Trauma exposure, alcohol consumption, and sleep quality: a latent growth curve model

This study examined the relations among precollege trauma exposure, alcohol use upon entering college, growth in alcohol use, and sleep quality in a sample of undergraduate students. Participants were 932 students from a large, urban, public university. Participants completed a survey upon entering college and then subsequent follow-up surveys each Spring semester. Precollege trauma exposure was associated with both baseline and growth in alcohol use, whereby higher levels of trauma were associated with higher baseline alcohol use, but with less steep increases in growth rate, as compared to those with lower levels of trauma. Baseline alcohol use was associated with sleep quality whereby those with higher levels of consumption demonstrated worsened sleep quality. This study provides longitudinal evidence for the relations among trauma, alcohol use, and sleep quality. Although the relationship between trauma and alcohol is well-established, further work is needed to identify how this relationship impacts additional health outcomes.

Molecular genetic overlap between posttraumatic stress disorder and sleep phenotypes

STUDY OBJECTIVES

Sleep problems are common, serving as both a predictor and symptom of posttraumatic stress disorder (PTSD), with these bidirectional relationships well established in the literature. While both sleep phenotypes and PTSD are moderately heritable, there has been a paucity of investigation into potential genetic overlap between sleep and PTSD. Here, we estimate genetic correlations between multiple sleep phenotypes (including insomnia symptoms, sleep duration, daytime sleepiness, and chronotype) and PTSD, using results from the largest genome-wide association study (GWAS) to date of PTSD, as well as publicly available GWAS results for sleep phenotypes within UK Biobank data (23 variations, encompassing four main phenotypes).

METHODS

Genetic correlations were estimated utilizing linkage disequilibrium score regression (LDSC), an approach that uses GWAS summary statistics to compute genetic correlations across traits, and Mendelian randomization (MR) analyses were conducted to follow up on significant correlations.

RESULTS

Significant, moderate genetic correlations were found between insomnia symptoms (rg range 0.36-0.49), oversleeping (rg range 0.32-0.44), undersleeping (rg range 0.48-0.49), and PTSD. In contrast, there were mixed results for continuous sleep duration and daytime sleepiness phenotypes, and chronotype was not correlated with PTSD. MR analyses did not provide evidence for casual effects of sleep phenotypes on PTSD.

CONCLUSION

Sleep phenotypes, particularly insomnia symptoms and extremes of sleep duration, have shared genetic etiology with PTSD, but causal relationships were not identified. This highlights the importance of further investigation into the overlapping influences on these phenotypes as sample sizes increase and new methods to investigate directionality and causality become available.

Sleep Quality Moderates the Relationship between Anxiety Sensitivity and PTSD Symptoms in Combat-exposed Veterans

Objective/Background: Posttraumatic stress disorder (PTSD) and related conditions (e.g., depression) are common in Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn (OEF/OIF/OND) veterans. High anxiety sensitivity (AS), defined as fear of anxiety and anxiety-related consequences, is related to greater PTSD and depressive symptoms; however, few studies have identified possible modifiers of these associations. The current study examined the moderating role of sleep quality in the associations between AS and PTSD and depressive symptoms. Participants: Participants were 155 OEF/OIF/OND community veterans ages 21-40 (12.3% women). Methods: Participants completed a semi-structured clinical interview for DSM-IV PTSD symptoms (Clinician Administered PTSD Scale; CAPS) and self-report measures of anxiety sensitivity (Anxiety Sensitivity Index), sleep quality (Pittsburgh Sleep Quality Index global score; PSQI), and depressive symptoms (Beck Depression Inventory-II; BDI-II). Results: Results of hierarchical linear regression models indicated that the main effects of AS and global PSQI score were significantly associated with greater PTSD and depressive symptoms (both with sleep items removed), above and beyond the covariates of trauma load and military rank. Sleep quality moderated the relationship between AS and PTSD symptoms (but not depressive symptoms), such that greater AS was associated with greater PTSD symptoms for individuals with good sleep quality, but not poor sleep quality. Conclusions: Sleep quality and AS account for unique variance in PTSD and depressive symptoms in combat-exposed veterans. AS may be less relevant to understanding risk for PTSD among combat-exposed veterans experiencing poor sleep quality.

Longitudinal Examination of the Impact of Resilience and Stressful Life Events on Alcohol Use Disorder Outcomes

Stressful life events (SLEs) are a risk factor for alcohol use problems, and there is a need for identification of factors that may offset this risk. Resilience is uniquely, inversely associated with alcohol use, but there remains a dearth of research examining the buffering effect of resilience toward alcohol use problems in the context of SLEs. Objectives: This study used prospective data from an epidemiological twin sample (N = 7441) to test whether resilience at Time 1 would act as a buffer for new onset SLEs (e.g. assault, marital problems) against risk for alcohol dependence (AD) symptoms at Time 2. Results: The final model, adjusted for familial relatedness and controlling for demographic covariates and Time 1 (lifetime) AD symptoms, identified significant main effects of resilience and SLEs; those with greater resilience at Time 1 reported fewer symptoms (β=-.087, p<.001) and those with greater new-onset SLEs reported greater symptoms (β=.116, p<.001) at Time 2. However, there was no significant interaction (β=-.008, p>.05). Conclusions: Although findings further support the association of resilience and SLEs with AD, results do not support the conceptualization of resilience as a buffer against the impact of future life stressors on alcohol use outcomes. This suggests other factors may be more relevant for understanding protective factors for alcohol use problems or the relation between resilience and SLEs on alcohol use outcomes.

Meta-Analysis of Associations Between Hypothalamic-Pituitary-Adrenal Axis Genes and Risk of Posttraumatic Stress Disorder

The hypothalamic-pituitary-adrenal (HPA) axis has been of interest in attempts to identify genetic vulnerability for posttraumatic stress disorder (PTSD). Although numerous HPA-axis genes have been implicated in candidate gene studies, the findings are mixed and interpretation is limited by study design and methodological inconsistencies. To address these inconsistencies in the PTSD candidate gene literature, we conducted meta-analyses of HPA-related genes from both a traditional single nucleotide polymorphism (SNP)-level analysis and a gene-level analysis, using novel methods aggregating markers in the same gene. Database searches (PubMed and PsycINFO) identified 24 unique articles examining six HPA-axis genes in PTSD; analyses were conducted on four genes (ADCYAP1R1, CRHR1, FKBP5, NR3C1) that met study eligibility criteria (original research, human subjects, main effect association study of selected genes, PTSD as an outcome, trauma-exposed control group) and had sufficient data and number of studies for use in meta-analysis, within 20 unique articles. Findings from SNP-level analyses indicated that two variants (rs9296158 in FKBP5 and rs258747 in NR3C1) were nominally associated with PTSD, ps = .001 and .001, respectively, following multiple testing correction. At the gene level, significant relations between PTSD and both NR3C1 and FKBP5 were detected and robust to sensitivity analyses. Although study limitations exist (e.g., varied outcomes, inability to test moderators), taken together, these results provide support for FKBP5 and NR3C1 in risk for PTSD. Overall, this work highlights the utility of meta-analyses in resolving discrepancies in the literature and the value of adopting gene-level approaches to investigate the etiology of PTSD.

Insomnia Disorder and Behaviorally Induced Insufficient Sleep Syndrome: Prevalence and Relationship to Depression in College Students

Background: College students are at increased risk for sleep disorders, including insomnia disorder and obtaining less than 6.5 hr of sleep per night by choice, or behaviorally induced insufficient sleep syndrome (BIISS). These disorders can have deleterious daytime consequences, including depression. This study aims to establish the prevalence of insomnia and BIISS disorders and examine associations of insomnia and BIISS with other sleep characteristics and depression. Methods: A subset of data from Spit for Science, a college risk behaviors and health study (n = 989) was used. Insomnia and BIISS were defined as mutually exclusive disorders, based on diagnostic criteria. Results: A majority (68%) of students were categorized as normal sleepers, followed by insomnia (22%), and BIISS (10%). Sleep duration was comparable between BIISS and insomnia, while daytime sleepiness was significantly higher in BIISS, and sleep latency was longer in insomnia (m = 44 vs. m = 13 min). Insomnia was associated with the highest depression symptoms, followed by BIISS, and normal sleep, controlling for demographics. Insomnia was associated with twice the risk of moderate or higher depression compared to normal sleep (CI: 1.60, 2.70, p < .001). Conclusion: These findings highlight the sleep difficulties endemic to college populations. Further, this study provides the first prevalence estimation of BIISS in college students and the first comparison of insomnia and BIISS on sleep characteristics and depressive symptoms. This study underscores the importance of targeted screening and intervention to improve both sleep and depression in this vulnerable population.

GxE effects of FKBP5 and traumatic life events on PTSD: A meta-analysis

BACKGROUND

Twin studies have demonstrated that both genetic and environmental factors influence risk for posttraumatic stress disorder (PTSD), and there is some evidence supporting the interplay of genes and environment (GxE). Many GxE studies within the PTSD literature have focused on genes implicated in the stress response system, such as FK506 binding protein 51 (FKBP5). Given inconsistencies across GxE literature as a whole, a meta-analysis to synthesize results is warranted.

METHODS

Studies were identified through PubMed and PsycINFO. A meta-analysis was conducted using a random effects model in the MAc package in R. Heterogeneity of the effect size distribution was examined with Cochran's Q statistic. A Simes procedure was used to test the gene-level GxE effect for FKBP5 interacting with trauma.

RESULTS

A significant gene-level GxE gene effect was demonstrated for FKBP5 when pooled across all four examined variants (rs1360780, rs3800373, rs9296158, rs9470080) when interacting with trauma exposure on PTSD. Significant large GxE effect sizes were also found for each independent variant. There was no evidence for heterogeneity of variance.

LIMITATIONS

Limitations include reduced power for detecting variability across moderators, potential bias due to failure of meta-analyzed studies to account for two-way covariate x gene and covariate x environment influences, and a high false discovery rate that is characteristic of GxE analyses.

CONCLUSIONS

This is the first study to quantify an overall gene-level effect of FKBP5 in a GxE analysis of PTSD, evidence which may be used to address current issues in the FKBP5 GxE literature (e.g., disparate variants, low sample sizes and power), as well as inform follow-up functional research.

Effects of social support on the association between precollege sexual assault and college-onset victimization

OBJECTIVE

This study examined the moderating and mediating effects of perceived social support on the association between precollege sexual assault (SA) and college-onset SA.

PARTICIPANTS

A representative sample of 6,132 undergraduates.

METHODS

The PLUM procedure in SPSS was used to test the moderation model, with individual regressions conducted in a hierarchical fashion. A weighted least squared mean and variance adjusted (WLSMV) mediation model was used to examine the mediating effect of social support.

RESULTS

Precollege SA significantly predicted college-onset SA. Social support significantly mediated the relation between precollege SA and college-onset SA. Social support was not a significant moderator of this relationship.

CONCLUSIONS

Given the high prevalence of SA among college populations, as well as the high rates of SA revictimization, identification of factors that may be related to repeated SA (eg, low social support) within this population are essential and may inform intervention, policy, and university student services.

Relation between coping and posttrauma cognitions on PTSD in a combat-trauma population

Individual differences in cognitive processes and coping behaviors play a role in the development and maintenance of posttraumatic stress disorder (PTSD). Given the large numbers of combat-exposed service members returning from the Operation Enduring Freedom (OEF), Operation Iraqi Freedom (OIF), and Operation New Dawn (OND) conflicts, exploring individual differences in cognitive-affective processes is important for informing our understanding of PTSD etiology and early intervention in military samples. The present study examined the unique main and interactive effects of negative posttrauma cognitions (i.e., negative beliefs about self [NS], the world [NW], and self-blame [SB]) and coping strategies (i.e., positive behavioral, positive cognitive, avoidant coping, and social and emotional coping) on PTSD diagnosis within 155 (M_age = 30.7, SD = 4.48) OEF/OIF/OND combat trauma-exposed veterans recruited from an ongoing study examining the effects of combat trauma and stress reactivity. In the final, stepwise logistic regression analysis, avoidant coping, but no other coping strategy, was significantly positively related to PTSD diagnosis in the initial step. Higher levels of NS, but not NW, were significantly associated with having a PTSD diagnosis, while SB was associated with decreased likelihood of PTSD, above and beyond coping strategies. A significant interaction effect was found between NS and positive cognitive coping, such that greater positive cognitive coping weakened the relationship between NS and PTSD. Examining and addressing coping behaviors and negative thoughts of self jointly may benefit assessment and intervention approaches in a combat-trauma population.

Does Parenting Influence the Enduring Impact of Severe Childhood Sexual Abuse on Psychiatric Resilience in Adulthood?

This study examined the effect of parenting on the association between childhood sexual abuse (CSA) and psychiatric resilience in adulthood in a large female twin sample (n = 1423) assessed for severe CSA (i.e., attempted or completed intercourse before age 16). Severe CSA was associated with lower resilience to recent stressors in adulthood (defined as the difference between their internalizing symptoms and their predicted level of symptoms based on cumulative exposure to stressful life events). Subscales of the Parental Bonding Instrument were significantly associated with resilience. Specifically, parental warmth was associated with increased resilience while parental protectiveness was associated with decreased resilience. The interaction between severe CSA and parental authoritarianism was significant, such that individuals with CSA history and higher authoritarianism scores had lower resilience. Results suggest that CSA assessment remains important for therapeutic work in adulthood and that addressing parenting may be useful for interventions in children with a CSA history.

The impact of resilience and subsequent stressful life events on MDD and GAD

BACKGROUND

There remains a dearth of research examining the "buffering" effect of resilience, wherein resilience at one point in time would be expected to protect an individual against development of psychopathology following future adverse life events.

METHODS

Using longitudinal data from an epidemiological twin sample (N = 7463), this study tested whether resilience would act as a buffer for stressful life events (SLEs) against risk for major depressive disorder (MDD) and generalized anxiety disorder (GAD). Resilience, demographics, and psychopathology were measured at Time 1 and recent SLEs and current MDD and GAD were measured at Time 2.

RESULTS

Final models, controlling for demographic covariates and Time 1 diagnosis, examined the impact of Time 1 resilience, recent SLEs, their interaction, and a three-way interaction adding sex on MDD and GAD.

CONCLUSIONS

The pattern of findings was the same for MDD and GAD, wherein main effects and two-way interactions of resilience and SLEs were significant, such that greater resilience was protective even in the context of high numbers of past-year SLEs. The three-way interaction was not significant, suggesting that the relationship between SLEs and resilience on psychopathology was the same for both men and women. Findings support the conceptualization of resilience as a buffer against the impact of future life stressors on common internalizing psychopathology. Longitudinal designs and trajectory-based studies that include recurring measures of SLEs could inform conceptualizations of resilience in the context of ongoing adversity and aid in developing interventions aimed at fostering healthy adaptation in the face of stressors.

Association of Posttraumatic Stress Disorder With rs2267735 in the ADCYAP1R1 Gene: A Meta-Analysis

Recent studies point to the potential role of the (pituitary) adenylate cyclase activating polypeptide receptor 1 (ADCYAP1R1) gene, which has been implicated in stress response, in posttraumatic stress disorder (PTSD). Multiple genetic association studies have examined potential PTSD risk related to this gene, with mixed results. We conducted a meta-analysis of rs2267735 in ADCYAP1R1 in PTSD. A literature search was conducted using PubMed and PsycINFO, resulting in nine studies that met criteria for inclusion in analysis. Biostat's Comprehensive Meta-Analysis was used to conduct the main meta-analysis on the combined sex sample, as well as two subanalyses examining effects separately in female and male participants. Results indicated that the C allele of rs2267735 conferred significant risk for PTSD in the combined sex data, OR = 1.210, 95% CI [1.007, 1.454], p = .042, and in the subsample of women and girls, OR = 1.328, 95% CI [1.026, 1.719], p = .031; but not in the subsample of men and boys, OR = 0.964, 95% CI [0.733, 1.269], p = .796. These results provide evidence for an association between ADCYAP1R1 and PTSD and indicate that there may indeed be sex differences. Implications of these findings, including the role of rs2267735 as one modulator of the stress system, are discussed.

An examination of the etiologic overlap between the genetic and environmental influences on insomnia and common psychopathology

BACKGROUND

Insomnia is comorbid with internalizing and externalizing psychiatric disorders. However, the extent to which the etiologic influences on insomnia and common psychopathology overlap is unclear. There are limited genetically informed studies of insomnia and internalizing disorders and few studies of overlap exist with externalizing disorders.

METHODS

We utilized twin data from the Virginia Adult Twin Studies of Psychiatric and Substance Use Disorders (total n = 7,500). Insomnia, internalizing disorders (major depressive disorder [MDD], generalized anxiety disorder [GAD]), and alcohol abuse or dependence (AAD) were assessed at two time points, while antisocial personality disorder (ASPD) was assessed once. Cholesky decompositions were performed in OpenMx and longitudinal measurement models were run on available phenotypes to reduce measurement error.

RESULTS

The latent additive genetic influences on insomnia overlapped significantly (56% for females, 74% for males) with MDD and were shared completely (100%) with GAD. There was significant overlap of latent unique environmental influences, with overlap ranging from 38 to 100% across disorders. In contrast, there was less genetic overlap between insomnia and externalizing disorders, with 18% of insomnia's heritability shared with AAD and 23% with ASPD. Latent unique environmental overlap between insomnia and both externalizing disorders was negligible.

CONCLUSIONS

The evidence for substantial genetic overlap between insomnia and stable aspects of both internalizing disorders suggests that there may be few insomnia-specific genes and investigation into unique environmental factors is important for understanding insomnia development. The modest overlap between insomnia and externalizing disorders indicates that these disorders are genetically related, but largely etiologically distinct.

Relationships between potentially traumatic events, sleep disturbances, and symptoms of PTSD and alcohol use disorder in a young adult sample

OBJECTIVE

Traumatic events, particularly those that are interpersonal in nature, are associated with increased risk for co-occurring sequelae, including sleep disturbances, posttraumatic stress disorder (PTSD), and alcohol use disorder (AUD). However, the associations between these phenotypes have not been explored among college students.

METHODS

We examined relationships between type of potentially traumatic event (PTE) exposure (pre-college) and sleep disturbances, as well as mediating effects of lifetime PTSD and AUD symptoms on these relationships, in a large undergraduate sample (N = 1599, 64.7% female). Hierarchical linear regressions were conducted, beginning with demographics and then adding interpersonal and accidental PTEs in a stepwise regression; mediation analyses were run.

RESULTS

Within the sample, 33.7% endorsed at least one interpersonal PTE, while 64.4% endorsed at least one accidental PTE. Hierarchical regressions demonstrated that interpersonal (β = 0.202, p = 0.000), but not accidental PTE exposure significantly predicted disturbed sleep. Both PTSD and AUD symptoms significantly mediated (p values < 0.001) the relationship between interpersonal PTE exposure and sleep, with indirect effects accounting for 61% and 17% of total effects, respectively. In the correlated mediation model, both disorders remained significant mediators (p < 0.001), with indirect effects accounting for 56% (PTSD symptoms) and 14% (AUD symptoms) of total effects on sleep.

CONCLUSIONS

Results suggest that interpersonal PTEs are more potent predictors of sleep problems than accidental PTEs. Further, trauma exposure psychiatric symptom sequelae (PTSD, AUD) account for part of the relationship between interpersonal PTE exposure and disturbed sleep, which both independently and jointly suggests that treating PTSD and AUD symptoms in college students may also improve sleep.

Sleep Disturbances in OEF/OIF/OND Veterans: Associations with PTSD, Personality, and Coping

STUDY OBJECTIVES

Sleep disturbances are well documented in relation to trauma exposure and posttraumatic stress disorder (PTSD), but correlates of such disturbances remain understudied in veteran populations. We conducted a preliminary study of sleep disturbances in Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn veterans (n = 133; mean [standard deviation] age = 29.8 [4.7] y).

METHODS

Veterans were assigned to one of three groups based on responses to the Clinician Administered PTSD Scale: control (no trauma-exposure [TE] or PTSD), TE, and PTSD. Sleep disturbance was assessed using the Pittsburgh Sleep Quality Index (PSQI). Measures of resilience, trauma load, personality, coping, alcohol use, and mild traumatic brain injury were also assessed via self-report.

RESULTS

The PTSD group had significantly more disturbed sleep (PSQI global score mean = 8.94, standard deviation = 3.12) than control (mean = 5.27, standard deviation = 3.23) and TE (mean = 5.34, standard deviation = 3.17) groups, but there were no differences between TE and control. The same pattern emerged across most PSQI subscales. Results of linear regression analyses indicated that current smoking, Army (versus other military branches), neuroticism, and using substances to cope were all significant correlates of higher sleep disturbance, whereas post-deployment social support was associated with less sleep disturbance. However, when combined together into a model with PTSD status, only neuroticism and substance use coping remained significant as predictors of more disturbed sleep.

CONCLUSIONS

These initial findings suggest that TE itself may not be an independent risk factor for disturbed sleep in veterans, and that neurotic personality and a tendency to cope by using substances may partially explain sleep disturbance, above and beyond a diagnosis of PTSD.

The Effects of a BDNF Val66Met Polymorphism on Posttraumatic Stress Disorder: A Meta-Analysis

OBJECTIVE

Given evidence that posttraumatic stress disorder (PTSD) is moderately heritable, a number of studies utilizing candidate gene approaches have attempted to examine the potential contributions of theoretically relevant genetic variation. Some of these studies have found sup port for a brain-derived neurotrophic factor (BDNF) variant, Val66Met, in the risk of developing PTSD, while others have failed to find this link.

METHODS

This study sought to reconcile these conflicting findings using a meta-analysis framework. Analyses were also used to determine whether there is significant heterogeneity in the link between this variant and PTSD. We conducted a systematic review of the literature on BDNF and PTSD from the PsycINFO and PubMed databases. A total of 11 studies were included in the analysis.

RESULTS

Findings indicate a marginally significant effect of the BDNF Val66Met variant on PTSD (p < 0.1). However, of the 11 studies included, only 2 suggested an effect with a non-zero confidence interval, one of which showed a z score of 3.31. We did not find any evidence for heterogeneity.

CONCLUSIONS

Findings from this meta-analytic investigation of the published literature provide little support for the Val66Met variant of BDNF as a predictor of PTSD. Future well-powered agnostic genome-wide association studies with more refined phenotyping are needed to clarify genetic influences on PTSD.

Genetic Pathways to Insomnia

This review summarizes current research on the genetics of insomnia, as genetic contributions are thought to be important for insomnia etiology. We begin by providing an overview of genetic methods (both quantitative and measured gene), followed by a discussion of the insomnia genetics literature with regard to each of the following common methodologies: twin and family studies, candidate gene studies, and genome-wide association studies (GWAS). Next, we summarize the most recent gene identification efforts (primarily GWAS results) and propose several potential mechanisms through which identified genes may contribute to the disorder. Finally, we discuss new genetic approaches and how these may prove useful for insomnia, proposing an agenda for future insomnia genetics research.

The genetics and epigenetics of PTSD: overview, recent advances, and future directions

This paper provides a brief summary and commentary on the growing literature and current developments related to the genetic underpinnings of posttraumatic stress disorder (PTSD). We first briefly provide an overview of the behavioral genetic literature on PTSD, followed by a short synopsis of the substantial candidate gene literature with a focus on genes that have been meta-analyzed. We then discuss the genome-wide association studies (GWAS) that have been conducted, followed by an introduction to other molecular platforms used in PTSD genomic studies, such as epigenetic and expression approaches. We close with a discussion of developments in the field that include the creation of the PTSD workgroup of the Psychiatric Genomics Consortium, statistical advances that can be applied to GWAS data to answer questions of heritability and genetic overlap across phenotypes, and bioinformatics techniques such as gene pathway analyses which will further advance our understanding of the etiology of PTSD.

An epidemiologic study of childhood sexual abuse and adult sleep disturbances

Childhood sexual abuse (CSA) is linked to negative consequences, including insomnia. Few studies have examined the enduring effects of CSA on adult insomnia. Given the relationship between sleep and poor health, a better understanding of these effects has clinical implications. We used a representative adult twin sample. Both sexes were assessed with a broad CSA variable, with a subset of females (n = 424) given additional items capturing escalating physical contact and abuse characteristics. A sum score of past-month insomnia symptoms was calculated from the Symptom Checklist-90 (shortened version). Logistic regression was used to estimate the effects of CSA, physical contact, and incident characteristics on insomnia symptoms. Of the full sample (N = 8,184), 9.8% reported CSA. CSA significantly predicted insomnia symptoms in the female sample (n = 1,407; odds ratio [OR] = 1.67, 95% confidence interval [CI] = 1.35-2.06, p < .0001) but the continuum of physical contact did not. Individually, more than 1 perpetrator and feeling forced/threatened increased sleep risk, whereas having a male perpetrator (vs. female or multiple) decreased risk. These associations did not hold when combined. In the mixed-sex sample (n = 6,777), we replicated our CSA finding (OR = 1.65, 95% CI = 1.34-2.04, p < .0001) and found that female gender (OR = 1.16, 95% CI = 1.03-1.30, p = .0125), but not the gender*CSA interaction, was significant. CSA predicts adult insomnia symptoms decades after abuse, but the small sample size for incident characteristics (n = 424) resulted in limited conclusions about associated risk.

A Longitudinal Twin Study of Insomnia Symptoms in Adults

OBJECTIVE

Twin modeling was used to conduct a genetically informative longitudinal analysis of insomnia symptoms in both sexes.

METHOD

Data from the Virginia Adult Twin Studies of Psychiatric and Substance Use Disorders (n = 7,500) were used. Past-month insomnia symptoms were assessed at two time points with the shortened version of the Symptom Checklist-90. A composite score for the insomnia items (trouble falling asleep, restless or disturbed sleep, early morning awakenings) was computed. Twin modeling on the composite score was conducted in OpenMx to decompose the phenotypic variance, to examine the longitudinal stability of etiologic influences on insomnia symptoms, and to test for sex differences.

RESULTS

Insomnia symptoms were most commonly endorsed at a mild severity level (composite score mean = 2.24, standard deviation = 2.51). There was no evidence for sex effects in either of the univariate models, and insomnia symptoms were found to be modestly heritable (~25% at Time 1 and ~22% at Time 2). In the longitudinal measurement model, which accounts for error of measurement, the heritability for the latent factor of insomnia symptoms increased substantially, and demonstrated quantitative sex differences. The heritability of the latent insomnia factor was ~59% in females and ~38% in males.

CONCLUSIONS

Genetic factors influence insomnia symptoms in adults, moreso for females than males, and these influences are largely stable over time. When taking into account measurement error, heritability estimates are substantial, but unique environmental factors continue to account for a large amount of variance in insomnia symptoms.

P5-13-15: Proteomic Identification of Predictive Biomarkers of Resistance to Neoadjuvant Chemotherapy in Luminal Breast Cancer: A Possible Role for 14–3-3 and BID?

Background: Chemotherapy resistance is a major obstacle in effective neoadjuvant treatment for oestrogen receptor (ER)-positive breast cancer. The ability to predict tumour response would allow chemotherapy administration to be directed towards only those patients who would benefit, thus maximising treatment efficiency. We aimed to identify protein biomarkers associated with chemotherapy resistance, using proteomic analysis of fresh ER-positive breast cancer samples, and then to perform pilot clinical validation experiments. Materials and Methods: Chemotherapy resistant and chemotherapy sensitive tumour samples were collected from breast cancer patients who received standard anthracycline-based neoadjuvant therapy consisting of epirubicin with cyclophosphamide followed by docetaxel. Comparative proteomics experiments were performed using invasive ductal carcinomas which demonstrated ER-positivity (luminal subtype). Protein expression was compared between chemotherapy resistant and chemotherapy sensitive tumour samples using 2-dimensional gel electrophoresis (2-DE) with MALDI-TOF/TOF mass spectrometry (MS). In addition the Panorama XPRESS Profiler725 antibody microarray, containing 725 antibodies from a wide variety of cell signalling and apoptosis pathways, was employed in the discovery phase. Differentially expressed proteins (DEPs) were submitted to Ingenuity Pathway Analysis (IPA) to identify any canonical pathway links. A pilot series of archival breast cancer samples, from patients treated with neoadjuvant anthracycline-based chemotherapy, was used for preliminary clinical validation of putative predictive biomarkers.

Results: Five datasets were generated by antibody microarray analysis, revealing 41 targets. Of these, 7 DEPs were identified in at least 2 datasets and these included 14–3-3, BID and Bcl-xL. The top canonical pathway matched in IPA was “ERK5 signaling”, which involved 6 DEPs, including 14–3-3. The “PI3/AKT” pathway also involved 6 DEPs, including 14–3-3 and Bcl-xL. Three datasets were generated using 2-DE with MALDI-TOF/TOF MS, containing over 300 DEPs. These included several isoforms of 14–3-3. Differential expression of 14–3-3, BID and Bcl-xL was confirmed by immunoblotting in samples used for the discovery phase. A pilot clinical validation using immunohistochemical analysis of archival breast cancers revealed 14–3-3 tau and tBID to be significantly associated with chemotherapy resistance.

Discussion: We have successfully utilised clinical tumour samples for the discovery of putative biomarkers of chemotherapy resistance using two complementary proteomic platforms. We propose a potential role for 14–3-3 tau and BID as predictive biomarkers of chemotherapy resistance in ER-positive tumours and further validation in a larger sample series is now required.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-15.

Antibody microarray analysis identifies biomarkers associated with radioresistant breast cancer cell lines

Abstract #5072

Background: Resistance to radiotherapy may be a significant factor in the development of local recurrence following surgical resection and radiotherapy. In addition, if patients with radioresistant breast cancers can be identified, harmful side effects from exposure to unnecessary ionizing radiation could be prevented. We aimed to develop a novel in vitro model of radioresistance using breast cancer cell lines and to subsequently identify molecular biomarkers which may be associated with the radioresistant phenotype. Antibody microarrays offer a complementary approach for proteomic analysis in conjunction with standard screening methods such as two dimensional gel electrophoresis/ mass spectrometry and other quantitative proteomic techniques. We previously utilised the Panorama Cell Signalling Antibody Microarray Kit (Sigma-Aldrich) consisting of 224 antibodies (Smith et al Mol Cancer Ther 5:2115-20, 2006). In this study we utilised a novel high density 725 antibody microarray to screen for proteins associated with radioresistance.&#x2028; Material and Methods: We established novel breast cancer cell sublines which were significantly resistant to radiotherapy when compared with the parental cells (T47D; MCF-7). The radioresistant sublines were created by irradiating cells in fractionated doses of 2Gy up to a total dose of 40Gy. Sufficient time was allowed for the cells to recover between subsequent irradiations. A dose response curve was assessed at the end of treatment to demonstrate a statistically significant increase in radioresistance for the novel cell subline when compared with parental cells. The radioresistant/parental cell pairs were analysed using the Panorama Antibody Microarray XPRESS Profiler725 Kit (Sigma-Aldrich). The microarray comprised 725 different antibodies on nitrocellulose coated microscope slides. The antibodies were selected from a wide variety of pathways, including apoptotic and cell signalling pathways.&#x2028; Results: Utilising a Cy3/Cy5 labelling strategy the antibody microarray approach yielded a number of a total of 28 targets for further study. Of these, three proteins were identified independently from both of the radioresistant cell lines. These were GFI1 (Growth Factor Independence-1), DR4 (Death Receptor 4) and Importin a1. Immunoblotting and other proteomic approaches have confirmed the identities and differential expression of some candidate protein targets.&#x2028; Conclusion: High density antibody microarrays potentially offer a powerful new proteomic technique to allow the global analysis of many proteins simultaneously. This analysis has produced both complementary and confirmatory data in our proteomic screening for putative biomarkers associated with radiotherapy resistance. We successfully identified a number of protein targets which may be associated with a radioresistant phenotype. Further confirmatory and validation studies are ongoing.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5072.

Neoadjuvant chemotherapy in breast cancer: early response prediction with quantitative MR imaging and spectroscopy

A prospective study was undertaken in women undergoing neoadjuvant chemotherapy for locally advanced breast cancer in order to determine the ability of quantitative magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to predict ultimate tumour response (percentage decrease in volume) or to detect early response. Magnetic resonance imaging and MRS were carried out before treatment and after the second of six treatment cycles. Pharmacokinetic parameters were derived from T₁-weighted dynamic contrast-enhanced MRI, water apparent diffusion coefficient (ADC) was measured, and tissue water : fat peak area ratios and water T₂ were measured using unsuppressed one-dimensional proton spectroscopic imaging (30 and 135 ms echo times). Pharmacokinetic parameters and ADC did not detect early response; however, early changes in water : fat ratios and water T₂ (after cycle two) demonstrated substantial prognostic efficacy. Larger decreases in water T₂ accurately predicted final volume response in 69% of cases (11/16) while maintaining 100% specificity and positive predictive value. Small/absent decreases in water : fat ratios accurately predicted final volume non-response in 50% of cases (3/6) while maintaining 100% sensitivity and negative predictive value. This level of accuracy might permit clinical application where early, accurate prediction of non-response would permit an early change to second-line treatment, thus sparing patients unnecessary toxicity, psychological morbidity and delay of initiation of effective treatment.

Cyclooxygenase-2 expression predicts survival in malignant pleural mesothelioma

The expression of cyclooxygenase 2 (COX-2) protein is increased in many tumours and may be associated with a more aggressive phenotype. We aimed to assess COX-2 expression in a large series of archival mesothelioma specimens. Archival tissue was obtained from 86 malignant pleural mesothelioma samples (histological subtype: 42 epithelial, 28 biphasic and 16 sarcomatoid). Overexpression of COX-2 was detected by immunohistochemical analysis. Positive staining was located in the cytoplasm of malignant tumour cells. Overall 51/86 (59%) tumour sections demonstrated COX-2 overexpression. The frequency varied with histological subtype with 31/42 (73%) of epithelial sections, 14/28 (50%) of biphasic sections and 6/16 (37%) of sarcomatoid sections recorded as positive. Kaplan Meier survival analysis indicated that overexpression of COX-2 was significantly related to improved prognosis (P < 0.001) and was an independent prognostic factor in multivariant analysis. Overexpression of COX-2 protein may confer a survival advantage in mesothelioma patients.

Phase I study of temozolomide plus paclitaxel in patients with advanced malignant melanoma and associated in vitro investigations

The purpose of this study was to determine activity of temozolomide combined with paclitaxel or epothilone B in vitro, and to investigate the combination of temozolomide with paclitaxel in a Phase I clinical trial. Melanoma cell lines A375P and DX3 were treated with temozolomide and either paclitaxel or epothilone B. Combination indices were determined to assess the degree of synergism. In a clinical study, 21 patients with malignant melanoma were treated with increasing doses of temozolomide (orally, days 1–5), in combination with a fixed dose of paclitaxel (i.v. infusion day 1), followed by dose escalation of the latter drug. Cycles of treatment were repeated every 3 weeks. Pharmacokinetics of both agents were determined on day 1, with temozolomide pharmacokinetics also assessed on day 5. All three compounds were active against the melanoma cell lines, with epothilone B being the most potent. There was a strong degree of synergism between temozolomide and either paclitaxel or epothilone B. In the clinical study, no pharmacokinetic interaction was observed between temozolomide and paclitaxel. Dose escalation of both drugs to clinically active doses was possible, with no dose-limiting toxicities observed at 200 mg m⁻² day⁻¹ temozolomide and 225 mg m⁻² day⁻¹ paclitaxel. There were two partial responses out of 15 evaluable patients. One patient remains alive and symptom-free at 4 years after treatment. Temozolomide and paclitaxel may be administered safely at clinically effective doses. Further evaluation of these combinations in melanoma is warranted.

Chromosomal alterations in breast cancer revealed by multicolour fluorescence in situ hybridization

The aim of this study was to characterise cytogenetically, breast cancer cell lines and primary tumours to identify chromosomal regions of interest in breast cancer. Multicolour fluorescence in situ hybridization (MFISH) and comparative genomic hybridization (CGH) were used to karyotype five established breast cancer cell lines and two short-term primary tumour cultures. Chromosome 8 was identified as a frequent target for aberrations in all cell lines and one primary culture by MFISH and CGH. CGH identified frequent gains of 1q (all samples) and 14q (all cell lines) and deletion of 22q (all samples). MFISH revealed a t(9;17) translocation in both primary tumours and the T47D cell line. MFISH analysis of the cell lines revealed a significant number of translocations previously unidentified in other studies using similar techniques, highlighting the necessity of utilising data from both primary cultures and established cell lines when investigating complex cytogenetic aberrations using MFISH and CGH.

Chromosomal analysis of non-small-cell lung cancer by multicolour fluorescent in situ hybridisation

The cytogenetic abnormalities in non-small-cell lung cancer remain elusive due primarily to the difficulty in obtaining metaphase spreads from solid tumours. We have used the molecular cytogenetic techniques of multicolour fluorescent in situ hybridisation (M-FISH) and comparative genomic hybridisation (CGH) to analyse four primary non-small-cell lung cancer samples and two established cell lines (COR-L23 and COR-L105) in order to identify common chromosomal aberrations. CGH revealed regions on 5p, 3q, 8q, 11q, 2q, 12p and 12q to be commonly over-represented and regions on 9p, 3p, 6q, 17p, 22q, 8p, 10p, 10q and 19p to be commonly under-represented. M-FISH revealed numerous complex chromosomal rearrangements. Translocations between chromosomes 5 and 14, 5 and 11 and 1 and 6 were observed in three of the six samples, with a further 14 translocations being observed in two samples each. Loss of the Y chromosome and gains of chromosomes 20 and 5p were also frequent. Chromosomes 4, 5, 8, 11, 12 and 19 were most frequently involved in interchromosomal translocations. Further investigation of the recurrent aberrations will be necessary to identify the specific breakpoints involved and any role they may have in the aetiology, diagnosis and prognosis of non-small-cell lung cancer.

Population pharmacokinetics of adjuvant cyclophosphamide, methotrexate and 5-fluorouracil (CMF)

Despite the success of adjuvant cyclophosphamide, methotrexate (MTX), 5-fluouracil (5-FU) (CMF) treatment for early stage breast cancer, more than 35% of patients die within 5 years of diagnosis. Optimisation of the dose of each component drug may improve survival and reduce toxicity. In this study, the pharmacokinetics of intravenous (i.v.) cyclophosphamide (600 mg/m(2)), MTX (40 mg/m(2)) and 5-FU (600 mg/m(2)) were determined in 46 women, with data on two consecutive courses available for 41 patients. A population analysis using NONMEM was performed to investigate the effect of patient covariates on pharmacokinetics (PK), and to estimate the relative magnitude of interindividual and interoccasion variability. Patient weight had a significant influence on the clearance of cyclophosphamide and on the volume of central compartment for MTX, whose clearance was dependent on renal function. For all three drugs, interoccasion variability was of the same order (20-40%) as that between individuals, suggesting a limited potential for dose-optimisation of this regimen.

A phase II study of pemetrexed disodium (LY231514) in patients with locally recurrent or metastatic breast cancer

A phase II study was conducted to evaluate the activity of pemetrexed in patients with locally recurrent or metastatic breast cancer. 38 patients, median age 52 years (range 36-71 years), were given pemetrexed 600 mg/m(2) as a 10-min intravenous (i.v.) infusion every 3 weeks. Median time from diagnosis to study entry was 48 months (range 14.7-310 months). 33 of 38 patients had prior chemotherapy; 16 adjuvant, 12 metastatic and 5 in both settings. Sites of disease included skin and soft tissue (19/38) nodes (18/38), lung (17/38), liver (13/38) and bone (3/38). An overall response rate of 28% (95% confidence interval (CI): 14.2-45.2%) in 10/36 evaluable patients (1 complete response (CR), 9 partial responses (PR)), included reductions in hepatic and pulmonary metastases. 5 of 10 responders had received taxoid or anthracycline therapy for metastatic disease; 3 of these 5 had also received adjuvant chemotherapy. Median duration of response was 8 months (range 1.6-14+ months), and median survival was 13 months (95% CI 9.56-17.38 months). 167 courses were given (median five per patient; range 1-9), with 37 reductions and 33 delays. Reasons for reduction included neutropenia (11%) and mucositis (5%), with delays due to raised LFTs (21%), neutropenia (12%) and other non-treatment related events. The major haematological toxicities (Common Toxicity Criteria) (CTC) were grade 3/4 neutropenia (47%) and thrombocytopenia (15.7%) of patients. There was one report of a grade 3 infection. Non-haematological toxicities (all grades 2/3) included elevated transaminases (92%), vomiting (34%), nausea (34%) and mucositis (32%). One episode of grade 4 diarrhoea was reported. Other toxicities included a skin rash, grade 2 (42%), 3 (5%) and 4 (13%), which was ameliorated by the use of prophylactic dexamethasone. These results suggest that pemetrexed has significant antitumour activity in advanced breast cancer with responses in patients who had previously received anthracyclines and taxoids.

Ifosfamide metabolism and DNA damage in tumour and peripheral blood lymphocytes of breast cancer patients

PURPOSE

This study was designed to determine individual variation in the metabolism of ifosfamide (IF) and any influence this may have on the degree of DNA damage produced in both peripheral blood lymphocytes (PBL) and in tumour tissue.

METHODS

The pharmacokinetics and metabolism of IF and also of doxorubicin (DOX) were determined in patients receiving IF/DOX neoadjuvant chemotherapy for the treatment of advanced breast cancer. The DNA-damaging effects of this regimen were measured using the comet assay in PBL and in breast tumour tissue obtained by fine needle aspirate. Parallel in vitro studies were carried out in order to establish if DNA damage caused by IF metabolites or DOX was predictive of cytotoxicity in breast cancer cell lines.

RESULTS

The median AUC, half-life and clearance of IF were found to be 291 microM.min, 5.2 h and 66 ml/min per m2, respectively. A high degree of interpatient variability (up to sevenfold) was observed in the metabolism of both IF and DOX and also in their metabolites. Treatment-related changes in the amount of DNA damage were observed in both PBL and tumour cells. That in PBL peaked 48 h after the end of IF infusion (median 17% damaged cells at 48 h compared to 4% damaged before treatment). DNA damage in tumour cells was not elevated above low pretreatment values (median 1.5% damaged cells) until 3 weeks after IF and DOX treatment (median 30% damaged cells), by which time damage in PBL showed almost complete resolution to basal levels. The DNA damage in PBL determined 24 h after the start of chemotherapy was found to be related to the AUC of 4-hydroxyifosfamide (4OHI; P = 0.05). The amount of damage in either tissue did not significantly correlate with clinical response or toxicity, but lower amounts of damage were observed in the tumour cells 3 weeks after treatment in those patients that subsequently relapsed, compared to those that remained disease free. DNA damage (more than 20% damaged cells) was observed after exposure to active IF metabolites at concentrations equal to or greater than the IC50 in MCF-7 and MDA-MB231 cell lines. At concentrations of 4OHI similar to those determined in vivo, an equivalent level of DNA damage was observed in PBL and in cell lines and was associated with significant growth inhibition. DNA damage induced by DOX was not predictive of cytotoxicity.

CONCLUSION

Systemic DNA damage appeared to be related to levels of the active metabolite, consistent with the results of in vitro investigations of DNA damage. Further studies are warranted to substantiate this observation and to explore the relationship between metabolism, DNA damage and antitumour activity.

Pharmacokinetics of carboplatin administered in combination with the bradykinin agonist Cereport (RMP-7) for the treatment of brain tumours

INTRODUCTION

Cereport (RMP-7) is a novel bradykinin agonist which is being developed as a modulator of the blood-brain barrier (BBB). In order to investigate the pharmacokinetics of carboplatin in combination with Cereport, we performed pharmacological studies in conjunction with early clinical trials.

METHODS

Pharmacokinetic samples were collected from eight patients in a phase I study (Cereport 100-300 ng/ kg) and ten patients in a phase II study (Cereport 300 ng/kg). Pharmacokinetic parameters for carboplatin were compared with respect to the dose of Cereport and with historical controls.

RESULTS

Cereport combined with carboplatin was well-tolerated, with mild haematological toxicities consistent with the target area under the concentration time curve (AUC) of 7 mg/ml x min. Although the clearance of carboplatin was within the range reported for this drug alone, the addition of Cereport resulted in a higher than expected carboplatin AUC. This effect was related to the dose of Cereport in the phase I study (AUC values 104-133% of target, Spearman rank correlation coefficient = 0.71, P < 0.001). The higher than expected AUC value was confirmed in the phase II study (AUC values 106-189% of target).

CONCLUSIONS

Co-administration of Cereport with carboplatin may result in a greater than predicted AUC. The mechanism of this possible interaction remains to be determined, although this did not result in any increased toxicity. Thus, the clinical potential of this combination in the treatment of brain tumours warrants further investigation.

O6-methylguanine-DNA methyltransferase in pretreatment tumour biopsies as a predictor of response to temozolomide in melanoma

Resistance of tumour cells to methylating and monochloroethylating agents in vitro and in vivo has been linked to levels of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). In a clinical trial of temozolomide in advanced malignant melanoma, the relationship between pretreatment MGMT levels in biopsies of cutaneous tumours and involved lymph nodes and clinical response to the drug has been studied. Among 50 evaluable patients, there were three complete responses (CR), four partial responses (PR), six with stable disease (SD) and 37 with progressive disease (PD), with an overall response rate of 14%. In 33 patients in whom MGMT level and clinical response could be evaluated, the tumour MGMT levels (fmol mg(-1) protein) were: CR, 158 +/- 119; PR, 607 +/- 481; NC, 171 +/- 101; PD, 185 +/- 42.3. Thus, measurements of pretreatment levels of MGMT in melanoma did not predict for response to temozolomide.

A phase I and pharmacokinetic study of LY231514, the multitargeted antifolate

LY231514 is a novel antifolate that principally inhibits thymidylate synthase, but with additional folate-dependent enzyme targets. A Phase I study of single-agent LY231514 administered as a daily i.v. infusion over 10 minutes for 5 days, repeated every 3 weeks, was conducted to evaluate the maximum tolerated dose, pharmacokinetic profile, and antitumor activity of the drug using this schedule. Thirty-eight patients with advanced malignancies that were refractory or not amenable to standard therapy were treated with a total of 116 courses of LY231514, escalating treatment doses through 10 dose levels, from 0.2-5.2 mg/m2/day. No objective clinical responses were observed, although minor antitumor activity not fulfilling the response criteria was seen in three patients. A maximum tolerated dose of 4.0 mg/m2/day was determined, with neutropenia as the predominant dose-limiting toxicity. Reversible disturbances of liver biochemistry, fulfilling the protocol definitions of dose-limiting toxicity, were also observed. Other toxicities included diarrhea, mucositis, skin rash, and fatigue. Pharmacokinetic studies were performed at all treatment levels. Analysis showed a linear relation between administered dose and both maximum plasma concentration (Cmax) and area under the plasma concentration/time curve. The drug was cleared with a day 1 total body clearance of 108.9 +/- 38.8 ml/min/m2, with plasma concentrations declining with a mean harmonic terminal half-life of 1.4 +/- 0.98 h. When given by this schedule, LY231514 is tolerable, and Phase II studies are in progress.

Preclinical and phase I clinical studies with the nonclassical antifolate thymidylate synthase inhibitor nolatrexed dihydrochloride given by prolonged administration in patients with solid tumors

PURPOSE

A phase I, multicenter trial of the thymidylate synthase (TS) inhibitor THYMITAQ (nolatrexed dihydrochloride; Agouron Pharmaceuticals, Inc, San Diego, CA) given by 5-day continuous infusion was performed to establish the maximum-tolerated dose (MTD) and to investigate pharmacokinetics, pharmacodynamics, and antitumor effects.

METHODS

In vitro and in vivo preclinical studies demonstrated increased activity with prolonged nolatrexed exposure. In 32 patients, nolatrexed was given as a 5-day infusion at 96 to 1,040 mg/m2/d for 5 days. Pharmacokinetics were determined from high-performance liquid chromatography (HPLC) analyses of plasma and urine. In addition to studying toxicity, plasma deoxyuridine (UdR) elevations were measured as a marker of TS inhibition.

RESULTS

The MTD was 904 mg/m2/d for 5 days and the recommended phase II dose is 800 mg/m2/d for 5 days. The dose-limiting toxicity was neutropenia with clinically significant thrombocytopenia and mucositis. These antiproliferative toxicities of nolatrexed were predictable and reversible. A partial response that lasted 3 months occurred in a patient with metastatic colorectal cancer. Pharmacokinetics were nonlinear, with the median plasma clearance (CI) decreasing from 151 mL/min/m2 (range, 124 to 211) at 96 mg/m2/d for 5 days to 49 mL/min/m2 (range, 30 to 84) at 768 mg/ m2/d for 5 days. The half-life (t1/2) was 173 minutes (range, 43 to 784) and 18% (range, 9% to 35%) of the dose was excreted unchanged in the urine. Plasma UdR increased, but returned to pretreatment levels after the end of infusion. Hematologic toxicity was significantly related to nolatrexed plasma concentrations and dose.

CONCLUSION

Nolatrexed can be safely administered to patients at a dose of 800 mg/m2/d over 5 days by continuous intravenous infusion and this schedule is associated with antitumor effects. The phase II evaluation of nolatrexed is ongoing.

A clinical and pharmacokinetic study of the combination of carboplatin and paclitaxel for epithelial ovarian cancer

The aim of this phase I study was to determine the maximum tolerated dose of a 3-h infusion of paclitaxel, combined with carboplatin at a fixed AUC of 7 mg ml-1 min every 4 weeks for up to six cycles and to evaluate any possible pharmacokinetic interaction. Twelve chemonaive patients with ovarian cancer were treated with paclitaxel followed by a 30-min infusion of carboplatin. Paclitaxel dose was escalated from 150 mg m-2 to 225 mg m-2 in cohorts of three patients. Carboplatin dose was based on renal function. Pharmacokinetic studies were performed in nine patients (at least two at each dose level). A total of 66 courses were evaluable for assessment. Grade 3 or 4 neutropenia was seen in 70% of the courses, however hospitalization was not required. Grade 3 or 4 thrombocytopenia occurred in 24% of the courses. Alopecia, myalgia and peripheral neuropathy were common but rarely severe. The pharmacokinetics of paclitaxel was non-linear and did not appear to be influenced by co-administration of carboplatin. The AUC of carboplatin was 7.0 +/- 1.4 mg ml-1 min, indicating that there was no pharmacokinetic interaction. The combination of carboplatin and paclitaxel may be administered as first-line treatment for advanced ovarian cancer. Although myelosuppression is the dose-limiting toxicity of the component drugs, the severity of thrombocytopenia was less than anticipated. The results of this study, with only a small number of patients, need to be confirmed in future investigations.

A phase I clinical study of the antipurine antifolate lometrexol (DDATHF) given with oral folic acid

Lometrexol is an antifolate which inhibits glycinamide ribonucleotide formyltransferase (GARFT), an enzyme essential for de novo purine synthesis. Extensive experimental and limited clinical data have shown that lometrexol has activity against tumours which are refractory to other drugs, notably methotrexate. However, the initial clinical development of lometrexol was curtailed because of severe and cumulative antiproliferative toxicities. Preclinical murine studies demonstrated that the toxicity of lometrexol can be prevented by low dose folic acid administration, i.e. for 7 days prior to and 7 days following a single bolus dose. This observation prompted a Phase I clinical study of lometrexol given with folic acid supplementation which has confirmed that the toxicity of lometrexol can be markedly reduced by folic acid supplementation. Thrombocytopenia and mucositis were the major toxicities. There was no clear relationship between clinical toxicity and the extent of plasma folate elevation. Associated studies demonstrated that lometrexol plasma pharmacokinetics were not altered by folic acid administration indicating that supplementation is unlikely to reduce toxicity by enhancing lometrexol plasma clearance. The work described in this report has identified for the first time a clinically acceptable schedule for the administration of a GARFT inhibitor. This information will facilitate the future evaluation of this class of compounds in cancer therapy.

Phase I study of pharmacologically based dosing of carboplatin with filgrastim support in women with epithelial ovarian cancer

PURPOSE

The aim of this study was to increase the dose intensity of carboplatin in women with International Federation of Gynecology and Obstetrics (FIGO) Stage Ic-IV epithelial ovarian cancer with the use of granulocyte colony-stimulating factor (G-CSF; filgrastim; Amgen, Thousand Oaks, CA).

PATIENTS AND METHODS

A phase I study of escalating target area under the curves (AUCs) of carboplatin with G-CSF (filgrastim) ws undertaken. The target AUCs were 5 mg/mL.min every 21 days for four cycles, 5 mg/mL.min every 14 days for four cycles, 7 mg/mL.min every 14 days for four cycles, 9 mg/mL.min every 14 days for four cycles, and 11 mg/mL.min every 14 days for four cycles. G-CSF was given at a dose of 5 microg/kg/d starting 24 hours after carboplatin administration and lasting until 24 hours before the next cycle and until day 14 after the last cycle.

RESULTS

We were able to escalate to an AUC level of 9 mg/mL.min every 14 days for four cycles. At this dose, severe thrombocytopenia, that necessitated dosage delays, and failure to give subsequent cycles of carboplatin were observed. We then reduced the AUC level to 8 mg/mL.min every 14 days for four cycles. However, severe thrombocytopenia was also observed at this level.

CONCLUSION

An AUC of 7 mg/mL.min every 14 days for four cycles is the maximum tolerated AUC level that can be achieved with G-CSF. Further escalations may be possible using either combinations of cytokines or peripheral stem-cell collections.

Phase I and pharmacokinetic study of a water-soluble etoposide prodrug, etoposide phosphate (BMY-40481)

Etoposide phosphate is a water-soluble prodrug of etoposide. A phase I and pharmacokinetic study has been performed over the dose range 25-110 mg/m2/day for 5 days (etoposide equivalent doses). The maximum tolerated dose (MTD) was 110 mg/m2/day for 5 days every 3 weeks and the dose-limiting toxicity was neutropenia. Other toxicities were mild, with the exception of 2 patients who displayed significant hypersensitivity reactions. The etoposide phosphate:etoposide area under the plasma concentration versus time curve (AUC) ratio was < 1% and the pharmacokinetic parameters for etoposide were within previously reported ranges. Pharmacodynamic analyses demonstrated that etoposide AUC and baseline white blood cell count were significant determinants of leucopenia (model r2 = 0.51).

The use of granulocyte colony-stimulating factor to deliver four cycles of ifosfamide and epirubicin every 14 days in women with advanced or metastatic breast cancer

Twenty patients with locally advanced or metastatic breast cancer were treated with four cycles of ifosfamide/mesna 5 g m-2 and epirubicin 60 mg m-2 every 14 days with granulocyte colony-stimulating factor (G-CSF, Filgrastim). Complete remission occurred in six out of the 20 patients (30%, 95% confidence interval 12-54%) and there were 12 partial responders (60%, 95% confidence interval 37-81%), thus giving an overall response rate of 90% (95% confidence interval 63-97%). Two patients had progressive disease. The median duration of response for those patients with metastatic disease was 7.3 (1.3-20.1+) months. The median survival time for these patients was 15 (5.3-27.9+) months. Of the four patients treated with locally advanced disease three achieved a complete clinical response and one a partial response. Three out of four of these patients subsequently underwent a mastectomy, and in one of these no viable tumour was seen. Our conclusion is that this regimen is excellent palliation for metastatic disease and possibly useful neoadjuvant treatment.

Pharmacokinetics, metabolism and clinical effect of ifosfamide in breast cancer patients

Ifosfamide (IFO) at a dose of 5 g/m2, was administered as a 24-h infusion to 15 patients with metastatic (12) or locally advanced (3) breast cancer (age range 33-59 years, median 46). Concurrent chemotherapy was doxorubicin (40 mg/m2) or epirubicin (60 mg/m2). Ifosfamide and its metabolites were measured in plasma and urine during and for 24 h after the infusion using a high performance thin layer chromatography (HPTLC) technique. Patients' haematological toxicity and biochemistry were monitored during treatment and patients were followed for up to 2 years after therapy. At the time of evaluation, 5 of the patients were alive, 2 of whom had not relapsed. A marked variation was observed in the pharmacokinetics and metabolism of ifosfamide in the evaluable patients. Clearance, volume of distribution and half-life of the drug were 3.48 +/- 0.88 1/h/m2, 0.56 +/- 0.22 l/kg and 4.68 +/- 2.01 h, respectively. There was no apparent correlation between these pharmacokinetic variables and patient age, weight or renal function. AUCs of the ultimate alkylating species isophosphoramide mustard (IPM) varied over 6-fold, as did those of the inactivated metabolite carboxyifosfamide (CX). AUCs of dechloroethylated metabolites varied 4-fold (3-dechloroethylifosfamide, 3-DCI) or 8-fold (2-DCI), while that of the parent compound varied only 2.5-fold. Variation in recovery of the metabolites in urine varied over an even wider range, total recovery varying from 17.5 to 81.8% of the dose administered. There was little apparent correlation between pharmacokinetic and metabolite parameters of IFO and haematological toxicity. However, there was a marked negative correlation between both progression-free interval and survival and the AUCs of the products of IFO activation (IPM and CX). In addition, the recovery of IPM in urine was higher in patients experiencing a partial response compared to those with progressive or stable disease. Recovery of dechloroethylated metabolites correlated positively with survival, if 1 poor prognosis patient was excluded. Although far from conclusive, these results give some insight into a possible mechanism of action of ifosfamide and indicate that some species other than IPM, as measured systemically, is responsible for the pharmacological effects of this drug.

Pharmacokinetics and pharmacodynamics of prolonged oral etoposide in women with metastatic breast cancer

The pharmacokinetics and pharmacodynamics of prolonged oral etoposide chemotherapy were investigated in 15 women with metastatic breast cancer who received oral etoposide 100 mg as a single daily dose for up to 15 days. There was considerable interpatient variability in the day 1 pharmacokinetic parameters: area under the plasma concentration time curve (AUC) (0-24 h) 1.95 +/- 0.87 mg/ml per min (mean +/- SD), apparent oral clearance 60.9 +/- 21.7 ml/min per 1.73 m2, peak plasma concentration 5.6 +/- 2.5 micrograms/ml, time to peak concentration 73 +/- 35 min and half-life 220 +/- 83 min. However, intrapatient variability in systemic exposure to etoposide was much less with repeated doses. The intrapatient coefficient of variation (CV) of AUC for day 8 relative to day 1 was 20% and for day 15 relative to day 1 was 15%, compared to the day 1 interpatient CV of 45%. Neutropenia was the principal toxicity. Day 1 pharmacokinetic parameters were related to the percentage decrease in absolute neutrophil count using the sigmoidal Emax equation. A good fit was found between day 1 AUC and neutrophil toxicity (R2 = 0.77). All patients who had a day 1 AUC > 2.0 mg/ml per min had WHO grade III or IV neutropenia. The predictive performance of the models for neutrophil toxicity was better for AUC (percentage mean predictive error 5%, percentage root mean square error 18.1%) than apparent oral clearance, peak plasma concentration, or daily dose (mg/m2). A limited sampling strategy was developed to predict AUC using a linear regression model incorporating a patient effect. Data sets were divided into training and test sets. The AUC could be estimated using a model utilizing plasma etoposide concentration at only two time points, 4 h and 6 h after oral dosing (R2 = 98.9%). The equation AUCpr = -0.376 + 0.631 x C4h + 0.336 x C6h was validated on the test set with a relative mean predictive error of -0.88% and relative root mean square error of 6.4%. These results suggest monitoring of AUC to predict subsequent myelosuppression as a strategy for future trials with oral etoposide.

Carboplatin and granulocyte colony-stimulating factor as first-line treatment for epithelial ovarian cancer: a phase I dose-intensity escalation study

A phase I study of frequently administered carboplatin with recombinant human granulocyte colony-stimulating factor (filgrastim) has been performed in patients with newly diagnosed epithelial ovarian cancer. Recombinant human granulocyte colony-stimulating factor was administered at a dose of 5 micrograms/kg/d for days 1 through 12 after carboplatin treatment. Carboplatin doses were calculated using a pharmacokinetic formula on an area under the curve (AUC) basis. Four doses of carboplatin were planned for each patient. The first cohort of patients received an AUC of 5 mg/mL x min every 3 weeks. Subsequently four additional cohorts received AUCs of 5, 7, 9, and 8 every 2 weeks. Non-hematologic toxicities were mild and not significant. The dose-limiting toxicity was thrombocytopenia and occurred at an AUC of 9. Most patients could complete treatment at an AUC of 7. Results for AUC 8 are awaited. Complete and partial responses were seen in most patients at all dose levels.

Identification of the major human hepatic cytochrome P450 involved in activation and N-dechloroethylation of ifosfamide

Two NADPH-dependent metabolic routes for the anticancer drug ifosfamide, 4-hydroxylation (activation) and N-dechloroethylation (a detoxication pathway), were studied in human liver microsomes to identify the cytochrome P450 enzymes involved. Naringenin, a grapefruit aglycone and an inhibitor of cytochrome P450 3A4 (CYP3A4)-catalysed reactions, was found to inhibit ifosfamide activation and N-dechloroethylation by human liver microsomes. IC50 for both reactions was of the order of 70 microM. The CYP3A4-specific inhibitor triacetyloleandomycin inhibited ifosfamide N-dechloroethylation by human liver microsomes with an IC50 of approximately 10 microM. Furthermore, anti-human CYP3A4 antiserum inhibited by about 80% N-dechloroethylation of ifosfamide by human liver microsomes. The relative levels of cytochromes P450 1A, 2C, 2E and 3A4 in 12 human livers were determined by western blotting analysis. A strong correlation (P < 0.001) was observed between CYP3A4 expression and both activation and N-dechloroethylation of ifosfamide. A role for human CYP3A4 in both pathways of ifosfamide metabolism was thus demonstrated. This was substantiated by the observation that the nifedipine oxidase activities of the 12 samples of human liver microsomes correlated with ifosfamide activation (P < 0.009) and N-dechloroethylation (P < 0.001). These findings have important clinical implications. The involvement of the same key cytochrome P450 enzyme in both reactions prohibits selective inhibition of the N-dechloroethylation pathway, as might be desirable to reduce toxic side effects. They also demonstrate the need to consider interaction with co-administered drugs that are CYP3A4 substrates.

Long-term oral etoposide in metastatic breast cancer: clinical and pharmacokinetic results

To evaluate the activity of long-term, single-agent oral etoposide against advanced breast cancer, this study employed etoposide 50 mg/day and 100 mg/day (given over 14 days) in previously treated and chemotherapy-naive patients with histologically confirmed, recurrent or metastatic breast cancer. Of 38 patients, 24 had had chemotherapy, 34 had prior radiotherapy, and 31 had received hormone therapy. Etoposide courses in both treatment groups were repeated every 4 weeks for at least two courses; delays were instituted when patients' total leukocyte nadir fell to or below 3.0 x 10(9)/l. Dose reductions were made in the 100-mg group (to 50 mg/day) if World Health Organization leukopenia grade 3 or higher was present. Plasma pharmacokinetic profiles were measured in selected patients to assess inter- and intrapatient variability in etoposide's oral bioavailability. No complete responses were achieved among the 36 patients evaluable for response, but eight patients had a partial response. Responses were more frequent at the 100-mg dose and in previously untreated patients (seven of eight partial responders had not had previous chemotherapy). Median duration of response was 16 weeks (range, 7 to 46). Myelosuppression (variable and unpredictable) and alopecia (universal) were the notable toxicities. Pharmacokinetic analyses of oral bioavailability revealed significant interpatient variability, but much less intrapatient variability when successive etoposide courses in individual patients were evaluated. Despite the relatively small number of patients in this study, the responses achieved by previously untreated patients suggest etoposide's value against breast cancer. Further trials should use pharmacokinetic studies to assess bioavailability as well as to help define 'target' etoposide doses, based on plasma etoposide levels, during treatment.