PIM Kinases as Potential Biomarkers and Therapeutic Targets in Inflammatory Arthritides.

The Proviral Integration site for the Moloney murine leukemia virus (PIM)-1 kinase and its family members (PIM-2 and PIM-3) regulate several cellular functions including survival, proliferation, and apoptosis. Recent studies showed their involvement in the pathogenesis of rheumatoid arthritis RA, while no studies are available on psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). The main objective of this study is to assess the expression of PIM kinases in inflammatory arthritides, their correlation with proinflammatory cytokines, and their variation after treatment with biologic disease-modifying anti-rheumatic drugs or JAK inhibitors. We evaluated PIM-1, -2, and -3 expression at the gene and protein level, respectively, in the peripheral blood mononuclear cells and serum of patients with RA, PsA, axSpA, and healthy individuals (CTR). All the samples showed expression of PIM-1, -2, and -3 kinases both at the gene and protein level. PIM-1 was the most expressed protein, PIM-3 the least. PIM kinase levels differed between controls and disease groups, with reduced PIM-1 protein and increased PIM-3 protein in all disease samples compared to controls. No difference was found in the expression of these molecules between the three different pathologies. PIM levels were not modified after 6 months of therapy. In conclusion, our preliminary data suggest a deregulation of the PIM pathway in inflammatory arthritides. In-depth studies on the role of PIM kinases in this field are warranted.

mTOR Inhibition Is Effective against Growth, Survival and Migration, but Not against Microglia Activation in Preclinical Glioma Models.

Initially introduced in therapy as immunosuppressants, the selective inhibitors of mTORC1 have been approved for the treatment of solid tumors. Novel non-selective inhibitors of mTOR are currently under preclinical and clinical developments in oncology, attempting to overcome some limitations associated with selective inhibitors, such as the development of tumor resistance. Looking at the possible clinical exploitation in the treatment of glioblastoma multiforme, in this study we used the human glioblastoma cell lines U87MG, T98G and microglia (CHME-5) to compare the effects of a non-selective mTOR inhibitor, sapanisertib, with those of rapamycin in a large array of experimental paradigms, including (i) the expression of factors involved in the mTOR signaling cascade, (ii) cell viability and mortality, (iii) cell migration and autophagy, and (iv) the profile of activation in tumor-associated microglia. We could distinguish between effects of the two compounds that were overlapping or similar, although with differences in potency and or/time-course, and effects that were diverging or even opposite. Among the latter, especially relevant is the difference in the profile of microglia activation, with rapamycin being an overall inhibitor of microglia activation, whereas sapanisertib was found to induce an M2-profile, which is usually associated with poor clinical outcomes.

A Vicious NGF-p75NTR Positive Feedback Loop Exacerbates the Toxic Effects of Oxidative Damage in the Human Retinal Epithelial Cell Line ARPE-19.

In spite of its variety of biological activities, the clinical exploitation of human NGF (hNGF) is currently limited to ocular pathologies. It is therefore interesting to test the effects of hNGF in preclinical models that may predict their efficacy and safety in the clinical setting of ocular disorders and compare the effects of hNGF with those of its analogs. We used a human retinal pigment cell line, ARPE-19 cells, to investigate the effects of hNGF and its analogs, mouse NGF (mNGF) and painless NGF (pNGF), on cell viability under basal conditions and after exposure to oxidative stimuli, i.e., hydrogen peroxide (H2O2) and ultraviolet (UV)-A rays. The effects of hNGF and pNGF were also tested on the gene expression and protein synthesis of the two NGF receptor subtypes, p75 neurotrophic receptors (p75NTR) and tyrosine kinase A (TrkA) receptors. We drew the following conclusions: (i) the exposure of ARPE-19 cells to H2O2 or UV-A causes a dose-dependent decrease in the number of viable cells; (ii) under baseline conditions, hNGF, but not pNGF, causes a concentration-dependent decrease in cell viability in the range of doses 1-100 ng/mL; (iii) hNGF, but not pNGF, significantly potentiates the toxic effects of H2O2 or of UV-A on ARPE-19 cells in the range of doses 1-100 ng/mL, while mNGF at the same doses presents an intermediate behavior; (iv) 100 ng/mL of hNGF triggers an increase in p75NTR expression in H2O2-treated ARPE-19 cells, while pNGF at the same dose does not; (v) pNGF, but not hNGF (both given at 100 ng/mL), increases the total cell fluorescence intensity for TrkA receptors in H2O2-treated ARPE-19 cells. The present findings suggest a vicious positive feedback loop through which NGF-mediated upregulation of p75NTR contributes to worsening the toxic effects of oxidative damage in the human retinal epithelial cell line ARPE-19. Looking at the possible clinical relevance of these findings, one can postulate that pNGF might show a better benefit/risk ratio than hNGF in the treatment of ocular disorders.

Emil Zuckerkandl and his Dental Tubercle (Historical Note).

One of the eponyms most frequently cited in dental morphology texts, together with the Carabelli tubercle of the first permanent maxillary molars, is the Zuckerkandl tubercle of deciduous molars. However, references about Emil Zuckerkandl in the field of dental history and this particular entity are scarce. The reason this dental eponym was pushed "into the shadows" probably lies in the many other anatomical parts (including another tubercle, the pyramidal one of the thyroids), which took their names from this great anatomist.

The effects of CHF6467, a new mutated form of NGF, on cell models of human glioblastoma. A comparison with wild-type NGF.

CHF6467 is a mutated form of human recombinant nerve growth factor (NGF). The mutation selectively disrupts the binding of NGF to its p75NTR receptor while maintaining the affinity toward TrkA receptor. Because of such different profile of receptor interaction, CHF6467 maintains unaltered the neurotrophic and neuroprotective properties of wild-type NGF but shows reduced algogenic activity.In this study, we investigated the effects of CHF6467 on mortality, proliferation, cell-damage and migration in three human glioblastoma cell lines (U87MG, T98G, LN18), and in the rat astrocytoma C6 cells. Both CHF6467 and wild-type NGF, given in the range 1-50 ng/ml, did not modify cell proliferation, metabolism and migration, as well as the number of live/dead cells.The present in vitro data are predictive of a lack of tumorigenic activity by both wild-type NGF and CHF6467 on these cell types in vivo, and warrant for CHF6467 further clinical development.

Clinical experience with CTLA-4 blockade for cancer immunotherapy: From the monospecific monoclonal antibody ipilimumab to probodies and bispecific molecules targeting the tumor microenvironment.

The immune checkpoint cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is an inhibitory regulator of T-cell mediated responses that has been investigated as target of monoclonal antibodies (mAbs) for cancer immunotherapy. The anti-CTLA-4 mAb ipilimumab represents the first immune checkpoint inhibitor that significantly improved overall survival in patients with unresectable/metastatic melanoma. The subsequent approved indications (often in the first-line setting) for melanoma and other advanced/metastatic solid tumors always require ipilimumab combination with nivolumab, an anti-programmed cell death protein 1 (PD-1) mAb. However, the improved clinical efficacy of the mAb combination is associated with increased immune-related adverse events, which might require treatment discontinuation even in responding patients. This drawback is expected to be overcome by the recent development of anti-CTLA-4 probodies proteolitycally activated in the tumor microenvironment and bispecific molecules targeting both CTLA-4 and PD-1, whose co-expression is characteristic of tumor-infiltrating T cells. These molecules would preferentially stimulate immune responses against the tumor, reducing toxicity toward normal tissues.

Prevalence of Type 2 and Type 1 Diabetes in Psoriatic Arthritis: An Italian Study.

OBJECTIVE: Psoriatic arthritis (PsA) is burdened by an increased susceptibility to cardiovascular diseases. Comorbid diabetes may represent one of the key factors contributing to this risk. The aim of our medical records review study was to investigate the prevalence of type 2 diabetes (T2D) and type 1 diabetes (T1D) in an Italian PsA cohort. METHODS: The clinical records of all patients consecutively seen at our clinic with a diagnosis of PsA during a 12-month period were reviewed to identify comorbid T2D or T1D. For comparison, a 1:1 age- and sex-matched group of individuals with noninflammatory diseases was recruited. RESULTS: The final study cohort comprised 408 patients. The prevalence of T2D was 7.8% (95% confidence interval, 5.6-10.8) in PsA and 4.4% in controls (95% confidence interval, 2.8-6.9; p = 0.04). Two cases (0.49%) of T1D were identified in the PsA cohort, whereas no cases were observed in controls. In a multivariate logistic regression model including age, disease duration, and body mass index (BMI) as covariates, increasing age (odds ratio [OR], 1.079; p = 0.006) and BMI (OR, 1.188; p = 0.011) but not PsA duration predicted being classified as having T2D. In a similar model accounting for age and BMI, average disease activity score including 28 joints and C-reactive protein showed a trend toward significance (OR, 1.639; p = 0.066). CONCLUSIONS: In conclusion, our data provide further support to the emerging evidence of an increased risk of T2D in PsA patients. Cardiometabolic comorbidity represents a significant aspect of integrated arthritis management to improve long-term cardiovascular outcomes and to provide a comprehensive treatment.

PDIA3 Expression in Glioblastoma Modulates Macrophage/Microglia Pro-Tumor Activation.

The glioblastoma (GB) microenvironment includes cells of the innate immune system identified as glioma-associated microglia/macrophages (GAMs) that are still poorly characterized. A potential role on the mechanisms regulating GAM activity might be played by the endoplasmic reticulum protein ERp57/PDIA3 (protein disulfide-isomerase A3), the modulation of which has been reported in a variety of cancers. Moreover, by using The Cancer Genome Atlas database, we found that overexpression of PDIA3 correlated with about 55% reduction of overall survival of glioma patients. Therefore, we analyzed the expression of ERp57/PDIA3 using specimens obtained after surgery from 18 GB patients. Immunohistochemical analysis of tumor samples revealed ERp57/PDIA3 expression in GB cells as well as in GAMs. The ERp57/PDIA3 levels were higher in GAMs than in the microglia present in the surrounding parenchyma. Therefore, we studied the role of PDIA3 modulation in microglia-glioma interaction, based on the ability of conditioned media collected from human GB cells to induce the activation of microglial cells. The results indicated that reduced PDIA3 expression/activity in GB cells significantly limited the microglia pro-tumor polarization towards the M2 phenotype and the production of pro-inflammatory factors. Our data support a role of PDIA3 expression in GB-mediated protumor activation of microglia.

Transcriptome analysis of alcohol-treated microglia reveals downregulation of beta amyloid phagocytosis.

BACKGROUND: Microglial activation contributes to the neuropathology associated with chronic alcohol exposure and withdrawal, including the expression of inflammatory and anti-inflammatory genes. In the current study, we examined the transcriptome of primary rat microglial cells following incubation with alcohol alone, or alcohol together with a robust inflammatory stimulus. METHODS: Primary microglia were prepared from mixed rat glial cultures. Cells were incubated with 75 mM ethanol alone or with proinflammatory cytokines ("TII": IL1ß, IFNγ, and TNFα). Isolated mRNA was used for RNAseq analysis and qPCR. Effects of alcohol on phagocytosis were determined by uptake of oligomeric amyloid beta. RESULTS: Alcohol induced nitrite production in control cells and increased nitrite production in cells co-treated with TII. RNAseq analysis of microglia exposed for 24 h to alcohol identified 312 differentially expressed mRNAs ("Alc-DEs"), with changes confirmed by qPCR analysis. Gene ontology analysis identified phagosome as one of the highest-ranking KEGG pathways including transcripts regulating phagocytosis. Alcohol also increased several complement-related mRNAs that have roles in phagocytosis, including C1qa, b, and c; C3; and C3aR1. RNAseq analysis identified over 3000 differentially expressed mRNAs in microglia following overnight incubation with TII; and comparison to the group of Alc-DEs revealed 87 mRNAs modulated by alcohol but not by TII, including C1qa, b, and c. Consistent with observed changes in phagocytosis-related mRNAs, the uptake of amyloid beta1-42, by primary microglia, was reduced by alcohol. CONCLUSIONS: Our results define alterations that occur to microglial gene expression following alcohol exposure and suggest that alcohol effects on phagocytosis could contribute to the development of Alzheimer's disease.

The Trabecular Bone Score Predicts Spine Fragility Fractures in Postmenopausal Caucasian Women Without Osteoporosis Independently of Bone Mineral Density.

INTRODUCTION: The trabecular bone score (TBS) is a gray-level textural metric that can be extracted from the two-dimensional lumbar spine dual-energy X-ray absorptiometry (DXA) image. TBS is related to bone microarchitecture. Several literature data suggest that TBS predicts fracture risk as well as lumbar spine bone mineral density (LS-BMD) measurements in postmenopausal women. OBJECTIVE: A retrospective case-control study assessing the ability of the TBS to predict spine fragility fractures (SFF) in postmenopausal women with or without osteoporosis (diagnosed by T-score≤-2.5). METHODS: LS-BMD and the TBS were determined in the L1-L4 vertebrae. Statistical analyses were carried out in the entire group of women (entire-group) (n.699), in women both with osteoporosis (osteoporosis-subgroup) (n.253) and those without osteoporosis (non-osteoporosis-subgroup) (n. 446). RESULTS: At the unpaired t-test, both the TBS and the LS-BMD (p≤0.001) were lower in women with SFF (n.62) in the entire-group. In the non-osteoporosis subgroup, the TBS (p≤0.009) was lower in women with SFF (n.29). In the osteoporosis subgroup, the LS-BMD (p≤0.003) was lower in women with SFF (n.33). Considering the TBS and LS-BMD separately in a block logistic regression, the TBS was associated with SFF in the entire-group (odds ratio (OR): 1.599, 95% confidence interval (CI): 1.021-2.128) and in the non-osteoporosis-subgroup (OR: 1.725, 95% CI:1.118-2.660) whereas LS-BMD was associated with SFF in the entire-group (OR: 1.611, 95% CI: 1.187-2.187) and in the osteoporosis-subgroup (OR: 2.383, 95% CI: 1.135-5.003). According to forward logistic regression, entering the TBS, LS-BMD and confounders as predictors, the LS-BMD in the entire-group (OR: 1.620, 95% CI: 1.229-2.135) and in the osteoporosis subgroup (OR: 2.344, 95% CI: 1.194-4.600), and the TBS in the non-osteoporosis subgroup (OR: 1.685, 95% CI: 1.131-2.511) were the only predictors of SFFs. CONCLUSIONS: In the entire-group, the TBS predicted SFFs almost as well as LS-BMD, but not independently of it. The TBS, but not LS-BMD, predicted SFFs in the non-osteoporosis subgroup.

Interactions between integrase inhibitors and human arginase 1.

The neuro-pathogenic mechanism(s) underlying HIV-associated neurocognitive disorders are mostly unknown. HIV-infected macrophages and microglial cells play a crucial role and the metabolic fate of l-arginine may be highly relevant to microglia activation. In this context, arginase (ARG), which uses l-arginine as substrate, can be on the same time a target and source of oxidative stress and inflammation. In this study, we investigated whether integrase strand transfer inhibitors share with the other antiretroviral drugs the ability to inhibit ARG activity. We used the previously validated cell model, namely the human microglia cell line, as well as the computational chemistry approach. Furthermore, here we characterized the activity of purified human ARG in a cell-free in vitro system, and investigated the effects of integrase strand transfer inhibitors in this newly validated model. Overall evidence shows that Dolutegravir, Raltegravir and Elvitegravir inhibit ARG activity.

Antiretrovirals inhibit arginase in human microglia.

Preliminary evidence in an animal model, that is, primary cultures of rat microglia cells, suggested that some antiretroviral drugs (ARVs), namely darunavir, atazanavir, efavirenz, and nevirapine, increase NO production through a mechanism involving the inhibition of arginase (ARG) activity. This study was conceived to investigate the effects of ARVs on ARG activity in a human experimental model. We compared CHME-5 human microglial immortalized cells under basal conditions with cells exposed to either IL-4, a mix of inflammatory cytokines, or both stimuli given together. We also tested the effects of ARVs on CHME-5 cell lysates after exposure to the above stimuli. Moreover, the interaction between the ARVs and ARG was investigated via computational chemistry. We found that ARVs consistently inhibit ARG activity both in intact and lysed cells. In docking studies, darunavir and atazanavir showed similar scores compared with both l-arginine and the ARG antagonist nor-NOHA. Efavirenz and nevirapine, which are less potent in inhibiting ARG in the biochemical assay, also had lower scores. In conclusion, the present findings in a human model support the notion that ARG pathway can present a new, additional molecular target for different ARVs in HIV treatments. We found that antiretroviral drugs (ARVs) consistently inhibit arginase (ARG)-I activity both in intact and lysed cells. In docking studies, darunavir (DRV) and atazanavir (ATV) showed similar scores compared to both l-arginine and the ARG antagonist, Nω-hydroxy-nor-arginine (nor-NOHA). Efavirenz (EFV) and nevirapine (NVP), which are less potent in inhibiting ARG in the biochemical assay, also had lower scores. In conclusion, the present findings in a human model support the notion that ARG pathway can be envisioned as an additional and new molecular target of different ARVs in HIV treatments.

The mTOR kinase inhibitors polarize glioma-activated microglia to express a M1 phenotype.

BACKGROUND: Increased activation of mammalian target of rapamycin (mTOR) is observed in numerous human cancers. Recent studies on the glioma kinome have identified several deregulated pathways that converge and activate mTOR. The available evidence on the role of microglia in CNS cancers would suggest a dual role, a tumoricidal role and -on the contrary- a role favoring tumor growth. METHODS: In the present paper, we have compared the effects of µM concentrations of rapamycin (RAPA) and its analog, RAD001 (RAD), on activated microglia; the latter was obtained by exposing cells to conditioned medium harvested either from inflammatory activated glioma cells (LI-CM) or from glioma cells kept under basal conditions (C-CM). RESULTS: Here we show that the inhibition of mTOR polarizes glioma-activated microglial cells towards the M1 phenotype, with cytotoxic activities, preventing the induction of the M2 status that promotes tumor growth. In fact RAPA and RAD significantly increased iNOS expression and activity, while on the same time significantly reducing IL-10 gene expression induced by C-CM, thus suggesting that the drugs prevent the acquisition of a M2 phenotype in response to glioma factors promoting a classic M1 activation. Similar results were obtained using the conditioned media obtained after glioma stimulation with LPS-IFNγ (LI-CM), which was found to induce a mixture of M1 and M2a/b polarization phenotypes. In these conditions, the inhibition of mTOR led to a significant up-regulation of iNOS, and in parallel to the down-regulation of both ARG and IL-10 gene expression. CONCLUSIONS: These data suggest that mTOR inhibition may prevent glioma induced M2 polarization of microglial cells and increase their cytotoxic potential, possibly resulting in antitumor actions.

Influence of the oral dissolution time on the absorption rate of locally administered solid formulations for oromucosal use: the flurbiprofen lozenges paradigm.

Flurbiprofen is a nonsteroidal anti-inflammatory agent preferentially used for local oromucosal treatment of painful and/or inflammatory conditions of the oropharynx such as gingivitis, stomatitis, periodontitis, pharyngitis and laryngitis. In this study, we have investigated the bioavailability of a new generic formulation of flurbiprofen lozenges developed by Epifarma Srl, compared to the originator Benactiv Gola® taken as reference. Within the framework of a formal bioequivalence study, we investigated in particular the putative influence of oral dissolution time (i.e. the time spent suckling the lozenge from its intake to complete dissolution) on the absorption rate, and the contribution of this factor to the total variability of plasma flurbiprofen during absorption. We found that the amount of flurbiprofen absorbed into the systemic circulation is not significantly higher for the test drug compared to that of the reference product. We observed that the length of oral dissolution time is inversely correlated to 10-min flurbiprofen plasma levels in the test but not in the reference formulation. We estimated that oral dissolution time accounts for about 14% of overall variability in flurbiprofen plasma 10 min after test drug administration.

High-dose colistin pharmacokinetics in critically ill patients receiving continuous renal replacement therapy.

BACKGROUND: Colistin, administered as intravenous colistimethate (CMS), is still used in the critical care setting and current guidelines recommend high dosage CMS in patients undergoing continuous renal replacement therapy (CRRT). Due to the paucity of real-life data, we aimed to describe colistin pharmacokinetic/pharmacodynamic (PK/PD) profile in a cohort of critically ill patients with infections due to carbapenem-resistant (CR) bacteria undergoing CRRT. RESULTS: All consecutive patients admitted to three Intensive Care Units (ICUs) of a large metropolitan University Hospital, treated with colistin for at least 48 h at the dosage of 6.75 MUI q12, after 9 MIU loading dose, and undergoing CRRT were included. After the seventh dose, patients underwent blood serial sampling during a time frame of 24 h. We included 20 patients, who had CR-Acinetobacter baumannii ventilator-associated pneumonia and were characterized by a median SAPS II and SOFA score of 41 [34.5-59.3] and 9 [6.7-11], respectively. Fifteen patients died during ICU stay and six recovered renal function. Median peak and trough colistin concentrations were 16.6 mcg/mL [14.8-20.6] and 3.9 mcg/mL [3.3-4.4], respectively. Median area under the time-concentration curve (AUC0 - 24) and average steady-state concentration (Css, avg) were 193.9 mcg h/mL [170.6-208.6] and 8.07 mcg/mL [7.1-8.7]. Probability of target attainment of colistin pharmacodynamics according to the fAUC0 - 24/MIC target ≥ 12 was 100% for MIC ≤ 2 mcg/mL and 85% for MIC = 4 mcg/ML, although exceeding the toxicity limit of Css, avg 3-4 mcg/mL. CONCLUSIONS: In critically ill patients with CR infections undergoing CRRT, recommended CMS dosage resulted in colistin plasmatic levels above bacterial MIC90, but exceeding the safety Css, avg. limit. TRIAL REGISTRATION: This trial was registered in ClinicalTrials.gov on 23/07/2021 with the ID NCT04995133 (https//clinicaltrials.gov/study/NCT04995133).

mTOR kinase, a key player in the regulation of glial functions: relevance for the therapy of multiple sclerosis.

The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase with a central role in the regulation of cell growth and proliferation, and several intracellular processes, such as mRNA transcription and translation, autophagy and cytoskeletal organization. The relevance of this pathway in the regulation of the immune system is well characterized. mTOR is essential for the proper activation and proliferation of effector T cells, restricts the development of regulatory T cells, and downregulates innate immune responses. Recently, a direct role of mTOR in the modulation of glial functions has also been recognized. Data from our group and others support the notion that mTOR is involved in microglial proinflammatory activation. The kinase regulates several intracellular processes in astrocytes, among which the rate of mRNA degradation of the inducible form of NO synthase. Therefore, the inhibition of mTOR kinase activity in glial cells results in anti-inflammatory actions, suggesting possible beneficial effects of mTOR inhibitors (like rapamycin) in the treatment of inflammatory-based pathologies of the central nervous system. In contrast, mTOR plays an important role in the regulation of oligodendrocyte development and myelination process as well as several neuronal functions, which may limit this therapeutic approach. Nevertheless, as reviewed here, there is robust evidence that rapamycin ameliorates the clinical course of both the relapsing-remitting and the chronic experimental autoimmune encephalomyelitis (EAE), and significantly reduces the hyperalgesia observed before clinical development of EAE. These findings may have important clinical implications for the therapy of multiple sclerosis.

Endocrine disruptors and human corpus luteum: in vitro effects of phenols on luteal cells function.

Endocrine disruptors are well known to impair fertility. The aim of the present study was to investigate the effects of bisphenol A (BPA) and nonylphenol (p-NP) on human luteal function in vitro. In particular, in luteal cells isolated from 21 human corpora lutea progesterone, prostaglandin (PG) F2α, PGE2 and vascular endothelial growth factor (VEGF) release, as well as VEGF expression were evaluated. BPA and p-NP negatively affected both luteal steroidogenesis and luteotrophic/ luteolytic factors balance, without influencing VEGF mRNA expression. Actually, BPA and p-NP impaired human luteal cells function in vitro, underlining the already suggested correlation between phenols and reproductive failure.

Validation of an UPLC-MS/MS method for quantitative analysis of raltegravir in human plasma samples.

BACKGROUND: An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the quantification of raltegravir (RTG) plasma concentrations in samples from HIV patients treated with the drug. METHODS: Plasma samples were extracted by liquid-liquid extraction followed by evaporation to dryness and reconstitution in mobile phase. The chromatographic separation was carried out on an AQUITY UPLC C18 column with an isocratic mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid (50:50 vol/vol). The detection was performed on a triple quadrupole tandem mass spectrometer using multi-reaction monitoring via electrospray ionization source with positive ionization mode. RESULTS: Under these conditions, a single chromatographic run could be completed within 1 minute. The method was validated by estimating the precision and the accuracy for inter- and intra-day analysis in the concentration range of 5-2560 ng/mL. The method was linear over the investigated range with all the correlation coefficients, r, greater than 0.995 on 5 replicates. The intra- and inter-day precision (percentage of coefficient of variation) ranged from 2.4% to 11.2%, and the inaccuracy (percent of relative standard deviation) ranged from 2.5% to 12.9%. No significant matrix effect was observed. The mean recovery value of RTG was 80%. CONCLUSIONS: This rapid and sensitive method was validated and could be applied to pharmacokinetic studies for the determination of RTG concentrations in human plasma samples.

Variability of raltegravir plasma levels in the clinical setting.

Therapeutic drug monitoring of raltegravir Ctrough levels was carried out in the setting of the Raltegravir Switch for Toxicity or Adverse events (RASTA) trial, a randomized pilot study exploring a 48-week safety and efficacy of treatment switch to raltegravir associated with tenofovir/emtricitabine or abacavir/lamivudine in patients with regimens with optimal virologic control. Blood sampling for measurement of raltegravir plasma levels was carried out at weeks 4, 12, 24, 36 and 48. Plasma samples were analysed by a recently developed and validated UPLC-MS method. A total of 164 samples from 39 patients were assayed. Analysis for intra- and inter-subject variability was restricted to those patients with 4 or more determinations, including 30 patients and 142 determinations. The intra- and inter-subject variability measures were 85.9 and 124.6%, respectively, with an intra-/inter-subject variability ratio of 69%. We also analysed data from a subset of patients with well-documented adherence to protocol, defined as protocol compliant population, including 21 patients and 93 determinations. In this subpopulation, we estimated intra- and inter-subject variability of 79.87% and 110%, respectively, with an intra-/inter-subject variability ratio of 72.6%. This study confirms the notion that raltegravir is a highly variable drug according to the European Medicines Agency criteria. While this condition does not favour the adoption of therapeutic drug monitoring in the clinical practice, the latter is deemed useful in patients with drug plasma concentrations below or near the threshold level of efficacy (since intracellular raltegravir levels might be as low as 5% of the corresponding plasma levels), or to identify drug-drug interactions of potential clinical relevance.