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Adaptor protein 2-associated kinase 1 (AAK1) is a member of the Ark1/Prk1 family of serine/threonine kinases and plays a role in modulating receptor endocytosis. AAK1 was identified as a potential therapeutic target for the treatment of neuropathic pain when it was shown that AAK1 knock out (KO) mice had a normal response to the acute pain phase of the mouse formalin model, but a reduced response to the persistent pain phase. Herein we report our early work investigating a series of pyrrolo[2,1- f ][1,2,4]triazines as part of our efforts to recapitulate this KO phenotype with a potent, small molecule inhibitor of AAK1. The synthesis, structure-activity relationships (SAR), and in vivo evaluation of these AAK1 inhibitors is described., Competing Interests: Conflict of interestThe authors declare no competing interests., (© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023.)

Long-acting (LA) human immunodeficiency virus-1 (HIV-1) antiretroviral therapy characterized by a ≥1 month dosing interval offers significant advantages over daily oral therapy. However, the criteria for compounds that enter clinical development are high. Exceptional potency and low plasma clearance are required to meet dose size requirements; excellent chemical stability and/or crystalline form stability is required to meet formulation requirements, and new antivirals in HIV-1 therapy need to be largely free of side effects and drug-drug interactions. In view of these challenges, the discovery that capsid inhibitors comprising a quinazolinone core tolerate a wide range of structural modifications while maintaining picomolar potency against HIV-1 infection in vitro , are assembled efficiently in a multi-component reaction, and can be isolated in a stereochemically pure form is reported herein. The detailed characterization of a prototypical compound, GSK878, is presented, including an X-ray co-crystal structure and subcutaneous and intramuscular pharmacokinetic data in rats and dogs.

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., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

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., Competing Interests: The authors declare no competing financial interest., (© 2022 American Chemical Society.)

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 .

GSK3532795 (formerly BMS-955176) is a second-generation HIV-1 maturation inhibitor that has shown broad spectrum antiviral activity and preclinical PK predictive of once-daily dosing in humans. Although efficacy was confirmed in clinical trials, the observation of gastrointestinal intolerability and the emergence of drug resistant virus in a Phase 2b clinical study led to the discontinuation of GSK3532795. As part of the effort to further map the maturation inhibitor pharmacophore and provide additional structural options, the evaluation of alternates to the C-3 phenyl substituent in this chemotype was pursued. A cyclohexene carboxylic acid provided exceptional inhibition of wild-type, V370A and ΔV370 mutant viruses in addition to a suitable PK profile following oral dosing to rats. In addition, a novel spiro[3.3]hept-5-ene was designed to extend the carboxylic acid further from the triterpenoid core while reducing side chain flexibility compared to the other alkyl substituents. This modification was shown to closely emulate the C-3 benzoic acid moiety of GSK3532795 from both a potency and PK perspective, providing a non-traditional, sp 3 -rich bioisostere of benzene. Herein, we detail additional modifications to the C-3 position of the triterpenoid core that offer effective replacements for the benzoic acid of GSK3532795 and capture the interplay between these new C-3 elements and C-17 modifications that contribute to enhanced polymorph coverage., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The design, synthesis and structure-activity relationships associated with a series of C2-substituted pyrazolopyrimidines as potent allosteric inhibitors of HIV-1 integrase (ALLINIs) are described. Structural modifications to these molecules were made in order to examine the effect on potency and, for select compounds, pharmacokinetic properties. We examined a variety of C2-substituted pyrazolopyrimidines and found that the C2-amide derivatives demonstrated the most potent antiviral activity of this class against HIV-1 infection in cell culture., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

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.

GSK3532795, formerly known as BMS-955176 (1), is a potent, orally active, second-generation HIV-1 maturation inhibitor (MI) that advanced through phase IIb clinical trials. The careful design, selection, and evaluation of substituents appended to the C-3 and C-17 positions of the natural product betulinic acid (3) was critical in attaining a molecule with the desired virological and pharmacokinetic profile. Herein, we highlight the key insights made in the discovery program and detail the evolution of the structure-activity relationships (SARs) that led to the design of the specific C-17 amine moiety in 1. These modifications ultimately enabled the discovery of 1 as a second-generation MI that combines broad coverage of polymorphic viruses (EC 50 <15 nM toward a panel of common polymorphisms representative of 96.5% HIV-1 subtype B virus) with a favorable pharmacokinetic profile in preclinical species.

The optimization of the 4-methoxy-6-azaindole series of HIV-1 attachment inhibitors (AIs) that originated with 1 to deliver temsavir (3, BMS-626529) is described. The most beneficial increases in potency and pharmacokinetic (PK) properties were attained by incorporating N-linked, sp 2 -hybridized heteroaryl rings at the 7-position of the heterocyclic nucleus. Compounds that adhered to a coplanarity model afforded targeted antiviral potency, leading to the identification of 3 with characteristics that provided for targeted exposure and PK properties in three preclinical species. However, the physical properties of 3 limited plasma exposure at higher doses, both in preclinical studies and in clinical trials as the result of dissolution- and/or solubility-limited absorption, a deficiency addressed by the preparation of the phosphonooxymethyl prodrug 4 (BMS-663068, fostemsavir). An extended-release formulation of 4 is currently in phase III clinical trials where it has shown promise as part of a drug combination therapy in highly treatment-experienced HIV-1 infected patients.

BMS-707035 is an HIV-1 integrase strand transfer inhibitor (INSTI) discovered by systematic optimization of N-methylpyrimidinone carboxamides guided by structure-activity relationships (SARs) and the single crystal X-ray structure of compound 10. It was rationalized that the unexpectedly advantageous profiles of N-methylpyrimidinone carboxamides with a saturated C2-substitutent may be due, in part, to the geometric relationship between the C2-substituent and the pyrimidinone core. The single crystal X-ray structure of 10 provided support for this reasoning and guided the design of a spirocyclic series 12 which led to discovery of the morpholino-fused pyrimidinone series 13. Several carboxamides derived from this bicyclic scaffold displayed improved antiviral activity and pharmacokinetic profiles when compared with corresponding spirocyclic analogs. Based on the excellent antiviral activity, preclinical profiles and acceptable in vitro and in vivo toxicity profiles, 13a (BMS-707035) was selected for advancement into phase I clinical trials., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The design and synthesis of a series of C28 amine-based betulinic acid derivatives as HIV-1 maturation inhibitors is described. This series represents a continuation of efforts following on from previous studies of C-3 benzoic acid-substituted betulinic acid derivatives as HIV-1 maturation inhibitors (MIs) that were explored in the context of C-28 amide substituents. Compared to the C-28 amide series, the C-28 amine derivatives exhibited further improvements in HIV-1 inhibitory activity toward polymorphisms in the Gag polyprotein as well as improved activity in the presence of human serum. However, plasma exposure of basic amines following oral administration to rats was generally low, leading to a focus on moderating the basicity of the amine moiety distal from the triterpene core. The thiomorpholine dioxide (TMD) 20 emerged from this study as a compound with the optimal antiviral activity and an acceptable pharmacokinetic profile in the C-28 amine series. Compared to the C-28 amide 3, 20 offers a 2- to 4-fold improvement in potency towards the screening viruses, exhibits low shifts in the EC 50 values toward the V370A and ΔV370 viruses in the presence of human serum or human serum albumin, and demonstrates improved potency towards the polymorphic T371A and V362I virus variants., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

HIV-1 maturation inhibition (MI) has been clinically validated as an approach to the control of HIV-1 infection. However, identifying an MI with both broad polymorphic spectrum coverage and good oral exposure has been challenging. Herein, we describe the design, synthesis, and preclinical characterization of a potent, orally active, second generation HIV-1 MI, BMS-955176 (2), which is currently in Phase IIb clinical trials as part of a combination antiretroviral regimen.

A series of C-3 phenyl- and heterocycle-substituted derivatives of C-3 deoxybetulinic acid and C-3 deoxybetulin was designed and synthesized as HIV-1 maturation inhibitors (MIs) and evaluated for their antiviral activity and cytotoxicity in cell culture. A 4-subsituted benzoic acid moiety was identified as an advantageous replacement for the 3'3'-dimethylsuccinate moiety present in previously disclosed MIs that illuminates new aspects of the topography of the pharmacophore. The new analogs exhibit excellent in vitro antiviral activity against wild-type (wt) virus and a lower serum shift when compared with the prototypical HIV-1 MI bevirimat (1, BVM), the first MI to be evaluated in clinical studies. Compound 9a exhibits comparable cell culture potency toward wt virus as 1 (WT EC50=16 nM for 9a compared to 10nM for 1). However, the potency of 9a is less affected by the presence of human serum, while the compound displays a similar pharmacokinetic profile in rats to 1. Hence 9a, the 4-benzoic acid derivative of deoxybetulinic acid, represents a new starting point from which to explore the design of a 2nd generation MI., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We have recently reported on the discovery of a C-3 benzoic acid (1) as a suitable replacement for the dimethyl succinate side chain of bevirimat (2), an HIV-1 maturation inhibitor that reached Phase II clinical trials before being discontinued. Recent SAR studies aimed at improving the antiviral properties of 2 have shown that the benzoic acid moiety conferred topographical constraint to the pharmacophore and was associated with a lower shift in potency in the presence of human serum albumin. In this manuscript, we describe efforts to improve the polymorphic coverage of the C-3 benzoic acid chemotype through modifications at the C-28 position of the triterpenoid core. The dimethylaminoethyl amides 17 and 23 delivered improved potency toward bevirimat-resistant viruses while increasing C24 in rat oral PK studies., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Herein, we describe the synthesis, antiviral structure-activity relationships (SAR), metabolic stability, and pharmacokinetic (PK) properties for a series of cyclopropylindolobenzazepine acylsulfonamide HCV NS5B polymerase inhibitors. Optimization of SAR, metabolic stability and PK led to the identification of compound 19 which was advanced into pre-IND enabling toxicology studies., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

6,6-Fused ring systems including tetrahydroisoquinolines and tetrahydropyrido[3,4-d]pyrimidines have been explored as possible replacements for the piperazine benzamide portion of the HIV-1 attachment inhibitor BMS-663068. In initial studies, the tetrahydroisoquinoline compounds demonstrate sub-nanomolar activity in a HIV-1 pseudotype viral infection assay used as the initial screen for inhibitory activity. Analysis of SARs and approaches to optimization for an improved drug-like profile are examined herein., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Integration of viral DNA into the host cell genome is an obligatory process for successful replication of HIV-1. Integrase catalyzes the insertion of viral DNA into the target DNA and is a validated target for drug discovery. Herein, we report the synthesis, antiviral activity and pharmacokinetic profiles of several C2-carbon-linked heterocyclic pyrimidinone-4-carboxamides that inhibit the strand transfer step of the integration process., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The biphenyl derivatives 2 and 3 are prototypes of a novel class of NS5A replication complex inhibitors that demonstrate high inhibitory potency toward a panel of clinically relevant HCV strains encompassing genotypes 1-6. However, these compounds exhibit poor systemic exposure in rat pharmacokinetic studies after oral dosing. The structure-activity relationship investigations that improved the exposure properties of the parent bis-phenylimidazole chemotype, culminating in the identification of the highly potent NS5A replication complex inhibitor daclatasvir (33) are described. An element critical to success was the realization that the arylglycine cap of 2 could be replaced with an alkylglycine derivative and still maintain the high inhibitory potency of the series if accompanied with a stereoinversion, a finding that enabled a rapid optimization of exposure properties. Compound 33 had EC50 values of 50 and 9 pM toward genotype-1a and -1b replicons, respectively, and oral bioavailabilities of 38-108% in preclinical species. Compound 33 provided clinical proof-of-concept for the NS5A replication complex inhibitor class, and regulatory approval to market it with the NS3/4A protease inhibitor asunaprevir for the treatment of HCV genotype-1b infection has recently been sought in Japan.

Described herein are structure-activity relationship studies that resulted in the optimization of the activity of members of a class of cyclopropyl-fused indolobenzazepine HCV NS5B polymerase inhibitors. Subsequent iterations of analogue design and syntheses successfully addressed off-target activities, most notably human pregnane X receptor (hPXR) transactivation, and led to significant improvements in the physicochemical properties of lead compounds. Those analogues exhibiting improved solubility and membrane permeability were shown to have notably enhanced pharmacokinetic profiles. Additionally, a series of alkyl bridged piperazine carboxamides was identified as being of particular interest, and from which the compound BMS-791325 (2) was found to have distinguishing antiviral, safety, and pharmacokinetic properties that resulted in its selection for clinical evaluation.

A series of highly potent HIV-1 attachment inhibitors with 4-fluoro-6-azaindole core heterocycles that target the viral envelope protein gp120 has been prepared. Substitution in the 7-position of the azaindole core with amides (12a,b), C-linked heterocycles (12c-l), and N-linked heterocycles (12m-u) provided compounds with subnanomolar potency in a pseudotype infectivity assay and good pharmacokinetic profiles in vivo. A predictive model was developed from the initial SAR in which the potency of the analogues correlated with the ability of the substituent in the 7-position of the azaindole to adopt a coplanar conformation by either forming internal hydrogen bonds or avoiding repulsive substitution patterns. 1-(4-Benzoylpiperazin-1-yl)-2-(4-fluoro-7-[1,2,3]triazol-1-yl-1H-pyrrolo[2,3-c]pyridin-3-yl)ethane-1,2-dione (BMS-585248, 12m) exhibited much improved in vitro potency and pharmacokinetic properties than the previous clinical candidate BMS-488043 (1). The predicted low clearance in humans, modest protein binding, and good potency in the presence of 40% human serum for 12m led to its selection for human clinical studies.

A series of HIV-1 attachment inhibitors containing a 4,6-diazaindole core were examined in an effort to identify a compound which improved upon the potency and oral exposure of BMS-488043 (2). BMS-488043 (2) is a 6-azaindole-based HIV-1 attachment inhibitor which established proof-of-concept for this mechanism in human clinical studies but required high doses and concomitant administration of a high fat meal to achieve efficacious exposures. Based on previous studies in indole and azaindole scaffolds, SAR investigation was concentrated around the key 7-position in the 4,6-diazaindole series and led to the discovery of molecules with 5- to 20-fold increases in potency and three- to seven-fold increases in exposure over 2 in a rat PK studies., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A series of 4-azaindole oxoacetic acid piperazine benzamides was synthesized and evaluated in an effort to identify an oral HIV-1 attachment inhibitor with the potential to improve upon the pre-clinical profile of BMS-378806 (7), an initial clinical compound. Modifications at the 7-position of the 4-azaindole core modulated potency significantly and SAR showed that certain compounds with a 5-membered ring heteroaryl group at that position were the most potent. Four of the compounds with the best profiles were evaluated in a rat pharmacokinetic model and all had superior oral bioavailability and lower clearance when compared with 7., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

4-Fluoro- and 4-methoxy-1-(4-benzoylpiperazin-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (2 and 3, respectively) have been characterized as potent inhibitors of HIV-1 attachment that interfere with the interaction of viral gp120 with the host cell receptor CD4. As part of an effort to understand fundamental aspects of this pharmacophore, discovered originally using a high throughput cell-based screen, modification and substitution of the piperazine ring was examined in the context of compounds 6a-ah. The piperazine ring was shown to be a critical element of the HIV-1 attachment inhibiting pharmacophore, acting as a scaffold to deploy the indole glyoxamide and benzamide in a topographical relationship that complements the binding site on gp120.

Lymphocyte depletion kinetics and time to emesis have previously been shown to correlate with radiation dose. However, the method for estimating dose from lymphocyte counts was cumbersome, and a tabulation of estimated dose vs. time to emesis published by the International Atomic Energy Agency did not agree well with a regression of data from many (>100) radiation accident cases. The time-to-emesis data have been reanalyzed, and the new regression corroborates the previously published table. Also, dose estimation from post-exposure lymphocyte counts has been simplified and no longer requires serial calculations. Instead, dose can be estimated by a simple table lookup, given the ratio of two lymphocyte counts and the time between blood samples.

Most clinicians will go their entire career without seeing a patient who has been involved in a nuclear or radiological incident, and many health care professionals feel ill equipped to respond to such incidents. To add to this difficulty, the medical response that is most appropriate for such an event varies, depending on the type of incident. As part of an effort to address these and other challenges for the medical community, the Centers for Disease Control and Prevention has developed a quick-reference for clinicians (based on the consensus of numerous stakeholders) that summarizes the key differences between various types of potential nuclear and radiological incidents in relation to some key medical response concerns. This paper is not intended for a clinical audience, but rather presents the and describes the framework upon which the is based, providing the health physics community with a clinical perspective of these events.

Purpose: To determine how often a prescribed threshold of hepatic contrast material enhancement is not reached at helical computed tomography (CT) of the liver in patients in a tertiary teaching hospital-based practice and which variables are predictive of failure., Materials and Methods: Hepatic helical CT was performed in 250 consecutive patients with computer-assisted bolus-tracking technology after either mechanical injection at 3 mL/sec (n = 177) or manual injection (n = 73) of 150 mL of iopamidol. Demographic variables were recorded. After 17 seconds, low-milliamperage monitoring scans were obtained every 6 seconds until hepatic enhancement of 50 HU over baseline was achieved. Time-enhancement curves were reviewed., Results: The threshold was not reached by 60 seconds in 88 patients (35%; default group). The success and default groups were similar in most variables and differed only in weight (P = .002), patient status (inpatient, outpatient, or emergency department; P < .001), and injection type (mechanical vs manual; P < .001). Ten patients (4%) did not achieve the threshold because of inappropriate placement of elliptic regions of interest., Conclusion: By using computer-assisted bolus-tracking technology, 35% of patients in a tertiary teaching hospital-based practice will not achieve a threshold of 50 HU above baseline by 60 seconds after injection initiation and will require the use of a set delay. Failures are more frequent in patients who are heavy and in inpatients. No historic or demographic factors are strongly predictive of failure.

Intact cells of Saccharomyces cerevisiae 139 hydrolyzed amino acid-p-nitroanilide by an activity similar to that of aminopeptidase II, as well-characterized external peptidase in yeast. In contrast, trimethionine, a model peptide used in transport assays, was not hydrolyzed by this aminopeptidase II-like activity, and the peptidase activity toward this substrate was localized in the soluble fraction of the yeast. We conclude that this tripeptide is taken up by S. cerevisiae intact and rapidly hydrolyzed inside the cell.

Guinea pig skin was depleted of Langerhans cells (LC) as assessed by ATPase and Ia staining using several techniques. The LCs were depleted either by tape-stripping or exposure of the animals to UV-B or UV-C radiation. Guinea-pigs were sensitized to 2,4-dinitrochlorobenzene (DNCB) by application of the sensitizer to the epidermis depleted of LC. Minimally suppressed contact reactions were found in animals exposed to both wavelengths of radiation, but this was shown to be a systemic rather than a local effect. Tape-stripping did not alter the degree of contact sensitivity when guinea-pigs were sensitized with a large dose of DNCB. When a non-sensitizing dose of DNCB was applied to the ear depleted of LC by tape-stripping, contact sensitivity resulted. Although the depletion of LCs was 97% following UV-B, 93% with UV-C and 78% after tape-stripping, at no time were LCs completely absent from the epidermis.