Metastatic breast tumors express increased tau, which promotes microtentacle formation and the reattachment of detached breast tumor cells

The cytoskeletal organization of detached and circulating tumor cells (CTCs) is currently not well defined and may provide potential targets for new therapies to limit metastatic tumor spread. In vivo, CTCs reattach in distant tissues by a mechanism that is tubulin-dependent and suppressed by polymerized actin. The cytoskeletal mechanisms that promote reattachment of CTCs match exactly with the mechanisms supporting tubulin microtentacles (McTN), which we have recently identified in detached breast tumor cells. In this study, we aimed to investigate how McTN formation is affected by the microtubule-associated protein, tau, which is expressed in a subset of chemotherapy-resistant breast cancers. We demonstrate that endogenous tau protein localizes to McTNs and is both necessary and sufficient to promote McTN extension in detached breast tumor cells. Tau-induced McTNs increase reattachment of suspended cells and retention of CTCs in lung capillaries. Analysis of patient-matched primary and metastatic tumors reveals that 52% possess tau expression in metastases and 26% display significantly increased tau expression over disease progression. Tau enrichment in metastatic tumors and the ability of tau to promote tumor cell reattachment through McTN formation support a model in which tau-induced microtubule stabilization provides a selective advantage during tumor metastasis.

Osteopontin induces angiogenesis through activation of PI3K/AKT and ERK1/2 in endothelial cells

Angiogenesis is a key step in tumor growth and metastasis. The mechanism by which osteopontin (OPN) induces the angiogenesis of endothelial cells remains unclear. Here, we show that OPN confers cytoprotection through the activation of the PI3K/Akt pathway with subsequent upregulation of Bcl-xL and activation of nuclear factor-kappaB. OPN enhances the expression of vascular endothelial growth factor (VEGF) through the phosphorylation of AKT and extracellular signal-regulated kinase (ERK). In turn, OPN-induced VEGF activates PI3K/AKT and the ERK1/2 pathway as a positive feedback signal. Blocking the feedback signal by anti-VEGF antibody, PI3-kinase inhibitor or ERK inhibitor can partially inhibit the OPN-induced human umbilical vein endothelial cell (HUVEC) motility, proliferation and tube formation, while blocking the signal by anti-OPN or anti-alphavbeta3 antibody completely abrogates the biological effects of OPN on HUVECs. In addition, blood vessel formation is also investigated in vivo. The antiangiogenesis efficacy of anti-OPN antibody in vivo is more effective than that of anti-VEGF antibody, which only blocks the feedback signals. These data show that OPN enhances angiogenesis directly through PI3K/AKT- and ERK-mediated pathways with VEGF acting as a positive feedback signal. The results suggest that OPN might be a valuable target for developing novel antiangiogenesis therapy for treatment of cancer.

Drug Response Indicator Test (DRIT) as a predictive test for treatment outcomes in advanced breast cancer patients (ABC)

1119

Background: There are limited options for selecting an optimal treatment regimen for ABC patients (pts). DRIT is a platform technology that provides a profile of a patient's tumor's sensitivity or resistance to commonly used chemotherapeutic, hormonal, or biological agents as a basis for individualized anticancer treatment approach. DRIT may allow physicians to choose more effective drug treatments before initiation of therapy and improve the efficacy and toxicity profile of cancer therapies. Methods: DRIT analysis is based on fluorescent dye-labeled monoclonal antibody staining followed by computer-assisted microscopy to quantitatively measure expression levels in tumor sections. The interpretation of DRI expression levels results in classification of tumors as sensitive or resistant to treatment with a mechanistically related drug. This study utilized the following drug/DRI combinations: hormonal therapy/estrogen receptor; capecitabine/thymidylate synthase; docetaxel, paclitaxel, abraxane/β-tubulin isoform III; trastuzumab/HER-2; gemcitabine/ribonucleotide reductase. DRIT was performed on the tumor tissue of consented study participants with ABC who were then deemed to be sensitive or resistant to a given agent/agents. We then analyzed retrospectively clinical treatment outcomes (clinically sensitive to therapy defined as-stable disease+partial response+complete response or resistant to therapy-no response to therapy) for 91 treatment interventions in 71 pts with the DRIT tissue data. Results: We found that the DRIT sensitivity was 0.99, with specificity of 0.59, positive predictive value of 0.88, negative predictive value of 0.93 and overall predictive value of 88% for treatment outcomes for this cohort of ABC pts. Conclusions: This study suggests that DRIT can provide more accurate prediction of treatment outcomes for ABC pts than the standard of care approach and therefore has a potential to avoid unnecessary ineffective drug treatment exposure. Prospective study in ABC pts is currently conducted at the UMGCC.

[Table: see text]

Epidermal growth factor receptor inhibitors as second-line treatment in advanced non-small cell lung cancer: A meta-analysis

7597

Background: Overall survival in lung cancer remains poor despite availability of chemotherapy, which is limited by its toxicity and drug resistance. Advancement in research resulted to the development of targeted therapies, specifically epidermal growth factor receptor (EGFR) inhibitors. Results of clinical studies on survival benefits of EGFR inhibitors were conflicting although beneficial improvements in the quality of life and adverse effects were consistently demonstrated. The aim of our study is to determine the overall survival benefit of EGFR inhibitors alone or in combination with chemotherapy in second-line treatment of advanced non-small cell lung cancer (NSCLC). Methods: We did a meta-analysis of all randomized controlled trials involving patients with advanced NSCLC who failed at least one prior chemotherapy and were given EGFR inhibitor alone or in combination with chemotherapy compared to placebo or chemotherapy, with overall survival as an outcome. Pre-planned subgroup analysis was done on studies comparing EGFR to placebo and chemotherapy.Results: Five of the six trials included were analyzed for overall survival involving 4482 patients. Treatment with EGFR tyrosine kinase inhibitor (TKI) showed a trend towards significant survival benefit (RR=0.96, 95% CI 0.93–1.00, p=0.04) compared to placebo or chemotherapy. Preplanned subgroup analysis demonstrated significant survival benefit with EGFR-TKI versus placebo (RR=0.92, 95% CI 0.86–0.97, p=0.003) but comparable efficacy with chemotherapy (RR=1, 95% CI 0.96–1.06, p=0.84).Conclusions: Second-line treatment with EGFR-TKI demonstrated significant survival benefit versus placebo and comparable survival effect to chemotherapy. Further research should be done to identify patients’ characteristics associated with good treatment response.

[Table: see text]

A predictive test for therapeutic treatment outcomes of advanced gastrointestinal cancer patients (AGC)

e15079

Background: There are currently limited options for selecting an optimal treatment regimen for AGC patients. The Drug Response Indicator Test (DRIT) is a platform technology that provides a detailed profile of a patient's tumor response to commonly used chemotherapeutic drugs, as a basis for individualized treatment. Establishment of DRIT will allow physicians to choose effective drug treatments to improve the efficacy of cancer therapies on an individual basis. Methods: DRIT analysis is based on fluorescent dye-labeled monoclonal antibody staining followed by computer-assisted microscopy to measure expression levels in tumor sections. The interpretation of the Drug Response Indicator (DRI) expression levels result in classification of tumors as sensitive or resistant to treatment with a mechanistically related drug. Clinical outcomes are then analyzed with respect to the DRI data. This study utilized the following drug/DRI combinations: capecitabine, 5-flurouracil/thymidylate synthase; docetaxel, paclitaxel, abraxane/β-tubulin isoform III; gemcitabine/ribonucleotide reductase; platinum salts/ERCC-1; Irinotecan/Topoisomerase I. Results: DRIT retrospective studies were performed on a cohort of 33 consented patients (pts) receiving 55 treatments for AGC at UMGCC. This cohort included pts treated for rectal/colon, gastric, esophageal & pancreatic cancers. DRIT sensitivity was 0.96, positive predictive value 0.84, negative predictive value 0.67 and overall predictive accuracy 83 %. DRI expression level cut-off points indicating sensitivity or resistance to a specific treatment were derived from previous retrospective breast cancer studies using similar drug complements (abstract 6075 San Antonio Breast Conference 2008). Conclusions: This study indicates that DRIT can provide accurate prediction of treatment outcomes for individual AGC patients. DRI expression level cut-off points indicating sensitivity or resistance to a specific treatment may be applied to both breast cancer & AGC. DRIT will allow for tailoring of chemotherapy based on the specific biomarker expression within each patient's tumor tissue.

[Table: see text]

Putting sexuality (back) into HIV/AIDS: issues, theory and practice

After more than twenty years of programming and activism aimed at stemming the sexual transmission of HIV (and addressing the needs of those most vulnerable to infection) the HIV/AIDS epidemic continues to grow worldwide. Taking up this concern, this paper argues that one of the reasons why HIV prevention has had limited success is because of inadequate conceptualization of human sexuality in such work. Giving sexuality a more prominent position in responses to the epidemic raises a range of issues, including theorization of gender, understanding of sexual subjectivity, the significance of pleasure (or lack of pleasure) in sexual decision-making, and conceptualization of sexual behaviour and culture. Taking these themes forward entails asking significant questions about the underlying paradigmatic and methodological commitments of mainstream HIV/AIDS research, especially the tendency to reproduce accounts of human sexuality as if it were a measurable form of conduct only. Advocating new approaches that take the meaning and symbolic value of sexualities into account complicates established orthodoxies in the field whilst offering potential for more effective HIV prevention strategies.

Factors influencing family physicians' drug prescribing behaviour in asthma management in primary care

INTRODUCTION

Little is known about the decision pathway that family physicians (FP) take in considering drug therapy for their asthma patients. This study aimed to explore the factors that influence FPs' decisions in prescribing medications for their asthma patients.

METHODS

A qualitative method using focus group discussions (FGD) was used to gather qualitative data based on a semi-structured topic guide from FPs of different training backgrounds and practices. 29 Singapore FPs working as private general practitioners (GP), polyclinic doctors and locums were recruited into five FGDs.

RESULTS

The FPs' asthma drug prescription decisions were related to the FPs' medical training and acquisition of asthma-related information and updates. Uncertainty of disease diagnosis, patients' beliefs and their perceptions of the disease and treatment, as well as the FPs' concerns about drug side effects, were significant considerations for the participants. Costs related to differential subsidies in the consultation fees and drugs between public polyclinics and GP clinics in the local primary healthcare system, was a key factor in influencing the FPs' asthma drug treatment decisions.

CONCLUSION

FPs' asthma drug prescribing behaviour is influenced by their medical training, disease definition, patient factors and drug costs in the context of the local primary healthcare system and policy.

A qualitative study of factors influencing family physicians' prescription of the Written Asthma Action Plan in primary care in Singapore

INTRODUCTION

The Written Asthma Action Plan (WAAP) educates patients on the early recognition and treatment of deteriorating asthma. It has been adopted in Singapore polyclinics and restructured hospitals in the past few years as recommended by the Singapore National Asthma Programme. Local asthma patients can choose to be treated by family physicians at public polyclinics or by private general practitioners (GPs). In a previous study, half of the physicians in primary care self-reported that they formulated an asthma action plan for their patients, but little is known about their actual practices. This qualitative study explored family physicians' views of WAAP and its implementation in primary care in Singapore.

METHODS

Qualitative data was obtained for 29 participants from polyclinics, GP clinics or locum doctors at five separate focus group discussions. The data was coded using NVivo-7 software, audited and analysed to identify emergent themes.

RESULTS

The participants generally perceived the usefulness of WAAP. While WAAP was widely used in polyclinics, GPs rarely used it. Even in polyclinics, usage varied and was associated with participants' training and practice of WAAP and task substitution to nurses. They perceived that WAAP would benefit only selected motivated patients who could understand and use it. They were hampered by language barriers in educating their multiracial patients and the perceived lack of time related to patient loads in polyclinics. The GPs lacked training and practice, role models and relied on verbal instructions as a personalised form of care delivery.

CONCLUSION

Family physicians generally perceived WAAP as useful, but implementation was hampered by lack of training and practice, language barriers and perceived benefits for patients.

A retrospective study of drug response indicator test (DRIT) as a predictive test for therapeutic treatment outcomes of advanced breast cancer patients (ABC)

Abstract #6075

We conducted a retrospective study of DRIT, an investigational diagnostic test to predict chemotherapy and endocrine therapy treatment outcomes in ABC. DRIT is a quantitative measurement of Drug Response Indicator (DRI) expression levels in formalin fixed, paraffin embedded tumor tissue. DRI chosen for each drug is related to the perceived mechanism of action of the drug. The quantitative measurement of DRI expression in the tumor tissue is based on the fluorescent dye-labeled monoclonal antibody (mAb) staining, followed by acquisition of digital images using computer-assisted microscopy, calibrated to an external standard. DRI expression measurement results in classification of the tumor as sensitive or resistant to a particular drug based on our in vitro studies of drug sensitivity/resistance in cell lines. If a tumor is classified as sensitive to a drug/s by DRIT, this predicts that the patient (Pt) will respond to treatment, while if a tumor is classified as resistant this predicts that the Pt will not respond to the drug/s therapy. Clinically the treatment outcome is classified into a responsive group (non-progressive disease,CR, PR, SD) & a non-responsive group (progressive disease, PD). The drugs & DRI tested are: capcitabine/thymidylate synthase; Taxanes /β-tubulin isoform III, trastuzamab/HER-2, Endocrine therapy/estrogen receptor, gemcitabine/ribonucleotide reductase. 51 ABC received mono or doublet therapy as first 3 lines of therapy-(80 treatments). The percent accuracy (number of accurate predictions/number of treatment interventions) for monotherapy is 87% (61/70), 100% (10/10) for doublet therapy and 89% (71/80) for all treatments. The accuracy of prediction for responsive patients is 86% (60/69) and 100% (11/11) for non responsive patients. DRIT diagnostic performance for 80 treatment outcome predictions for endocrine therapy and mono and doublet chemotherapy is as follows: sensitivity 1.00, specificity 0.55, positive predictive value 0.87, negative predictive value 1.00, and overall accuracy 0.88. For the standard of care outcomes, the favorable response rate for the 80 treatments is 75% (60/80), the potential favorable response rate with DRIT input is 86% (60/69) with 11 ineffective treatments identified by DRIT accurately 100% (11/11). Thus, DRIT input can identify effective (86%) & ineffective (100%) treatments in this cohort of ABC patients. DRIT is under developement as a diagnostic test to predict treatment outcomes prior to the selection of a particular drug for anticancer therapy, so that the most effective drug can be prescribed for an individual cancer patient. This retrospective study in ABC patients shows that DRIT has a potential to be a useful test to predict treatment outcomes.
 Supported in part by Maryland Industry Partnership Program – MIPS.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6075.

Improving head growth in preterm infants--a randomised controlled trial II: MRI and developmental outcomes in the first year

BACKGROUND

Very preterm infants are at risk of poor growth and neurodevelopmental outcome. Illness and difficulties overcoming the challenges of feeding these infants often lead to undernutrition in the first few weeks.

OBJECTIVE

To explore the relationships between early nutrition, post-natal head growth, quantitative magnetic resonance imaging (MRI) and developmental outcome in the first year among infants born before 29 weeks' gestation.

DESIGN

Infants born before 29 weeks' gestation were randomised to receive hyperalimented or standard feeding regimen from birth to 34 weeks' postmenstrual age (PMA). The primary outcome was occipitofrontal circumference (OFC) at 36 weeks' OFC. Quantitative MRI was performed at 40 weeks' PMA. Developmental assessment using Bayley Scales of Infant Development II (BSID II) was carried out at 3 and 9 months post-term.

RESULTS

109 infants survived to the end of the first year PMA. 65 infants underwent MRI scan. 81 and 71 infants were seen at 3 and 9 months post-term. Quantitative MRI findings, mental development index (MDI) and psychomotor development index (PDI) were not statistically different between the two groups. Total brain volume (TBV) at 40 weeks' PMA, MDI and PDI at 3 months post-term correlated significantly with energy deficit at 28 days of age

CONCLUSIONS

Improving early energy deficit in very preterm infants may promote brain growth. Quantitative MRI may have a role to play in predicting developmental outcome. Post-natal growth at 36 weeks' PMA and quantitative MRI finding at 40 weeks' PMA appear to be closely related to mental outcomes in the first year.

TRIAL REGISTRATION NUMBER

ISRCTN 19509258.

Magnetic resonance direct thrombus imaging of the evolution of acute deep vein thrombosis of the leg

BACKGROUND

Accurate diagnosis of acute recurrent deep vein thrombosis (DVT) is relevant to avoid improper diagnosis and unnecessary life-long anticoagulant treatment. Compression ultrasound has high accuracy for a first episode of DVT, but is often unreliable in suspected recurrent disease. Magnetic resonance direct thrombus imaging (MR DTI) has been shown to accurately detect acute DVT. The purpose of this prospective study was to determine the MR signal change during 6 months follow-up in patients with acute DVT.

PATIENTS/METHODS

This study was a prospective study of 43 consecutive patients with a first episode of acute DVT demonstrated by compression ultrasound. All patients underwent MR DTI. Follow-up was performed with MR-DTI and compression ultrasound at 3 and 6 months respectively. All data were coded, stored and assessed by two blinded observers.

RESULTS

MR direct thrombus imaging identified acute DVT in 41 of 43 patients (sensitivity 95%). There was no abnormal MR-signal in controls, or in the contralateral extremity of patients with DVT (specificity 100%). In none of the 39 patients available at 6 months follow-up was the abnormal MR-signal at the initial acute DVT observed, whereas in 12 of these patients (30.8%) compression ultrasound was still abnormal.

CONCLUSION

Magnetic resonance direct thrombus imaging normalizes over a period of 6 months in all patients with diagnosed DVT, while compression ultrasound remains abnormal in a third of these patients. MR-DTI may potentially allow for accurate detection in patients with acute suspected recurrent DVT, and this should be studied prospectively.