Lipoprotein modifications by gingipains of Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Several studies have shown an association between periodontitis and cardiovascular disease (CVD). Atherosclerosis is the major cause of CVD, and a key event in the development of atherosclerosis is accumulation of lipoproteins within the arterial wall. Bacteria are the primary etiologic agents in periodontitis and Porphyromonas gingivalis is the major pathogen in the disease. Several studies support a role of modified low-density lipoprotein (LDL) in atherogenesis; however, the pathogenic stimuli that induce the changes and the mechanisms by which this occur are unknown. This study aims to identify alterations in plasma lipoproteins induced by the periodontopathic species of bacterium, P. gingivalis, in vitro.

MATERIAL AND METHODS

Plasma lipoproteins were isolated from whole blood treated with wild-type and gingipain-mutant (lacking either the Rgp- or Kgp gingipains) P. gingivalis by density/gradient-ultracentrifugation and were studied using 2-dimensional gel electrophoresis followed by matrix-assisted laser desorption/ionization mass spectrometry. Porphyromonas gingivalis-induced lipid peroxidation and antioxidant levels were measured by thiobarbituric acid-reactive substances and antioxidant assay kits, respectively, and lumiaggregometry was used for measurement of reactive oxygen species (ROS) and aggregation.

RESULTS

Porphyromonas gingivalis exerted substantial proteolytic effects on the lipoproteins. The Rgp gingipains were responsible for producing 2 apoE fragments, as well as 2 apoB-100 fragments, in LDL, and the Kgp gingipain produced an unidentified fragment in high-density lipoproteins. Porphyromonas gingivalis and its different gingipain variants induced ROS and consumed antioxidants. Both the Rgp and Kgp gingipains were involved in inducing lipid peroxidation.

CONCLUSION

Porphyromonas gingivalis has the potential to change the expression of lipoproteins in blood, which may represent a crucial link between periodontitis and CVD.

Reduction of quality of life in prostate cancer patients: experience among 6200 men in the Nordic countries

OBJECTIVE

Although many studies have dealt with adverse effects (AEs) and quality of life (QoL) in prostate cancer (PCa) patients, the quantification of the patients' perspective on AE-related reduction in QoL has been less studied. This study describes the impact of self-reported local (erectile, bowel, urinary dysfunction) or systemic (mental distress, fatigue, virility loss) AEs on QoL reduction.

MATERIALS AND METHODS

Nordic PCa patients completed a questionnaire containing 84 multiple-choice questions. The main outcome variable of the survey was patient-reported PCa-induced QoL reduction, assessed by descriptive and regression analyses. The level of significance was p < 0.05.

RESULTS

Among 6200 patients, 39% described their QoL as reduced owing to the PCa trajectory: radical prostatectomy group (RPGroup): 42%, radiotherapy without hormones (RADGroup): 27%, hormones (HormGroup): 47% and no treatment (NoTrtGroup): 19%. Except for the NoTrtGroup, urinary leakage and fatigue doubled the risk of QoL reduction, while virility loss and erectile dysfunction tripled the risk. Significant intergroup differences emerged for the age-adjusted odds of QoL reduction: RPGroup (0.66), RADGroup (0.40), HormGroup (0.95) and NoTrtGroup (0.22).

CONCLUSIONS

After RP, RAD or hormone treatment of PCa, systemic AEs, in particular loss of virility, significantly reduce PCa patients' QoL similarly to or more than local AEs. The probability of reduced QoL is highest during hormone treatment and lowest in patients without anticancer therapy, and seems lower in patients treated with RAD without hormones than after RP. The treatment-related risk of reduced QoL due to systemic AEs should become a part of the pretreatment counselling of patients.

Magnetic resonance enterography is feasible and reliable in multicenter clinical trials in patients with Crohn's disease, and may help select subjects with active inflammation

BACKGROUND

Reliable tools for patient selection are critical for clinical drug trials.

AIM

To evaluate a consensus-based, standardised magnetic resonance enterography (MRE) protocol for selecting patients for inclusion in Crohn's disease (CD) multicenter clinical trials.

METHODS

This study recruited 20 patients [Crohn's Disease Activity Index (CDAI) scores: <150 (n = 8); 150-220 (n = 4); 220-450 (n = 8)], to undergo ileocolonoscopy and two MREs (with and without colonic contrast) within a 14-day period. Procedures were scored centrally using, Magnetic Resonance Index of Activity (MaRIA), and both Crohn's Disease Endoscopic Index of Severity (CDEIS) and Simplified Endoscopic Score (SES-CD).

RESULTS

37 MREs were acquired. Both MREs were evaluable in 16 patients for calculation of test-retest and inter-reader reliability scores. The MaRIA scores for the terminal ileum had excellent test-retest and inter-reader reliability, with correlations >0.9. The proximal ileum showed strong within-reader agreement (0.90-0.96), and fair between-reader agreement (0.59-0.72). MRE procedures were tolerable. MaRIA scores correlated with CDEIS and SES-CD (0.63 and 0.71), but not with CDAI (0.34). MRE identified 3 patients with intra-abdominal complications, who would otherwise have been included in clinical trials. Furthermore, both MRE and ileocolonoscopy identified active bowel wall inflammation in 2 patients with CDAI <150, and none in 1 patient with CDAI > 220. Data quality was good/excellent in 85% of scans, and fair or better in 96%.

CONCLUSIONS

Magnetic resonance enterography of high-quality and reproducibility was feasible in a global multi- centre setting, with evidence for improved selectivity over CDAI and ileocolonoscopy in identifying appropriate CD patients for inclusion in therapeutic intervention trials.

STatistically Assigned Response Criteria in Solid Tumors (STARCIST)

Background

Several reproducibility studies have established good test-retest reliability of FDG-PET in various oncology settings. However, these studies are based on relatively short inter-scan periods of 1–3 days while, in contrast, response assessments based on FDG-PET in early phase drug trials are typically made over an interval of 2–3 weeks during the first treatment cycle. With focus on longer, on-treatment scan intervals, we develop a data-driven approach to calculate baseline-specific cutoff values to determine patient-level changes in glucose uptake that are unlikely to be explained by random variability. Our method takes into account the statistical nature of natural fluctuations in SUV as well as potential bias effects.

Methods

To assess variability in SUV over clinically relevant scan intervals for clinical trials, we analyzed baseline and follow-up FDG-PET scans with a median scan interval of 21 days from 53 advanced stage cancer patients enrolled in a Phase 1 trial. The 53 patients received a sub-pharmacologic drug dose and the trial data is treated as a ’test-retest’ data set. A simulation-based tool is presented which takes as input baseline lesion SUVmax values, the variance of spurious changes in SUVmax between scans, the desired Type I error rate, and outputs lesion and patient based cut-off values. Bias corrections are included to account for variations in tracer uptake time.

Results

In the training data, changes in SUVmax follow an approximately zero-mean Gaussian distribution with constant variance across levels of the baseline measurements. Because of constant variance, the coefficient of variation is a decreasing function of the magnitude of baseline SUVmax. This finding is consistent with published results, but our data shows greater variability. Application of our method to NSCLC patients treated with erlotinib produces results distinct from those based on the EORTC criteria. Based on data presented here as well as previous repeatability studies, the proposed method has greater statistical power to detect a significant %-decrease on SUVmax compared to published criteria relying on symmetric thresholds.

Conclusions

Defining patient-specific, baseline dependent cut-off values based on the (null) distribution of naturally occurring fluctuations in glucose uptake enable identification of statistically significant changes in SUVmax. For lower baseline values, the produced cutoff values are notably asymmetric with relatively large changes (e.g. >50 %) required for statistical significance. For use with prospectively defined endpoints, the developed method enables the use of one-armed trials to detect pharmacodynamic drug effects based on FDG-PET. The clinical importance of changes in SUVmax is likely to remain dependent on both tumor biology and the type of treatment.

Clinical pharmacokinetics of AZD3199, an inhaled ultra-long-acting β2-adrenoreceptor agonist (uLABA)

Objective

The clinical pharmacokinetics of AZD3199, an ultra-long-acting β₂-agonist, were investigated in healthy volunteers and patients with asthma or chronic obstructive pulmonary disease (COPD).

Materials and methods

Five studies are presented: one single ascending dose study in healthy Caucasian males; two multiple ascending dose studies in healthy males, one in Caucasians and one in Japanese; a Phase IIA asthma study; and a Phase IIB COPD study. Subjects received AZD3199 via a Spira nebulizer (Turbuhaler; equivalent delivered doses 5–3200 μg) or Turbuhaler (single delivered doses of 120–1920 μg or repeated delivered once-daily doses 240–1,680 μg). AZD3199 pharmacokinetics were assessed using total plasma concentration and urinary excretion, and tolerability using adverse events, clinical laboratory tests, and physical examinations.

Results

AZD3199 appeared rapidly in the systemic circulation following single and multiple dosing in healthy volunteers and patients (maximum plasma concentration within 30 minutes), with dose-proportional time-independent pharmacokinetics. Plasma exposure to unmetabolized drug was similar in healthy volunteers and patients with asthma, but relatively lower in patients with COPD. Estimated terminal half-life was up to 142 hours in healthy Caucasian males. AZD3199 was well tolerated and showed no or at most mild systemic effects.

Conclusion

AZD3199 plasma exposure in healthy volunteers and patients suggested linear pharmacokinetics and a long half-life. Systemic availability was similar in healthy subjects and patients with asthma, but was lower in patients with COPD. These clinical trials suggest that AZD3199 is well-tolerated in healthy male volunteers and patients, with no safety concerns identified to preclude further evaluation.

The role of Porphyromonas gingivalis gingipains in platelet activation and innate immune modulation

Platelets are considered to have important functions in inflammatory processes and as actors in the innate immunity. Several studies have shown associations between cardiovascular disease and periodontitis, where the oral anaerobic pathogen Porphyromonas gingivalis has a prominent role in modulating the immune response. Porphyromonas gingivalis has been found in atherosclerotic plaques, indicating spreading of the pathogen via the circulation, with an ability to interact with and activate platelets via e.g. Toll-like receptors (TLR) and protease-activated receptors. We aimed to evaluate how the cysteine proteases, gingipains, of P. gingivalis affect platelets in terms of activation and chemokine secretion, and to further investigate the mechanisms of platelet-bacteria interaction. This study shows that primary features of platelet activation, i.e. changes in intracellular free calcium and aggregation, are affected by P. gingivalis and that arg-gingipains are of great importance for the ability of the bacterium to activate platelets. The P. gingivalis induced a release of the chemokine RANTES, however, to a much lower extent compared with the TLR2/1-agonist Pam3 CSK4 , which evoked a time-dependent release of the chemokine. Interestingly, the TLR2/1-evoked response was abolished by a following addition of viable P. gingivalis wild-types and gingipain mutants, showing that both Rgp and Kgp cleave the secreted chemokine. We also demonstrate that Pam3 CSK4 -stimulated platelets release migration inhibitory factor and plasminogen activator inhibitor-1, and that also these responses were antagonized by P. gingivalis. These results supports immune-modulatory activities of P. gingivalis and further clarify platelets as active players in innate immunity and in sensing bacterial infections, and as target cells in inflammatory reactions induced by P. gingivalis infection.

Transient paradoxical bronchospasm associated with inhalation of the LAMA AZD9164: analysis of two Phase I, randomised, double-blind, placebo-controlled studies

Background

AZD9164 has demonstrated potential as an inhaled, long-acting, muscarinic antagonist (LAMA) bronchodilator. However, in patients with COPD, but not in healthy subjects, a transient initial drop in FEV₁ was observed following inhalation of nebulised doses of AZD9164 in citrate buffer.

Two additional studies were conducted to further assess the safety and tolerability of multiple ascending doses of AZD9164 in 27 white and 18 Japanese healthy subjects and in 4 patients with COPD. In these studies, AZD9164 was inhaled via Turbuhaler™.

Methods

These were Phase I, randomised, double-blind, placebo-controlled, multiple ascending dose (MAD) studies conducted in Sweden and UK. Healthy subjects (mean age 25.9 yrs) and patients with COPD (mean age 66 yrs, mean post-bronchodilator FEV₁ 60.1% predicted normal value) were randomised 2:1 to active treatment (400, 1000 or 2800 μg delivered doses of AZD9164) or placebo.

Results

No safety or tolerability concerns were identified in the healthy subjects at doses up to and including 2800 μg and both studies confirmed the bronchodilator effect of AZD9164. However, the first 3 patients in the COPD cohort who received AZD9164 (1000 μg) experienced a transient fall in FEV₁ 5 to 15 minutes after inhalation of AZD9164 while the patient receiving placebo did not. The study safety review process then resulted in cessation of further activities on AZD9164. Retrospective analysis showed that two healthy subjects had also had transient falls in FEV₁ shortly after inhalation of AZD9164 400 and 2800 μg respectively, although neither reported any related respiratory symptoms or other AEs.

Conclusions

These results show that transient paradoxical bronchoconstriction can occur in some healthy subjects, in addition to patients with COPD, following inhalation of AZD9164 and that the citrate buffer used in the nebulised formulation cannot have been the only cause of the drop in FEV₁ in previous studies. As preclinical data do not provide an explanation, the reasons for this brief post-dose drop in FEV₁ remain unclear. However, these results highlight the importance of monitoring lung function immediately post-dose when investigating novel inhaled treatments, even when a rapid onset of effect is not expected.

Trial registration

Clinicaltrials.gov NCT01016951 and NCT01096563.

Sample size and threshold estimation for clinical trials with predictive biomarkers

With the increasing availability of newly discovered biomarkers personalized drug development is becoming more commonplace. Unless evidence of the dependence of clinical benefit on biomarker classification is a priori unequivocal, personalized drug development needs to jointly investigate treatments and biomarkers in clinical trials. Motivated by the development of contemporary cancer treatments, we propose targeting three main questions sequentially in order to determine (1) whether a drug is efficacious, (2) whether a biomarker can personalize treatment, and (3) how to define personalization. For time-to-event data satisfying the Cox proportional hazards model, we show that (1) and (2) may not directly involve the variance of an interaction term but of a contrast with smaller variance. An asymptotically exact covariance matrix for the parameter vector in the CPH model is derived to construct sample size formulae and an inference approach for thresholds of continuous biomarkers. The covariance matrix also reveals strategies for greater efficiency in trial design, for example, when the biomarker is binary or does not modulate the effect of treatment in the control arm. We motivate our approach by studying the outcome of a contemporary cancer study.

Comparison of the bronchodilator and systemic effects of AZD3199, an inhaled ultra-long-acting β₂-adrenoceptor agonist, with formoterol in patients with asthma

OBJECTIVES

Pharmacologically mediated bronchodilation is important in the management of asthma, and is primarily achieved with β₂-agonists. Novel compounds should preferably have a longer duration of action and a better systemic side effect profile than established alternatives at comparable peak bronchodilation. This single-dose crossover study was conducted to investigate and compare with formoterol the bronchodilatory and systemic effects, tolerability and safety of AZD3199, a novel ultra-long-acting β₂-agonist (uLABA).

METHODS

Patients with asthma (n = 37) were randomized to receive AZD3199 (120, 480, 1920 µg), formoterol (9, 36 µg) or placebo inhaled via a Turbuhaler™. Bronchodilation was evaluated by maximum (E(max)) and average 22-26 h (E₂₂₋₂₆) forced expiratory volume in 1 second (FEV1). Serum potassium was evaluated by minimum (E(min)) and 0-4 h average (E(av)) determined from serial measurements. AZD3199 and formoterol were compared on the basis of relative dose potency. Adverse events, clinical laboratory tests and physical examinations were markers for safety and tolerability, with plasma AZD3199 as the indicator of drug exposure.

RESULTS

All active treatments dose-dependently increased E(max) and AZD3199 (480 and 1920 µg) and formoterol (36 µg) significantly increased E(₂₂₋₂₆) versus placebo. Relative dose potency between AZD3199 and formoterol was 50-fold on the microgram scale with respect to E max and 11-fold with respect to E(₂₂₋₂₆). Small, dose-dependent effects on potassium, heart rate and QTc were seen after administration of AZD3199 compared with placebo. These well-known dose-related class effects of β₂-agonists were mild. Notably, serum potassium suppression was less pronounced after AZD3199 compared with formoterol at similar bronchodilation. Overall, AZD3199 was well tolerated.

CONCLUSIONS

AZD3199 480 µg and 1920 µg produced 24-hour bronchodilation. At comparable peak bronchodilator effect, AZD3199 was associated with a lower level of systemic side effects than formoterol. AZD3199 was well tolerated, with no safety concerns identified to preclude further investigation. ClinicalTrials.gov study identifier: NCT00736489.

Efficacy and safety of AZD3199 vs formoterol in COPD: a randomized, double-blind study

BACKGROUND

We investigated the efficacy and safety of AZD3199, a novel inhaled ultra-LABA, with the main aim of establishing a dose that would maintain 24-hour bronchodilation in patients with COPD.

METHODS

Patients (n = 329) were randomized to AZD3199 (200, 400 or 800 μg o.d.), formoterol (9 μg b.i.d.) or placebo via Turbuhaler® in a parallel group study. The primary objective of the study was to compare the clinical efficacy of three doses of AZD3199 inhaled once daily with 9 μg formoterol twice daily and placebo, over a 4-week treatment period in adults with moderate-to-severe COPD. After 4 weeks, peak (0-4 h) and trough (24-26 h) forced expiratory volume in 1 second (FEV1) were assessed as the primary efficacy outcome variables.

RESULTS

All AZD3199 doses significantly increased mean peak and trough FEV1 versus placebo (106-171 ml and 97-110 ml increases, respectively), but with no clear dose-response; the level of bronchodilation was comparable to or greater than that achieved with formoterol. Forced vital capacity (FVC) at peak bronchodilation also significantly increased with AZD3199 versus placebo (153-204 ml). COPD symptom scores and reliever use were reduced with AZD3199, while FEV1 reversibility was unaltered. Adverse events were mild-to-moderate, with no safety concerns identified. Drug exposure was dose-proportional, but lower than predicted from healthy volunteers.

CONCLUSIONS

All three doses of AZD3199 produced 24-hour bronchodilation, but with no clear dose-response, suggesting that doses of 200 μg or less may be sufficient to maintain bronchodilation over 24 hours in patients with COPD. No safety concerns were identified. Further studies are required to determine the once-daily AZD3199 dose for COPD.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT00929708.

An industry statistician's perspective on PHC drug development

In the past decade, the cost of drug development has increased significantly. The estimates vary widely but frequently quoted numbers are staggering-it takes 10-15 years and billions of dollars to bring a drug to patients. To a large extent this is due to many long, expensive and ultimately unsuccessful drug trials. While one approach to combat the low yield on investment could be to continue searching for new blockbusters, an alternative method would lead us to focus on testing new targeted treatments that have a strong underlying scientific rationale and are more likely to provide enhanced clinical benefit in population subsets defined by molecular diagnostics. Development of these new treatments, however, cannot follow the usual established path; new strategies and approaches are required for the co-development of novel therapeutics and the diagnostic. In this paper we will review, from the point of view of industry, the approaches to, and challenges of drug development strategies incorporating predictive biomarkers into clinical programs. We will outline the basic concepts behind co-development with predictive biomarkers and summarize the current regulatory paradigm. We will present guiding principles of personalized health care (PHC) development and review the statistical, strategic, regulatory and operational challenges that statisticians regularly encounter on development programs with a PHC component. Some practical recommendations for team statisticians involved in PHC drug development are included. The majority of the examples and recommendations are drawn from oncology but broader concepts apply across all therapeutic areas.

Local and systemic effects of inhaled AZD9164 compared with tiotropium in patients with COPD

There is still a need for new agents which improve upon the therapeutic index of tiotropium, the current standard of care for many patients with chronic obstructive pulmonary disease (COPD). We examined in patients with COPD the efficacy of single doses of AZD9164, an M(3)-selective muscarinic antagonist, to identify an appropriate dose-range for future studies. COPD patients (n = 28) inhaled AZD9164 (100, 400 and 1200 μg), tiotropium (18 μg) and placebo at 5 study centre visits (Clinicaltrials.gov identifier NCT00939211). The effects of these test drugs on average (E(av)), peak (E(max)) and trough (E(22-26)) forced expiratory volume in one second (FEV(1)) were assessed, as were systemically-mediated effects and the safety and exposure of single doses of AZD9164. AZD9164 100, 400 and 1200 μg caused increases in FEV(1) to peak effects of 12, 17 and 12% above baseline respectively, following an initial transient and dose-related fall in FEV(1) and associated increase in mild respiratory symptoms such as cough. Bronchodilation was maintained overnight, with minimal FEV(1) decline. AZD9164 400 and 1200 μg produced larger effects than tiotropium on E(22-26) (p < 0.05; both doses) while AZD9164 400 μg also had larger effects on E(max) (p = 0.001) and E(av) (p < 0.05). There were no serious adverse events and statistically significant systemic effects were observed only with AZD9164 1200 μg. AZD9164 may improve upon the therapeutic index of tiotropium, increasing the magnitude and duration of lung function improvements without increasing systemically-mediated adverse events. The initial bronchoconstrictor effect of AZD9164 requires further investigation.

The power of FDG-PET to detect treatment effects is increased by glucose correction using a Michaelis constant

BACKGROUND

We recently showed improved between-subject variability in our [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) experiments using a Michaelis-Menten transport model to calculate the metabolic tumor glucose uptake rate extrapolated to the hypothetical condition of glucose saturation: MRglucmax=Ki*(KM+[glc]), where Ki is the image-derived FDG uptake rate constant, KM is the half-saturation Michaelis constant, and [glc] is the blood glucose concentration. Compared to measurements of Ki alone, or calculations of the scan-time metabolic glucose uptake rate (MRgluc = Ki * [glc]) or the glucose-normalized uptake rate (MRgluc = Ki*[glc]/(100 mg/dL), we suggested that MRglucmax could offer increased statistical power in treatment studies; here, we confirm this in theory and practice.

METHODS

We compared Ki, MRgluc (both with and without glucose normalization), and MRglucmax as FDG-PET measures of treatment-induced changes in tumor glucose uptake independent of any systemic changes in blood glucose caused either by natural variation or by side effects of drug action. Data from three xenograft models with independent evidence of altered tumor cell glucose uptake were studied and generalized with statistical simulations and mathematical derivations. To obtain representative simulation parameters, we studied the distributions of Ki from FDG-PET scans and blood [glucose] values in 66 cohorts of mice (665 individual mice). Treatment effects were simulated by varying MRglucmax and back-calculating the mean Ki under the Michaelis-Menten model with KM = 130 mg/dL. This was repeated to represent cases of low, average, and high variability in Ki (at a given glucose level) observed among the 66 PET cohorts.

RESULTS

There was excellent agreement between derivations, simulations, and experiments. Even modestly different (20%) blood glucose levels caused Ki and especially MRgluc to become unreliable through false positive results while MRglucmax remained unbiased. The greatest benefit occurred when Ki measurements (at a given glucose level) had low variability. Even when the power benefit was negligible, the use of MRglucmax carried no statistical penalty. Congruent with theory and simulations, MRglucmax showed in our experiments an average 21% statistical power improvement with respect to MRgluc and 10% with respect to Ki (approximately 20% savings in sample size). The results were robust in the face of imprecise blood glucose measurements and KM values.

CONCLUSIONS

When evaluating the direct effects of treatment on tumor tissue with FDG-PET, employing a Michaelis-Menten glucose correction factor gives the most statistically powerful results. The well-known alternative 'correction', multiplying Ki by blood glucose (or normalized blood glucose), appears to be counter-productive in this setting and should be avoided.

18F-FDG PET as a surrogate biomarker in non-small cell lung cancer treated with erlotinib: newly identified lesions are more informative than standardized uptake value

This study assesses the predictive value of (18)F-FDG PET for overall survival in lung cancer patients treated with a targeted drug.

METHODS

(18)F-FDG PET was performed in 125 second- or third-line non-small cell lung cancer (NSCLC) patients with a baseline Eastern Cooperative Oncology Group performance status less than 3 before treatment with erlotinib (150 mg daily) and 2 wk into treatment. The predictive value of (18)F-FDG PET, clinical parameters, and epithelial growth factor receptor (EGFR) mutation status for survival duration was evaluated by fitting accelerated failure time models.

RESULTS

New lesions on PET at 2 wk, EGFR mutation status, performance status, and baseline tumor burden were independent and significant predictors of overall survival. Reduction of maximum standardized uptake value by at least 35% was predictive of survival only when EGFR mutation status was not accounted for.

CONCLUSION

(18)F-FDG PET in second- or third-line NSCLC patients at 2 wk after starting treatment with erlotinib carries information about overall survival. Parametric survival modeling enables a quantitative assessment of the predictive value of (18)F-FDG PET in the context of clinical and laboratory information. New-lesion status by (18)F-FDG PET at 2 wk is a potential surrogate biomarker for survival in NSCLC.

Quantitation of glucose uptake in tumors by dynamic FDG-PET has less glucose bias and lower variability when adjusted for partial saturation of glucose transport

Background

A retrospective analysis of estimates of tumor glucose uptake from 1,192 dynamic 2-deoxy-2-(¹⁸F)fluoro-D-glucose-positron-emission tomography [FDG-PET] scans showed strong correlations between blood glucose and both the uptake rate constant [K_i] and the metabolic rate of glucose [MRGluc], hindering the interpretation of PET scans acquired under conditions of altered blood glucose. We sought a method to reduce this glucose bias without increasing the between-subject or test-retest variability and did this by considering that tissue glucose transport is a saturable yet unsaturated process best described as a nonlinear function of glucose levels.

Methods

Patlak-Gjedde analysis was used to compute K_i from 30-min dynamic PET scans in tumor-bearing mice. MRGluc was calculated by factoring in the blood glucose level and a lumped constant equal to unity. Alternatively, we assumed that glucose consumption is saturable according to Michaelis-Menten kinetics and estimated a hypothetical maximum rate of glucose consumption [MRGluc^MAX] by multiplying K_i and (K_M + [glucose]), where K_M is a half-saturation Michaelis constant for glucose uptake. Results were computed for 112 separate studies of 8 to 12 scans each; test-retest statistics were measured in a suitable subset of 201 mice.

Results

A K_M value of 130 mg/dL was determined from the data based on minimizing the average correlation between blood glucose and the uptake metric. Using MRGluc^MAX resulted in the following benefits compared to using MRGluc: (1) the median correlation with blood glucose was practically zero, and yet (2) the test-retest coefficient of variation [COV] was reduced by 13.4%, and (3) the between-animal COVs were reduced by15.5%. In statistically equivalent terms, achieving the same reduction in between-animal COV while using the traditional MRGluc would require a 40% increase in sample size.

Conclusions

MRGluc appeared to overcorrect tumor FDG data for changing glucose levels. Applying partial saturation correction using MRGluc^MAX offered reduced bias, reduced variability, and potentially increased statistical power. We recommend further investigation of MRGluc^MAX in quantitative studies of tumor FDG uptake.

Hepatocyte growth factor in patients with coronary artery disease and its relation to periodontal condition

Hepatocyte growth factor (HGF) is an angiogenic, cardioprotective factor important for tissue and vascular repair. High levels of HGF are associated with chronic inflammatory diseases, such as coronary artery disease (CAD) and periodontitis, and are suggested as a marker of the ongoing atherosclerotic event in patients with CAD. Periodontal disease is more prevalent among patients with CAD than among healthy people. Recent studies indicate a reduced biological activity of HGF in different chronic inflammatory conditions. Biologically active HGF has high affinity to heparan sulfate proteoglycan (HSPG) on cell-membrane and extracellular matrix. The aim of the study was to investigate the serum concentration and the biological activity of HGF with ELISA and surface plasmon resonance (SPR), respectively, before and at various time points after percutaneous coronary intervention (PCI) in patients with CAD, and to examine the relationship with periodontal condition. The periodontal status of the CAD patients was examined, and the presence of P. gingivalis in periodontal pockets was analyzed with PCR. The HGF concentration was significantly higher, at all time-points, in patients with CAD compared to the age-matched controls (P< 0.001), but was independent of periodontal status. The HGF concentration and the affinity to HSPG adversely fluctuated over time, and the biological activity increased one month after intervention in patients without periodontitis. We conclude that elevated concentration of HGF but with reduced biological activity might indicate a chronic inflammatory profile in patients with CAD and periodontitis.

True adherence with the Turbuhaler in young children with asthma

OBJECTIVE

To investigate true adherence with a dry powder inhaler, the Turbuhaler (TBH), in children with asthma. True adherence was calculated by multiplying adherence to treatment with inhaler competence, that is correct use of the inhaler.

PATIENTS AND DESIGN

In an 18-month study, children aged 5-10 years with asthma received twice daily budesonide via a TBH. Parents and children were trained in the correct use of the inhaler before the study started. For each inhalation, peak inspiratory flow through the TBH (PIF(TBH)) was recorded with an electronic pneumotachograph. The PIF(TBH) recordings were used to calculate true adherence for the first and last 45-day periods in the study by multiplying adherence in using the device (percentage of days with PIF(TBH) recordings) with inhaler competence (correct use of inhaler defined as PIF(TBH) values >40 l/min).

MAIN OUTCOME MEASURES

True adherence, adherence, inhaler competence and PIF(TBH).

RESULTS

115 children were treated. The mean (morning and evening) true adherence during the first 45 days was 81.6% (range 78.1-86.4%) and during the last 45 days 57.4% (44.0-66.9%). Mean adherence was 86.0% and 59.3%, whereas mean inhaler competence was 94.7% and 96.2%, respectively. Thus the decline in true adherence was due to the decline in adherence. The largest decline in true adherence occurred in older children.

CONCLUSIONS

True adherence with budesonide TBH treatment decreased significantly during the 18-month study due to a decrease in adherence. Inhaler competence with the correct use of the budesonide TBH was high and unchanged over the study period.