Histology independent drug development - Is this the future for cancer drugs?

The Cancer Drug Development Forum (CDDF)'s 'Histology independent drug development - is this the future for cancer drugs?' workshop was set up to explore the current landscape of histology independent drug development, review the current regulatory landscape and propose recommendations for improving the conduct of future trials. The first session considered lessons learnt from previous trials, including innovative solutions for reimbursement. The session explored why overall survival represents the most valuable endpoint, and the importance of duration of response, which can be captured with swimmer and spider plots. The second session on biomarker development and treatment optimisation considered current regulations for companion diagnostics, FDA guidance on histology independent drug development in oncology, and the need to establish cut-offs for the biomarker of tumour mutational burden to identify the patients most likely to benefit from PDL1 treatment. The third session reviewed novel trial designs, including basket, umbrella and platform trials, and statistical approaches of hierarchical modelling where homogeneity between study cohorts enables information to be borrowed between cohorts. The discussion highlighted the need to agree 'common assessment standards' to facilitate pooling of data across studies. In the fourth session, the sharing of data sets was recognised as a key step for improving equity of access to precision medicines across Europe. The session considered how the European Health Data Space (EHDS) could streamline access to medical records, emphasizing the importance of introducing greater accountability into the digital space. In conclusion the workshop proposed 11 recommendations to facilitate histology agnostic drug development.

The oldest peracarid crustacean reveals a Late Devonian freshwater colonization by isopod relatives

Peracarida (e.g. woodlice and side-swimmers) are, together with their sister-group Eucarida (e.g. krill and decapods), the most speciose group of modern crustaceans, suggested to have appeared as early as the Ordovician. While eucarids' incursion onto land consists of mainly freshwater and littoral grounds, some peracarids have evolved fully terrestrial ground-crawling ecologies, inhabiting even our gardens in temperate regions (e.g. pillbugs and sowbugs). Their fossil record extends back to the Carboniferous and consists mainly of marine occurrences. Here, we provide a complete re-analysis of a fossil arthropod-Oxyuropoda-reported in 1908 from the Late Devonian floodplains of Ireland, and left with unresolved systematic affinities despite a century of attempts at identification. Known from a single specimen preserved in two dimensions, we analysed its anatomy using digital microscopy and multispectral macroimaging to enhance the contrast of morphological structures. The new anatomical characters and completeness of Oxyuropoda, together with a phylogenetic analysis with representatives of all major Eumalacostraca groups, indicate that Oxyuropoda is a crown peracarid, part of a clade including amphipods and isopods. As such, Oxyuropoda is the oldest known species Peracarida, and provides evidence that derived peracarids had an incursion into freshwater and terrestrial environments as early as the Famennian, more than 360 Ma.

Assessing goodness-of-fit for evaluation of dose-proportionality

For the clinical development of a new drug, the determination of dose-proportionality is an essential part of the pharmacokinetic evaluations, which may provide early indications of non-linear pharmacokinetics and may help to identify sub-populations with divergent clearances. Prior to making any conclusions regarding dose-proportionality, the goodness-of-fit of the model must be assessed to evaluate the model performance. We propose the use of simulation-based visual predictive checks to improve the validity of dose-proportionality conclusions for complex designs. We provide an illustrative example and include a table to facilitate review by regulatory authorities.

A proposal for a new PhD level curriculum on quantitative methods for drug development

This paper provides an overview of "Improving Design, Evaluation and Analysis of early drug development Studies" (IDEAS), a European Commission-funded network bringing together leading academic institutions and small- to large-sized pharmaceutical companies to train a cohort of graduate-level medical statisticians. The network is composed of a diverse mix of public and private sector partners spread across Europe, which will host 14 early-stage researchers for 36 months. IDEAS training activities are composed of a well-rounded mixture of specialist methodological components and generic transferable skills. Particular attention is paid to fostering collaborations between researchers and supervisors, which span academia and the private sector. Within this paper, we review existing medical statistics programmes (MSc and PhD) and highlight the training they provide on skills relevant to drug development. Motivated by this review and our experiences with the IDEAS project, we propose a concept for a joint, harmonised European PhD programme to train statisticians in quantitative methods for drug development.

A Bayesian model to estimate the cutoff and the clinical utility of a biomarker assay

To enable targeted therapies and enhance medical decision-making, biomarkers are increasingly used as screening and diagnostic tests. When using quantitative biomarkers for classification purposes, this often implies that an appropriate cutoff for the biomarker has to be determined and its clinical utility must be assessed. In the context of drug development, it is of interest how the probability of response changes with increasing values of the biomarker. Unlike sensitivity and specificity, predictive values are functions of the accuracy of the test, depend on the prevalence of the disease and therefore are a useful tool in this setting. In this paper, we propose a Bayesian method to not only estimate the cutoff value using the negative and positive predictive values, but also estimate the uncertainty around this estimate. Using Bayesian inference allows us to incorporate prior information, and obtain posterior estimates and credible intervals for the cut-off and associated predictive values. The performance of the Bayesian approach is compared with alternative methods via simulation studies of bias, interval coverage and width and illustrations on real data with binary and time-to-event outcomes are provided.

A statistical approach for analyzing data from the in vivo Pig-a gene mutation assay

The in vivo Pig-a gene mutation assay serves to evaluate the genotoxic potential of chemicals. In the rat blood-based assay, the lack of CD59 on the surface of erythrocytes is quantified via fluorophore-labeled antibodies in conjunction with flow cytometric analysis to determine the frequency of Pig-a mutant phenotype cells. The assay has achieved regulatory relevance as it is suggested as an in vivo follow-up test for Ames mutagens in the recent ICH M7 [25] step 4 document. However, very little work exists regarding suitable statistical approaches for analyzing Pig-a data. In the current report, we present a statistical strategy based on a two factor model involving 'treatment' and 'time' incl. their interaction and a baseline covariate for log proportions to compare treatment and vehicle data per time point as well as in time. In doing so, multiple contrast tests allow us to discover time-related changes within and between treatment groups in addition to multiple treatment comparisons to a control group per single time point. We compare our proposed strategy with the results of classical Dunnett and Wilcoxon-Mann-Whitney tests using two data sets describing the mode of action of Chlorambucil and Glycidyl methacrylate both analyzed in a 28-day treatment schedule.

Knowledge-Based System ADNEXPERT to Assist the Sonographic Diagnosis of Adnexal Tumors

ADNEXPERT is a knowledge-based system for the computer- assisted ultrasound diagnosis of adnexal tumors. In a case-based approach, ADNEXPERT used histopathologic and sonographic data from 2,290 adnexal tumors. After an ultrasound examination, the gynecologist interacts with the system. A maximum of 15 questions are posed; all but one question (age) relate to the sonographic findings. The help system gives online access to an ultrasound image library. Once the dialogue is complete, ADNEXPERT assesses the adnexal tumor pathology and makes a histological classification. A certainty factor (CF) model is used for knowledge representation. The CFs of the knowledge base are computed from the case database. During system evaluation, the accuracy of ADNEXPERT was tested by 69 new adnexal tumor cases, for which verified histopathological diagnoses were available. ADNEXPERT accurately assessed pathology in 49 cases (71%); in 10 cases (14%) correct indications to pathology were given; no diagnostic hints were attained in 2 cases (3%); and 8 cases (12%) were falsely diagnosed. Based on the positive results of the evaluation, ADNEXPERT will be tested under clinical conditions.

Model selection based on combined penalties for biomarker identification

The growing role of targeted medicine has led to an increased focus on the development of actionable biomarkers. Current penalized selection methods that are used to identify biomarker panels for classification in high-dimensional data, however, often result in highly complex panels that need careful pruning for practical use. In the framework of regularization methods, a penalty that is a weighted sum of the L₁ and L₀ norm has been proposed to account for the complexity of the resulting model. In practice, the limitation of this penalty is that the objective function is non-convex, non-smooth, the optimization is computationally intensive and the application to high-dimensional settings is challenging. In this paper, we propose a stepwise forward variable selection method which combines the L₀ with L₁ or L₂ norms. The penalized likelihood criterion that is used in the stepwise selection procedure results in more parsimonious models, keeping only the most relevant features. Simulation results and a real application show that our approach exhibits a comparable performance with common selection methods with respect to the prediction performance while minimizing the number of variables in the selected model resulting in a more parsimonious model as desired.

Increasing the efficiency of oncology basket trials using a Bayesian approach

With the rapid growth of targeted and immune-oncology therapies, novel statistical design approaches are needed to increase the flexibility and efficiency of early phase oncology trials. Basket trials enroll patients with defined biological deficiencies, but with multiple histologic tumor types (or indications), to discover in which indications the drug is active. In such designs different indications are typically analyzed independently. This, however, ignores potential biological similarities among the indications. Our research provides a statistical methodology to enhance such basket trials by assessing the homogeneity of the response rates among indications at an interim analysis, and applying a Bayesian hierarchical modeling approach in the second stage if the efficacy is deemed reasonably homogenous across indications. This increases the power of the study by allowing indications with similar response rates to borrow information from each other. Via simulations, we quantify the efficiency gain of our proposed approach relative to the conventional parallel approach. The operating characteristics of our method depend on the similarity of the response rates between the different indications. If the response rates are comparable in most or all indications after treatment with the investigational drug, a substantial increase in efficiency as compared to the conventional approach can be obtained as fewer patients are required or a higher power is attained. We also demonstrate that efficacy again decreases if the response rates vary considerably among tumor types but it is still better than the conventional approach.

The seroprevalence of antithyroid peroxidase antibodies in bipolar families and bipolar twins: results from two longitudinal studies

Background

Previous studies of our group among bipolar offspring and bipolar twins showed significant higher prevalence’s and levels of antithyroid peroxidase antibodies (TPO-Abs) in offspring and co-twins (without a mood disorder) compared to controls, suggesting that TPO-Abs might be considered as vulnerability factor (trait marker) for BD development.

Objectives

Here we elucidate, in the same cohorts, but now after 12- and 6-year follow-up, whether TPO-abs should be considered as a ‘trait’ marker for BD. The present study aims to investigate whether TPO-Abs (1) are stable over time, (2) are associated with lithium-exposure, (3) share a common genetic background with BD and are related to psychopathology.

Results

In bipolar offspring and twins, the prevalence of TPO-Abs is stable over time (r_s = .72 p < .001 resp. r_s = .82, p < .001) and not associated with lithium use. At follow-up, an increased prevalence of TPO-abs was again observed in bipolar offspring (10,4% versus 4%) and higher TPO-abs titers were still present in co-twins of bipolar cases compared to control twins [mean 1.06 IU/ml (SD .82) versus mean .82 IU/ml (SD .67)], although statistical significance was lost.

Conclusions

Although our results show a trend toward an increased inherited risk of the co-occurrence of BD and thyroid autoimmunity, large-scale studies can only draw final conclusions. Nationwide epidemiological and GWAS studies reach such numbers and support the view of a possible common (autoimmune) etiology of severe mood disorders and chronic recurrent infections and autoimmunity, including thyroid autoimmunity.

AKT1 (E17K) mutation profiling in breast cancer: prevalence, concurrent oncogenic alterations, and blood-based detection

Background

The single hotspot mutation AKT1 [G49A:E17K] has been described in several cancers, with the highest incidence observed in breast cancer. However, its precise role in disease etiology remains unknown.

Methods

We analyzed more than 600 breast cancer tumor samples and circulating tumor DNA for AKT1^E17K and alterations in other cancer-associated genes using Beads, Emulsions, Amplification, and Magnetics digital polymerase chain reaction technology and targeted exome sequencing.

Results

Overall AKT1^E17K mutation prevalence was 6.3 % and not correlated with age or menopausal stage. AKT1^E17K mutation frequency tended to be lower in patients with grade 3 disease (1.9 %) compared with those with grade 1 (11.1 %) or grade 2 (6 %) disease. In two cohorts of patients with advanced metastatic disease, 98.0 % (n = 50) and 97.1 % (n = 35) concordance was obtained between tissue and blood samples for the AKT1^E17K mutation, and mutation capture rates of 66.7 % (2/3) and 85.7 % (6/7) in blood versus tissue samples were observed. Although AKT1-mutant tumor specimens were often found to harbor concurrent alterations in other driver genes, a subset of specimens harboring AKT1^E17K as the only known driver alteration was also identified. Initial follow-up survival data suggest that AKT1^E17K could be associated with increased mortality. These findings warrant additional long-term follow-up.

Conclusions

The data suggest that AKT1^E17K is the most likely disease driver in certain breast cancer patients. Blood-based mutation detection is achievable in advanced-stage disease. These findings underpin the need for a further enhanced-precision medicine paradigm in the treatment of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2626-1) contains supplementary material, which is available to authorized users.

A study of genetic and environmental contributions to structural brain changes over time in twins concordant and discordant for bipolar disorder

This is the first longitudinal twin study examining genetic and environmental contributions to the association between liability to bipolar disorder (BD) and changes over time in global brain volumes, and global and regional measures of cortical surface area, cortical thickness and cortical volume. A total of 50 twins from pairs discordant or concordant for BD (monozygotic: 8 discordant and 3 concordant pairs, and 1 patient and 3 co-twins from incomplete pairs; dizygotic: 6 discordant and 2 concordant pairs, and 1 patient and 7 co-twins from incomplete pairs) underwent magnetic resonance imaging twice. In addition, 57 twins from healthy twin pairs (15 monozygotic and 10 dizygotic pairs, and 4 monozygotic and 3 dizygotic subjects from incomplete pairs) were also scanned twice. Mean follow-up duration for all twins was 7.5 years (standard deviation: 1.5 years). Data were analyzed using structural equation modeling software OpenMx. The liability to BD was not associated with global or regional structural brain changes over time. Although we observed a subtle increase in cerebral white matter in BD patients, this effect disappeared after correction for multiple comparisons. Heritability of brain changes over time was generally low to moderate. Structural brain changes appear to follow similar trajectories in BD patients and healthy controls. Existing brain abnormalities in BD do not appear to progressively change over time, but this requires additional confirmation. Further study with large cohorts is recommended to assess genetic and environmental influences on structural brain abnormalities in BD, while taking into account the influence of lithium on the brain.

Analysis of plasma protein biomarkers from the phase 3 CONCUR study of regorafenib in Asian patients with metastatic colorectal cancer (mCRC)

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Background: In the randomized phase 3 CONCUR trial (NCT01584830), regorafenib significantly improved overall survival (OS) and progression-free survival (PFS) vs placebo (PBO) in Asian patients (n = 136 regorafenib; n = 68 PBO) with treatment-refractory mCRC (HR [95% CI]: OS 0.55 [0.40‒0.77]; PFS 0.31 (0.22‒0.44]). Protein biomarker data from the phase 3 CORRECT trial of mostly Western patients with mCRC identified TIE-1 as a potential predictor of clinical response to regorafenib; however, this association was not significant in multivariable analyses. We present an exploratory protein biomarker analysis of patients in CONCUR. Methods: Sixteen proteins of interest, many of which are involved in angiogenesis, were quantified by multiplex immunoassay or ELISA in plasma samples collected at study entry from 121/204 (59%) patients (n = 83 regorafenib; n = 38 PBO). Potential predictive and prognostic effects were evaluated. Results: The biomarker cohort was representative of the overall study population in major baseline demographic factors, OS (HR 0.61; 95% CI 0.40‒0.93), and PFS (HR 0.25; 95% CI 0.16‒0.39). Elevated levels of ANG-2 (HR 2.46; p = 0.0016) and VEGF-A (HR 1.38; p = 0.03) were associated with poor OS prognosis; however, no significant association with treatment OS benefit for regorafenib vs PBO was observed for either marker (ANG-2: HR 0.76; p = 0.3307; VEGF-A: HR 0.83; p = 0.20). Elevated levels of five plasma proteins were associated with poor PFS prognosis: ANG-2 (HR 1.73; p = 0.0085), VEGF-A (HR 1.30; p = 0.0308), IL-8 (HR 1.67; p = 0.0014), VWF (HR 2.39; p = 0.0029), and IGF-BP2 (HR 1.71; p = 0.0384). Elevated levels of IL-8 (HR 0.70; p = 0.019), VWF (HR 0.53; p = 0.0312), and IGF-BP2 (HR 0.60; p = 0.0336) showed a modest interaction with regorafenib PFS; however, these results did not reach statistical significance after adjustment for multiple testing (p = 0.0045). Conclusions: None of the plasma proteins analyzed were predictive of regorafenib clinical benefit as measured by both OS and PFS in Asian patients with mCRC. These results, as well as those in CORRECT, suggest that rationally selected protein markers are not suitable to predict treatment benefit of regorafenib. Clinical trial information: NCT01584830.

A Neutralizing Prolactin Receptor Antibody Whose In Vivo Application Mimics the Phenotype of Female Prolactin Receptor-Deficient Mice

The prolactin receptor (PRLR) has been implicated in a variety of physiological processes (lactation, reproduction) and diseases (breast cancer, autoimmune diseases). Prolactin synthesis in the pituitary and extrapituitary sites is regulated by different promoters. Dopamine receptor agonists such as bromocriptine can only interfere with pituitary prolactin synthesis and thus do not induce a complete blockade of PRLR signaling. Here we describe the identification of a human monoclonal antibody 005-C04 that blocks PRLR-mediated signaling at nanomolar concentrations in vitro. In contrast to a negative control antibody, the neutralizing PRLR antibody 005-C04 inhibits signal transducer and activator of transcription 5 phosphorylation in T47D cells and proliferation of BaF3 cells stably expressing murine or human PRLRs in a dose-dependent manner. In vivo application of this new function-blocking PRLR antibody reflects the phenotype of PRLR-deficient mice. After antibody administration female mice become infertile in a reversible manner. In lactating dams, the antibody induces mammary gland involution and negatively interferes with lactation capacity as evidenced by reduced milk protein expression in mammary glands and impaired litter weight gain. Antibody-mediated blockade of the PRLR in vivo stimulates hair regrowth in female mice. Compared with peptide-derived PRLR antagonists, the PRLR antibody 005-C04 exhibits several advantages such as higher potency, noncompetitive inhibition of PRLR signaling, and a longer half-life, which allows its use as a tool compound also in long-term in vivo studies. Therefore, we suggest that this antibody will help to further our understanding of the role of auto- and paracrine PRLR signaling in health and disease.

Abstract 5239: KRAS wild-type status as detected by circulating tumor DNA analysis may be a prognostic or predictive factor for clinical benefit in patients with unresectable, locally advanced or metastatic pancreatic cancer (PC) treated with the MEK inhibitor refametin

Background: Mutationally-activated KRAS is present in 90% of pancreatic ductal adenocarcinoma (PDAC) and may represent an early genetic driver, being commonly found in low-grade pancreatic lesions (Eser et al. 2014 BJC 111:817). Refametinib is a potent oral allosteric MEK 1/2 inhibitor with both single-agent activity and synergistic activity in combination with gemcitabine in preclinical models of pancreatic cancer (PC). A Phase 1B/2 study in patients with locally advanced, unresectable or metastatic PC and no prior systemic therapy was conducted and recently reported (Van Laethem et al., ASCO 2014; NCT01251640). We report here on the exploratory biomarker findings from this study.

Methods: KRAS mutational analysis was conducted via liquid biopsy at baseline on circulating tumor DNA (ctDNA) by BEAMing (Sysmex-Inostics) as well as circulating micro RNA (miRNA) from plasma collected at baseline and post-dose and analyzed by qPCR using an Exiqon panel of 752 miRNAs and an innovative data preprocessing method for normalization and imputation of undetermined values. Tumor molecular characterization was performed on archival tumor tissue and included targeted tumor gene next-generation sequencing with FOUNDATION ONE and the analysis of Ki67 proliferation index.

Results: Samples for biomarker analysis were obtained from 69 treated patients. Forty-six (67%) had detectable KRAS mutations by liquid biopsy. KRAS G12D, G12V and G12R were the most frequent mutations. Interestingly, KRAS wild-type patients had better efficacy outcomes compared to mutant KRAS patients (mut/WT, respectively): overall response rate 15%/30% (OR 2.4, p = 0.147), median progression-free survival (mPFS) 3.7/8.8 mo (HR 0.32, p = 0.001), and overall survival (OS) 7.1/18.2 mo (HR 0.28, p = 0.001). There was a trend correlating KRAS mutant allele frequency with response. The CA19.9 levels correlated with KRAS mutational status. Tumor exome sequencing was performed from 16 patients, 15 of which had a KRAS mutation (G12D or G12V). The discordancy rate compared to BEAMing KRAS data was 26% (4/15).

Conclusions: The high prevalence of KRAS mutations in patients with PC has been confirmed using BEAMing technology. In this study, there was an association between improved mPFS and OS in KRAS WT patients. Together with lower baseline levels of CA19.9 in the KRAS WT cohort, we conclude that liquid biopsy may be an approach to identify prognostic or predictive markers in PDAC treated with refametinib and gemcitabine. This hypothesis is sustained by the finding that poor clinical response showed increasing allele frequency of mutant KRAS. These results require confirmation in a larger trial.

Citation Format: Michael Teufel, Jean-Luc Van Laethem, Hanno Riess, Marius Giurescu, Vittorio L. Garosi, Anke Schulz, Richardus Vonk, Henrik Seidel, Joachim Reischl, Barrett H. Childs. KRAS wild-type status as detected by circulating tumor DNA analysis may be a prognostic or predictive factor for clinical benefit in patients with unresectable, locally advanced or metastatic pancreatic cancer (PC) treated with the MEK inhibitor refametin [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5239. doi:10.1158/1538-7445.AM2015-5239

Genetic and environmental influences on cortical surface area and cortical thickness in bipolar disorder

BACKGROUND

The risk of developing bipolar disorder (BD) has been linked to structural brain abnormalities. The degree to which genes and environment influence the association of BD with cortical surface area remains to be elucidated. In this twin study, genetic and environmental contributions to the association between liability to develop BD and surface area, thickness and volume of the cortex were examined.

METHOD

The study cohort included 44 affected monozygotic (nine concordant, 12 discordant) and dizygotic (four concordant, 19 discordant) twin pairs, and seven twins from incomplete discordant monozygotic and dizygotic discordant twin pairs. In addition, 37 monozygotic and 24 dizygotic healthy control twin pairs, and six twins from incomplete monozygotic and dizygotic control pairs were included.

RESULTS

Genetic liability to develop BD was associated with a larger cortical surface in limbic and parietal regions, and a thicker cortex in central and parietal regions. Environmental factors related to BD were associated with larger medial frontal, parietal and limbic, and smaller orbitofrontal surfaces. Furthermore, thinner frontal, limbic and occipital cortex, and larger frontal and parietal, and smaller orbitofrontal volumes were also associated with environmental factors related to BD.

CONCLUSIONS

Our results suggest that unique environmental factors play a prominent role in driving the associations between liability to develop BD and cortical measures, particularly those involving cortical thickness. Further evaluation of their influence on the surface and thickness of the cortical mantle is recommended. In addition, cortical volume appeared to be primarily dependent on surface and not thickness.

Dermatoglyphics in relation to brain volumes in twins concordant and discordant for bipolar disorder

Palmar and finger dermatoglyphics are formed between the 10th and the 17th weeks of gestation and their morphology can be influenced by genetic or environmental factors, interfering with normal intrauterine development. As both the skin and the brain develop from the same embryonal ectoderm, dermatoglyphic alterations may be informative for early abnormal neurodevelopmental processes in the brain. We investigated whether dermatoglyphic alterations are related to structural brain abnormalities in bipolar disorder and to what extent they are of a genetic and of an environmental origin. Dermatoglyphics and volumetric data from structural MRI were obtained in 53 twin pairs concordant or discordant for bipolar disorder and 51 healthy matched control twin pairs. Structural equation modeling was used. Bipolar disorder was significantly positively associated with palmar a-b ridge count (ABRC), indicating higher ABRC in bipolar patients (rph=.17 (CI .04-.30)). Common genes appear to be involved because the genetic correlation with ABRC was significant (rph-A=.21 (CI .05-.36). Irrespective of disease, ABRC showed a genetically mediated association with brain volume, indicated by a significant genetic correlation rph-A of respectively -.36 (CI -.52 to -.22) for total brain, -.34 (CI -.51 to -.16) total cortical volume, -.27 (CI -.43 to -.08) cortical gray matter and -.23 (CI -.41 to -.04) cortical white matter. In conclusion, a genetically determined abnormal development of the foetal ectoderm between the 10th and 15th week of gestation appears related to smaller brain volumes in (subjects at risk for) bipolar disorder.

Estradiol release kinetics determine tissue response in ovariectomized rats

Estrogen replacement is an effective therapy of postmenopausal symptoms such as hot flushes, bone loss, and vaginal dryness. Undesired estrogen effects are the stimulation of uterine and mammary gland epithelial cell proliferation as well as hepatic estrogenicity. In this study, we examined the influence of different estradiol release kinetics on tissue responsivity in ovariectomized (OVX) rats. Pulsed release kinetics was achieved by ip or sc administration of estradiol dissolved in physiological saline containing 10% ethanol (EtOH/NaCl) whereas continuous release kinetics was achieved by sc injection of estradiol dissolved in benzylbenzoate/ricinus oil (1+4, vol/vol). Initial 3-d experiments in OVX rats showed that pulsed ip estradiol administration had profoundly reduced stimulatory effects on the uterus and the liver compared with continuous release kinetics. On the other hand, both administration forms prevented severe vaginal atrophy. Based on these results, we compared the effects of pulsed (sc in EtOH/NaCl) vs. continuous (sc in benzylbenzoate/ricinus oil) estradiol release kinetics on bone, uterus, mammary gland, and liver in a 4-month study in OVX rats. Ovariectomy-induced bone loss was prevented by both administration regimes. However, pulsed estradiol resulted in lower uterine weight, reduced induction of hepatic gene expression, and reduced mammary epithelial hyperplasia relative to continuous estradiol exposure. We conclude that organ responsivity is influenced by different hormone release kinetics, a fact that might be exploited to reduce undesired estradiol effects in postmenopausal women.

Premorbid school performance in twins concordant and discordant for bipolar disorder

BACKGROUND

Although the genetic risk to develop bipolar disorder is present from conception, the first frank symptoms of the illness generally become evident in late adolescence or early adulthood. However, except for pediatric bipolar disorder (PBD), it is still unclear when the first signs of the illness in adults become apparent and whether these are related to the genetic risk to develop bipolar disorder. This study examined whether underperformance at school precedes the onset of the illness and is a genetically related risk marker for developing bipolar disorder.

METHODS

Information on school performance was obtained using objective archival data from 53 bipolar twin pairs (24 monozygotic (MZ), 29 dizygotic (DZ)) and 42 healthy matched control twin pairs (23 MZ, 19 DZ).

RESULTS

Affected twin pairs completed significantly fewer years of education than did control twin pairs with no difference between bipolar patients and their non-bipolar cotwins. The underperformance at school in the affected twin pairs occurred in early adolescence at a significantly younger age than the control twin pairs and preceded the onset of the first frank episode of bipolar disorder by thirteen years. Median age at onset of underperformance was not different in the patients and their non-bipolar cotwins. The association between liability of bipolar disease and age of first underperformance was significant and could be explained by genetic factors.

LIMITATIONS

The sample is not a population based twin sample.

CONCLUSION

Underperformance at school during early adolescence may be a genetic marker for the vulnerability to develop bipolar disorder.

A dynamic model of circadian rhythms in rodent tail skin temperature for comparison of drug effects

Menopause-associated thermoregulatory dysfunction can lead to symptoms such as hot flushes severely impairing quality of life of affected women. Treatment effects are often assessed by the ovariectomized rat model providing time series of tail skin temperature measurements in which circadian rhythms are a fundamental ingredient. In this work, a new statistical strategy is presented for analyzing such stochastic-dynamic data with the aim of detecting successful drugs in hot flush treatment. The circadian component is represented by a nonlinear dynamical system which is defined by the van der Pol equation and provides well-interpretable model parameters. Results regarding the statistical evaluation of these parameters are presented.

Recommendations on the statistical analysis of the Comet assay

In 2010, the Statisticians in the Pharmaceutical Industry (PSI) Toxicology Special Interest Group met to discuss the design and analysis of the Comet assay. The Comet assay is one potential component of the package of safety studies required by regulatory bodies. As these studies usually involve a three-way nested experimental design and as the distribution of the measured response is usually either lognormal or lognormal plus a point mass at zero, the analysis is not straightforward. This has led to many different types of analysis being proposed in the literature, with several different methods applied within the pharmaceutical industry itself. This article summarises the PSI Toxicology Group's discussions and recommendations around these issues.

Willingness to Donate Human Samples for Establishing a Dermatology Research Biobank: Results of a Survey

There is a rising need for biomaterial in dermatological research with regard to both quality and quantity. Research biobanks as organized collections of biological material with associated personal and clinical data are of increasing importance. Besides technological/methodological and legal aspects, the willingness to donate samples by patients and healthy volunteers is a key success factor. To analyze the theoretical willingness to donate blood and skin samples, we developed and distributed a questionnaire. Six hundred nineteen questionnaires were returned and analyzed. The willingness to donate samples of blood (82.5%) and skin (58.7%) is high among the population analyzed and seems to be largely independent of any expense allowance. People working in the healthcare system, dermatological patients, and higher qualified individuals seem to be in particular willing to donate material. An adequate patient insurance as well as an extensive education about risks and benefits is requested. In summary, there is a high willingness to donate biological samples for dermatological research. This theoretical awareness fits well with our own experiences in establishing such a biobank.

Shortened treatment duration of glucocorticoid-induced skin atrophy in rats

Glucocorticoids (GCs) belong to the most widely used anti-inflammatory drugs at all. However, their topical use is limited by their side effect potential, with skin atrophy being the most prominent one. Thus, determining the atrophogenic potential of novel compounds is of importance for drug development. Currently, the most frequently performed model in the base and pharmaceutical research is the hr/hr rat model of GC-induced skin atrophy that lasts for 19 days. In this study, we analysed statistically skin atrophy experiments retrospectively to ascertain (i) the earliest time-point, at which skin atrophy is significantly induced; and (ii) whether the differences between the GC treatment groups change until the end of the experiment. We show here that the treatment duration of rat skin atrophy models might be reduced to 5 days for economical and ethical reasons.

Comparative analysis of the uterine and mammary gland effects of progesterone and medroxyprogesterone acetate

OBJECTIVES

In combined hormone replacement therapy (HRT) progestins are used to inhibit estradiol-activated uterine epithelial cell proliferation. In comparison to estradiol-only therapy, combined HRT leads to enhanced proliferation of mammary epithelial cells. In a quantitative mouse model, we assessed the balance between uterine and undesired mammary gland effects for two progestins that are widely used in HRT, progesterone and medroxyprogesterone acetate.

STUDY DESIGN

Mice were ovariectomized and after 14 days they were treated subcutaneously with either vehicle, estradiol (100 ng) or estradiol plus increasing doses of progesterone or medroxyprogesterone acetate for three weeks.

MAIN OUTCOME MEASURES

Measures for progestogenic mammary gland activity were stimulation of side-branching and stimulation of epithelial cell proliferation. Progestogenic activity in the uterus was assessed by measuring inhibition of estradiol-activated uterine epithelial cell proliferation. ED(50) and ID(50) values for the distinct readouts were obtained and dissociation factors for uterine versus mammary gland activity were calculated.

RESULTS

MPA demonstrated uterine activity and mitogenic activity in the mammary gland at the same doses. In contrast, progesterone showed uterine activity at doses lower than those leading to significant stimulation of epithelial cell proliferation in the mammary gland.

CONCLUSIONS

Progestins do not behave the same. Use of the natural hormone progesterone, but not MPA, in combined hormone therapy might offer a safety window between uterine effects and undesired proliferative activity in the mammary gland.

Effects of synthetic gestagens on fish reproduction

Although it is well known that estrogenic steroidal hormones are able to affect the sexual development and reproduction of fish at low concentrations, no data on environmental effects of the class of progestogenic hormones are available yet. Synthetic gestagens (progestins) are a component in oral contraceptives. Upon their use, a fraction of the progestins will be excreted via urine into the aquatic environment. On the basis of their pharmacological action in mammals, it is supposed that fish reproduction is the most sensitive endpoint for the progestin treatment. In order to test this assumption, the effects of two progestins currently marketed in contraceptive formulations, levonorgestrel (LNG) and drospirenone (DRSP), were investigated in adult fathead minnows (Pimephales promelas) following an Organization for Economic Cooperation and Development 21-d fish reproduction screening assay draft protocol with additional end points. Levonorgestrel was tested at measured concentrations of 0.8, 3.3, and 29.6 ng/L, and DRSP at concentrations of 0.66, 6.5, and 70 microg/L. Both tested progestins caused an inhibition of reproduction. For LNG, this occurred at concentrations of >or=0.8 ng/L, no no-observed-effect concentration (NOEC) could be defined. Higher concentrations resulted in masculinization of females with de novo synthesis of nuptial tubercles. Drospirenone treatment, however, affected the reproductive success of fathead minnow at concentrations of 6.5 microg/L and higher with a clear dose-response relationship and a NOEC of 0.66 microg/L, which is above environmentally relevant concentrations.

GPR30 does not mediate estrogenic responses in reproductive organs in mice

The G protein-coupled receptor Gpr30 (Gper) was recently claimed to bind to estradiol and to activate cytoplasmic signal transduction pathways in response to estradiol. However, there are conflicting data regarding the role of Gpr30 as an estrogen receptor (ER): several laboratories were unable to demonstrate estradiol binding to GPR30 or estradiol-activated signal transduction in Gpr30-expressing cells. To clarify the potential role of Gpr30 as an ER, we generated Gpr30-deficient mice. Although Gpr30 was expressed in all reproductive organs, histopathological analysis did not reveal any abnormalities in these organs in Gpr30-deficient mice. Mutant male and female mice were as fertile as their wild-type littermates, indicating normal function of the hypothalamic-pituitary-gonadal axis. Moreover, we analyzed estrogenic responses in two major estradiol target organs, the uterus and the mammary gland. For that purpose, we examined different readout paradigms such as morphological measures, cellular proliferation, and target gene expression. Our data demonstrate that in vivo Gpr30 is dispensable for the mediation of estradiol effects in reproductive organs. These results are in clear contrast to the phenotype of mice lacking the classic ER alpha (Esr1) or aromatase (Cyp19a1). We conclude that the perception of Gpr30 (based on homology related to peptide receptors) as an ER might be premature and has to be reconsidered.

Comparative analysis of the uterine and mammary gland effects of drospirenone and medroxyprogesterone acetate

The role of progestins in combined hormone therapy is the inhibition of uterine epithelial cell proliferation. The Women's Health Initiative study provided evidence for an increased risk of breast cancer in women treated with conjugated equine estrogens plus the synthetic progestin medroxyprogesterone acetate (MPA), compared with conjugated equine estrogens-only treatment. These findings continue to be discussed, and it remains to be clarified whether the results obtained for MPA in the Women's Health Initiative study are directly applicable to other progestins used in hormone therapy. In this study we compared in a mouse model the effects of the synthetic progestins, MPA, and drospirenone in two major target organs: the uterus and mammary gland. As quantitative measures of progestin activity, we analyzed maintenance of pregnancy, ductal side branching in the mammary gland, and proliferation of mammary and uterine epithelial cells as well as target gene induction in both organs. The outcome of this study is that not all synthetic progestins exhibit the same effects. MPA demonstrated uterine activity and mitogenic activity in the mammary gland at the same doses. In contrast, drospirenone behaved similarly to the natural hormone, progesterone, and exhibited uterine activity at doses lower than those leading to considerable proliferative effects in the mammary gland. We hypothesize that the safety of combined hormone therapy in postmenopausal women may be associated with a dissociation between the uterine and mammary gland activities of the progestin component.

In vivo characterization of estrogen receptor modulators with reduced genomic versus nongenomic activity in vitro

Estrogen receptor (ER) ligands that are able to prevent postmenopausal bone loss, but have reduced activity in the uterus and the mammary gland might be of great value for hormone therapy. It is well established that the classical ER can activate genomic as well as nongenomic signal transduction pathways. In this study, we analyse the in vivo behaviour of ER ligands that stimulate nongenomic ER effects to the same extent as estradiol, but show clearly reduced activation of genomic ER effects in vitro. Using different readout parameters such as morphological changes, cellular proliferation, and target gene induction, we are able to demonstrate that ER ligands with reduced genomic activity in vitro show a better dissociation of bone versus uterine and mammary gland effects than estradiol that stimulates genomic and nongenomic effects to the same extent. We conclude that pathway-selective ER ligands may represent an interesting option for hormone therapy.

Effect of introduced species and habitat alteration on the occurrence and distribution of euryhaline fishes in fresh- and brackish-water habitats on Aruba, Bonaire and Curaçao (South Caribbean)

We conducted an ichthyological survey during the dry season of 2006 on the semi-arid islands of Aruba, Bonaire and Curaçao to provide information on species composition, richness and distribution in natural and non-natural aquatic habitats. The dry season species assemblages (N = 9 species) comprised less species than the wet seasons, and these data refine our knowledge of the indigenous fish fauna and its refuge localities during phases of drought and ensuing high salinity. A hierarchical cluster analysis reveals that the three islands have different species compositions with Curaçao being the most diverse, probably due to its having the most habitats and freshwaters present throughout the year. Species richness was unrelated to salinity and species diversity was highest in canalised streams. In the dry season fewer amphidromous species are present than in the wet season. We found no significant effect of human-induced changes on the presence or absence of fish species in the Netherlands Antilles. The presence of exotic species (including Xiphophorus helleri on Aruba, a first record for this island, and Oreochromis mossambicus and Poecilia reticulata occurring on all three islands) did not have a clear effect on the presence of indigenous species, nor did human alteration of the habitats have an influence on the occurrence of fish species.

Assessing non-inferiority of a new treatment in a three-arm trial in the presence of heteroscedasticity

In this paper, we describe an adjusted method to facilitate non-inferiority tests in a three-arm design. While the methodology is readily available in the situation of homogeneous group variances, the adjusted method will also maintain the alpha-level in the presence of heteroscedasticity. We propose explicit criteria for an optimal allocation. Depending on the pattern of heterogeneity, remarkably unbalanced designs are power optimal. We will apply the method to a randomized clinical trial and a toxicological experiment.

The relevance of placental location at 20-23 gestational weeks for prediction of placenta previa at delivery: evaluation of 8650 cases

OBJECTIVE

To determine the correlation between placental position at 20-23 weeks and incidence of birth complications caused by placental position.

SUBJECTS AND METHODS

In an ongoing prospective study, placental position was determined by transabdominal sonography as part of anomaly scanning at 20-23 gestational weeks, followed by transvaginal sonography in uncertain or suspicious situations. Examination was performed in 9532 cases; feedback was obtained from 8650 patients (90.7%).

RESULTS

Transabdominal sonography was followed by transvaginal scan in 363 of 8650 cases (4.2%). In 8551 cases (98.9%), we found normal placental position, with the placenta not reaching the internal os and a Cesarean section rate of 17.1% (1458/8551). The incidence of 'low placental position', with the placenta reaching the internal os was 0.66% (57/8650), with a Cesarean section rate of 21% (12/57). In 0.49% (42/8650) of cases, the placenta overlapped the internal os at 20-23 weeks; Cesarean section because of placenta previa or bleeding was performed in 28 of 8650 cases (0.32%). Vaginal delivery was possible in 43% of cases (13/30), when the overlap did not exceed 25 mm. If the overlap exceeded 25 mm (12 cases), no vaginal delivery was reported. There was no reported case of placenta previa missed at the 20-23-week scan.

CONCLUSION

At 20-23 weeks, a combination of routine transabdominal and indication-based transvaginal location of placental position is a powerful tool in predicting placenta previa at delivery. The advantage of determining placental position at this stage of pregnancy is a low false-positive rate compared to at earlier stages of pregnancy. We conclude that an overlapping placenta at 20-23 weeks has the consequence of a high probability of placenta previa at delivery. An overlap of 25 mm or more at 20-23 weeks seems to be incompatible with later vaginal delivery.

Variability of human hepatic UDP-glucuronosyltransferase activity

The availability of a unique series of liver samples from human subjects, both control patients (9) and those with liver disease (6; biliary atresia (2), retransplant, chronic tyrosinemia type I, tyrosinemia, Wilson's disease) allowed us to characterize human hepatic UDP-glucuronosyltransferases using photoaffinity labeling, immunoblotting and enzymatic assays. There was wide inter-individual variation in photoincorporation of the photoaffinity analogs, [32P]5-azido-UDP-glucuronic acid and [32P]5-azido-UDP-glucose and enzymatic glucuronidation of substrates specific to the two subfamilies of UDP-glucuronosyltransferases. However, the largest differences were between subjects with liver disease. Glucuronidation activities toward one substrate from each of the UDP-glucuronosyltransferases subfamilies, 1A and 2B, for control and liver disease, respectively, were 1.7-4.5 vs 0.4-4.7 nmol/mg x min for hyodeoxycholic acid (2B substrate) and 9.2-27.9 vs 8.1-75 nmol/mg x min for pchloro-m-xylenol (1A substrate). Microsomes from a patient with chronic tyrosinemia (HL32) photoincorporated [32P]5-azido-UDP-glucuronic acid at a level 1.5 times higher than the other samples, was intensely photolabeled by [32P]5-azido-UDP-glucose and had significantly higher enzymatic activity toward p-chloro-m-xylenol. Immunoblot analysis using anti-UDP-glucuronosyltransferase antibodies demonstrated wide inter-individual variations in UDP-glucuronosyltransferase protein with increased UDP-glucuronosyltransferase protein in HL32 microsomes, corresponding to one of the bands photolabeled by both probes. Detailed investigation of substrate specificity, using substrates representative of both the 1A (bilirubin, 4-nitrophenol) and 2B (androsterone, testosterone) families was carried out with HL32, HL38 (age and sex matched control) and HL18 (older control). Strikingly increased (5-8-fold) glucuronidation activity was seen in comparison to HL18 only with the phenolic substrates. The results indicate that one or more phenol-specific UDP-glucuronosyltransferase 1A isoforms are expressed at above normal levels in this tyrosinemic subject.

Variability of human hepatic UDP-glucuronosyltransferase activity

The availability of a unique series of liver samples from human subjects, both control patients (9) and those with liver disease (6; biliary atresia (2), retransplant, chronic tyrosinemia type I, tyrosinemia, Wilson's disease) allowed us to characterize human hepatic UDP-glucuronosyltransferases using photoaffinity labeling, immunoblotting and enzymatic assays. There was wide inter-individual variation in photoincorporation of the photoaffinity analogs, [32P]5-azido-UDP-glucuronic acid and [32P]5-azido-UDP-glucose and enzymatic glucuronidation of substrates specific to the two subfamilies of UDP-glucuronosyltransferases. However, the largest differences were between subjects with liver disease. Glucuronidation activities toward one substrate from each of the UDP-glucuronosyltransferases subfamilies, 1A and 2B, for control and liver disease, respectively, were 1.7-4.5 vs 0.4-4.7 nmol/mg x min for hyodeoxycholic acid (2B substrate) and 9.2-27.9 vs 8.1-75 nmol/mg x min for pchloro-m-xylenol (1A substrate). Microsomes from a patient with chronic tyrosinemia (HL32) photoincorporated [32P]5-azido-UDP-glucuronic acid at a level 1.5 times higher than the other samples, was intensely photolabeled by [32P]5-azido-UDP-glucose and had significantly higher enzymatic activity toward p-chloro-m-xylenol. Immunoblot analysis using anti-UDP-glucuronosyltransferase antibodies demonstrated wide inter-individual variations in UDP-glucuronosyltransferase protein with increased UDP-glucuronosyltransferase protein in HL32 microsomes, corresponding to one of the bands photolabeled by both probes. Detailed investigation of substrate specificity, using substrates representative of both the 1A (bilirubin, 4-nitrophenol) and 2B (androsterone, testosterone) families was carried out with HL32, HL38 (age and sex matched control) and HL18 (older control). Strikingly increased (5-8-fold) glucuronidation activity was seen in comparison to HL18 only with the phenolic substrates. The results indicate that one or more phenol-specific UDP-glucuronosyltransferase 1A isoforms are expressed at above normal levels in this tyrosinemic subject.

Kappa-like indices of observer agreement viewed from a latent class perspective

It is common practice to assess consistency of diagnostic ratings in terms of 'agreement beyond chance'. To explore the interpretation of such a term we consider relevant statistical techniques such as Cohen's kappa and log-linear models for agreement on nominal ratings. We relate these approaches to a special latent class concept that decomposes observed ratings into a class of systematically consistent and a class of fortuitous ratings. This decomposition provides a common framework in which the specific premises of Cohen's kappa and of log-linear models can be identified and put into perspective. As a result it is shown that Cohen's kappa may be an inadequate and biased index of chance-corrected agreement in studies of intra-observer as well as inter-observer consistency. We suggest a more critical use and interpretation of measures gauging observer reliability by the amount of agreement beyond chance.

History of syringe sharing in prison and risk of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus infection among injecting drug users in Berlin

BACKGROUND

Injecting drug users (IDU) are at risk of parenterally transmitted diseases such as hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) infection. We investigated whether a history of syringe sharing in prison is a risk factor for these infections. In the longitudinal part of the study, HBV, HCV, and HIV seroincidence rates were determined.

METHODS

The participants were recruited by multisite-sampling at different agencies for IDU. Data on risk behaviour were obtained by a standardized questionnaire. Serological markers for HBV, HCV, and HIV were determined. Logistic regression analysis was performed to adjust for confounding effects.

RESULTS

A history of syringe sharing in prison was significantly associated with HBV (adjusted prevalence odds ratio [POR] = 3.9, 95% confidence interval [CI]: 2-10), HCV (POR = 9.7, 95% CI: 3-33), and HIV infection (POR = 10.4, 95% CI: 4-29). The HIV seroincidence rate was 5.9 per 100 person-years. None of the IDU receiving methadone maintenance treatment (MMT) seroconverted whereas the HIV incidence was 8.5 among IDU not in MMT (P = 0.01).

CONCLUSIONS

The increased risk of HBV, HCV, and HIV infection among IDU who had shared syringes in prison warrants specific preventive action. The longitudinal data suggest that IDU in MMT have a lower risk of HIV infection.

Knowledge-based system ADNEXPERT to assist the sonographic diagnosis of adnexal tumors

ADNEXPERT is a knowledge-based system for the computer-assisted ultrasound diagnosis of adnexal tumors. In a case-based approach, ADNEXPERT used histopathologic and sonographic data from 2,290 adnexal tumors. After an ultrasound examination, the gynecologist interacts with the system. A maximum of 15 questions are posed; all but one question (age) relate to the sonographic findings. The help system gives online access to an ultrasound image library. Once the dialogue is complete, ADNEXPERT assesses the adnexal tumor pathology and makes a histological classification. A certainty factor (CF) model is used for knowledge representation. The CFs of the knowledge base are computed from the case database. During system evaluation, the accuracy of ADNEXPERT was tested by 69 new adnexal tumor cases, for which verified histopathological diagnoses were available. ADNEXPERT accurately assessed pathology in 49 cases (71%); in 10 cases (14%) correct indications to pathology were given; no diagnostic hints were attained in 2 cases (3%); and 8 cases (12%) were falsely diagnosed. Based on the positive results of the evaluation, ADNEXPERT will be tested under clinical conditions.

[Referral to a clinical-genetic center for genetic counseling in mental disorders]

OBJECTIVE

Evaluation of the genetic counselling for psychiatric disorders in a clinical genetic service.

DESIGN

Retrospective.

SETTING

Clinical Genetic Service Rotterdam, the Netherlands.

METHOD

Evaluation of the psychiatric genetic counselling during the period 1985-1992 (n = 49).

RESULTS

Psychiatric disorders were the indication for genetic counselling in 1%. A minority of the consultants were referred by the psychiatrist. The most common question was the risk of future children becoming affected by a psychiatric disorder already present in the family. The male-female ratio was about one for the whole group of consultants. Affected relatives were significantly more frequent in the woman's family than in the man's. The average number of affected individuals in a family was 3.6.

CONCLUSION

Genetic counselling for psychiatric disorders in a clinical genetic service is requested infrequently considering the frequency of these problems. This may be related to a lack of need for information and counselling in potential consultants or to adequate information by treating physicians, but also to insufficient recognition by general practitioners and psychiatrists of questions patients and their family have.