Procedural outcome and risk prediction in patients with implantable cardioverter-defibrillator (ICD) undergoing transvenous lead extraction: a GALLERY subgroup analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Device complications, such as infection or lead dysfunction necessitating transvenous lead extraction (TLE) are continuously rising amongst patients with indwelling transvenous implantable cardioverter-defibrillator (ICD).

Objectives

Aim of this study was to characterize the procedural outcome and risk factors of patients with indwelling 1- and 2-chamber ICD undergoing TLE.

Methods

We conducted a subgroup analysis of all 1- and 2-chamber ICD patients in the GALLERY (GermAn Laser Lead Extraction RegistrY) database. Predictors for procedural failure and all-cause mortality were assessed.

Results

A total of 854 patients with ICD undergoing TLE were identified, who were younger (62.9±13.8 vs. 70.7±13.0 years; p<0.001), less likely to be female (20.8 vs. 27.1%; p<0.001) and had a higher proportion of patients with coronary artery disease (51.5 vs. 38.6%; p<0.001) and highly reduced ejection fraction (32.0 vs. 23.0%; p>0.001), when compared to non-ICD patients. Leading extraction indication was lead dysfunction (48.0 vs. 21.9%; p<0.001), followed by device-related infection (45.6 vs. 73.0%; p<0.001). There were no differences in overall procedural complications (4.3 vs. 4.3%; p=0.980), clinical success rate (97.9 vs. 97.8%; p=0.861) or procedure-related (0.8 vs. 0.5%; p=0.292) and all-cause mortality (3.4 vs. 3.7%; 0.742) between groups. Multivariate analysis revealed lead age≥10 years (OR:5.75, 95%CI:2.0-16.2; p=0.001) as independent predictor for procedural failure. Systemic infection as extraction indication (OR:9.57, 95%CI:2.2-42.4; p=0.003) and procedural complications (OR:8.0, 95%CI:2.8-23.3; p<0.001) were identified as risk factors for all-cause mortality. Predictors for systemic infection in ICD patients were atrial fibrillation (OR: 2.22, 95%CI: 1.51-3.27; p<0.001), diabetes mellitus (OR: 2.28, 95%CI: 1.59-3.25; p<0.001) and chronic kidney disease (OR: 2.0, 95%CI: 1.39-2.89; p<0.001).

Conclusions

Transvenous lead extraction is safe and efficacious in patients with 1- and 2-chamber ICD. Although lead dysfunction is the leading indication for extraction, systemic device-related infection is the main driver of all-cause mortality for ICD patients undergoing TLE.

Increased prevalence of metabolic syndrome in patients with bipolar disorder compared to a selected control group-a Northern Netherlands LifeLines population cohort study

OBJECTIVES

Metabolic syndrome (MetS) is highly prevalent among patients with bipolar disorder (BD). The aims of this cross-sectional study were to determine the prevalence of MetS in Dutch BD subjects and compare it with a control group, to examine the association of demographic and clinical characteristics with MetS in BD, and to determine the extent to which metabolic dysregulation is treated in those patients.

METHODS

493 Dutch adult patients (≥ 18 years) with BD receiving psychotropic drugs and 493 matched control subjects were compared using data from the biobank Lifelines. We determined MetS according to the National Cholesterol Education Program Adult Treatment Panel III-Adapted (NCEP ATP III-A) criteria. The difference in the prevalence of MetS and the associations with characteristics were analyzed with logistic regression.

RESULTS

BD subjects (30.6%) showed a significantly higher prevalence of MetS compared to the control group (14.2%) (p < .001, OR:2.67, 95% CI:1.94-3.66). Univariate analysis showed that smoking, body mass index (BMI) and antidepressant drug use were associated with MetS. Multivariate analysis showed that smoking (OR:2.01) was independently associated with MetS in BD. For hypertension, hyperglycemia and lipid disorder pharmacological treatment was provided to respectively 69.5%, 24% and 18.4% of the BD subjects in our sample.

LIMITATIONS

Duration of illness of BD subjects was unknown.

CONCLUSIONS

This study demonstrated a higher prevalence of MetS in Dutch BD subjects compared to persons without BD. In addition, a remarkable undertreatment of some of the components of MetS was found.

1255Comprehensive analysis of pacemaker patients with and without abandoned leads undergoing transvenous lead extraction: A GALLERY subgroup analysis

OnBehalf

GALLERY investigators

Background

The number of cardiac implantable electronic device (CIED)-associated complications such as infection, lead dysfunction or thrombotic events is continuously rising and thus making transvenous lead extraction (TLE) an ever more needed procedure in clinical practice today. Patients with abandoned leads represent a special cohort with a potentially higher susceptibility to CIED-related infections and vascular complications. Moreover, according to literature abandoned leads seem to be associated with more procedural complications and mortality during TLE. 

Aim

 

The aim of this study was to provide an insight on safety, procedural outcome and risk prediction on pacemaker patients with abandoned leads undergoing TLE from the largest national laser-sheath registry to date.

Methods + Results:

We conducted a retrospective analysis of the GALLERY database, which collected 2533 patients undergoing TLE in Germany between 2013 and 2017. Out of 903 pacemaker patients, who underwent TLE, 226 patients (25.0%) with abandoned leads were identified. Those patients had a higher number of leads per patient (3.2 ± 0.8 vs. 1.9 ± 0.3; ns) and longer lead dwell-times (168.0 ± 89.7 vs. 123.0 ± 69.2 months; p &lt; 0.0001) compared to pacemaker patients without abandoned leads. There were no differences in age (71.5 vs. 72.3 years; ns), body mass index (26.5 ± 4.5 vs. 26.78 ± 4.8 kg/m2; ns) or gender distribution (69.0 vs. 66.5% male; ns). Leading indication for TLE was device infection with no difference between groups (79.7 vs 77.8 %; ns). There were no differences in terms of pacemaker dependency, length of hospitalization or comorbidities. Patients with abandoned leads had longer procedure times (112.0 ± 69.0 vs. 86.4 ± 53.0 minutes; p &lt; 0.0001) and a higher incidence of procedural complications (6.6 vs. 3.1%; p = 0.03), but there were no differences in neither procedural and clinical success rates (96.5 vs. 97.3%; ns), nor all-cause mortality (1.33 vs. 2.66%; ns). Multivariate logistic regression revealed abandoned leads (OR 2.1, CI 1.0-4.4, p = 0.04) and female gender (OR 2.4, CI 1.2-4.9, p = 0.02) as independent predictors for procedural complications. Systemic infection (OR 5.4, CI 2.0-14.8, p = 0.001) and chronic kidney disease (OR 4.0, CI 1.5-10.7, p = 0.007) were strong predictors for all-cause mortality in patients with indwelling pacemaker. Patient age &gt; 75 years (OR 3.9, CI 2.7-5.6, p &lt; 0.0001) and a lead dwell-time &gt; 10 years (OR 1.6, CI 1.1-2.2, p = 0.01) were identified as risk factors for an infectious cause for TLE. 

Conclusion

Abandoned leads are frequently encountered in pacemaker patients undergoing TLE and pose an important risk factor for procedural complications. Systemic CIED-related infections are the strongest driver of mortality in this patient cohort and urgently call for further improvements in early diagnosis and prevention.

The utility of PET-CT in the staging and management of advanced and recurrent malignant melanoma

BACKGROUND

Accurate pre-operative staging and correct surgical selection of patients with malignant melanoma reduces unnecessary morbidity and mortality, improves distant control and may improve survival. ¹⁸F-fluorodeoxyglucose Positron Emission Tomography Computed Tomography (¹⁸F-FDG PET-CT) has been shown to be useful in exclusion of metastatic sites and aids in surgical planning in stage III and potentially resectable stage IV disease. The primary objective of the study was to determine whether the use of PET-CT alters the initial staging and management of patients with advanced and recurrent melanoma.

METHOD

Retrospective analysis of clinical records of patients with malignant melanoma referred for staging PET-CT over a three-year period at our institution was performed. Pre- and post-PET-CT stage was recorded and a descriptive analysis was done to determine whether PET-CT resulted in a change in stage grouping and whether this change effected a change in clinical management.

RESULTS

A change in stage grouping occurred in 21/39 (53.8%) of patients, 76.2% of which were up-staged and 23.8% down staged. On analysis of stage III/IV and recurrent melanoma, a change in stage occurred in 90% of stage III, 50% of stage IV and 50% of recurrent melanoma patients. This effected a change in management in 86.7% of patients with stage III, IV and recurrent melanoma collectively.

CONCLUSION

PET-CT is a useful tool in the staging and subsequent management of melanoma. Its utility is pronounced in advanced and recurrent melanoma.

The distress thermometer as a prognostic tool for one-year survival among patients with lung cancer

INTRODUCTION

The use of patient-reported outcome measures is increasingly advocated to support high-quality cancer care. We therefore investigated the added value of the Distress Thermometer (DT) when combined with known predictors to assess one-year survival in patients with lung cancer.

METHODS

All patients had newly diagnosed or recurrent lung cancer, started systemic treatment, and participated in the intervention arm of a previously published randomised controlled trial. A Cox proportional hazards model was fitted based on five selected known predictors for survival. The DT-score was added to this model and contrasted to models including the EORTC-QLQ-C30 global QoL score (quality of life) or the HADS total score (symptoms of anxiety and depression). Model performance was evaluated through improvement in the -2 log likelihood, Harrell's C-statistic, and a risk classification.

RESULTS

In total, 110 patients were included in the analysis of whom 97 patients accurately completed the DT. Patients with a DT score ≥5 (N = 51) had a lower QoL, more symptoms of anxiety and depression, and a shorter median survival time (7.6 months vs 10.0 months; P = 0.02) than patients with a DT score <5 (N = 46). Addition of the DT resulted in a significant improvement in the accuracy of the model to predict one-year survival (P < 0.001) and the discriminatory value (C-statistic) marginally improved from 0.69 to 0.71. The proportion of patients correctly classified as high risk (≥85% risk of dying within one year) increased from 8% to 28%. Similar model performance was observed when combining the selected predictors with QoL and symptoms of anxiety or depression.

CONCLUSIONS

Use of the DT allows clinicians to better identify patients with lung cancer at risk for poor outcomes, to further explore sources of distress, and subsequently personalize care accordingly.

Investigation of the potential of buffalo and couch grasses to grow on AFIs and for removal of nutrients from paper mill wastewater

The potential growth of buffalo grass (Stenotaphrum secundatum) and couch grass (Cynodon dactylon) on artificial floating islands (AFIs) and their ability to remove total nitrogen (TN) and total phosphorus (TP) from a simulated paper mill wastewater was studied. This was done to assess the potential of AFIs for removal of nutrients from aerated stabilization basins (ASBs) that had occasional growth of blue-green algae (BGA) to bloom levels. Small scale AFIs were prepared using polyethylene foam and planted with the grasses in 30 L of tested water. Trials were conducted in a plastic covered greenhouse over a three-month period where temperatures ranged from 15 to 44 °C. The results showed that both buffalo and couch grasses can adapt to planting in AFIs showing increases of 125% and 148% in wet weight, respectively. Nutrient uptake by buffalo grass and couch grass were found to be similar. Percentage uptakes of TP and TN from the synthetic water by the buffalo grass were 82% and 47%, whereas by couch grass, uptakes were 83% and 45%, respectively.

Physiological movement disorder-like features during typical motor development

AIM

To compare physiological age-relatedness between dyskinesia (dystonia/choreoathetosis), dystonia and ataxia rating scale scores in healthy children.

METHOD

Three movement disorders specialists quantified dyskinetic-like features in healthy children (n = 52; 4-16 years) using the Dyskinesia Impairment Scale (DIS = DIS-choreoathetosis (DIS-C) + DIS-dystonia (DIS-D)). We compared the age-related regression coefficients of the DIS with data processed from previous studies on dystonia and ataxia rating scales (Burke-Fahn-Marsden Movement and Disability Scales (BFMMS and BFMDS) and Scale for Assessment and Rating of Ataxia (SARA), International Cooperative Ataxia Rating Scale (ICARS) and Brief Ataxia Rating Scale (BARS)).

RESULTS

Dyskinetic scores were obtained in 79% (DIS); 65% (DIS-D) and 17% (DIS-C) versus dystonic and ataxic scores in 98% (BFMMS) and 89% (SARA/ICARS/BARS) of the children. Age-related DIS and DIS-D scores (B = -0.90 and 0.77; p < 0.001) were correlated with age-related BFMMS scores (B = -0.49; p < 0.001; r = 0.87; p < 0.001), whereas DIS-C scores were age-independent. Ataxic scores revealed stronger age-related regression coefficients than dyskinetic and dystonic scores (4-8 years; p < 0.05).

INTERPRETATION

In healthy children, comparison between physiological dyskinesia, dystonia and ataxia rating scale scores revealed: 1. inverse age-relatedness for dystonic and ataxic scores, but not for choreoathetotic scores, 2. interrelated dystonic DIS-D and BFMMS scores, 3. the strongest age-related expression by ataxic scores. In healthy children, these physiological movement disorder-like features are interpreted as an expression of the developing underlying motor centres.

[The dysregulated brain - Consequences of spatial and temporal brain complexity for bipolar disorder pathophysiology and diagnosis]

BACKGROUND

Despite the existence of several pathophysiological theories about bipolar disorder, it has so far been difficult to find diagnostic biomarkers and to develop new pharmacologic treatments based on the more novel theories.

AIM

To reflect on the causes and consequences of problems that beset pathophysiological research into psychiatric disorders in general and bipolar disorder in particular.

METHOD

In this essay we address the problems facing professionals engaged in research into bipolar disorder and we interpret these problem in the light of brain complexity.

RESULTS

The complexity of the brain can be divided into two types: spatial complexity, which reflects the various physiological levels of the central nervous system (genetic, molecular, cellular, neuronal circuits and phenomenological levels), and temporal complexity, i.e. neurodevelopment. We discuss the consequences of these two types of complexity and make suggestions relating to clinical practice and pathophysiological psychiatric research.

CONCLUSION

To achieve further progress in the field of brain research, we need to acquire a deeper understanding of the spatial and temporal complexity of the brain and consider the possible consequences of such knowledge for the pathophysiology and treatment of psychiatric illnesses such as bipolar disorder.

Identification of microRNA biomarkers for response of advanced soft tissue sarcomas to eribulin: Translational results of the EORTC 62052 trial

BACKGROUND

Recent phase II and III clinical trials demonstrated anti-tumour activity of eribulin, a tubulin-interacting cytotoxic agent, in patients with metastatic soft tissue sarcoma (STS). In this exploratory study, we aimed to identify putative microRNA biomarkers that associate with eribulin sensitivity or resistance in STS.

MATERIALS AND METHODS

Archival tumour tissue from primary tumours or metastatic lesions was collected prior to eribulin treatment, from 65 consenting patients involved in the EORTC trial 62052. This phase II study (ClinicalTrials.gov identifier NCT00413192) included multiple subtypes of STS. Tissue was available from 21 leiomyosarcomas, 14 adipocytic sarcomas, 9 synovial sarcomas and 21 other sarcoma histotypes. Total RNA was isolated from formalin-fixed, paraffin-embedded tumour samples and analysed using Taqman^® Low Density Arrays to determine microRNA expression profiles. The expression of a total of 756 microRNAs was assessed. Progression-free survival at week 12 (RECIST 1.0) measured as a binary variable, was the primary end-point of the clinical trial and used as a primary response measure for correlative studies. Seventeen of 53 (32.1%) evaluable patients in the analysed subset had non-progressive disease at week 12 and were defined as responders.

RESULTS

The expression of 26 individual microRNAs (p < 0.05) differed significantly between non-responders and responders. Additional microRNAs of potential relevance were identified when considering the different histological subgroups.

CONCLUSIONS

The expression level of particular microRNAs in STS tissue samples may predict response to eribulin. Further validation studies as well as a preclinical assessment of the underlying molecular mechanisms are required.

Loss of SLCO1B3 drives taxane resistance in prostate cancer

BACKGROUND

Both taxanes, docetaxel and cabazitaxel, are effective treatments for metastatic castration-resistant prostate cancer (mCRPC). However, resistance to taxanes is common. Our objective was to investigate mechanisms of taxane resistance in prostate cancer.

METHODS

Two docetaxel-resistant patient-derived xenografts (PDXs) of CRPC were established (PC339-DOC and PC346C-DOC) in male athymic nude mice by frequent intraperitoneal administrations of docetaxel. Next-generation sequencing was performed on PDX tissue pre- and post-docetaxel resistance and gene expression profiles were compared. [(14)C]-docetaxel and [(14)C]-cabazitaxel uptake assays in vitro and cytotoxicity assays were performed to validate direct involvement of transporter genes in taxane sensitivity.

RESULTS

Organic anion-transporting polypeptide (SLCO1B3), an influx transporter of docetaxel, was significantly downregulated in PC346C-DOC tumours. In accordance with this finding, intratumoural concentrations of docetaxel and cabazitaxel were significantly decreased in PC346C-DOC as compared with levels in chemotherapy-naive PC346C tumours. In addition, silencing of SLCO1B3 in chemo-naive PC346C resulted in a two-fold decrease in intracellular concentrations of both taxanes. Overexpression of SLCO1B3 showed higher sensitivity to docetaxel and cabazitaxel.

CONCLUSIONS

The SLCO1B3 determines intracellular concentrations of docetaxel and cabazitaxel and consequently influences taxane efficacy. Loss of the drug transporter SLCO1B3 may drive taxane resistance in prostate cancer.

Understanding taxanes in prostate cancer; importance of intratumoral drug accumulation

BACKGROUND

Resistance to docetaxel is common in metastatic castration-resistant prostate cancer (mCRPC) and may be caused by sub-therapeutic intratumoral drug concentrations. Cabazitaxel demonstrated survival benefit in docetaxel-pretreated and docetaxel-refractory patients. In this study, we investigated whether the superior antitumor activity of cabazitaxel in mCRPC is explained by higher intratumoral cabazitaxel levels. Since recent studies suggest a reduced efficacy of docetaxel following treatment with novel androgen receptor (AR)-targeted agents, we also investigated taxane efficacy in an enzalutamide-resistant tumor model.

METHODS

Intratumoral concentrations of docetaxel and cabazitaxel were correlated with antitumor activity in docetaxel-naïve, docetaxel-resistant, and enzalutamide-resistant patient-derived xenografts (PDXs) of prostate cancer.

RESULTS

Intratumoral drug levels were negatively related to intrinsic and acquired resistance to docetaxel. Also, the observed stronger antitumor activity of cabazitaxel was associated with increased cumulative exposure and higher intratumoral of cabazitaxel concentrations in all PDXs.

CONCLUSIONS

The superior antitumor activity of cabazitaxel in docetaxel- and enzalutamide-resistant tumors can be partly attributed to higher intratumoral drug concentrations. Especially for patients who are intrinsically resistant to docetaxel resulting from suboptimal intratumoral docetaxel concentrations, cabazitaxel may be the preferred chemotherapeutic agent. Prostate 76:927-936, 2016. © 2016 Wiley Periodicals, Inc.

Relationship Between Sunitinib Pharmacokinetics and Administration Time: Preclinical and Clinical Evidence

Background and Objective

Circadian rhythms may influence the pharmacokinetics of drugs. This study aimed to elucidate whether the pharmacokinetics of the orally administered drug sunitinib are subject to circadian variation.

Methods

We performed studies in male FVB-mice aged 8–12 weeks, treated with single-dose sunitinib at six dosing times. Plasma and tissue samples were obtained for pharmacokinetic analysis and to monitor messenger RNA (mRNA) expression of metabolizing enzymes and drug transporters. A prospective randomized crossover study was performed in which patients took sunitinib once daily at 8 a.m., 1 p.m., and 6 p.m at three subsequent courses. Patients were blindly randomized into two groups, which determined the sequence of the sunitinib dosing time. The primary endpoint in both studies was the difference in plasma area under the concentration–time curve (AUC) of sunitinib and its active metabolite SU12662 between dosing times.

Results

Sunitinib and SU12662 plasma AUC in mice followed an ~12-h rhythm as a function of administration time (p ≤ 0.04). The combined AUC from time zero to 10 h (AUC₁₀) was 14–27 % higher when sunitinib was administered at 4 a.m. and 4 p.m. than at 8 a.m. and 8 p.m. Twenty-four-hour rhythms were seen in the mRNA levels of drug transporters and metabolizing enzymes. In 12 patients, sunitinib trough concentrations (C_trough) were higher when the drug was taken at 1 p.m. or 6 p.m. than when taken at 8 a.m. (C_{trough-1 p.m}. 66.0 ng/mL; C_{trough-6 p.m.} 58.9 ng/mL; C_{trough-8 a.m.} 50.7 ng/mL; p = 0.006). The AUC was not significantly different between dosing times.

Conclusions

Our results indicate that sunitinib pharmacokinetics follow an ~12-h rhythm in mice. In humans, morning dosing resulted in lower C_trough values, probably resulting from differences in elimination. This can have implications for therapeutic drug monitoring.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-015-0239-5) contains supplementary material, which is available to authorized users.

Evaluation of a smartphone human activity recognition application with able-bodied and stroke participants

Background

Mobile health monitoring using wearable sensors is a growing area of interest. As the world’s population ages and locomotor capabilities decrease, the ability to report on a person’s mobility activities outside a hospital setting becomes a valuable tool for clinical decision-making and evaluating healthcare interventions. Smartphones are omnipresent in society and offer convenient and suitable sensors for mobility monitoring applications. To enhance our understanding of human activity recognition (HAR) system performance for able-bodied and populations with gait deviations, this research evaluated a custom smartphone-based HAR classifier on fifteen able-bodied participants and fifteen participants who suffered a stroke.

Methods

Participants performed a consecutive series of mobility tasks and daily living activities while wearing a BlackBerry Z10 smartphone on their waist to collect accelerometer and gyroscope data. Five features were derived from the sensor data and used to classify participant activities (decision tree). Sensitivity, specificity and F-scores were calculated to evaluate HAR classifier performance.

Results

The classifier performed well for both populations when differentiating mobile from immobile states (F-score > 94 %). As activity recognition complexity increased, HAR system sensitivity and specificity decreased for the stroke population, particularly when using information derived from participant posture to make classification decisions.

Conclusions

Human activity recognition using a smartphone based system can be accomplished for both able-bodied and stroke populations; however, an increase in activity classification complexity leads to a decrease in HAR performance with a stroke population. The study results can be used to guide smartphone HAR system development for populations with differing movement characteristics.

Highly efficient and scalable chemoenzymatic syntheses of (R)- and (S)-lactaldehydes

Biocatalytic asymmetric reductions have been key steps in the synthesis of 1,1-dimethoxy-2-propanone, catalyzed by suitable ketoreductases to (S)- and (R)-1,1-dimethoxy-2-propanol, obtained in ≥99.9% ee and excellent yield. Removal of the protecting group gave the (S)- and (R)-lactaldehydes in excellent yield and purity.

Anxiety and depression during pregnancy in Central America: a cross-sectional study among pregnant women in the developing country Nicaragua

BACKGROUND

Around the world, maternal psychopathology during pregnancy is associated with a range of negative consequences for mother and child. Nevertheless, in Central America the magnitude of this public health problem is still unknown. The objective of this first explorative study was to investigate the prevalence and severity of anxiety and depression during pregnancy in the Central American developing country Nicaragua, as well as the availability of mental health care and to compare with a developed country.

METHODS

A population-based cohort of pregnant women in Nicaragua (N = 98) was compared with a parallel cohort in the Netherlands (N = 4725) on symptoms of anxiety (Spielberger State Trait Anxiety Inventory) and depression (Edinburgh Postnatal Depression Scale). Associations with the women's knowledge how to reach professional psychological support were assessed using multivariable linear regression analyses.

RESULTS

Of the Nicaraguan women, 41 % had symptoms of anxiety and 57 % symptoms of depression, versus 15 % and 6 % of the Dutch women. Symptom scores of both anxiety and depression were significantly higher in Nicaragua (p < 0.001). However, only 9.6 % of the women indicated that professional psychological help was available for the Nicaraguan pregnant women, which was associated with an increased anxiety score.

CONCLUSIONS

In Nicaragua, both prevalence and severity of symptoms of antenatal anxiety and depression are substantially higher than in developed countries. However, availability of psychological help is very limited for pregnant Nicaraguan women. These findings indicate that there is need for further research and support for these women, to prevent negative consequences for both mother and child.

Lysosomal Sequestration Determines Intracellular Imatinib Levels

The intracellular uptake and retention (IUR) of imatinib is reported to be controlled by the influx transporter SLC22A1 (organic cation transporter 1). We recently hypothesized that alternative uptake and/or retention mechanisms exist that determine intracellular imatinib levels. Here, we systematically investigate the nature of these mechanisms. Imatinib uptake in cells was quantitatively determined by liquid chromatography-tandem mass spectrometry. Fluorescent microscopy was used to establish subcellular localization of imatinib. Immunoblotting, cell cycle analyses, and apoptosis assays were performed to evaluate functional consequences of imatinib sequestration. Uptake experiments revealed high intracellular imatinib concentrations in HEK293, the leukemic cell lines K562 and SD-1, and a gastrointestinal stromal tumor cell line GIST-T1. We demonstrated that imatinib IUR is time-, dose-, temperature-, and energy-dependent and provide evidence that SLC22A1 and other potential imatinib transporters do not substantially contribute to the IUR of imatinib. Prazosin, amantadine, NH4Cl, and the vacuolar ATPase inhibitor bafilomycin A1 significantly decreased the IUR of imatinib and likely interfere with lysosomal retention and accumulation of imatinib. Costaining experiments with LysoTracker Red confirmed lysosomal sequestration of imatinib. Inhibition of the lysosomal sequestration had no effect on the inhibition of c-Kit signaling and imatinib-mediated cell cycle arrest but significantly increased apoptosis in imatinib-sensitive GIST-T1 cells. We conclude that intracellular imatinib levels are primarily determined by lysosomal sequestration and do not depend on SLC22A1 expression.

Circadian variation in tamoxifen pharmacokinetics in mice and breast cancer patients

The anti-estrogen tamoxifen is characterized by a large variability in response, partly due to pharmacokinetic differences. We examined circadian variation in tamoxifen pharmacokinetics in mice and breast cancer patients. Pharmacokinetic analysis was performed in mice, dosed at six different times (24-h period). Tissue samples were used for mRNA expression analysis of drug-metabolizing enzymes. In patients, a cross-over study was performed. During three 24-h periods, after tamoxifen dosing at 8 a.m., 1 p.m., and 8 p.m., for at least 4 weeks, blood samples were collected for pharmacokinetic measurements. Differences in tamoxifen pharmacokinetics between administration times were assessed. The mRNA expression of drug-metabolizing enzymes showed circadian variation in mouse tissues. Tamoxifen exposure seemed to be highest after administration at midnight. In humans, marginal differences were observed in pharmacokinetic parameters between morning and evening administration. Tamoxifen C(max )and area under the curve (AUC)0-8 h were 20 % higher (P < 0.001), and tamoxifen t(max) was shorter (2.1 vs. 8.1 h; P = 0.001), indicating variation in absorption. Systemic exposure (AUC0-24 h) to endoxifen was 15 % higher (P < 0.001) following morning administration. The results suggest that dosing time is of marginal influence on tamoxifen pharmacokinetics. Our study was not designed to detect potential changes in clinical outcome or toxicity, based on a difference in the time of administration. Circadian rhythm may be one of the many determinants of the interpatient and intrapatient pharmacokinetic variability of tamoxifen.

A comparison of the University of New Brunswick Test of Prosthetic Function and the Assessment of Capacity for Myoelectric Control

BACKGROUND

Valid outcome measures are required for gathering evidence on when, how and using which prosthetic components to start prosthetic fitting to children with congenital upper limb deficiencies and those following acquired upper limb amputation. We have been using the University of New Brunswick Test of Prosthetic Function (UNB, which measures skill and spontaneity of prosthetic use) in our country since 1996, and the Assessment of Capacity for Myoelectric Control (ACMC, which was developed for persons using a myoelectric prosthesis) since 2008.

AIM

We wanted to explore whether the UNB and the ACMC measure the same construct (i.e., assess convergent validity), and whether the ACMC can also be used for assessing children and adolescents who use a body-powered upper-limb prosthesis.

DESIGN

Observational.

SETTING

Inpatient.

POPULATION

All the 19 children and adolescents who were visiting the outpatient clinic for rehabilitation of children with upper limb deficiencies and amputations at our institute from January 2010 to December 2011 and had a myoelectric (15 participants) or body-powered prosthesis (4 participants).

METHODS

The participants were assessed by the age-appropriate UNB subtest; 60 assessments were performed in total. Two tests (moving a plastic glass half-full with water from table to the sink, and tying apron at the back) were added to obtain the ACMC scores.

RESULTS

Simple and autocorrelation-adjusted correlation and regression analyses demonstrated that ACMC score is highly positively correlated with UNB spontaneity and skill score in children and adolescents who use a myoelectric prosthesis. Neither of the two associations could be observed in children and adolescents who use a body-powered prosthesis.

CONCLUSION

The results suggest that both tests can be used for assessing children and adolescents who use a myolectric prosthesis, but only the UNB appears to be appropriate for those who use a body-powered prosthesis.

CLINICAL REHABILITATION IMPACT

This small study indicates that either the ACMC or the UNB are applicable for assessing children and adolescents who use a myolectric upper-limb prosthesis because of congenital upper limb deficiencies or acquired upper limb amputation, but only the UNB seems to be applicable for those children or adolescents who use a body-powered prosthesis.

Phase I study of RGB-286638, a novel, multitargeted cyclin-dependent kinase inhibitor in patients with solid tumors

PURPOSE

RGB-286638 is a multitargeted inhibitor with targets comprising the family of cyclin-dependent kinases (CDK) and a range of other cancer-relevant tyrosine and serine/threonine kinases. The objectives of this first in human trial of RGB-286638, given i.v. on days 1 to 5 every 28 days, were to determine the maximum tolerated dose (MTD) and to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of this new drug.

EXPERIMENTAL DESIGN

Sequential cohorts of 3 to 6 patients were treated per dose level. Blood, urine samples, and skin biopsies for full PK and/or PD analyses were collected.

RESULTS

Twenty-six patients were enrolled in 6-dose levels from 10 to 160 mg/d. Four dose-limiting toxicities were observed in 2 of the 6 patients enrolled at the highest dose level. These toxicities were AST/ALT elevations in 1 patient, paroxysmal supraventricular tachycardias (SVTs), hypotension, and an increase in troponin T in another patient. The plasma PK of RGB-286638 was shown to be linear over the studied doses. The interpatient variability in clearance was moderate (variation coefficient 7%-36%). The PD analyses in peripheral blood mononuclear cells, serum (apoptosis induction) and skin biopsies (Rb, p-Rb, Ki-67, and p27(KIP1) expression) did not demonstrate a consistent modulation of mechanism-related biomarkers with the exception of lowered Ki-67 levels at the MTD level. The recommended MTD for phase II studies is 120 mg/d.

CONCLUSIONS

RGB-286638 is tolerated when administered at 120 mg/d for 5 days every 28 days. Prolonged disease stabilization (range, 2-14 months) was seen across different dose levels.

Abstract A99: Docetaxel-resistance can be overcome by enhancing intratumoral taxane concentrations to a threshold level for efficacy

Introduction / objectives: Metastatic castration resistant prostate cancer (mCRPC) patients are treated with docetaxel (DOC) as a first line of treatment. Although DOC improves survival of mCRPC patients, resistance to DOC is commonly developed, hampering clinical efficacy. We hypothesized that there is a minimum exposure level for antitumor activity and therefore investigated the relation between intratumoral concentrations and antitumor activity for DOC and second-line treatment cabazitaxel (CABA) in DOC-naive and DOC-resistant patient-derived prostate cancer (PC) xenograft models.

Materials and methods: DOC-resistant PC xenografts were generated previously by treatment of tumor-bearing mice with a single dose of DOC (33 mg/kg) followed by additional dosing at growth recurrence and upon subsequent passaging. Intratumoral concentrations of DOC and CABA were measured in the following xenografts: PC374 (DOC-sensitive), PC339 (poorly sensitive) and in the PC339-DOC resistant xenograft. Naïve PC339 and PC374 bearing mice were treated with a single injection of DOC or CABA of 8.3; 16.5 or 33 mg/kg. PC339-DOC -bearing mice, resistant to DOC at 33 mg/kg, were treated with a single injection of DOC 16.5; 33 or 50 mg/kg and sacrificed at 7 days post treatment. Intratumoral concentrations of DOC and CABA were correlated to the log ratio of tumor volume (TV) at start of treatment (day 0) divided by TV at sacrifice (day 7).

Results: In mice dosed with DOC 33 mg /kg, intratumoral concentrations were higher in PC374 compared to PC339: 1.6 ± 05ng/mg tissue and 0.28 ± 0.13 ng/mg tissue, respectively (P =0.001). Moreover, CABA levels were higher than those of DOC in both PC374 and PC339 tumors: 5.3 ± 1.3 ng/mg tissue and 4.1 ± 1.8 ng/mg tissue, respectively (P= 0.0005, P= 0.005). In PC339 tumors, CABA antitumor activity and intratumoral concentrations were strongly correlated (r = -0.87, P &lt;0.0001). Although DOC at 33 mg/kg was inactive in PC339-DOC bearing mice, increased dosing to 50 mg/kg may overcame drug resistance, resulting in a significant increase in intratumoral concentrations from 0.29 ± 0.09 ng/mg after dosing with 33 mg/kg to 1.1 ± 0.25 ng/mg after treatment with 50 mg/kg (P=0.005). In this xenograft antitumor response and intratumoral concentrations were strongly correlated (r=-0.84, P=0.004). For both DOC and CABA, a minimum exposure level (or ‘threshold’ concentration) for anti-tumor efficacy of 1.5 ng taxane/mg tumor tissue was found for naïve and DOC-resistant PC xenografts.

Conclusions: These preclinical data pinpoint a sustained relationship between intratumoral concentrations and antitumor activity of taxanes in DOC resistant PC models. A minimum exposure level for effective intratumoral concentrations for both taxanes was defined that still applies in DOC-resistance. These data indicate that efforts to improve taxane uptake in DOC-resistant tumors may still be a relevant strategy to improve treatment outcome of mCRPC patients.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A99.

Citation Format: Ellen S. de Morree, Corrina M. de Ridder, Peter de Bruijn, Herman Burger, Erik A.C. Wiemer, Ron H.J. Mathijssen, Ronald de Wit, Wytske van Weerden. Docetaxel-resistance can be overcome by enhancing intratumoral taxane concentrations to a threshold level for efficacy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A99.