Impact of perioperative right ventricular assist device on ventricular arrhythmias in patients with continuous flow left ventricular assist device

Background

Patients with continuous flow left ventricular assist device (LVAD) may develop right ventricular failure in perioperative period of LVAD implantation. Some of these patients require temporary support with right ventricular assist device (RVAD). There is paucity of data regarding the impact of RVAD support on incidence of ventricular arrhythmias (VA) in LVAD patients.

Purpose

To assess the impact of perioperative RVAD support on the incidence of VA in the first 6 months after LVAD implant.

Methods

This is a retrospective study including 316 patients undergoing LVAD implantation at the University of Nebraska Medical Center, USA since 2012. Patients were divided into 2 groups- those who required perioperative RVAD support (BiVAD group) and those who did not require it (LVAD only group). VA was defined as any sustained ventricular tachyarrhythmia lasting more than 30 seconds or requiring therapy from implantable cardioverter-defibrillator. Incidence of VA in the first 6 months post-LVAD implantation was analyzed and compared between the groups using Cox proportional hazards regression analysis.

Results

Out of 316 total patients, 52 (16%) patients required RVAD support. The difference in age, gender, race and medications between the two groups was not statistically significant. The patients in BiVAD group had a higher incidence of post-LVAD VA (35%) as compared to LVAD only group (21%). On Cox proportional hazards regression analysis, the difference was found to be statistically significant even after adjusting for history of pre-LVAD VAs (HR: 2.27; p=0.02) (Figure 1).

Conclusion

In this large single center cohort of LVAD patients, we noticed a statistically higher incidence of VA in subgroup of patients requiring perioperative RVAD support.

Figure 1

Funding Acknowledgement

Type of funding source: None

Specific class of intrapartum antibiotics relates to maturation of the infant gut microbiota: a prospective cohort study

OBJECTIVE

To evaluate the potential impact of intrapartum antibiotics, and their specific classes, on the infant gut microbiota in the first year of life.

DESIGN

Prospective study of infants in the New Hampshire Birth Cohort Study (NHBCS).

SETTINGS

Rural New Hampshire, USA.

POPULATION OR SAMPLE

Two hundred and sixty-six full-term infants from the NHBCS.

METHODS

Intrapartum antibiotic use during labour and delivery was abstracted from medical records. Faecal samples collected at 6 weeks and 1 year of age were characterised by 16S rRNA sequencing, and metagenomics analysis in a subset of samples.

EXPOSURES

Maternal exposure to antibiotics during labour and delivery.

MAIN OUTCOME MEASURE

Taxonomic and functional profiles of faecal samples.

RESULTS

Infant exposure to intrapartum antibiotics, particularly to two or more antibiotic classes, was independently associated with lower microbial diversity scores as well as a unique bacterial community at 6 weeks (GUnifrac, P = 0.02). At 1 year, infants in the penicillin-only group had significantly lower α diversity scores than infants not exposed to intrapartum antibiotics. Within the first year of life, intrapartum exposure to penicillins was related to a significantly lower increase in several taxa including Bacteroides, use of cephalosporins was associated with a significantly lower rise over time in Bifidobacterium and infants in the multi-class group experienced a significantly higher increase in Veillonella dispar.

CONCLUSIONS

Our findings suggest that intrapartum antibiotics alter the developmental trajectory of the infant gut microbiome, and specific antibiotic types may impact community composition, diversity and keystone immune training taxa.

TWEETABLE ABSTRACT

Class of intrapartum antibiotics administered during delivery relates to maturation of infant gut microbiota.

Abstract GS5-02: Cardiovascular function and the effect of exercise training during adjuvant breast cancer treatment. Results from The EBBA-II trial

Background: Breast cancer survival rates have improved, but cardiovascular disease is a competing cause of death among breast cancer survivors, and treatment-induced cardio-toxicity remains a major concern. The effect of aerobic exercise on cardiovascular function during adjuvant breast cancer treatment is not yet well established.

Material & methods: The women participating in the Energy Balance and Breast Cancer Aspect (EBBA)-II trial are aged 18-75 years and diagnosed with stage I-II breast cancer. VO2max was assessed at three separate times, prior to surgery and at 6 and 12 months after, using a maximum exercise test on a treadmill (modified Balke protocol).The patients were randomized after surgery to a control group (n=188, usual care) or an intervention group (n=187) stratified by menopausal status. The 12 months exercise intervention program started 2-3 weeks after surgery and the patients received a detailed training program based on their own VO2max at baseline. They met for training sessions in groups of 10-12 women for 60 minutes twice a week during a 12 month period, and were in addition asked to perform at least 120 minutes of exercise at home (a total of 240 minutes of exercise weekly).Analyses were done on an intention-to-treat basis (NCT02240836).

Preliminary results: Breast cancer patients (n=375) with a mean age at diagnosis of 55.2 years (27.0-75.0 years) had a mean body mass index (BMI) of 25.1kg/m2, a mean VO2max before surgery of 31.5 ml•min−1•kg−1, and 57 % of the patients underwent chemotherapy (paclitaxel, epirubicin/cyclophosphamide based adjuvant chemotherapy). Comparing the intervention group to the control group, the intervention group had a decrease in VO2max of 2.7% after 6 months, but they improved their VO2max by 2.3 % at 12 months compared to before surgery (p=0.001). Breast cancer patients in the control group had a 10 % reduction in VO2max 6 months after surgery (p<0.001), and a 3.8% decrease in VO2max was observed at 12 months compared to before surgery (p<0.001). Among patients in the control group who received chemotherapy, a decline in VO2max by 5.3 ml•min−1•kg−1 (16.2%) (p<0.001) at 6 months was observed. This reduction in VO2max at 6 months was most pronounced in patients who received paclitaxel alone, or paclitaxel in combination with epirubicin/cyclophosphamide (6.1 ml•min−1•kg−1, 18.7% decrease). In comparison, patients in the intervention group who received chemotherapy had a decline of 2.4 ml•min−1•kg−1 (7.6%) in VO2max at 6 and after 12 months VO2max was equal to before surgery. Differences in VO2max at 6 and after 12 month between groups were in favor of the intervention group (p<0.05).

Conclusion: Our findings strongly support that tailored exercise training during adjuvant breast cancer treatment may counteract a decline in cardiovascular function, and in particular among those receiving chemotherapy. Our study supports incorporation of supervised clinical exercise programs into breast cancer treatment guidelines.

Final results of the trial at SABCS 2018 (the trial closes October 15, 2018) total included N=539 (NCT02240836)

Citation Format: Thune I, Husøy A, Frydenberg H, Flote VG, Fjeldheim F, Bertheussen GF, Lundgren S, Lømo J, Wist EA, McTiernan A, Schlichting E. Cardiovascular function and the effect of exercise training during adjuvant breast cancer treatment. Results from The EBBA-II trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS5-02.

Abstract P6-13-01: Proteomic response in breast cancer treated with neoadjuvant chemotherapy with and without bevacizumab: Reverse phase protein array (RPPA) results from NeoAva - A randomized phase II study

BACKGROUND: Patients with HER2 negative primary tumors of ≥25 mm were treated with neoadjuvant chemotherapy (4 x FEC100 + 12 weeks of taxane-based therapy) and randomized (1:1) to receive bevacizumab or not. Mammography, ultrasound and MR imaging were used for response evaluation, in addition to the final pathology assessment after surgery.

HYPOTHESIS: RPPA proteomic analyses support identification of molecular mechanisms associated with clinical response to bevacizumab treatment.

METHODS: Tumor responses were evaluable in 132 patients; of which 66 received bevacizumab. Ratio of the tumor size at final pathology assessment, and at inclusion was calculated to obtain a continuous scale of response reflecting the percentage of tumor shrinkage in response to therapy. Tumor material was obtained at screening, 12 weeks into treatment and at surgical removal of tumors at 25 weeks. Lysates from each sample was analyzed on reverse phase protein arrays (RPPA) for expression levels of 210 proteins of which 54 were phospho-specific.

RESULTS: Several proteins were found for which expression prior to treatment reflected a better response on tumor shrinkage in the combination treatment arm (chemotherapy+bevacizumab). The proteomic response from week 0 to 12 in both treatment arms had an overall similar profile regarding up- and down-regulated proteins; however, the combination treatment (FEC100 + bevacizumab) induced a more pronounced effect on regulation of each protein. This might reflect the capability of bevacizumab therapy to potentiate the effects of the anthracyclin based chemotherapy from week 0 to 12. Conversely, from week 12-25 (taxane-based therapy + bevacizumab) this effect was lost or even reversed, except for certain phosphoproteins where potentiation imposed by bevacizumab was sustained throughout the whole treatment period. We are in the process of analyzing the impact of phosphorylation and thus protein activation states on treatment response. Furthermore, tumors with low hormone receptor pathway score demonstrated a better response in the combination treatment (chemotherapy+bevacizumab). Additionally, in these good responders the hormone signaling pathway was significantly upregulated during treatment. Further investigations are conducted to determine if this was due to selective ablation of hormone receptor negative tumor cells, or a re-programming of the molecular phenotype of cells present prior to treatment. The above mentioned results have potentially important clinical relevance and will be further investigated with respect to subtypes and the biological pathways affected by antiangiogenic therapy.

Citation Format: Haugen MH, Lindgjærde OC, Krohn M, Zhao W, Lindholm EM, Silwal-Pandit L, Borgen E, Garred Ø, Fangberget A, Holmen MM, Schlichting E, Skjerven H, Lundgren S, Wist E, Naume B, Mælandsmo GM, Lu Y, Børresen-Dale A-L, Mills GB, Engebråten O. Proteomic response in breast cancer treated with neoadjuvant chemotherapy with and without bevacizumab: Reverse phase protein array (RPPA) results from NeoAva - A randomized phase II study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-13-01.

Abstract P4-14-01: A time course study of genomic instability in breast cancer patients receiving neoadjuvant therapy with or without bevacizumab

Tumor heterogeneity is an area of intense research, revealing tumors with high complexity consisting of different subclones and infiltrating cells. Identification of subclones that are resistant to therapy may be critical to improve treatment outcome.

The NeoAva study is a randomized phase II, clinical trial of Her2 negative breast cancer patients treated in a neoadjuvant setting with chemotherapy (FEC and taxane) +/- bevacizumab. Core needle biopsies were obtained at screening and after 12 weeks, and the tumor was surgically removed after 25 weeks. DNA copy number changes in the tumors were analyzed using Affymetrix SNP Array 6.0. Allele specific copy number changes were assessed using the Allele-Specific Copy number Analysis of Tumors (ASCAT) algorithm (Van Loo, Norgard et al., PNAS 2010) and allele-specific Piecewise Constant Fitting (asPCF) algorithms (Nilsen, Liestol et al., BMC Genomics 2012). Measures of genomic instability were obtained through the complex arm-wise aberration index (CAAI) that captures local rearrangements (‘firestorms’) (Russnes, Vollan et al., Sci Transl Med 2010).

Changes in copy number aberrations between the three different time points were observed in almost all tumors. Some tumors showed a decrease in tumor percentage and aberrations after just 12 weeks of treatment, where others showed loss of aberrations only at the time of surgery (25 weeks). Most of the tumors that did retain aberrations at all time points during treatment, did not demonstrate any decrease in tumor size. Other profiles indicated subclonal reduction, where some aberrations are kept throughout treatment and others disappear. Many of the tumors shrinking in size showed fewer whole arm aberrations than before treatment, but retained their focal amplicons. Some of the tumor aberrations seem to disappear after 12 weeks, but to reappear after 25 weeks, but with the addition of novel aberration.

Complex rearrangements were identified in 67% of tumors before treatment. The most frequent ‘firestorms’ were found on 20p, 11q and 8p. Some events were persistent through therapy, but the majority changed. An association between complex tumor genomes and patients having progressive disease/non-responders were observed.

These results show the complex structure of a tumor and suggest that heterogeneity will influence the response to treatment. The subclonal patterns of tumors may be of great importance for clinical decision-making, as well as for monitoring treatment efficacy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-14-01.

Abstract P4-14-02: Molecular response in breast cancer tumors treated with neoadjuvant chemotherapy with and without bevacizumab: Results from NeoAva - A randomized phase II study

Patients treated with bevacizumab in addition to regular neoadjuvant chemotherapy achieve an increased rate of pathological complete response (pCR). The molecular characteristics of responding and non-responding tumors, including how treatment combinations influence the gene expression profiles and the signaling pathways, may be useful predictors of antiangiogenic response.

The NeoAva study included patients with HER2 negative primary tumors of ≥25 mm that were randomized (1:1) to receive neoadjuvant chemotherapy (4 x FEC100 + 12 weeks of taxane-based therapy) with or without bevacizumab. Mammography, ultrasound and MR imaging were used for response evaluation, in addition to final pathology assessment.

In the first part of the study 74 patients were evaluable for tumor response. The tumor size at time of inclusion was T2, T3 and T4 in 24.3%, 67.6% and 8.1% of the patients, respectively. Lymph node metastases were detected in 56.7% of the patients at inclusion and 82.4% were hormone receptor positive. There were no significant differences in the tumor size, lymph node or hormone receptor status between the treatment arms.

The patients were randomized with bevacizumab + chemotherapy (n = 37) and treatment with chemotherapy alone (n = 37). Of the nine patients who achieved pCR in breast and axilla (12.2%), seven patients received bevacizumab (7/37), while two were treated with chemotherapy alone (2/37). Four of the patients with pCR were hormone receptor negative, of which three received bevacizumab. Of the remaining five hormone receptor positive tumors that achieved complete response, four received bevacizumab.

In the second part of the study we evaluated gene expression signatures by RNA microarray and the time-response of pathways to treatment, using pathway analysis that integrates copy number and gene expression (Paradigm). Biopsies for molecular analyses were collected before therapy, after 12 weeks, and at surgery. Treatment associated gene expression changes to chemotherapy were subtracted, and bevacizumab associated differential expression was observed for 1069 genes. Furthermore, molecular profiling of the tumor tissue was performed at DNA level by copy number analysis (Affymetrix, SNP6.0) and mRNA level by gene expression arrays(Agilent 60K). At the screening time point, we found high proliferation through the activity of cyclin E and B and the transcription factors E2F1 and FOXM1. At 12 weeks, there was a strong increase in predicted p53 signaling, due to increased activity of downstream target genes. The 12 week timepoint was also characterized by an increase of Calmodulin 1, MAPK3, as well as Peroxisome proliferator-activated receptor alpha (PPAR-alpha), and both trends continued to the 25 week time point. At 25 weeks, there were broad increases in ERK1/2, JUN, and FOS signaling. The 25 week timepoint also showed a T-cell response signature that from increased activity of GATA3, IL6/IL6R, IL4, and NFATC1 and NFATC2. These results suggest that there are measurable and strongly significant aberrations in molecular activity during treatment, which may be useful to monitor treatment response.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-14-02.

Abstract P1-13-13: Association between the serum concentrations of tamoxifen and its metabolites and age during steady state breast cancer treatment

It has been suggested that the concentrations of tamoxifen and its demethylated metabolites increase with age. Here, we measured the serum concentrations of the active tamoxifen metabolites, 4OHtamoxifen (4OHtam), 4OHNdesmethyltamoxifen (4OHNDtam, Endoxifen), tamoxifen and its demethylated metabolites. Their relations to age were examined. 151 breast estrogen receptor and/or progesterone receptor positive cancer patients were included. Tamoxifen and its metabolites were measured by liquid chromatography-tandem mass spectrometry. Their serum concentrations were related to the age of the patients. The concentrations of 4OHNDtam, tamoxifen, NDtam (N-desmethyltamoxifen), and NDDtam (N-desdimethyltamoxifen) were positively correlated to age (n = 151, P = 0.017, 0.045, 0.011, and 0.001 respectively). Up to tenfold inter-patient variation in the serum concentrations was observed. The median (inter-patient range) of the concentrations 4OHNDtam in the age groups 30-49, 50-69 and >69 years were 44 (65) ng/ml, 51 (116) ng/ml, and 54 (159) ng/ml, respectively. We conclude that the serum concentrations of 4OHNDtam (endoxifen), tamoxifen and its demethylated metabolites increase with age during steady state tamoxifen treatment. The observed high inter-patient range in serum concentrations of tamoxifen and its metabolites, especially in the highest age group, suggest that use of therapeutic monitoring of tamoxifen and its metabolites is warranted.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-13-13.

Abstract P6-09-03: Fatigue after breast cancer may be related to conditions other than the cancer. The impact of comorbidity is essential

Purpose: Fatigue after treatment for breast cancer is common, but is also prevalent in people with chronic diseases such as heart failure, diabetes, and depression etc. The primary objective was to compare the level of fatigue between BC patients one year after end of treatment with data from a representative survey of the Norwegian population (GenPop). Secondary aim was to explore the association between chronic conditions and fatigue and in both samples.

Design and Method: 245 patients treated with chemo –and/or radiotherapy after surgery, were assessed one year after treatment. Comorbidity was recorded by clinical examinations in patients and by self-report in the GenPop (N = 652). Fatigue was measured by the 3-item subscale of the EORTC QLQ-C30, with higher scores on the 0–100 scale implying more fatigue. Analysis of covariance was applied to compare age-adjusted mean scores between groups.

Results: Mean age was 58 (9) years in patients and 52 (14) years in GenPop. 23% of patients and 32% of GenPop had one or more of the following conditions; cardiovascular- or pulmonary disease, diabetes or depression. No significant differences were found in fatigue between BC patients and GenPop (mean score 26.7 vs. 29.7). Comorbidity was the greatest determinant of increased fatigue, regardless of BC treatment. Patients with comorbidity were significantly more fatigued than those without comorbidity (mean difference 10.4), as found in the GenPop (mean difference 13.3).

Conclusion: Similar fatigue levels in BC patients and GenPop one year after treatment is promising, but longer follow-up is needed. Comorbidity conditions should always be assessed when evaluating fatigue and other patient related outcomes. Prevention or treatment of common chronic conditions might be considered in rehabilitation programs to reduce fatigue in cancer survivors.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-09-03.

P4-06-05: Prognostic Impact of Disseminated and Circulating Tumor Cells in Patients Treated for Locally Advanced Breast Cancer

INTRODUCTION: Neoadjuvant systemic therapy (NST) in breast cancer patients is an established approach to reduce tumor size prior to surgery and to assess the clinical effect of therapy on the breast cancer disease. The current study was designed to identify primary tumor resistance factors to epirubicin and paclitaxel therapy in patients with locally advanced breast cancer (Chrisanthar et al PLoSOne 2008 and 2011). As a substudy, the incidence of disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) before and after therapy, was investigated. The aim was to evaluate the prognostic impact of DTCs and CTCs as well as to evaluate the effect of NST on DTCs and CTCs.

PATIENTS AND METHODS: Patients with locally advanced non-inflammatory breast cancer (T3-4and/or N2) were included in the study. The patients were randomly allocated to primary treatment either with epirubicin 90mg/m2 or paclitaxel 200mg/m2, with cross-over design if no response/progression, followed by mastectomy and axillary dissection. Bone marrow (BM) aspiration and peripheral blood (PB) samples were collected before NST (BM1/PB1)(n=230), at the time of surgery (BM2/PB2)(n=69; logistic reasons caused reduced sampling) and 12 months after randomization (BM3/PB3)(n=162). Detection of DTCs/CTCs was performed by standard immunocytochemical analysis of 2×106 mononuclear cells stained for cytokeratin by AE1AE3 antibodies. Patient outcomes were evaluated over a 10-year follow-up period. Univariate and multivariable proportional hazards models were estimated to assess the prognostic significance of DTC for disease-free survival (DFS) and overall survival (OS).

RESULTS: Before NST (BM1) 21.3% were DTC positive, compared to 15.9% and 26.5% at BM2 and BM3, respectively. Of those that both had BM1 and BM3 performed, 68% concordance and 22% overlap among positive cases was observed. Presence of DTCs in BM3 predicted reduced DFS (HR 2.2; 95% CI 1.3−3.7; p=0.007) and OS (HR 3.0; 95% CI 1.8−5.2; p>0.001). DTC status before NST had no impact on outcome. No difference in the results was observed after exclusion of patients with limited M1 status at diagnosis (25 and 13 of those analysed for BM1 and BM3, respectively). The incidence of CTCs before NST was 4.9 % compared to 1.4% and 4.3 % at PB2 and PB3, respectively. Presence of CTC before NST was associated with reduced overall survival (HR 2.4; 95% CI 1.2−5.0; p=0.018), but CTC status was not significant for DFS or at other time points. In the multivariable analysis, DTC status at BM3 remained as a prognostic factor for both DFS (HR 2.0; 95% CI 1.1−3.6) and OS (HR 2.1; 95% CI 1.04−4.2).

CONCLUSION: In patients with locally advanced breast cancer, the presence of CTCs at the time of diagnosis identified high risk patients. However, the sensitivity of the performed CTC analysis was too low for further interpretation. Presence of DTCs 12 months after neoadjuvant therapy increased the risk for relapse and death. The best clinical utility of DTC analysis appears to be as a monitoring tool during follow up, in a “window of opportunity” for selection of patients to secondary adjuvant treatment intervention within clinical trials.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-06-05.

Cyclophosphamide induces mRNA, protein and enzyme activity of cytochrome P450 in rat

The effects of cyclophosphamide (CPA) on CYP enzymes in vivo and its auto induction in rat were investigated in Wistar/Fu male rats at a single dose (40 or 200 mg kg(-1)) or as repeated dose of 200 mg kg(-1) CPA. After a single dose of CPA, mRNAs of CYPs 2B1, 2B2, 3A2, 2C11 were significantly induced up to 220-, 6.7-, 5.0- and 5.8-fold at the low dose CPA, and 4800-, 52-, 22- and 2.5-fold at the high dose. CYP2B1/2 and CYP3A proteins were increased by 4- and 2-fold (low dose) and by 28- and 1.7-fold (high dose). CYP2C11 protein levels were not altered. Microsomal activities of CYP2B, CYP3A and 2C11 were increased by 2-, 1.8- and 1.3-fold at low dose CPA, and 3.2-, 1.7- and 1.6-fold at high dose. A significant (p<0.05) decrease in CPA concentration and a significant (p<0.05) increase in 4-OH-CPA levels were observed with repeated administration of CPA. Acute induction effect on CYP2B1, 2B2, 2C11 and 3A2 and a substantial up regulation of CYP2B1 mRNA were observed after a single dose of CPA, auto induction was observed by repeated administration.

Characterisation of the signal transduction cascade caused by propofol in rat neurons: from the GABA(A) receptor to the cytoskeleton

The anaesthetic propofol interacts with the GABA(A) receptor, but its cellular signalling pathways are not fully understood. Propofol causes reorganisation of the actin cytoskeleton into ring structures in neurons. Is this reorganisation a specific effect of propofol as apposed to GABA, and which cellular pathways are involved? We used fluorescence-marked actin in cultured rat neurons to evaluate the percentage of actin rings caused by propofol or GABA in combination with rho, rho kinase (ROK), PI3-kinase or tyrosine kinase inhibitors, with or without the presence of extracellular calcium. Confocal microscopy was performed on propofol-stimulated cells and changes in actin between cellular compartments were studied with Western blot. Propofol (3 microg x ml-1), but not GABA (5 microM), caused transcellular actin ring formation, that was dependent on influx of extracellular calcium and blocked by rho, ROK, PI3-kinase or tyrosine kinase inhibitors. Propofol uses rho/ROK to translocate actin from the cytoskeleton to the membrane and its actin ring formation is dependent on an interaction site close to the GABA site on the GABA(A) receptor. GABA does not cause actin rings, implying that this is a specific effect of propofol.

Friction of fatty acids in nanometer-sized contacts of different adhesive strength

The effects of adhesion, contact area, and pressure on the lubricating properties of self-assembled monolayers on steel have been investigated with friction force microscopy. The adsorbed molecules were fatty acids with varying degrees of unsaturation (0-2 double bonds; stearic, oleic, and linoleic acid) and a rosin acid (dehydroabietic acid), adsorbed from n-hexadecane solution. The friction of these loose-packed monolayers was studied in dry N2 gas and in ethanol. Low adhesion (in ethanol) resulted in a linear increase in friction force at low loads, that is, F = muL, whereas higher adhesion (in N2 gas) gave an apparent area-dependence at low loads of the form F = S(c)A, where S(c) is the critical shear stress. A recent model for the contact mechanics of a compliant elastic film confined between stiffer substrates was applied to the data obtained in dry N2. Using this approach, we obtained interfacial energies of the compliant monolayers in good agreement with van der Waals-Lifshitz theory. With a low monolayer elastic modulus of E'(1)=0.2 GPa, we obtained a slightly higher value of Sc for stearic acid than that established for more close-packed stearic acid monolayers. An increase of mu and S(c) was found with increasing degree of unsaturation of the fatty acid.

Adjuvant cyclic Tamoxifen and Megestrol acetate treatment in postmenopausal breast cancer patients – Longterm follow-up

AIMS

To evaluate possible differences in effect on recurrence-free survival (RFS) and overall survival (OS) in node positive postmenopausal breast cancer patients receiving Tamoxifen or cyclic Tam and Megestrol acetate as adjuvant treatment.

METHODS

Between 1989 and 1994, 489 patients with pT(1-2)pN+ hormone receptor positive or unknown tumours were included in a randomized national multicenter study to receive either Tam alone or cyclic Tam (8 weeks) and MA (8 weeks) for 2 years. Final follow-up was completed as of June 2002. Time from start of treatment to first recurrence and novel primary breast tumour, overall survival and cancer specific survival were estimated.

RESULTS

No differences in RFS, OS or cancer specific survival were observed between the two treatment groups.

CONCLUSIONS

Adjuvant treatment used as standard Tam alone, compared to Tam and MA, as employed in this group of patients gave similar outcomes. Side effects that led to cessation of study medication were observed in both arms.

Effects of CYP2D6 and SULT1A1 genotypes including SULT1A1 gene copy number on tamoxifen metabolism

BACKGROUND

Tamoxifen is hydroxylated by cytochrome P450 (CYP) 2D6 to the potent metabolites 4-hydroxytamoxifen (4OHtam) and 4-hydroxy-N-demethyltamoxifen (4OHNDtam), which are both conjugated by sulphotransferase (SULT)1A1. Clinical studies indicate that CYP2D6 and SULT1A1 genotypes are predictors for treatment response to tamoxifen. Therefore, we examined the relationship between CYP2D6 genotype, SULT1A1 genotype, SULT1A1 copy number and the pharmacokinetics of tamoxifen.

PATIENTS AND METHODS

The serum levels of tamoxifen and metabolites of 151 breast cancer patients were measured by high-pressure liquid chromatography-tandem mass spectrometry. The CYP2D6 and SULT1A1 polymorphisms and SULT1A1 copy number were determined by long PCR, PCR-based restriction fragment length polymorphism, DNA sequencing and fluorescence-based PCR.

RESULTS

The levels of 4OHtam, 4OHNDtam and N-demethyltamoxifen were associated with CYP2D6 predicted enzymatic activity (P < 0.05). The SULT1A1 genotype or copy number did not influence the levels of tamoxifen and its metabolites. However, the ratios of N-demethyltamoxifen/tamoxifen and N-dedimethyltamoxifen/N-demethyltamoxifen were related to SULT1A1 genotype.

CONCLUSION

CYP2D6 and SULT1A1 genotypes may partly explain the wide inter-individual variations in the serum levels of tamoxifen and its metabolites. We propose that therapeutic drug monitoring should be included in studies linking CYP2D6 and SULT1A1 genotypes to clinical outcome.