Genetic variant predicts bevacizumab-induced hypertension in ECOG-5103 and ECOG-2100

BACKGROUND

Bevacizumab has broad anti-tumour activity, but substantial risk of hypertension. No reliable markers are available for predicting bevacizumab-induced hypertension.

METHODS

A genome-wide association study (GWAS) was performed in the phase III bevacizumab-based adjuvant breast cancer trial, ECOG-5103, to evaluate for an association between genotypes and hypertension. GWAS was conducted in those who had experienced systolic blood pressure (SBP) >160 mm Hg during therapy using binary analysis and a cumulative dose model for the total exposure of bevacizumab. Common toxicity criteria (CTC) grade 3-5 hypertension was also assessed. Candidate SNP validation was performed in the randomised phase III trial, ECOG-2100.

RESULTS

When using the phenotype of SBP>160 mm Hg, the most significant association in SV2C (rs6453204) approached and met genome-wide significance in the binary model (P=6.0 × 10(-8); OR=3.3) and in the cumulative dose model (P=4.7 × 10(-8); HR=2.2), respectively. Similar associations with rs6453204 were seen for CTC grade 3-5 hypertension but did not meet genome-wide significance. Validation study from ECOG-2100 demonstrated a statistically significant association between this SNP and grade 3/4 hypertension using the binary model (P-value=0.037; OR=2.4).

CONCLUSIONS

A genetic variant in SV2C predicted clinically relevant bevacizumab-induced hypertension in two independent, randomised phase III trials.

Abstract P1-12-01: Clinical impact of internet-based tools to help guide therapeutic decisions for metastatic breast cancer (MBC)

Background: Clinical practice guidelines are an important resource to help guide management of patients with MBC. However, guidelines are sometimes difficult to apply to individual patients, particularly when there are 2 or more treatment options with similar levels of evidence. We sought to determine whether expert recommendations on MBC treatment, delivered via an interactive, online decision support tool, would change or confirm the treatment decisions of community practitioners. We further sought to analyze changes in practice patterns and expert recommendations over time by comparing data from the current tool (2013) with data from a similar tool developed previously (2012).

Methods: Both online decision support tools were developed based on input from a panel of 5 experts. Each expert provided treatment recommendations for more than 400 patient scenarios based on a simplified set of variables: disease phenotype (HR status, HER2 status), previous therapy, visceral crisis (yes/no), and rate of disease progression. Users of the tool are prompted to enter specific patient criteria, and are asked to state their intended management approach for that particular patient case. The tool then shows the recommendations of the 5 MBC experts for the specific patient case that the user entered. Finally, the user is prompted to indicate whether the experts’ recommendation confirmed or changed their intended management approach. An analysis of expert recommendations and user-selected treatments was performed to compare results of the 2013 and 2012 tools.

Results: The 2012 decision support tool was utilized by 697 individuals who entered more than 1000 patient case scenarios. Users indicated that the experts’ recommendations changed their intended management approach for 30% of the cases, confirmed their approach for 36%, and did not impact their intended approach for 34%. Utilization data for the 2013 tool are pending. Expert recommendations in the 2012 vs 2013 tools changed to reflect emerging developments in guidelines, evidence, and clinical practice. For example, in 2012 there was no expert consensus on use of everolimus + hormonal therapy for HR+, HER2- patient cases, whereas in 2013, everolimus-based therapy was recommended by the majority of experts (3 out of 5) for 12 different HR+, HER2- cases. There was no consensus among the experts on the use of pertuzumab + trastuzumab and a taxane for HER2+ MBC in 2012, whereas in 2013 at least 3 out of 5 experts recommended it for a total of 36 HER2+ cases. At least 3 of 5 experts recommended trastuzumab emtansine for 96 different HER2+ cases in 2013 vs 0 in 2012. In both 2012 and 2013, the greatest variability in expert treatment recommendations was observed for HR-, HER2- cases.

Conclusions: An online tool providing expert advice on specific MBC patient scenarios either confirmed or changed the clinical approach for a majority of community practitioners. Decision support tools may increase the number of clinicians who make optimal treatment decisions for patients with MBC, especially when new data, agent indications, and guideline updates must be incorporated. Detailed comparisons of expert and user responses from the 2012 and 2013 decision support tools will be presented.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-12-01.

Abstract P5-17-01: Bevacizumab (B) in the adjuvant treatment of breast cancer - first toxicity results from Eastern Cooperative Oncology Group trial E5103

Background: A previous feasibility trial (E2104 – Ann Oncol 23(2):331–7,2012) suggested incorporation of B into anthracycline-containing adjuvant therapy was feasible but ongoing cardiac monitoring was required to define the true impact of B on cardiac function.

Methods: Patients (pts) were assigned 1:2:2 to one of three treatment arms. In addition to doxorubicin and cyclophosphamide followed by weekly paclitaxel, patients received either placebo (Arm A – AC>T) or B during chemotherapy (Arm B - BAC>BT), or B during chemotherapy followed by B monotherapy (15 mg/kg q3wk) for an additional 10 cycles (Arm C – BAC>BT>B). Randomization was stratified and B dose adjusted for choice of AC schedule (classical q3wk − 15 mg/kg; dose dense(dd) q2 wk − 10 mg/kg). When indicated, radiation and hormonal therapy were administered concurrently with B (for Arm C pts). The primary cardiac endpoint was the incidence of clinically apparent cardiac dysfunction (CHF)defined as symptomatic decline in left ventricular ejection fraction (LVEF) to below the lower limit of normal (LLN) or symptomatic diastolic dysfunction as assessed by independent review. Cumulative toxicity data as of Jan 23, 2012 are presented.

Results: From 11.07 to 2.11, 4994 pts were enrolled. Median age was 52; 80% received ddAC. Chemotherapy associated toxicities including myelosuppression (Grade 4 neutropenia 16/20/19%) and neuropathy (Grade ≥ 3 8/8/8%) were similar across all arms. Grade ≥ 3 hypertension/thrombosis/proteinuria/hemorrhage was reported by 7/3/<1/<1% of B-treated pts. 99 pts developed CHF, most commonly reported at the post-AC or post-T evaluation. After a median follow-up of 26 months, the cumulative incidence of clinical CHF at 15 months from randomization in Arm A/B/C was 1.0/1.7/2.9% respectively. Median age of CHF pts was 57; median baseline LVEF of CHF pts was 60.

OT3-01-05: PARP Inhibition after Preoperative Chemotherapy in Patients with Triple-Negative Breast Cancer (TNBC) or Known BRCA 1/2 Mutations: Hoosier Oncology Group BRE09-146

Background

Based on recently reported I-SPY trial, TNBC patients who had residual disease category II or III had 2-year disease free survival (DFS) of only ∼40% (J Clin Oncol 2009;27:18s). Currently, no standard systemic therapy exists for this high-risk group. It represents a real opportunity to explore the potential impact of novel therapies. Recent laboratory and early clinical studies (Nature 2005;434:913) identified a unique sensitivity to DNA-damaging chemotherapy and PARP inhibition. We initiated a randomized phase II trial of DNA-damaging chemotherapy (cisplatin) or PARP-inhibition + cisplatin in TNBC patients with substantial residual invasive disease after standard anthracycline and/or taxane containing neoadjuvant chemotherapy.

Methods: To ensure a high-risk population, patients must have residual disease category 0–2 based on the Miller-Payne classification system, residual cancer burden classification II or III, residual lymph node involvement, or at least 2 cm of residual invasive disease in the breast. After completion of standard radiation therapy (when indicated), patients are randomized 1:1 to cisplatin (75 mg/M2 IV Day 1 every 3 weeks x 4 cycles) alone or in combination with PARP inhibition (PF-01367338 — 24 mg IV D1, 2, 3 of each 3 week cycle with a single dose escalation to 30 mg in the absence of significant toxicity in cycle 1 followed by maintenance PARP inhibition weekly x 24 weeks). The primary objective is 2-year DFS. To detect an improvement in 2-year DFS from 40% with cisplatin alone to 63.2% in the cisplatin + PF-01367338 arm (corresponding to HR=0.5), with 80% power using a one-side log-rank test with 0.10 level of significance, 102 patients are required in the primary analysis. Secondary objectives include safety, 1-year DFS, overall survival, and biomarkers of tumor recurrence, resistance to chemotherapy and/or PARP inhibition. Two dose escalation safety cohorts (N=13) were completed without dose limiting toxicity; the randomized portion began enrolment in 11/2010 has enrolled 20 patients as of 05/2011.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-01-05.

P1-08-01: Survival in Metastatic Breast Cancer (MBC): No Evidence for Improved Survival Following Distant Recurrence after Adjuvant Chemotherapy

Population-based studies have suggested improved survival for patients diagnosed with MBC in recent years, presumably due to the availability of new and more effective therapies (Chia et al. Cancer 2007; Dawood et al. JCO, 2008). The objective of this analysis was to determine if survival improved for patients who participated in Eastern Cooperative Oncology Group (ECOG) adjuvant trials and later developed MBC.

Methods: Adjuvant trials coordinated by the ECOG that accrued patients between 1978 and 2002 were reviewed (n=12), which included followup until 2010. Cytotoxic and biologic agents approved for MBC during this time included paclitaxel (1994), capecitabine and trastuzumab (1998), docetaxel and gemcitabine (2004), lapatinib and ixabepilone (2007), and bevacizumab (2008). Survival following distant recurrence was estimated for 4 time periods ranging from 6–10 years, and adjusted for baseline covariates in a Cox proportional hazards model. Because distant relapse free interval (DRFI) was the covariate most strongly associated with survival after recurrence, and the potential for “gap time” bias this could introduce, logrank tests for other covariates and estimates of effects were computed stratified on DRFI (0-3, >3-6, > 6 years). HER2 status was not routinely available and thus not included.

Results: The 12 trials included 14,752 patients (93% received adjuvant chemotherapy); 3711 (25.2%) developed distant recurrence. Median survival after distant recurrence was 20 months; the estimated 5 and 10-year survival rates were 16.3% and 6.1%, respectively. Median survival by time period is shown in the table, stratified by DRFI. Median survival did not significantly change over time by DRFI (≤3 years, p=0.15; >3 yr, p=0.57). In a Cox proportional hazards model, factors associated with inferior survival after adjusting for other covariates included shorter DRFI (<3 years vs. 3–6 years — hazard ratio [HR] 1.60, p<0.001, and > 6 vs. < 3 years — HR 2.23, p <0.001), ER-negative disease (HR 1.30, p<0.001), PR-negative disease (HR 1.36, P<0.0001), number of positive axillary nodes at diagnosis (1-3 vs. 0 nodes — HR 1.28, 4–9 vs. 0 nodes — HR 1.51, > 9 vs. 0 nodes — HR 1.51, p<0.0001), and black vs. white race (HR 1.29, p=0.0003), but not age at recurrence (p=0.07). When the year of recurrence was added to the Cox proportional hazards model using the intervals shown in the table below, it was not significantly associated with survival. Results were similar when 1978–2010 was assessed by 5–6 year intervals.

Conclusions: In contrast to reports from population-based studies, we do not observe any improvement in survival over time for patients who develop distant recurrence after adjuvant chemotherapy. There remains a critical unmet need for new therapies for MBC, especially for those who recur after adjuvant chemotherapy.

OT3-02-04: TBCRC 012: ABCDE, a Phase II Randomized Study of Adjuvant Bevacizumab, Metronomic Chemotherapy (CM), Diet and Exercise after Preoperative Chemotherapy for Breast Cancer

Background Patients (pts) with residual breast cancer after neoadjuvant chemotherapy are at increased risk of recurrence; no proven risk-reduction strategies exist, supporting exploration of novel therapies in the post-preoperative setting. Bevacizumab (B) combined with chemotherapy is active in metastatic disease; ongoing studies are exploring the efficacy of adjuvant combination chemotherapy and B. DFCI 05–055 (Mayer et al, ASCO 2007, 2008) demonstrated the feasibility of 1 year B after preoperative chemotherapy. Also, increasing data support risk reduction through lifestyle interventions (Segal, Ligibel et al, ASCO 2011). The ABCDE trial was designed to evaluate extended adjuvant B in a high risk post-preoperative cohort, and also assess the contribution of exercise to a dietary intervention.

Eligibility Criteria Eligible pts have HER2− breast cancer and have received preoperative anthracycline and/or taxane-based chemotherapy with residual invasive disease at surgery. Acceptable stages include: triple negative if preop stages I-III, or ER+/PR+ if stage III preop or IIB postop. Acceptable organ function and standard B exclusions apply. Registration must occur between 28–180 days after last surgery.

Specific Aims Primary endpoint is recurrence-free survival at a median follow-up of 6 years. Secondary endpoints include B pharmacogenomics, evaluation of the impact of exercise on quality of life and biomarkers associated with recurrence, and prospective examination of cardiac toxicity. Residual tissue-based predictors of outcome will be extensively explored, including PAM50, Ki67, and VEGF hypoxia signature.

Methods This is a 2 × 2 randomized study with a first randomization to 6 months (mo) B 15 mg/kg every 3 weeks (wks) plus 6 mo CM (C 50 mg daily, M 2.5 mg twice daily days 1, 2 each wk), followed by 2.5 years B 15 mg/kg every 6–8 wks, versus observation. A second randomization is to a 1 year telephone-based lifestyle intervention, offering dietary modification alone, or in combination with a structured exercise program.

Statistical Methods and Accrual Total sample size is 660 pts within the Translational Breast Cancer Research Consortium. Overall power is 0.80 to detect a hazard ratio of 0.59−0.68, depending on pt population. Accrual initiated early 2011 and is expected to continue for the next 36 months.

Conclusions Patients with residual disease after preoperative chemotherapy are at high risk of recurrence and have unmet medical needs. To our knowledge, this is the only trial testing a prolonged but less intensive adjuvant B schedule in this clinical setting. Results of this study could have critical implications for the management of this patient population and for the design of future clinical trials with anti-angiogenic agents.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-02-04.

A phase II pilot trial incorporating bevacizumab into dose-dense doxorubicin and cyclophosphamide followed by paclitaxel in patients with lymph node positive breast cancer: a trial coordinated by the Eastern Cooperative Oncology Group

BACKGROUND

E2104 was designed to evaluate the safety of two different strategies incorporating bevacizumab into anthracycline-containing adjuvant therapy as a precursor to a definitive randomized phase III trial.

PATIENTS AND METHODS

Patients were sequentially assigned to one of two treatment arms. In addition to dose-dense doxorubicin and cyclophosphamide followed by paclitaxel (Taxol) (ddAC→T), all patients received bevacizumab (10 mg/kg every 2 weeks × 26) initiated either concurrently with AC (Arm A: ddBAC→BT→B) or with paclitaxel (Arm B: ddAC→BT→B). The primary end point was incidence of clinically apparent cardiac dysfunction (CHF).

RESULTS

Patients enrolled were 226 in number (Arm A 104, Arm B 122). Grade 3 hypertension, thrombosis, proteinuria and hemorrhage were reported for 12, 2, 2 and <1% of patients, respectively. Two patients developed grade 3 or more cerebrovascular ischemia. Three patients in each arm developed CHF. There was no significant difference between arms in the proportion of patients with an absolute decrease in left ventricular ejection fraction of >15% or >10% to below the lower limit of normal post AC or post bevacizumab.

CONCLUSIONS

Incorporation of bevacizumab into anthracycline-containing adjuvant therapy does not result in prohibitive cardiac toxicity. The definitive phase III trial (E5103) was activated with systematic and extensive cardiac monitoring to define the true impact of bevacizumab on cardiac function.

A pilot study of vascular endothelial growth factor inhibition with bevacizumab in patients with lymphedema following breast cancer treatment

Abstract #6142

Purpose: Lymphedema is a significant long-term complication of primary therapy for breast cancer but little is known regarding its etiology and persistence other than relation to the number of lymph nodes (LN) removed. We suggest the following model: Mechanical disruption of normal lymphatic drainage leads to increased back pressure on lymphatic vessels producing an increase in interstitial fluid pressure (IFP). The increased in IFP triggers local production of VEGF-C to stimulate compensatory lymphangiogenesis. As VEGF-A (and to a lesser extent –C) also increases vascular permeability, the consequent increase in interstitial fluid and edema predominate. Anecdotally, several patients (pts) with metastatic disease treated with bevacizumab monotherapy noted improvement in long-standing lymphedema. This pilot study was conducted to explore these observations prospectively.&#x2028; Methods: We used an existing biospecimen bank to conduct a case-control study to compare VEGF-A, -C, -D and VEGFR-3 serum concentrations in breast cancer pts with and without lymphedema (matched for age and LN status). In a separate pilot trial, pts with significant unilateral lymphedema receive bevacizumab, 15 mg/kg every 3 weeks. Baseline assessments include arm volume, interstitial fluid pressure (IFP), extracellular fluid volume by lymphometer (ECF), quality of life (QOL) and plasma VEGF-C, -D, and R-3. IFP is measured serially for 24 hours after the first treatment; arm volume, ECF, QOL, and plasma VEGF-C/D/R-3 are assessed at 3 and 6 weeks.&#x2028; Results: Samples were available for 16 pts with chronic lymphedema and 24 matched controls. Median VEGF-C levels were significantly increased in pts with lymphedema (6895 pg/ml vs. 5349 pg/ml, p=0.001). Median VEGF-A levels were slightly higher in pts with lymphedema (375 pg/ml vs.250 pg/ml, p=NS). Eight pts have been enrolled in the pilot trial thus far. Median duration of lymphedema was 4.4 years (2.2-16.6) Median time since surgery was 7.1 years (3.4-17.6); median time since radiation (n=7) was 4.4 years (2.3-7.9). Complete IFP data is available in 5 pts. Baseline IFP was significantly higher in the affected compared to unaffected arm (9.04 vs. -2.07 mmHg; p=0.0017). Median IFP in the affected arm decreased an average of 42.6% 24 hours after bevacizumab infusion (11.1 vs. 6.9 mmHg; p=0.09). Total arm circumference decreased by an average of 2.8 cm three weeks after initial treatment.&#x2028; Conclusions: Preliminary data supports the hypothesis that VEGF plays a central role in the development and persistence of lymphedema after local therapy for breast cancer. Inhibiting VEGF acutely decreases IFP and may be an effective treatment. Treatment and accrual to the pilot trial continues; full data will be available by December 2008.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6142.

Dual targeting of EphA2 and ER restores tamoxifen sensitivity in ER/EphA2-positive breast cancer

Abstract #3020

Background: Overexpression and altered function of EphA2 receptor tyrosine kinase are critical in the progression of breast cancer and provide a novel target for breast cancer therapy. We have previously demonstrated that EphA2 overexpression decreases estrogen dependence and tamoxifen sensitivity both in vitro and in vivo. EA5, a novel monoclonal antibody that mimicks the binding of ephrin A to EphA2, reverses the effect of EphA2 overexpression and restores tamoxifen sensitivity in EphA2-transfected MCF-7 cells (MCF-7EphA2) in vitro. Here we report the impact of EA5 on in vivo tumor growth and its ability to overcome in vivo tamoxifen resistance in MCF-7EphA2 xenografts. Furthermore, we investigated the mechanisms by which EphA2 overexpression decreases the estrogen dependence and contributes to tamoxifen resistance in ER+ breast cancer models.&#x2028; Material and Methods: MCF-7 cells transfected with vector (MCF-7neo) or EphA2 (MCF-7EphA2) were implanted in the right and left mammary fat pads of athymic mice. Treatment with EA5 (5 mg/kg/i.p./5 days/week), vehicle, tamoxifen (1 mg/oral gavage/5 days/week), or EA5 and tamoxifen in combination was initiated once tumors were established. To explore the role of EphA2 overexpression on ER-dependent mechanisms, we used two different ER+/EphA2-transfected cell line models (MCF-7neo/ MCF-7EphA2 and T47Dneo/ T47DEphA2). We measured ER activity and expression of ER-dependent proteins in response to 17β-estradiol (E2;10-10 M), 4-hydroxy-tamoxifen (10-6 M, and EA5 antibody (3μg/mL). Interaction of ER and EphA2 was investigated using GST-pulldown and co-immunoprecipitation approaches. Gene array studies suggested that EphA2 may impact ER via noncanonical pathways, leading to an investigation of focal adhesion kinase (FAK) signaling.&#x2028; Results: EA5 inhibits primary tumor growth and restores tamoxifen sensitivity in the MCF-7EphA2 in vivo model;EA5 had no impact on in vivo tumor growth in MCF-7neo xenografts. Using T47DEphA2 in vitro model, we verified that EphA2 decreases ER activation in response to E2 stimulation consistent with our earlier results in MCF-7EphA2 model. We found no direct interaction between ER and EphA2 and no difference in expression of canonical ER-dependent proteins, ER coactivators or corepressors. However, E2 stimulation phosphorylates FAKTyr925 in ER+/EphA2+ cell lines but not in ER+/EphA2- cell lines. Treatment of T47DEphA2 cells with EA5 and tamoxifen leads to dephosphorylation of FAKTyr925 in the presence of E2 stimulation.&#x2028; Conclusion: Our data demonstrate that dual targeting of EphA2 and ER is a promising approach for delaying resistance to tamoxifen. The data support our hypothesis that EphA2 impacts ER function via a FAK dependent pathway.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3020.

Review of Growth Inhibitory Peptide as a biotherapeutic agent for tumor growth, adhesion, and metastasis

This review surveys the biological activities of an alpha-fetoprotein (AFP) derived peptide termed the Growth Inhibitory Peptide (GIP), which is a synthetic 34 amino acid segment produced from the full length 590 amino acid AFP molecule. The GIP has been shown to be growth-suppressive in both fetal and tumor cells but not in adult terminally-differentiated cells. The mechanism of action of this peptide has not been fully elucidated; however, GIP is highly interactive at the plasma membrane surface in cellular events such as endocytosis, cell contact inhibition and cytoskeleton-induced cell shape changes. The GIP was shown to be growth-suppressive in nine human tumor types and to suppress the spread of tumor infiltrates and metastases in human and mouse mammary cancers. The AFP-derived peptide and its subfragments were also shown to inhibit tumor cell adhesion to extracellular matrix (ECM) proteins and to block platelet aggregation; thus it was expected that the GIP would inhibit cell spreading/migration and metastatic infiltration into host tissues such as lung and pancreas. It was further found that the cyclic versus linear configuration of GIP determined its biological and anti-cancer efficacy. Genbank amino acid sequence identities with a variety of integrin alpha/beta chain proteins supported the GIP's linkage to inhibition of tumor cell adhesion and platelet aggregation. The combined properties of tumor growth suppression, prevention of tumor cell-to-ECM adhesion, and inhibition of platelet aggregation indicate that tumor-to-platelet interactions present promising targets for GIP as an anti-metastatic agent. Finally, based on cholinergic studies, it was proposed that GIP could influence the enzymatic activity of membrane acetylcholinesterases during tumor growth and metastasis. It was concluded that the GIP derived from full-length AFP represents a growth inhibitory motif possessing instrinsic properties that allow it to interfere in cell surface events such as adhesion, migration, metastasis, and aggregation of tumor cells.

Selection bias in clinical trials

All research is subject to bias that may systematically distort results. Though over 50 types of bias in analytical research have been identified and many classification schemes proposed, this review focuses on the special problem of selection bias in clinical trials. We demonstrate the systematic nature of selection bias in clinical research. We describe the common sources of selection bias in clinical trials including the (inappropriate) use of historical controls, stage migration, inclusion/exclusion criteria, the use of multiple subset analyses, and investigator bias. We then move from the general to the specific, using the recent experience of high dose chemotherapy for breast cancer as an illustrative example. Finally, we suggest means to avoid falling into the many selection bias traps that often confront clinical researchers.

Effects of handling intensity and live weight on blood acid-base status in finishing pigs

The objective of this study was to determine the effect of live weight on the plasma acid-base response of pigs subjected to various handling intensities. Eighty pigs (equal numbers of barrows and gilts) were used in a completely randomized block design with a 2 x 2 x 2 factorial arrangement of the following treatments: 1) live weight (light [104 kg] vs. heavy [128 kg]), 2) handling intensity (low vs. high), and 3) gender (barrows vs. gilts). Before the handling test, pigs were weighed, venous blood samples were taken to establish baseline levels, and rectal temperature was measured. Pigs were allowed to rest for 2 h before being subjected to the handling treatments, which consisted of moving the pigs through a course (12.2 m long x 0.91 m wide), for a total of eight laps. Animals on the high-intensity treatment were moved rapidly through the course and subjected to a total of 16 single shocks (two shocks per lap) with an electric livestock goad, whereas pigs on the low-intensity treatment were moved at their own pace using a moving panel and a paddle. Rectal temperature and a venous blood sample were taken immediately after handling and at 2 h after handling. Blood plasma was assayed for pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), saturated oxygen (SO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess, and lactate. Live weight had no effect on the baseline measurements. After handling, light pigs had higher (P < 0.05) blood SO2 (65.6 vs. 57.2+/-2.80%) and showed a greater (P < 0.05) increase in PO2 from baseline to post-handling than heavy pigs (15.6 vs. 8.3+/-2.63 mmHg). Post-handling, pigs on the high- compared with the low-intensity handling treatment had greater (P < 0.001) lactate (19.1 vs. 4.9+/-0.56 mmol/L) and PO2 (51.6 vs. 36.5+/-2.44 mmHg) with lower (P < 0.001) TCO2 (18.6 vs. 34.7+/-0.64 mmol/L), pH (7.02 vs. 7.36+/-0.015), HCO3 (16.7 vs. 33.0+/-0.62 mmol/L), and base excess (-14.2 vs. 7.5+/-0.75) values. There were no effects of gender on blood measurements or rectal temperatures. Results from this study highlight a major effect of pig handling intensity, a limited effect of live weight, and no effect of gender on blood acid-base responses to handling.

Tracking neurons recorded from tetrodes across time

Tetrodes allow isolation of multiple neurons at a single recording site by clustering spikes. Due to electrode drift and perhaps due to time-varying neuronal properties, positions and shapes of clusters change in time. As data is typically collected in sequential files, to track neurons across files one has to decide which clusters from different files belong to the same neuron. We report on a semi-automated neuron tracking procedure that uses computed similarities between the mean spike waveforms of the clusters. The clusters with the most similar waveforms are assigned to the same neuron, provided their similarity exceeds a threshold. To set this threshold, we calculate two distributions: of within-file similarities, and of best matches in the across adjacent file similarities. The threshold is set to the value that optimally separates the two distributions. We compare different measures of similarity (metrics) by their ability to separate these distributions. We find that these metrics do not differ drastically in their performance, but that taking into account the cross-channel noise correlation significantly improves performance of all metrics. We also demonstrate the method on an independent dataset and show that neurons, as assigned by the procedure, have consistent physiological properties across files.

Probing feature selectivity of neurons in primary visual cortex with natural stimuli

One way to characterize neural feature selectivity is to model the response probability as a nonlinear function of the output of a set of linear filters applied to incoming signals. Traditionally these linear filters are measured by probing neurons with correlated Gaussian noise ensembles and calculating correlation functions between incoming signals and neural responses. It is also important to derive these filters in response to natural stimuli, which have been shown to have strongly non-Gaussian spatiotemporal correlations. An information-theoretic method has been proposed recently for reconstructing neural filters using natural stimuli in which one looks for filters whose convolution with the stimulus ensemble accounts for the maximal possible part of the overall information carried the sequence of neural responses. Here we give a first-time demonstration of this method on real neural data, and compare responses of neurons in cat primary visual cortex driven with natural stimuli, noise ensembles, and moving gratings. We show that the information-theoretic method achieves the same quality of filter reconstruction for natural stimuli as that of well-established white-noise methods. Major parameters of neural filters derived from noise ensembles and natural stimuli, as well as from moving gratings are consistent with one another. We find that application of the reverse correlation method to natural stimuli ensembles leads to significant distortions in filters for a majority of studied cells with non-zero reverse-correlation filter.

Relationships between longissimus glycolytic potential and swine growth performance, carcass traits, and pork quality

The relationships between glycolytic potential and growth performance, carcass traits, and pork quality were investigated in a group of 72 pigs from the same genetic line. Glycolytic potential (GP) was determined on live-animal biopsy samples and postmortem samples taken from the longissimus muscle, and free glucose concentration was measured on the exudate from the longissimus muscle taken postmortem. The mean live-animal and postmortem GP and free glucose values were 201.6 micromol/g (range = 113.8 to 301.1), 149.8 micromol/g (range = 91.0 to 270.5) and 110.1 mg/dL (range = 30.0 to 406.0), respectively. Correlations between live-animal and postmortem GP and free glucose ranged from 0.47 to 0.70; however, all three measures were weakly related to growth and carcass traits (r = 0.03 to -0.22; P > 0.05). Correlations of GP and free glucose values with fresh pork quality measurements were moderate (r = 0.23 [P < 0.05] to -0.63 [P < 0.001]). Regression analysis suggested that a one standard deviation increase in live-animal and postmortem GP and free glucose resulted in an increase in L* values (0.99, 1.32, and 2.05, respectively) and drip loss (0.85, 1.10, and 1.39 percentage units, respectively), as well as a decrease in ultimate pH (0.05, 0.11, and 0.16, respectively). Correlations between GP and cooking loss and tenderness and juiciness scores ranged between 0.16 (P > 0.05) to 0.34 (P < 0.01). Free glucose concentration showed no relationship (P > 0.05) with cooking loss, tenderness, and juiciness. Regression analysis suggested that a one standard deviation increase in live-animal and postmortem GP increased cooking loss (1.26% and 1.65%, respectively) and would improve taste panel tenderness (0.54 and 0.44, respectively) and juiciness (0.40 and 0.48, respectively) scores. Increasing GP and free glucose was also associated with decreased longissimus fat and protein, and increased moisture contents (r = 0.14 [P > 0.05] to -0.45 [P < 0.001]). Overall, relationships with fresh meat quality characteristics were stronger for free glucose values than either live-animal or postmortem GP. Results from this study indicate that decreasing longissimus GP and free glucose concentrations may improve pork color and water-holding capacity.

Exploiting the hallmarks of cancer: the future conquest of breast cancer

What separates a malignant from a normal cell? This question has occupied scientists for decades. Although a simple answer remains elusive, several hallmarks of malignancy have been identified. These critical features include uncontrolled proliferation, insensitivity to negative growth regulation, evasion of apoptosis, lack of senescence, invasion and metastasis, angiogenesis and genomic elasticity. Existing therapies predominantly target proliferation either with cytotoxic agents, ionising radiation or more targeted attacks on growth factor signalling pathways. Our most successful therapies to date inhibit proliferation via the oestrogen receptor (ER) and HER2 pathways. Further improvements in therapy must attack the other hallmarks of malignancy and will undoubtedly be accompanied by a better means of individual patient selection for such therapies. Indeed, each of these hallmarks presents a therapeutic opportunity. To believe otherwise would be to assume that a feature is both biologically crucial, yet therapeutically unimportant, an unlikely paradox. Here, we suggest the hallmarks of malignancy as a conceptual framework for understanding novel breast cancer therapies.

Occult central nervous system involvement in patients with metastatic breast cancer: prevalence, predictive factors and impact on overall survival

BACKGROUND

As screening central nervous system (CNS) imaging is not routinely performed, the incidence and clinical relevance of occult CNS metastases in advanced breast cancer is unknown.

PATIENTS AND METHODS

All patients screened for participation in one of four clinical trials were included; each of the trials excluded patients with known CNS involvement and required screening CNS imaging. A cohort of breast cancer patients with symptomatic CNS metastases was identified from the IU Cancer Center Tumor Registry for comparison.

RESULTS

From November 1998 to August 2001, 155 screening imaging studies were performed. Twenty-three patients (14.8%) had occult CNS metastases. HER-2 overexpression (P = 0.02) and number of metastatic sites (P = 0.03) were predictive of CNS involvement by multivariate analysis. Median survival from time of metastasis (1.78 versus 2.76 years; P <0.0001) and from screening (4.67 versus 10.4 months; P = 0.0013) was shorter in patients with than without occult CNS metastasis. Survival among patients with occult CNS metastasis was similar to patients with symptomatic CNS disease.

CONCLUSIONS

Patients with CNS involvement, whether occult or symptomatic, have an impaired survival. Occult CNS metastasis is relatively common, but impact on survival of treating occult CNS disease in patients with progressive systemic metastases is questionable.

The Snark is a Boojum: the continuing problem of drug resistance in the antiangiogenic era

If your Snark be a Snark, that is right: Fetch it home by all means-you may serve it with greens, And it's handy for striking a light. "But oh, beamish nephew, beware of the day, If your Snark be a Boojum! For then You will softly and suddenly vanish away, And never be met with again!" Lewis Carroll The Hunting of the Snark

Combined anti-microtubule therapy: a phase II study of weekly docetaxel plus estramustine in patients with metastatic breast cancer

BACKGROUND

Docetaxel and estramustine exert anti-tumor effects by inhibiting microtubule function. In vitro data suggest synergism with this combination. This phase II study evaluated the response rate and toxicity of docetaxel and estramustine in patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS

Patients were treated with docetaxel 35 mg/m(2) on day 2 and estramustine phosphate 280 mg p.o. tds days 1-3 weekly for 3 of 4 weeks, for a maximum of six treatment cycles.

RESULTS

Thirty-nine patients were enrolled between August 1999 and March 2001; 36 were eligible. Of 31 evaluable patients, responses were observed in 15 patients (47%); two patients (6%) obtained a complete response. Median time to treatment failure was 6 months; median survival was 1 year. Thromboembolic toxicity occurred in 11% of patients: three experienced deep venous thromboses and one had a fatal pulmonary embolism. Myelosuppression was minimal with this regimen.

CONCLUSIONS

Despite modest activity in metastatic breast cancer, the toxicity observed with the combination of estramustine and docetaxel precludes the routine use of this combination in the treatment of breast cancer. Further studies using this compound in metastatic breast cancer are not warranted.

A randomized phase II pilot trial of adjuvant marimastat in patients with early-stage breast cancer

BACKGROUND

This pilot trial was performed to evaluate the safety, toxicity and pharmacokinetics of chronic therapy with the matrix metalloproteinase inhibitor marimastat in the adjuvant treatment of breast cancer.

PATIENTS AND METHODS

Patients with high-risk node negative or node positive breast cancer received marimastat either 5 or 10 mg p.o. b.i.d. for 12 months. Marimastat was given either as a single agent following completion of adjuvant chemotherapy or concurrently with tamoxifen.

RESULTS

Sixty-three patients were enrolled from June 1997 to May 1998. All patients have completed 12 months of treatment or have discontinued therapy due to toxicity, relapse or intercurrent illness. Moderate (WHO criteria) arthralgia/arthritis was reported by 34% of patients receiving 5 mg b.i.d. and 45% of patients receiving 10 mg b.i.d.; severe arthralgia/arthritis was reported by 6% and 23% of patients, respectively. Six patients (19%) receiving 5 mg b.i.d. and 11 (35%) receiving 10 mg b.i.d. discontinued marimastat therapy due to toxicity. Trough plasma levels were rarely within the target range for biological activity (40-200 ng/ml) with mean concentration for patients receiving: 5 mg b.i.d. = 7.5; 5 mg b.i.d. plus tamoxifen = 6.9; 10 mg b.i.d. = 11.9; 10 mg b.i.d. plus tamoxifen = 12.8.

CONCLUSIONS

A randomized adjuvant trial with marimastat is not warranted as chronic administration cannot maintain plasma levels with the target range.

The impact of longissimus glycolytic potential and short-term feeding of magnesium sulfate heptahydrate prior to slaughter on carcass characteristics and pork quality

The objective of this study was to compare the effects of longissimus glycolytic potential (GP) and of time of feeding of supplemental magnesium sulfate heptahydrate on carcass and pork quality traits. The study was carried out in a 2 x 2 x 4 factorial arrangement; the treatments were sex (castrate vs gilt), GP (Low [normal] vs High), and time of feeding of magnesium sulfate-fortified diets (0 [control] vs 2 vs 3 vs 5 d prior to slaughter). Glycolytic potential was determined on a biopsy sample of longissimus from the live animal prior to the start of the study. A total of 144 pigs were allotted to the feeding-time treatments on the basis of sex (castrate and gilt), weight, and GP. Pigs were placed in individual pens and had free access to water. Prior to the start of the study, pigs were given ad libitum access to a standard finisher diet. During the study, animals were fed at a fixed level of 2.75 kg of a standard finisher diet/day; the fortified diet contained 3.2 g/d of additional magnesium. At the end of the feeding period, animals were transported to a commercial packing facility and slaughtered within 15 min of arrival. Fresh meat quality was measured on the longissimus. There were no treatment interactions. Carcass traits were similar across time of feeding treatments. Backfat thickness at the last lumbar vertebra and 10th rib were lower (P < 0 .05) for High than for Low GP pigs. High GP pigs had lower ultimate pH (P < 0.001) and higher drip (P < 0.05) and purge loss (P < 0.01) than Low GP pigs. Drip loss was reduced (P < 0.05) for pigs fed the magnesium-fortified diet for 5 and 2 but not for 3 d compared to controls (8.98, 7.29, 7.89, and 7.41 for the 0-, 2-, 3-, and 5-d treatments, respectively, SEM 0.447). Purge loss was similar for all of the time of feeding treatments. Longissimus L* values were lower (P < 0.05) for the 2-d treatment than for the controls. Results from this study suggest an inconsistent effect of short-term feeding of magnesium sulfate on muscle color and drip loss in pigs with both Low (normal) and High GP.

Fertility after unilateral cryptorchidism. Paternity, time to conception, pretreatment testicular location and size, hormone and sperm parameters

OBJECTIVE

To further evaluate whether fertility is decreased among a cohort of men with previous unilateral cryptorchidism as compared with a control group of men.

SUBJECTS AND METHODS

Formerly unilateral cryptorchid men who had undergone orchiopexy between the years of 1955 and 1975 at the Children's Hospital of Pittsburgh and a control group of men who were matched for age of an unrelated surgery at the same institution were evaluated by review of medical records and by completion of a questionnaire. 359 previously cryptorchid men were identified as having attempted paternity. Of these men, 320 had information concerning preoperative testicular location and 163 for preoperative testicular size. 106 of these men had levels of testosterone, inhibin B, FSH, and LH measured, while 95 of the men had semen analyses.

RESULTS

Among men who had attempted paternity, there was no statistical difference in success of paternity between the previously unilateral group (89.7%) and the control group (93.7%). There was no difference in the mean time to conception (7.1 +/- 0.7 months for the unilateral group vs. 6.9 +/- 2.3 for the control group). Within the unilateral group in regard to success at paternity, no difference was found compared with the age of orchiopexy, preoperative testicular location, or preoperative testicular size. Inhibin B levels were lower among the unilateral group. FSH, LH, testosterone, sperm density, motility and morphology were not different, but considerable variation was noted within the cryptorchid group.

CONCLUSIONS

In this continued evaluation of a cohort of previously cryptorchid men who had undergone unilateral orchiopexy, paternity does not appear to be significantly compromised after unilateral cryptorchidism. Unilateral cryptorchidism appears to be one of several factors contributing to infertility, similar to those found in the general population. No correlation was found between success at paternity and the age of orchiopexy, preoperative testicular size or preoperative testicular location. Inhibin B levels were lower while FSH, LH, T and sperm parameters did not differ.

Variability and information in a neural code of the cat lateral geniculate nucleus

A central theme in neural coding concerns the role of response variability and noise in determining the information transmission of neurons. This issue was investigated in single cells of the lateral geniculate nucleus of barbiturate-anesthetized cats by quantifying the degree of precision in and the information transmission properties of individual spike train responses to full field, binary (bright or dark), flashing stimuli. We found that neuronal responses could be highly reproducible in their spike timing (approximately 1-2 ms standard deviation) and spike count (approximately 0.3 ratio of variance/mean, compared with 1.0 expected for a Poisson process). This degree of precision only became apparent when an adequate length of the stimulus sequence was specified to determine the neural response, emphasizing that the variables relevant to a cell's response must be controlled to observe the cell's intrinsic response precision. Responses could carry as much as 3.5 bits/spike of information about the stimulus, a rate that was within a factor of two of the limit the spike train could transmit. Moreover, there appeared to be little sign of redundancy in coding: on average, longer response sequences carried at least as much information about the stimulus as would be obtained by adding together the information carried by shorter response sequences considered independently. There also was no direct evidence found for synergy between response sequences. These results could largely, but not entirely, be explained by a simple model of the response in which one filters the stimulus by the cell's impulse response kernel, thresholds the result at a fairly high level, and incorporates a postspike refractory period.

Adjuvant chemotherapy for tumors of one centimeter or less: the law of diminishing returns

The role of adjuvant chemotherapy in treatment of breast cancers of 1 cm or less is controversial. Careful consideration must be given to the overall risk of recurrence and death and to the absolute benefit of adjuvant chemotherapy, given that risk. Studies in this group of patients indicate that their overall survival rate is 90% to 99%. The absolute benefit of chemotherapy in this setting is most likely 1% or less. Adjuvant chemotherapy has significant toxicities, including cognitive dysfunction, early menopause, leukemia, and even death. Following a realistic and detailed discussion between patient and oncologist, some patients may choose chemotherapy. However, for the majority of patients with breast cancers of 1 cm or less, the minimal benefit of adjuvant chemotherapy does not justify the risk of the treatment.