Human cardiovascular disease model predicts xanthine oxidase inhibitor cardiovascular risk.

Some health concerns are often not identified until late into clinical development of drugs, which can place participants and patients at significant risk. For example, the United States Food and Drug Administration (FDA) labeled the xanthine oxidase inhibitor febuxostat with a"boxed" warning regarding an increased risk of cardiovascular death, and this safety risk was only identified during Phase 3b clinical trials after its approval. Thus, better preclinical assessment of drug efficacy and safety are needed to accurately evaluate candidate drug risk earlier in discovery and development. This study explored whether an in vitro vascular model incorporating human vascular cells and hemodynamics could be used to differentiate the potential cardiovascular risk associated with molecules that have similar on-target mechanisms of action. We compared the transcriptomic responses induced by febuxostat and other xanthine oxidase inhibitors to a database of 111 different compounds profiled in the human vascular model. Of the 111 compounds in the database, 107 are clinical-stage and 33 are FDA-labelled for increased cardiovascular risk. Febuxostat induces pathway-level regulation that has high similarity to the set of drugs FDA-labelled for increased cardiovascular risk. These results were replicated with a febuxostat analog, but not another structurally distinct xanthine oxidase inhibitor that does not confer cardiovascular risk. Together, these data suggest that the FDA warning for febuxostat stems from the chemical structure of the medication itself, rather than the target, xanthine oxidase. Importantly, these data indicate that cardiovascular risk can be evaluated in this in vitro human vascular model, which may facilitate understanding the drug candidate safety profile earlier in discovery and development.

Identification of 2,2-Dimethylbutanoic Acid (HST5040), a Clinical Development Candidate for the Treatment of Propionic Acidemia and Methylmalonic Acidemia.

Propionic acidemia (PA) and methylmalonic acidemia (MMA) are rare autosomal recessive disorders of propionyl-CoA (P-CoA) catabolism, caused by a deficiency in the enzymes P-CoA carboxylase and methylmalonyl-CoA (M-CoA) mutase, respectively. PA and MMA are classified as intoxication-type inborn errors of metabolism because the intramitochondrial accumulation of P-CoA, M-CoA, and other metabolites results in secondary inhibition of multiple pathways of intermediary metabolism, leading to organ dysfunction and failure. Herein, we describe the structure-activity relationships of a series of short-chain carboxylic acids which reduce disease-related metabolites in PA and MMA primary hepatocyte disease models. These studies culminated in the identification of 2,2-dimethylbutanoic acid (10, HST5040) as a clinical candidate for the treatment of PA and MMA. Additionally, we describe the in vitro and in vivo absorption, distribution, metabolism, and excretion profile of HST5040, data from preclinical studies, and the synthesis of the sodium salt of HST5040 for clinical trials.

A novel small molecule approach for the treatment of propionic and methylmalonic acidemias.

Propionic Acidemia (PA) and Methylmalonic Acidemia (MMA) are inborn errors of metabolism affecting the catabolism of valine, isoleucine, methionine, threonine and odd-chain fatty acids. These are multi-organ disorders caused by the enzymatic deficiency of propionyl-CoA carboxylase (PCC) or methylmalonyl-CoA mutase (MUT), resulting in the accumulation of propionyl-coenzyme A (P-CoA) and methylmalonyl-CoA (M-CoA in MMA only). Primary metabolites of these CoA esters include 2-methylcitric acid (MCA), propionyl-carnitine (C3), and 3-hydroxypropionic acid, which are detectable in both PA and MMA, and methylmalonic acid, which is detectable in MMA patients only (Chapman et al., 2012). We deployed liver cell-based models that utilized PA and MMA patient-derived primary hepatocytes to validate a small molecule therapy for PA and MMA patients. The small molecule, HST5040, resulted in a dose-dependent reduction in the levels of P-CoA, M-CoA (in MMA) and the disease-relevant biomarkers C3, MCA, and methylmalonic acid (in MMA). A putative working model of how HST5040 reduces the P-CoA and its derived metabolites involves the conversion of HST5040 to HST5040-CoA driving the redistribution of free and conjugated CoA pools, resulting in the differential reduction of the aberrantly high P-CoA and M-CoA. The reduction of P-CoA and M-CoA, either by slowing production (due to increased demands on the free CoA (CoASH) pool) or enhancing clearance (to replenish the CoASH pool), results in a net decrease in the CoA-derived metabolites (C3, MCA and MMA (MMA only)). A Phase 2 study in PA and MMA patients will be initiated in the United States.

A Phase 1 Study to Assess the Relative Bioavailability, Food Effect, and Safety of a Tablet Formulation of GSK2838232, a Novel HIV Maturation Inhibitor in Healthy Participants After Single and Repeated Doses.

GSK2838232 is a novel, potent HIV-1 maturation inhibitor for use in regimen-based combination antiretroviral therapy from a once-daily oral dose boosted with a pharmacoenhancer (ritonavir or cobicistat). This phase 1 study in healthy participants was conducted in 2 parts. Part 1 (n = 14) assessed the relative bioavailability of single doses of a 200-mg GSK2838232 tablet and capsule formulation boosted with 100 mg ritonavir in fed and fasted (tablet-only) subjects. Part 2 (n = 10) assessed the pharmacokinetics of repeated 500-mg once-daily doses of GSK2838232 without a pharmacoenhancing boosting agent. In part 1, GSK2838232 demonstrated comparable bioavailability following a single dose of 200 mg GSK2838232 as capsule and tablet formulations in combination with ritonavir (RTV) under fed conditions, with lower intrasubject variability observed for the tablet formulation. In part 2, following administration of 500 mg GSK2838232 once daily for 11 days under fed conditions, Cmax , AUC0-τ , and Cτ showed a small degree of accumulation (1.2- to 1.3-fold) of GSK2838232. The median tmax was approximately 4 hours on both day 1 and day 11 when given with food. The mean t½ was approximately 23 hours on day 11. Steady-state concentrations were achieved by day 3 with a geometric mean steady-state Cτ on day 11 of 28 ng/mL. The tablet formulation was generally well tolerated as a single 200-mg dose with RTV under fed and fasted conditions and following administration of multiple daily doses (11 days) of 500 mg unboosted.

CTLA-4 and PD-1 dual blockade induces SIV reactivation without control of rebound after antiretroviral therapy interruption.

The primary human immunodeficiency virus (HIV) reservoir is composed of resting memory CD4+ T cells, which often express the immune checkpoint receptors programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4), which limit T cell activation via synergistic mechanisms. Using simian immunodeficiency virus (SIV)-infected, long-term antiretroviral therapy (ART)-treated rhesus macaques, we demonstrate that PD-1, CTLA-4 and dual CTLA-4/PD-1 immune checkpoint blockade using monoclonal antibodies is well tolerated, with evidence of bioactivity in blood and lymph nodes. Dual blockade was remarkably more effective than PD-1 blockade alone in enhancing T cell cycling and differentiation, expanding effector-memory T cells and inducing robust viral reactivation in plasma and peripheral blood mononuclear cells. In lymph nodes, dual CTLA-4/PD-1 blockade, but not PD-1 alone, decreased the total and intact SIV-DNA in CD4+ T cells, and SIV-DNA and SIV-RNA in B cell follicles, a major site of viral persistence during ART. None of the tested interventions enhanced SIV-specific CD8+ T cell responses during ART or viral control after ART interruption. Thus, despite CTLA-4/PD-1 blockade inducing robust latency reversal and reducing total levels of integrated virus, the degree of reservoir clearance was still insufficient to achieve viral control. These results suggest that immune checkpoint blockade regimens targeting PD-1 and/or CTLA-4, if performed in people living with HIV with sustained aviremia, are unlikely to induce HIV remission in the absence of additional interventions.

A Phase IIa Study Evaluating Safety, Pharmacokinetics, and Antiviral Activity of GSK2838232, a Novel, Second-generation Maturation Inhibitor, in Participants With Human Immunodeficiency Virus Type 1 Infection.

BACKGROUND: GSK2838232 is a second-generation, potent, small-molecule, oral human immunodeficiency virus type 1 (HIV-1) maturation inhibitor for once-daily administration boosted with a pharmacoenhancer. METHODS: The phase 2a, proof-of-concept study was an open-label, adaptive dose-ranging design. Safety, pharmacokinetics, and efficacy of GSK2838232 boosted by cobicistat were evaluated in individuals with HIV-1 infection. The study participants (N = 33) received GSK2838232 once daily across a range of doses (20-200 mg) with cobicistat 150 mg for 10 days. RESULTS: GSK2838232 was safe and well tolerated with no clinically meaningful changes in safety parameters or adverse events. Exposure (maximum concentration and area under the concentration-time curve from time zero to the concentration at 24 hours postdose) increased 2- to 3-fold with repeated dosing in an approximately dose-proportional manner, reaching steady-state by day 8 with a half-life (t½) from 16.3 to 19.2 hours. Clearance and t½ values were not dependent on dose. Viral load declined from baseline with all GSK2838232 doses. Mean maximum declines from baseline to day 11 in HIV-1 RNA log10 copies/mL with the 20-mg, 50-mg, 100-mg, and 200-mg cohorts were -0.67, -1.56, -1.32, and -1.70, respectively. CD4+ cell counts increased at doses ≥50 mg. CONCLUSIONS: GSK2838232 with cobicistat was well tolerated and exhibited efficacy as a short-term monotherapy in participants with HIV-1. This positive proof-of-concept study supports the continued development of GSK2838232 for the treatment of HIV as part of combination antiretroviral therapy. CLINICAL TRIALS REGISTRATION: NCT03045861.

The safety, tolerability, and pharmacokinetic profile of GSK2838232, a novel 2nd generation HIV maturation inhibitor, as assessed in healthy subjects.

This work aimed to assess the safety, tolerability, pharmacokinetics (PK), and relative bioavailability of GSK2838232, an investigational HIV maturation inhibitor. GSK2838232 was administered over four dose-escalation studies in healthy subjects which assessed single oral doses (5-250 mg) and repeat doses (up to 200 mg once or twice daily) ±100 mg ritonavir (RTV) once daily. GSK2838232 administration (up to 250 mg) to 124 subjects across four studies resulted in few mild adverse events (AEs) with similar frequencies to placebo. There were no clearly identified drug-related AEs. GSK2838232 tested fasted was quickly absorbed with a tmax of 2-3 hours. With food, the absorption was delayed and more variable, with ~60% increase in AUC and Cmax. Overall, following single doses GSK2838232 AUC and Cmax generally exhibited proportional PK from 50 to 100 mg dose without RTV and from 50 to 250 mg with RTV and following repeated doses of 20-200 mg with RTV. In relative bioavailability studies, a micronized formulation was found to be suitable for development. At steady state, RTV increased GSK2838232 AUC and Cmax by 10- and 3-fold, respectively. Half-life was prolonged from ~17 hours nonboosted to ~34 hours with RTV. This boosting effect was also seen in repeat-dose GSK2838232 studies, which achieved the targeted plasma exposure with GSK2838232 as a once-daily regimen of up to 200 mg with RTV. The results of these studies demonstrated a favorable safety and PK profile for GSK2838232 and support its investigation for the treatment of HIV infection.

Discovery of a novel and potent class of anti-HIV-1 maturation inhibitors with improved virology profile against gag polymorphisms.

A new class of betulin-derived α-keto amides was identified as HIV-1 maturation inhibitors. Through lead optimization, GSK8999 was identified with IC50 values of 17nM, 23nM, 25nM, and 8nM for wild type, Q369H, V370A, and T371A respectively. When tested in a panel of 62 HIV-1 isolates covering a diversity of CA-SP1 genotypes including A, AE, B, C, and G using a PBMC based assay, GSK8999 was potent against 57 of 62 isolates demonstrating an improvement over the first generation maturation inhibitor BVM. The data disclosed here also demonstrated that the new α-keto amide GSK8999 has a mechanism of action consistent with inhibition of the proteolytic cleavage of CA-SP1.

Facial recognition of happiness among older adults with active and remitted major depression.

Biased emotion processing in depression might be a trait characteristic independent of mood improvement and a vulnerable factor to develop further depressive episodes. This phenomenon of among older adults with depression has not been adequately examined. In a 2-year cross-sectional study, 59 older patients with either active or remitted major depression, or never-depressed, completed a facial emotion recognition task (FERT) to probe perceptual bias of happiness. The results showed that depressed patients, compared with never depressed subjects, had a significant lower sensitivity to identify happiness particularly at moderate intensity of facial stimuli. Patients in remission from a previous major depressive episode but with none or minimal symptoms had similar sensitivity rate to identify happy facial expressions as compared to patients with an active depressive episode. Further studies would be necessary to confirm whether recognition of happy expression reflects a persistent perceptual bias of major depression in older adults.

The design of 8-hydroxyquinoline tetracyclic lactams as HIV-1 integrase strand transfer inhibitors.

A novel series of HIV-1 integrase strand transfer inhibitors were designed using the venerable two-metal binding pharmacophore model and incorporating structural elements from two different literature scaffolds. This manuscript describes a number of 8-hydroxyquinoline tetracyclic lactams with exceptional antiviral activity against HIV-1 and little loss of potency against the IN signature resistance mutations Q148K and G140S/Q148H.

A Hybrid Reality Radiation-Free Simulator for Teaching Wire Navigation Skills.

OBJECTIVES: Surgical simulation is an increasingly important method to facilitate the acquiring of surgical skills. Simulation can be helpful in developing hip fracture fixation skills because it is a common procedure for which performance can be objectively assessed [ie, the tip-apex distance (TAD)]. The procedure requires fluoroscopic guidance to drill a wire along an osseous trajectory to a precise position within bone. The objective of this study was to assess the construct validity for a novel radiation-free simulator designed to teach wire navigation skills in hip fracture fixation. METHODS: Novices (n = 30) with limited to no surgical experience in hip fracture fixation and experienced surgeons (n = 10) participated. Participants drilled a guide wire in the center-center position of a synthetic femoral head in a hip fracture simulator, using electromagnetic sensors to track the guide-wire position. Sensor data were gathered to generate fluoroscopic-like images of the hip and guide wire. Simulator performance of novice and experienced participants was compared to measure construct validity. RESULTS: The simulator was able to discriminate the accuracy in guide-wire position between novices and experienced surgeons. Experienced surgeons achieved a more accurate TAD than novices (13 vs. 23 mm, respectively, P = 0.009). The magnitude of improvement on successive simulator attempts was dependent on the level of expertise; TAD improved significantly in the novice group, whereas it was unchanged in the experienced group. CONCLUSIONS: This hybrid reality, radiation-free hip fracture simulator, which combines real-world objects with computer-generated imagery, demonstrates construct validity by distinguishing the performance of novices and experienced surgeons. There is a differential effect depending on the level of experience, and it could be used as an effective training tool in novice surgeons.

The Effect of Repeated Ketamine Infusion Over Facial Emotion Recognition in Treatment-Resistant Depression: A Preliminary Report.

In contrast to improvement in emotion recognition bias by traditional antidepressants, the authors report preliminary findings that changes in facial emotion recognition are not associated with response of depressive symptoms after repeated ketamine infusions or relapse during follow-up in treatment-resistant depression.

Antiviral characteristics of GSK1265744, an HIV integrase inhibitor dosed orally or by long-acting injection.

GSK1265744 is a new HIV integrase strand transfer inhibitor (INSTI) engineered to deliver efficient antiviral activity with a once-daily, low-milligram dose that does not require a pharmacokinetic booster. The in vitro antiviral profile and mechanism of action of GSK1265744 were established through integrase enzyme assays, resistance passage experiments, and cellular assays with site-directed molecular (SDM) HIV clones resistant to other classes of anti-HIV-1 agents and earlier INSTIs. GSK1265744 inhibited HIV replication with low or subnanomolar efficacy and with a selectivity index of at least 22,000 under the same culture conditions. The protein-adjusted half-maximal inhibitory concentration (PA-EC50) extrapolated to 100% human serum was 102 nM. When the virus was passaged in the presence of GSK1265744, highly resistant mutants with more than a 10-fold change (FC) in EC50 relative to that of the wild-type were not observed for up to 112 days of culture. GSK1265744 demonstrated activity against SDM clones containing the raltegravir (RAL)-resistant Y143R, Q148K, N155H, and G140S/Q148H signature variants (FC less than 6.1), while these mutants had a high FC in the EC50 for RAL (11 to >130). Either additive or synergistic effects were observed when GSK1265744 was tested in combination with representative anti-HIV agents, and no antagonistic effects were seen. These findings demonstrate that, similar to dolutegravir, GSK1265744 is differentiated as a new INSTI, having a markedly distinct resistance profile compared with earlier INSTIs, RAL, and elvitegravir (EVG). The collective data set supports further clinical development of GSK1265744.

A review of the role of simulation in developing and assessing orthopaedic surgical skills.

Orthopaedic surgical skill is traditionally acquired during training in an apprenticeship model that has been largely unchanged for nearly 100 years. However, increased pressure for operating room efficiency, a focus on patient safety, work hour restrictions, and a movement towards competency-based education are changing the traditional paradigm. Surgical simulation has the potential to help address these changes. This manuscript reviews the scientific background on skill acquisition and surgical simulation as it applies to orthopaedic surgery. It argues that simulation in orthopaedics lags behind other disciplines and focuses too little on simulator validation. The case is made that orthopaedic training is more efficient with simulators that facilitate deliberate practice throughout resident training and more research should be focused on simulator validation and the refinement of skill definition.

Synthesis and Biological Evaluation of Macrocyclized Betulin Derivatives as a Novel Class of Anti-HIV-1 Maturation Inhibitors.

A macrocycle provides diverse functionality and stereochemical complexity in a conformationally preorganized ring structure, and it occupies a unique chemical space in drug discovery. However, the synthetic challenge to access this structural class is high and hinders the exploration of macrocycles. In this study, efficient synthetic routes to macrocyclized betulin derivatives have been established. The macrocycle containing compounds showed equal potency compared to bevirimat in multiple HIV-1 antiviral assays. The synthesis and biological evaluation of this novel series of HIV-1 maturation inhibitors will be discussed.

Pyridopyrimidinone inhibitors of HIV-1 RNase H.

Using a structure based pharmacophore design, a weak inhibitor of RNase H, identified from a small library of two metal binding HIV-1 integrase inhibitors, was optimized for potency and physicochemical properties. This manuscript describes the SAR and in vivo DMPK for the pyridopyrimidinone class of inhibitors.

Neurocognitive performance and serial intravenous subanesthetic ketamine in treatment-resistant depression.

The N-methyl-D-aspartate glutamate receptor antagonist ketamine has demonstrated rapid antidepressant effects in treatment-resistant depression (TRD). However, evaluation of ketamine's neurocognitive aspects in TRD has started to be explored. This study aims to (1) examine baseline neurocognitive performance and change in severity of depressive symptoms through six ketamine infusions, (2) examine the neurocognitive effects after completion of serial infusions and whether changes were associated to relapse to depression. Six IV infusions of 0.5 mg/Kg ketamine over 40 min were conducted on a Monday-Wednesday-Friday schedule during a 12-d period on 15 patients with TRD followed by a 4-wk observational period. Neurocognitive functioning was assessed using the CogState battery at baseline and at each follow-up visit. Tasks were designed to test attention, memory (working, visual, and verbal), speed of processing, and set shifting. The likelihood of response through six infusions was greater among depressed subjects with lower attention at baseline (F(1,13)=5.59, p=0.034). Significant improvement was found in scores of visual memory (F(4,33.82)=5.12, p=0.002), simple working memory (F(4, 24.85)=3.29, p=0.027) and complex working memory (F(4, 32.76)=4.18, p=0.008) after the last ketamine infusion. However, neurocognitive changes were accounted for by improvement in the severity of depressive symptom. The acute neurocognitive effect after completion of repeated infusions was not associated with the likelihood of subsequent relapse during follow-up. Our findings suggest a potential baseline neurocognitive predictor of ketamine response and the apparently lack of short-term neurocognitive impairment after completion of six ketamine infusions in TRD.

Naphthyridinone (NTD) integrase inhibitors 4. Investigating N1 acetamide substituent effects with C3 amide groups.

A series of N1 acetamide substituted naphthyridinone HIV-1 integrase inhibitors have been explored to understand structure-activity relationships (SAR) with various C3 amide groups. Investigations were evaluated using integrase enzyme inhibition, antiviral activity and protein binding effects to optimize the sub-structures. Lipophilicity was also incorporated to understand ligand lipophilic efficiency as a function of the structural modifications. Three representative analogs were further examined in a peripheral blood mononuclear cell (PBMC) antiviral assay as well as in vitro and in vivo drug metabolism and pharmacokinetic studies.

Inhibition of the ribonuclease H activity of HIV-1 reverse transcriptase by GSK5750 correlates with slow enzyme-inhibitor dissociation.

Compounds that efficiently inhibit the ribonuclease (RNase) H activity of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) have yet to be developed. Here, we demonstrate that GSK5750, a 1-hydroxy-pyridopyrimidinone analog, binds to the enzyme with an equilibrium dissociation constant (K(d)) of ~400 nM. Inhibition of HIV-1 RNase H is specific, as DNA synthesis is not affected. Moreover, GSK5750 does not inhibit the activity of Escherichia coli RNase H. Order-of-addition experiments show that GSK5750 binds to the free enzyme in an Mg(2+)-dependent fashion. However, as reported for other active site inhibitors, binding of GSK5750 to a preformed enzyme-substrate complex is severely compromised. The bound nucleic acid prevents access to the RNase H active site, which represents a possible biochemical hurdle in the development of potent RNase H inhibitors. Previous studies suggested that formation of a complex with the prototypic RNase H inhibitor ß-thujaplicinol is slow, and, once formed, it dissociates rapidly. This unfavorable kinetic behavior can limit the potency of RNase H active site inhibitors. Although the association kinetics of GSK5750 remains slow, our data show that this compound forms a long lasting complex with HIV-1 RT. We conclude that slow dissociation of the inhibitor and HIV-1 RT improves RNase H active site inhibitors and may circumvent the obstacle posed by the inability of these compounds to bind to a preformed enzyme-substrate complex.