Physiologically based pharmacokinetic (PBPK) modelling has evolved to accommodate different routes of drug administration and enables prediction of drug concentrations in tissues as well as plasma. The inhalation route of administration has proven successful in treating respiratory diseases but can also be used for rapid systemic delivery, holding great promise for treatment of diseases requiring systemic exposure. The objective of this work was to develop a PBPK model that predicts plasma and tissue concentrations following inhalation administration of the PI3Kδ inhibitor nemiralisib. A PBPK model was built in GastroPlus® that includes a complete mechanistic description of pulmonary absorption, systemic distribution and oral absorption following inhalation administration of nemiralisib. The availability of clinical data obtained after intravenous, oral and inhalation administration enabled validation of the model with observed data and accurate assessment of pulmonary drug absorption. The PBPK model described in this study incorporates novel use of key parameters such as lung systemic absorption rate constants derived from human physiological lung blood flows, and implementation of the specific permeability-surface area product per millilitre of tissue cell volume (SpecPStc) to predict tissue distribution. The inhaled PBPK model was verified using plasma and bronchoalveolar lavage fluid concentration data obtained in human subjects. Prediction of tissue concentrations using the permeability-limited systemic disposition tissue model was further validated using tissue concentration data obtained in the rat following intravenous infusion administration to steady state. Fully mechanistic inhaled PBPK models such as the model described herein could be applied for cross molecule assessments with respect to lung retention and systemic exposure, both in terms of pharmacology and toxicology, and may facilitate clinical indication selection.

Background Phosphoinositide-3-kinase-delta (PI3Kδ) inhibition is a promising therapeutic approach for inflammatory conditions due to its role in leucocyte proliferation, migration and activation. However, the effect of PI3Kδ inhibition on group 2 innate lymphoid cells (ILC2s) and inflammatory eosinophils remains unknown. Using a murine model exhibiting persistent airway inflammation we sought to understand the effect of PI3Kδ inhibition, montelukast and anti-IL5 antibody treatment on IL33 expression, group-2-innate lymphoid cells, inflammatory eosinophils, and goblet cell metaplasia. Results Mice were sensitised to house dust mite and after allowing inflammation to resolve, were re-challenged with house dust mite to re-initiate airway inflammation. ILC2s were found to persist in the airways following house dust mite sensitisation and after re-challenge their numbers increased further along with accumulation of inflammatory eosinophils. In contrast to montelukast or anti-IL5 antibody treatment, PI3Kδ inhibition ablated IL33 expression and prevented group-2-innate lymphoid cell accumulation. Only PI3Kδ inhibition and IL5 neutralization reduced the infiltration of inflammatory eosinophils. Moreover, PI3Kδ inhibition reduced goblet cell metaplasia. Conclusions Hence, we show that PI3Kδ inhibition dampens allergic inflammatory responses by ablating key cell types and cytokines involved in T-helper-2-driven inflammatory responses.

Optimization of a previously reported lead series of PI3Kδ inhibitors with a novel binding mode led to the identification of a clinical candidate compound 31 (GSK251). Removal of an embedded Ames-positive heteroaromatic amine by reversing a sulfonamide followed by locating an interaction with Trp760 led to a highly selective compound 9. Further optimization to avoid glutathione trapping, to enhance potency and selectivity, and to optimize an oral pharmacokinetic profile led to the discovery of compound 31 (GSK215) that had a low predicted daily dose (45 mg, b.i.d) and a rat toxicity profile suitable for further development.

A macrocyclization approach has been explored on a series of benzoxazine phosphoinositide 3-kinase δ inhibitors, resulting in compounds with improved potency, permeability, and in vivo clearance while maintaining good solubility. The thermodynamics of binding was explored via surface plasmon resonance, and the binding of lead macrocycle 19 was found to be almost exclusively entropically driven compared with progenitor 18, which demonstrated both enthalpic and entropic contributions. The pharmacokinetics of macrocycle 19 was also explored in vivo, where it showed reduced clearance when compared with the progenitor 18. This work adds to the growing body of evidence that macrocyclization could provide an alternative and complementary approach to the design of small-molecule inhibitors, with the potential to deliver differentiated properties.

Optimization of a lead series of PI3Kδ inhibitors based on a dihydroisobenzofuran core led to the identification of potent, orally bioavailable compound 19. Selectivity profiling of compound 19 showed similar potency for class III PI3K, Vps34, and PI3Kδ, and compound 19 was not well-tolerated in a 7-day rat toxicity study. Structure-based design led to an improvement in selectivity for PI3Kδ over Vps34 and, a focus on oral phramacokinetics properties resulted in the discovery of compound 41, which showed improved toxicological outcomes at similar exposure levels to compound 19.

Global or national scale flood early warning systems (FEWS) can benefit developing countries and ungauged regions that lack observational data, computational infrastructure, and/or the human capacity for streamflow modelling. Existing land surface models (LSM) typically generate forecasts using coarse resolution grid cells which, at least for streamflow, have little value when used for flood warning at local scales. We present the design and development of a new automated computational system, using existing, well-established open source software tools that quickly downscales (or maps) the runoff generated from such coarse grid-based LSMs onto high-resolution vector-based stream networks then routes the results using a vector-based river routing model. We conducted experiments using the ERA-Interim/Land reanalysis data – a 35-year retrospective gridded runoff data product from the European Center for Medium-range Weather Forecasts (ECMWF) – to assess our fast downscaling system. The accuracy of our approach is comparable to the Global Flood Awareness System (GloFAS) – a well-established gridded routing model using the same forcings – but our method provides streamflow predictions on significantly higher resolution stream networks. We found that the river network resolution has negligible effect on the simulated streamflow with our model routing. In other words, we can forecast streamflow for very small stream segments and potentially improve local flood awareness and response much more successfully than previously possible using readily available climate forcings from LSMs.

This study describes the pharmacokinetic (PK) and pharmaco-dynamic (PD) profile of N-(5-(4-(5-(((2R,6S)-2,6-dimethylmorpholino)methyl)oxazol-2-yl)-1H-indazol-6-yl)-2-methoxypyridin-3-yl)methanesulfonamide (GSK2292767A), a novel low-solubility inhaled phosphoinositide 3-kinase delta (PI3Kδ) inhibitor developed as an alternative to 2-(6-(1H-indol-4-yl)-1H-indazol-4-yl)-5-((4-isopropylpiperazin-1-yl)methyl)oxazole (nemiralisib), which is a highly soluble inhaled inhibitor of PI3Kδ with a lung profile consistent with once-daily dosing. GSK2292767A has a similar in vitro cellular profile to nemiralisib and reduces eosinophilia in a murine PD model by 63% (n = 5, P < 0.05). To explore whether a low-soluble compound results in effective PI3Kδ inhibition in humans, a first time in human study was conducted with GSK2292767A in healthy volunteers who smoke. GSK2292767A was generally well tolerated, with headache being the most common reported adverse event. PD changes in induced sputum were measured in combination with drug concentrations in plasma from single (0.05–2 mg, n = 37), and 14-day repeat (2 mg, n = 12) doses of GSK2292767A. Trough bronchoalveolar lavage (BAL) for PK was taken after 14 days of repeat dosing. GSK2292767A displayed a linear increase in plasma exposure with dose, with marginal accumulation after 14 days. Induced sputum showed a 27% (90% confidence interval 15%, 37%) reduction in phosphatidylinositol-trisphosphate (the product of phosphoinositide 3-kinase activation) 3 hours after a single dose. Reduction was not maintained 24 hours after single or repeat dosing. BAL analysis confirmed the presence of GSK2292767A in lung at 24 hours, consistent with the preclinical lung retention profile. Despite good lung retention, target engagement was only present at 3 hours. This exposure-response disconnect is an important observation for future inhaled drug design strategies considering low solubility to drive lung retention.

Purpose To examine if pulmonary P-glycoprotein (P-gp) is functional in an intact lung; impeding the pulmonary absorption and increasing lung retention of P-gp substrates administered into the airways. Using calculated physico-chemical properties alone build a predictive Quantitative Structure-Activity Relationship (QSAR) model distinguishing whether a substrate’s pulmonary absorption would be limited by P-gp or not. Methods A panel of 18 P-gp substrates were administered into the airways of an isolated perfused mouse lung (IPML) model derived from Mdr1a / Mdr1b knockout mice. Parallel intestinal absorption studies were performed. Substrate physico-chemical profiling was undertaken. Using multivariate analysis a QSAR model was established. Results A subset of P-gp substrates (10/18) displayed pulmonary kinetics influenced by lung P-gp. These substrates possessed distinct physico-chemical properties to those P-gp substrates unaffected by P-gp (8/18). Differential outcomes were not related to different intrinsic P-gp transporter kinetics. In the lung, in contrast to intestine, a higher degree of non-polar character is required of a P-gp substrate before the net effects of efflux become evident. The QSAR predictive model was applied to 129 substrates including eight marketed inhaled drugs, all these inhaled drugs were predicted to display P-gp dependent pulmonary disposition. Conclusions Lung P-gp can affect the pulmonary kinetics of a subset of P-gp substrates. Physico-chemical relationships determining the significance of P-gp to absorption in the lung are different to those operative in the intestine. Our QSAR framework may assist profiling of inhaled drug discovery candidates that are also P-gp substrates. The potential for P-gp mediated pulmonary disposition exists in the clinic.

Induction of IFNα in the upper airways via activation of TLR7 represents a novel immunomodulatory approach to the treatment of allergic asthma. Exploration of 8-oxoadenine derivatives bearing saturated oxygen or nitrogen heterocycles in the N-9 substituent has revealed a remarkable selective enhancement in IFNα inducing potency in the nitrogen series. Further potency enhancement was achieved with the novel (S)-pentyloxy substitution at C-2 leading to the selection of GSK2245035 (32) as an intranasal development candidate. In human cell cultures, compound 32 resulted in suppression of Th2 cytokine responses to allergens, while in vivo intranasal administration at very low doses led to local upregulation of TLR7-mediated cytokines (IP-10). Target engagement was confirmed in humans following single intranasal doses of 32 of ≥20 ng, and reproducible pharmacological response was demonstrated following repeat intranasal dosing at weekly intervals.

Purpose We developed and tested a novel Quantitative Structure-Activity Relationship (QSAR) model to better understand the physicochemical drivers of pulmonary absorption, and to facilitate compound design through improved prediction of absorption. The model was tested using a large array of both existing and newly designed compounds.Methods Pulmonary absorption data was generated using the isolated perfused respiring rat lung (IPRLu) model for 82 drug discovery compounds and 17 marketed drugs. This dataset was used to build a novel QSAR model based on calculated physicochemical properties. A further 9 compounds were used to test the model's predictive capability.Results The QSAR model performed well on the 9 compounds in the "Test set" with a predicted versus observed correlation of R-2 = 0.85, and >65% of compounds correctly categorised. Calculated descriptors associated with permeability and hydrophobicity positively correlated with pulmonary absorption, whereas those associated with charge, ionisation and size negatively correlated.Conclusions The novel QSAR model described here can replace routine generation of IPRLu model data for ranking and classifying compounds prior to synthesis. It will also provide scientists working in the field of inhaled drug discovery with a deeper understanding of the physicochemical drivers of pulmonary absorption based on a relevant respiratory compound dataset.

Introduction GSK2245035 is a novel small molecule TLR7 agonist in development as an immunomodulatory, intranasal treatment for allergic airways disease aiming to reduce Th2 and enhance Th1/Treg responses to aeroallergens via the local induction of type1 interferons (IFN). Methods Human blood and PBMC assays were conducted to determine the potency of GSK2240035 for IFNα vs TNFα induction. The immunomodulatory effect of GSK2245035 on T cell cytokine responses was assessed in allergen activated human PBMC cultures . In vitro profiling of GSK2245035 was conducted in Cynomolgus monkey blood; target engagement in the airways was evaluated by intranasal (IN) dosing to Cynomolgus monkeys and measuring nasal scrape IFN stimulated gene expression (ISG) and systemic biomarkers. Results GSK2245035 is a highly potent TLR7 agonist inducing IFNα production in human in vitro assays (pEC50 PBMC 9.7: blood 9.2) whilst showing selectivity over TNFα induction (pEC50 PBMC 6.4: blood 4.9). Other cytokines (IL12, IFNγ and IL10) that regulate Th2 cell responses were also induced. GSK2245035 reduced levels of Th2 cytokines released in allergen driven atopic PBMC cultures and enhanced IL10 and IFNγ production. GSK2245035 showed comparable IFNα potency and IFNα/TNFα selectivity in Cynomolgus monkey and human blood cultures. IN delivery in Cynomolgus monkeys enabled identification of a panel of ISGs upregulated in nasal tissue and systemic biomarkers of target engagement (IP-10). Conclusions GSK2245035 is a potent inducer of IFNα and modulates the Th2 response to allergens in vitro . PD biomarkers of target engagement in Cynomolgus monkey were identified aiding selection of starting dose in clinical studies.

P-glycoprotein (P-gp) mediated efflux is recognised to alter the absorption and disposition of a diverse range of substrates. Despite evidence showing the presence of P-gp within the lung, relatively little is known about the transporter's effect upon the absorption and distribution of drugs delivered via the pulmonary route. Here, we present data from an intact isolated rat lung model, alongside two isolated mouse lung models using either chemical or genetic inhibition of P-gp. Data from all three models show inhibition of P-gp increases the extent of absorption of a subset of P-gp substrates (e.g. rhodamine 123 and loperamide) whose physico-chemical properties are distinct from those whose pulmonary absorption remained unaffected (e.g. digoxin and saquinavir). This is the first study showing direct evidence of P-gp mediated efflux within an intact lung, a finding that should warrant consideration as part of respiratory drug discovery and development as well as in the understanding of pulmonary pharmacokinetic (PK)-pharmacodynamic (PD) relationships.

The aim of the present investigation was to compare the onset of action and intrinsic activity of the long-acting beta(2)-agonist GW597901 with the fast- and short-acting salbutamol as model compounds using an isolated human lung reperfusion model. Twelve resected human lung lobes were challenged with methacholine (MCh) and subsequently nebulised with either GW597901 or salbutamol. Prostaglandin E-2 (PGE(2)) concentrations in the perfusion fluid were compared with the dose of MCh that was required to induce a bronchoconstriction. After successful MCh provocation, nebulisation of GW597901 and salbutamol fully reversed any observed bronchoconstriction. The bronchodilating effect was more pronounced for GW597901. Salbutamol revealed an immediate onset of action while the effect of GW597901 was observed with an approximate delay of 6 min. Higher doses of MCh were required for a successful bronchial challenge in the presence of elevated PGE(2) levels (r = 0.8171, p <= 0.05). For the first time, an isolated perfused human lung model has been established for comparing the onset of action and potency of a short- and long-acting beta(2)-agonist. We therefore conclude that it is an alternative for determination of drug effect characteristics and suitable for supplementing or predicting clinical data. (C) 2012 Elsevier B.V. All rights reserved.

Background: The aim of the present investigation was to compare the pulmonary absorption of the novel long-acting beta(2)-agonist GW597901 with salbutamol and to determine the influence of an induced bronchoconstriction on the pharmacokinetics of the compounds using a human lung reperfusion model.Methods: In an initial study with six lung perfusions the pharmacokinetic properties of the beta(2)-agonists were determined. We then investigated the influence of an induced bronchoconstriction on the pulmonary absorption in six lung lobes for each drug. Therefore, methacholine (MCh) challenge agent was nebulised prior to administration of the beta(2)-agonists.Results: As expected, the extent of pulmonary absorption of salbutamol into the perfusate was more pronounced than for the more lipophilic GW597901. Although the observed differences were not statistically significant they were further supported by analysis of tissue concentrations. In contrast, we observed a statistically significant influence of the bronchoprovocation with MCh on the pulmonary absorption of both beta(2)-agonists, but this effect was not limited to a successfully induced bronchoconstriction. A prominent decline of salbutamol distribution into perfusion fluid was also observed when the organic cation transporter substrate carnitine was nebulised prior to the bronchodilator.Conclusions: Nebulised methacholine had a significant influence on the pharmacokinetics of bronchodilators. Since we observed this effect independently of a successfully induced bronchoconstriction and also after nebulisation of carnitine we suggest a significant delay of pulmonary absorption of inhaled salbutamol and GW597901 due to competition for a cation/carnitine drug transporter, most likely OCTN2. (C) 2012 Elsevier Ltd. All rights reserved.

The early development of the U.K. Role 4 pain service has already been described. This article will describe developments up to October 2010, and present the results of projects used in assessing the effect of this service.