound GSK3739936, while maintaining antiviral potency. Structure-activity relationships (SAR) and rat pharmacokinetic profiles of this series are discussed.

Design, Synthesis, and Preclinical Profiling of GSK3739936 (BMS-986180), an Allosteric Inhibitor of HIV-1 Integrase with Broad-Spectrum Activity toward 124/125 Polymorphs.

Allosteric HIV-1 integrase inhibitors (ALLINIs) have garnered special interest because of their novel mechanism of action: they inhibit HIV-1 replication by promoting aberrant integrase multimerization, leading to the production of replication-deficient viral particles. The binding site of ALLINIs is in a well-defined pocket formed at the interface of two integrase monomers that is characterized by conserved residues along with two polymorphic amino acids at residues 124 and 125. The design, synthesis, and optimization of pyridine-based allosteric integrase inhibitors are reported here. Optimization was conducted with a specific emphasis on the inhibition of the 124/125 polymorphs such that the designed compounds showed excellent potency in vitro against majority of the 124/125 variants. In vivo profiling of promising preclinical lead 29 showed that it exhibited a good pharmacokinetic (PK) profile in preclinical species, which resulted in a low predicted human efficacious dose. However, findings in rat toxicology studies precluded further development of 29.

Pemphigus foliaceus in a patient with gastrointestinal stromal tumor treated with adjuvant imatinib mesylate.

Pemphigus is an autoimmune bullous disease with a number of described associations, including medications, which have been grouped into three structural categories - thiol drugs, phenol drugs, and drugs with neither functional group [1]. Discontinuation of the offending medication is considered a mainstay of therapy. We report a patient in whom the onset of pemphigus foliaceus was associated with initiation of imatinib mesylate adjuvant therapy in a patient with resected gastrointestinal stromal tumor (GIST). Imatinib was continued because of the survival benefit to the patient with a resected, high risk GIST. Treatment with rituximab resulted in near resolution of his blistering rash and follow up enzyme-linked immunosorbent assay (ELISA) demonstrated reference range immunoreactivity for both desmoglein 1 and desmoglein 3. After dose increase of imatinib therapy owing to tumor growth, the patient subsequently again developed a similar eruption. Re-biopsy and ELISA were consistent with recurrence of pemphigus. In conclusion, although the patient's pemphigus was cleared with a single cycle of rituximab infusions while continuing imatinib therapy, the disease returned after imatinib dose was increased a year later, suggesting a dose-response relationship.

Neutrophil-predominant bullous pemphigoid induced by checkpoint inhibitors: A case series.

Checkpoint inhibitors have been revolutionary in the treatment of metastatic melanoma, non-small-cell lung cancer, and renal cell carcinoma. By restricting negative feedback of T-cells, checkpoint inhibitors allow the immune system to identify and destroy malignant cells. This enhanced immune response is efficacious in the treatment of the aforementioned malignancies; however, it may lead to immune-related adverse events. Bullous pemphigoid (BP) is a well-documented cutaneous adverse reaction of checkpoint inhibitors, with a majority of cases reporting an eosinophil-predominant or mixed inflammatory infiltrate. We report two cases of neutrophil-predominant BP presenting in patients on checkpoint inhibitors.

Discovery and Optimization of Novel Pyrazolopyrimidines as Potent and Orally Bioavailable Allosteric HIV-1 Integrase Inhibitors.

The standard of care for HIV-1 infection, highly active antiretroviral therapy (HAART), combines two or more drugs from at least two classes. Even with the success of HAART, new drugs with novel mechanisms are needed to combat viral resistance, improve adherence, and mitigate toxicities. Active site inhibitors of HIV-1 integrase are clinically validated for the treatment of HIV-1 infection. Here we describe allosteric inhibitors of HIV-1 integrase that bind to the LEDGF/p75 interaction site and disrupt the structure of the integrase multimer that is required for the HIV-1 maturation. A series of pyrazolopyrimidine-based inhibitors was developed with a vector in the 2-position that was optimized by structure-guided compound design. This resulted in the discovery of pyrazolopyrimidine 3, which was optimized at the 2- and 7-positions to afford 26 and 29 as potent allosteric inhibitors of HIV-1 integrase that exhibited low nanomolar antiviral potency in cell culture and encouraging PK properties.

5,6,7,8-Tetrahydro-1,6-naphthyridine Derivatives as Potent HIV-1-Integrase-Allosteric-Site Inhibitors.

A series of 5,6,7,8-tetrahydro-1,6-naphthyridine derivatives targeting the allosteric lens-epithelium-derived-growth-factor-p75 (LEDGF/p75)-binding site on HIV-1 integrase, an attractive target for antiviral chemotherapy, was prepared and screened for activity against HIV-1 infection in cell culture. Small molecules that bind within the LEDGF/p75-binding site promote aberrant multimerization of the integrase enzyme and are of significant interest as HIV-1-replication inhibitors. Structure-activity-relationship studies and rat pharmacokinetic studies of lead compounds are presented.

Overuse of Magnetic Resonance Imaging in the Diagnosis and Treatment of Moderate to Severe Osteoarthritis.

Background: MRI in the evaluation of end-stage knee joint osteoarthritis (OA) is usually unnecessary when radiographic and clinical evidence of gonarthrosis is clear. The purpose of this study was to assess the prevalence of MRI scans ordered in patients with radiographically obvious gonarthrosis and to examine the characteristics of health care providers who ordered these imaging studies. Methods: We retrospectively identified 164 patients diagnosed with moderate to severe OA who were referred for total knee replacement (TKA) over a one-year period. The percentage of patients who had an MRI scan with or without X-ray, within the preceding 3 months prior to referral, were calculated. Subgroups were analyzed to identify characteristics that may influence the decision to order an MRI, including K-L grade, provider type, level of training, and practice location. Results: Of 145 patients, 19 (13.1%) presented with an MRI scan. Between the number of MRI scans ordered, there was a significant difference when comparing physicians versus non-physicians, with physicians ordering less MRI scans (p=0.018). There was a significant difference when comparing non-academic versus academic, with academic providers ordering less MRI scans (p=0.044). There was no significant difference with fellowship training or provider proximity to our academic institution. Conclusions: In this study, 13.1% of patients with radiographically obvious knee OA obtained an MRI prior to referral for TKA. Non-physicians and non-academic physicians were more likely to order MRI scans. Improved education for referring providers may be necessary to decrease overuse of MRI in the diagnosis of moderate to severe arthritis. Level of Evidence: Level II.

Immune-modulating enzyme indoleamine 2,3-dioxygenase is effectively inhibited by targeting its apo-form.

For cancer cells to survive and proliferate, they must escape normal immune destruction. One mechanism by which this is accomplished is through immune suppression effected by up-regulation of indoleamine 2,3-dioxygenase (IDO1), a heme enzyme that catalyzes the oxidation of tryptophan to N-formylkynurenine. On deformylation, kynurenine and downstream metabolites suppress T cell function. The importance of this immunosuppressive mechanism has spurred intense interest in the development of clinical IDO1 inhibitors. Herein, we describe the mechanism by which a class of compounds effectively and specifically inhibits IDO1 by targeting its apo-form. We show that the in vitro kinetics of inhibition coincide with an unusually high rate of intrinsic enzyme-heme dissociation, especially in the ferric form. X-ray crystal structures of the inhibitor-enzyme complexes show that heme is displaced from the enzyme and blocked from rebinding by these compounds. The results reveal that apo-IDO1 serves as a unique target for inhibition and that heme lability plays an important role in posttranslational regulation.

Dermatology ECHO - an innovative solution to address limited access to dermatology expertise.

INTRODUCTION: The present maldistribution of dermatologists in the USA may make it difficult for patients to access timely and quality care. Access to specialty care may be even more challenging for rural and underserved patients due to geographical limitations and other socioeconomic hardships. With over one-third of primary care patients seeking care for at least one skin problem, it is important to follow the American Academy of Dermatology Special Positioning Workgroup\'s core areas of impact regarding treatment of conditions that affect millions of patients by using a team-based approach and telemedicine technologies. The objective of this study was to demonstrate the Dermatology Extension for Community Healthcare Outcomes (ECHO) project approach in multidisciplinary telementoring and education of primary care providers (PCPs) in treatment and management of complex, costly, and common skin diseases via live interactive video technologies. METHODS: Dermatology ECHO is a distance education telementoring platform that uses a multidisciplinary case-based approach in a non-judgemental environment. A team of specialists, including general dermatologists, pediatric dermatologists, a dermatopathologist, a clinical psychologist, and a nurse practitioner, meets via video with a number of PCPs from isolated, rural, or underserved areas to discuss de-identified patient cases and present dermatology-specific continuing medical education (CME)-approved didactic presentations. The University of Missouri, Department of Dermatology, leads the first Dermatology ECHO in the USA. They partner with various primary care clinics across Missouri to provide mentoring in the treatment of skin conditions. Missouri Telehealth Network provides operational support through the Show-Me ECHO project. The network also assists with provider recruitment activities. RESULTS: The authors describe a patient case to illustrate the effect of ECHO on provider distance learning and patient outcomes. A 69-year-old woman from rural Missouri was spurred by a rooster. She presented to her primary care clinic six times over a 2-month period. She was prescribed several different medications and underwent tests and one procedure, including vaccination. After the patient\'s case was presented during the Dermatology ECHO session, she was correctly diagnosed with a Mycobacterium skin infection, and new recommendations were made. The patient improved significantly within 2 weeks. CONCLUSIONS: As specialty medical evidence-based recommendations continue to increase, providers practicing in isolated rural and underserved areas may find it challenging to keep up with the new knowledge. Dermatology ECHO creates a community of practice that allows participating providers to discuss complex cases, receive specific guidance and mentoring, and participate in CME presentations. The case presented here supports the authors\' observations that Dermatology ECHO is an appropriate platform for learning evidence-based medical knowledge via videoconferencing technology.

Initial Clinical Guidelines for Co-Occurring Autism Spectrum Disorder and Gender Dysphoria or Incongruence in Adolescents.

Evidence indicates an overrepresentation of youth with co-occurring autism spectrum disorders (ASD) and gender dysphoria (GD). The clinical assessment and treatment of adolescents with this co-occurrence is often complex, related to the developmental aspects of ASD. There are no guidelines for clinical care when ASD and GD co-occur; however, there are clinicians and researchers experienced in this co-occurrence. This study develops initial clinical consensus guidelines for the assessment and care of adolescents with co-occurring ASD and GD, from the best clinical practices of current experts in the field. Expert participants were identified through a comprehensive international search process and invited to participate in a two-stage Delphi procedure to form clinical consensus statements. The Delphi Method is a well-studied research methodology for obtaining consensus among experts to define appropriate clinical care. Of 30 potential experts identified, 22 met criteria as expert in co-occurring ASD and GD youth and participated. Textual data divided into the following data nodes: guidelines for assessment; guidelines for treatment; six primary clinical/psychosocial challenges: social functioning, medical treatments and medical safety, risk of victimization/safety, school, and transition to adulthood issues (i.e., employment and romantic relationships). With a cutoff of 75% consensus for inclusion, identified experts produced a set of initial guidelines for clinical care. Primary themes include the importance of assessment for GD in ASD, and vice versa, as well as an extended diagnostic period, often with overlap/blurring of treatment and assessment.

Discovery of S3-Truncated, C-6 Heteroaryl Substituted Aminothiazine ß-Site APP Cleaving Enzyme-1 (BACE1) Inhibitors.

Truncation of the S3 substituent of the biaryl aminothiazine 2, a potent BACE1 inhibitor, led to a low molecular weight aminothiazine 5 with moderate activity. Despite its moderate activity, compound 5 demonstrated significant brain Aß reduction in rodents. The metabolic instability of 5 was overcome by the replacement of the 6-dimethylisoxazole, a metabolic soft spot, with a pyrimidine ring. Thus, truncation of the S3 substituent represents a viable approach to the discovery of orally bioavailable, brain-penetrant BACE1 inhibitors.

Targeting the BACE1 Active Site Flap Leads to a Potent Inhibitor That Elicits Robust Brain Aß Reduction in Rodents.

By targeting the flap backbone of the BACE1 active site, we discovered 6-dimethylisoxazole-substituted biaryl aminothiazine 18 with 34-fold improved BACE1 inhibitory activity over the lead compound 1. The cocrystal structure of 18 bound to the active site indicated two hydrogen-bond interactions between the dimethylisoxazole and threonine 72 and glutamine 73 of the flap. Incorporation of the dimethylisoxazole substitution onto the related aminothiazine carboxamide series led to pyrazine-carboxamide 26 as a very potent BACE1 inhibitor (IC50 < 1 nM). This compound demonstrated robust brain Aß reduction in rat dose-response studies. Thus, compound 26 may be useful in testing the amyloid hypothesis of Alzheimer's disease.

Discovery of Isonicotinamides as Highly Selective, Brain Penetrable, and Orally Active Glycogen Synthase Kinase-3 Inhibitors.

GSK-3 is a serine/threonine kinase that has numerous substrates. Many of these proteins are involved in the regulation of diverse cellular functions, including metabolism, differentiation, proliferation, and apoptosis. Inhibition of GSK-3 may be useful in treating a number of diseases including Alzheimer's disease (AD), type II diabetes, mood disorders, and some cancers, but the approach poses significant challenges. Here, we present a class of isonicotinamides that are potent, highly kinase-selective GSK-3 inhibitors, the members of which demonstrated oral activity in a triple-transgenic mouse model of AD. The remarkably high kinase selectivity and straightforward synthesis of these compounds bode well for their further exploration as tool compounds and therapeutics.

Channel Gating Regulation by the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) First Cytosolic Loop.

In this study, we present data indicating a robust and specific domain interaction between the cystic fibrosis transmembrane conductance regulator (CFTR) first cytosolic loop (CL1) and nucleotide binding domain 1 (NBD1) that allows ion transport to proceed in a regulated fashion. We used co-precipitation and ELISA to establish the molecular contact and showed that binding kinetics were not altered by the common clinical mutation F508del. Both intrinsic ATPase activity and CFTR channel gating were inhibited severely by CL1 peptide, suggesting that NBD1/CL1 binding is a crucial requirement for ATP hydrolysis and channel function. In addition to cystic fibrosis, CFTR dysregulation has been implicated in the pathogenesis of prevalent diseases such as chronic obstructive pulmonary disease, acquired rhinosinusitis, pancreatitis, and lethal secretory diarrhea (e.g. cholera). On the basis of clinical relevance of the CFTR as a therapeutic target, a cell-free drug screen was established to identify modulators of NBD1/CL1 channel activity independent of F508del CFTR and pharmacologic rescue. Our findings support a targetable mechanism of CFTR regulation in which conformational changes in the NBDs cause reorientation of transmembrane domains via interactions with CL1 and result in channel gating.