Paclitaxel plus bevacizumab versus paclitaxel alone for metastatic breast cancer

BACKGROUND

In an open-label, randomized, phase 3 trial, we compared the efficacy and safety of paclitaxel with that of paclitaxel plus bevacizumab, a monoclonal antibody against vascular endothelial growth factor, as initial treatment for metastatic breast cancer.

METHODS

We randomly assigned patients to receive 90 mg of paclitaxel per square meter of body-surface area on days 1, 8, and 15 every 4 weeks, either alone or with 10 mg of bevacizumab per kilogram of body weight on days 1 and 15. The primary end point was progression-free survival; overall survival was a secondary end point.

RESULTS

From December 2001 through May 2004, a total of 722 patients were enrolled. Paclitaxel plus bevacizumab significantly prolonged progression-free survival as compared with paclitaxel alone (median, 11.8 vs. 5.9 months; hazard ratio for progression, 0.60; P<0.001) and increased the objective response rate (36.9% vs. 21.2%, P<0.001). The overall survival rate, however, was similar in the two groups (median, 26.7 vs. 25.2 months; hazard ratio, 0.88; P=0.16). Grade 3 or 4 hypertension (14.8% vs. 0.0%, P<0.001), proteinuria (3.6% vs. 0.0%, P<0.001), headache (2.2% vs. 0.0%, P=0.008), and cerebrovascular ischemia (1.9% vs. 0.0%, P=0.02) were more frequent in patients receiving paclitaxel plus bevacizumab. Infection was more common in patients receiving paclitaxel plus bevacizumab (9.3% vs. 2.9%, P<0.001), but febrile neutropenia was uncommon (<1% overall).

CONCLUSIONS

Initial therapy of metastatic breast cancer with paclitaxel plus bevacizumab prolongs progression-free survival, but not overall survival, as compared with paclitaxel alone. (ClinicalTrials.gov number, NCT00028990 [ClinicalTrials.gov].).

Competitive Hebbian learning through spike-timing-dependent synaptic plasticity

Hebbian models of development and learning require both activity-dependent synaptic plasticity and a mechanism that induces competition between different synapses. One form of experimentally observed long-term synaptic plasticity, which we call spike-timing-dependent plasticity (STDP), depends on the relative timing of pre- and postsynaptic action potentials. In modeling studies, we find that this form of synaptic modification can automatically balance synaptic strengths to make postsynaptic firing irregular but more sensitive to presynaptic spike timing. It has been argued that neurons in vivo operate in such a balanced regime. Synapses modifiable by STDP compete for control of the timing of postsynaptic action potentials. Inputs that fire the postsynaptic neuron with short latency or that act in correlated groups are able to compete most successfully and develop strong synapses, while synapses of longer-latency or less-effective inputs are weakened.

Randomized phase III trial of capecitabine compared with bevacizumab plus capecitabine in patients with previously treated metastatic breast cancer

PURPOSE

This randomized phase III trial compared the efficacy and safety of capecitabine with or without bevacizumab, a monoclonal antibody to vascular endothelial growth factor, in patients with metastatic breast cancer previously treated with an anthracycline and a taxane.

PATIENTS AND METHODS

Patients were randomly assigned to receive capecitabine (2,500 mg/m2/d) twice daily on day 1 through 14 every 3 weeks, alone or in combination with bevacizumab (15 mg/kg) on day 1. The primary end point was progression-free survival (PFS), as determined by an independent review facility.

RESULTS

From November 2000 to March 2002, 462 patients were enrolled. Treatment arms were balanced. No significant differences were found in the incidence of diarrhea, hand-foot syndrome, thromboembolic events, or serious bleeding episodes between treatment groups. Of other grade 3 or 4 adverse events, only hypertension requiring treatment (17.9% v 0.5%) was more frequent in patients receiving bevacizumab. Combination therapy significantly increased the response rates (19.8% v 9.1%; P = .001); however, this did not result in a longer PFS (4.86 v 4.17 months; hazard ratio = 0.98). Overall survival (15.1 v 14.5 months) and time to deterioration in quality of life as measured by the Functional Assessment Of Cancer Treatment--Breast were comparable in both treatment groups.

CONCLUSION

Bevacizumab was well tolerated in this heavily pretreated patient population. Although the addition of bevacizumab to capecitabine produced a significant increase in response rates, this did not translate into improved PFS or overall survival.

Arterial thromboembolic events in patients with metastatic carcinoma treated with chemotherapy and bevacizumab

BACKGROUND

Although combination treatment with bevacizumab (humanized monoclonal antibody against vascular endothelial growth factor) and chemotherapy improves survival of patients with various metastatic carcinomas, an increased risk of arterial thromboembolic events has been observed in some trials. We characterized this risk by performing post hoc analyses of randomized controlled trials that evaluated combination treatment with bevacizumab and chemotherapy versus chemotherapy alone. Low-dose aspirin was permitted in these trials, and its safety was also analyzed.

METHODS

Data were pooled from five randomized controlled trials that included a total of 1745 patients with metastatic colorectal, breast, or non-small-cell lung carcinoma. The risk of an arterial or venous thromboembolic event was assessed by simple incidence rates, rates per 100 person-years, and/or hazard ratios (HRs). The association between patient characteristics and risk of an arterial thromboembolic event was investigated primarily by Cox proportional hazards regression. The relationship between low-dose aspirin and bleeding was explored by incidence rates and rates per 100 person-years.

RESULTS

Combined treatment with bevacizumab and chemotherapy, compared with chemotherapy alone, was associated with increased risk for an arterial thromboembolic event (HR = 2.0, 95% confidence interval [CI] = 1.05 to 3.75; P = .031) but not for a venous thromboembolic event (HR = 0.89, 95% CI = 0.66 to 1.20; P = .44). The absolute rate of developing an arterial thromboembolism was 5.5 events per 100 person-years for those receiving combination therapy and 3.1 events per 100 person-years for those receiving chemotherapy alone (ratio = 1.8, 95% CI = 0.94 to 3.33; P = .076). Development of an arterial thromboembolic event was associated with a prior arterial thromboembolic event (P<.001) or age of 65 years or older (P = .01). Baseline or on-study aspirin use was associated with modest increases in grade 3 and 4 bleeding events in both treatment groups, from 3.6% to 4.7% for bevacizumab-treated patients and from 1.7% to 2.2% for control subjects.

CONCLUSIONS

Combination treatment with bevacizumab and chemotherapy, compared with chemotherapy alone, was associated with an increased risk of arterial thromboembolism but not venous thromboembolism.

HIV-1 and T cell dynamics after interruption of highly active antiretroviral therapy (HAART) in patients with a history of sustained viral suppression

Identifying the immunologic and virologic consequences of discontinuing antiretroviral therapy in HIV-infected patients is of major importance in developing long-term treatment strategies for patients with HIV-1 infection. We designed a trial to characterize these parameters after interruption of highly active antiretroviral therapy (HAART) in patients who had maintained prolonged viral suppression on antiretroviral drugs. Eighteen patients with CD4(+) T cell counts >/= 350 cells/microliter and viral load below the limits of detection for >/=1 year while on HAART were enrolled prospectively in a trial in which HAART was discontinued. Twelve of these patients had received prior IL-2 therapy and had low frequencies of resting, latently infected CD4 cells. Viral load relapse to >50 copies/ml occurred in all 18 patients independent of prior IL-2 treatment, beginning most commonly during weeks 2-3 after cessation of HAART. The mean relapse rate constant was 0.45 (0.20 log(10) copies) day(-1), which was very similar to the mean viral clearance rate constant after drug resumption of 0.35 (0.15 log(10) copies) day(-1) (P = 0.28). One patient experienced a relapse delay to week 7. All patients except one experienced a relapse burden to >5,000 RNA copies/ml. Ex vivo labeling with BrdUrd showed that CD4 and CD8 cell turnover increased after withdrawal of HAART and correlated with viral load whereas lymphocyte turnover decreased after reinitiation of drug treatment. Virologic relapse occurs rapidly in patients who discontinue suppressive drug therapy, even in patients with a markedly diminished pool of resting, latently infected CD4(+) T cells.

Cereblon is a direct protein target for immunomodulatory and antiproliferative activities of lenalidomide and pomalidomide

Thalidomide and the immunomodulatory drug, lenalidomide, are therapeutically active in hematological malignancies. The ubiquitously expressed E3 ligase protein cereblon (CRBN) has been identified as the primary teratogenic target of thalidomide. Our studies demonstrate that thalidomide, lenalidomide and another immunomodulatory drug, pomalidomide, bound endogenous CRBN and recombinant CRBN–DNA damage binding protein-1 (DDB1) complexes. CRBN mediated antiproliferative activities of lenalidomide and pomalidomide in myeloma cells, as well as lenalidomide- and pomalidomide-induced cytokine production in T cells. Lenalidomide and pomalidomide inhibited autoubiquitination of CRBN in HEK293T cells expressing thalidomide-binding competent wild-type CRBN, but not thalidomide-binding defective CRBN^YW/AA. Overexpression of CRBN wild-type protein, but not CRBN^YW/AA mutant protein, in KMS12 myeloma cells, amplified pomalidomide-mediated reductions in c-myc and IRF4 expression and increases in p21^WAF-1 expression. Long-term selection for lenalidomide resistance in H929 myeloma cell lines was accompanied by a reduction in CRBN, while in DF15R myeloma cells resistant to both pomalidomide and lenalidomide, CRBN protein was undetectable. Our biophysical, biochemical and gene silencing studies show that CRBN is a proximate, therapeutically important molecular target of lenalidomide and pomalidomide.

Genetic variation in the 5q31 cytokine gene cluster confers susceptibility to Crohn disease

Linkage disequilibrium (LD) mapping provides a powerful method for fine-structure localization of rare disease genes, but has not yet been widely applied to common disease. We sought to design a systematic approach for LD mapping and apply it to the localization of a gene (IBD5) conferring susceptibility to Crohn disease. The key issues are: (i) to detect a significant LD signal (ii) to rigorously bound the critical region and (iii) to identify the causal genetic variant within this region. We previously mapped the IBD5 locus to a large region spanning 18 cM of chromosome 5q31 (P<10(-4)). Using dense genetic maps of microsatellite markers and single-nucleotide polymorphisms (SNPs) across the entire region, we found strong evidence of LD. We bound the region to a common haplotype spanning 250 kb that shows strong association with the disease (P< 2 x 10(-7)) and contains the cytokine gene cluster. This finding provides overwhelming evidence that a specific common haplotype of the cytokine region in 5q31 confers susceptibility to Crohn disease. However, genetic evidence alone is not sufficient to identify the causal mutation within this region, as strong LD across the region results in multiple SNPs having equivalent genetic evidence-each consistent with the expected properties of the IBD5 locus. These results have important implications for Crohn disease in particular and LD mapping in general.

Cerebral metabolic and cognitive decline in persons at genetic risk for Alzheimer's disease

The major known genetic risk for Alzheimer's disease (AD), apolipoprotein E-4 (APOE-4), is associated with lowered parietal, temporal, and posterior cingulate cerebral glucose metabolism in patients with a clinical diagnosis of AD. To determine cognitive and metabolic decline patterns according to genetic risk, we investigated cerebral metabolic rates by using positron emission tomography in middle-aged and older nondemented persons with normal memory performance. A single copy of the APOE-4 allele was associated with lowered inferior parietal, lateral temporal, and posterior cingulate metabolism, which predicted cognitive decline after 2 years of longitudinal follow-up. For the 20 nondemented subjects followed longitudinally, memory performance scores did not decline significantly, but cortical metabolic rates did. In APOE-4 carriers, a 4% left posterior cingulate metabolic decline was observed, and inferior parietal and lateral temporal regions demonstrated the greatest magnitude (5%) of metabolic decline after 2 years. These results indicate that the combination of cerebral metabolic rates and genetic risk factors provides a means for preclinical AD detection that will assist in response monitoring during experimental treatments.

Visceral abdominal-fat accumulation associated with use of indinavir

BACKGROUND

After the addition of the protease inhibitor indinavir to combination drug regimens for HIV-1 infection, some patients have experienced an increase in abdominal girth with symptoms of abdominal fullness, distension, or bloating. We aimed to find out whether this collection of symptoms was associated with changes in abdominal fat and whether such changes were associated with indinavir use.

METHODS

Abdominal computed tomography was used in ten HIV-1-positive patients who had such abdominal symptoms to measure total adipose tissue (TAT) and visceral adipose tissue (VAT) at the umbilicus (L4 vertebral level). The VAT:TAT ratio in the ten cases was compared with that in ten HIV-1-infected patients who had been using indinavir without abdominal symptoms for at least 6 months and ten HIV-1-infected patients who were not using indinavir.

FINDINGS

The mean VAT:TAT ratios for the three groups-non-users, symptom-free indinavir users, and symptomatic indinavir users-were 0.40 (SD 0.15), 0.59 (0.18), and 0.70 (0.20), respectively (p=0.004). The VAT:TAT ratio correlated with duration of indinavir use (r=0.47, p=0.01). The mean areas of VAT for the three groups were 106 cm2 (SD 72), 141 cm2 (65) and 202 cm2 (93), respectively (p=0.03). The mean body-mass index of the groups was similar, and patients in the two indinavir groups did not gain a significant amount of weight after starting the drug. Serum triglyceride values increased after starting indinavir and correlated with VAT:TAT ratios.

INTERPRETATION

Our data suggest that some HIV-1-infected patients on indinavir treatment accumulate intra-abdominal fat that may cause abdominal symptoms. Recent evidence suggests that other HIV-1 protease inhibitors may be associated with changes in body-fat distribution. Larger studies of protease-inhibitor treatment are needed to investigate this association further and to investigate metabolic or endocrine mechanisms that may underlie this phenomenon.

Association of vascular endothelial growth factor and vascular endothelial growth factor receptor-2 genetic polymorphisms with outcome in a trial of paclitaxel compared with paclitaxel plus bevacizumab in advanced breast cancer: ECOG 2100

PURPOSE

No biomarkers have been identified to predict outcome with the use of an antiangiogenesis agent for cancer. Vascular endothelial growth factor (VEGF) genetic variability has been associated with altered risk of breast cancer and variable promoter activity. Therefore, we evaluated the association of VEGF genotype with efficacy and toxicity in E2100, a phase III study comparing paclitaxel versus paclitaxel plus bevacizumab as initial chemotherapy for metastatic breast cancer.

PATIENTS AND METHODS

DNA was extracted from tumor blocks of patients from E2100. Three hundred sixty-three samples were available to evaluate associations between genotype and outcome. Genotyping was performed for selected polymorphisms in VEGF and VEGF receptor 2. Testing for associations between each polymorphism and efficacy and toxicity was performed.

RESULTS

The VEGF-2578 AA genotype was associated with a superior median overall survival (OS) in the combination arm when compared with the alternate genotypes combined (hazard ratio = 0.58; 95% CI, 0.36 to 0.93; P = .023). The VEGF-1154 A allele also demonstrated a superior median OS with an additive effect of each active allele in the combination arm but not the control arm (hazard ratio = 0.62; 95% CI, 0.46 to 0.83; P = .001). Two additional genotypes, VEGF-634 CC and VEGF-1498 TT, were associated with significantly less grade 3 or 4 hypertension in the combination arm when compared with the alternate genotypes combined (P = .005 and P = .022, respectively).

CONCLUSION

Our data support an association between VEGF genotype and median OS as well as grade 3 or 4 hypertension when using bevacizumab in metastatic breast cancer.

NF-kappaB promotes breast cancer cell migration and metastasis by inducing the expression of the chemokine receptor CXCR4

Metastasis of cancer cells is a complex process involving multiple steps including invasion, angiogenesis, and trafficking of cancer cells through blood vessels, extravasations, organ-specific homing, and growth. While matrix metalloproteinases, urokinase-type plasminogen activator, and cytokines play a major role in invasion and angiogenesis, chemokines such as stromal derived factor-1alpha (SDF-1alpha) and their receptors such as CXCR4 are thought to play a critical role in motility, homing, and proliferation of cancer cells at specific metastatic sites. We and others have previously reported that the extracellular signal-activated transcription factor NF-kappaB up-regulates the expression of matrix metalloproteinases, urokinase-type plasminogen activator, and cytokines in highly metastatic breast cancer cell lines. In this report, we demonstrate that NF-kappaB regulates the motility of breast cancer cells by directly up-regulating the expression of CXCR4. Overexpression of the inhibitor of kappaB (IkappaB) in breast cancer cells with constitutive NF-kappaB activity resulted in reduced expression of CXCR4 and a corresponding loss of SDF-1alpha-mediated migration in vitro. Introduction of CXCR4 cDNA into IkappaB-expressing cells restored SDF-1alpha-mediated migration. Electrophoretic mobility shift assays and transient transfection assays revealed that the NF-kappaB subunits p65 and p50 bind directly to sequences within the -66 to +7 region of the CXCR4 promoter and activate transcription. We also show that the cell surface expression of CXCR4 and the SDF-1alpha-mediated migration are enhanced in breast cancer cells isolated from mammary fat pad xenografts compared with parental cells grown in culture. A further increase in CXCR4 cell surface expression and SDF-1alpha-mediated migration was observed with cancer cells that metastasized to the lungs. Taken together, these results implicate NF-kappaB in the migration and the organ-specific homing of metastatic breast cancer cells.

Validity of accelerometry for the assessment of moderate intensity physical activity in the field

PURPOSE

This study was undertaken to examine the validity of accelerometry in assessing moderate intensity physical activity in the field and to evaluate the metabolic cost of various recreational and household activities.

METHODS

Twenty-five subjects completed four bouts of overground walking at a range of self-selected speeds, played two holes of golf, and performed indoor (window washing, dusting, vacuuming) and outdoor (lawn mowing, planting shrubs) household tasks. Energy expenditure was measured using a portable metabolic system, and motion was recorded using a Yamax Digiwalker pedometer (walking only), a Computer Science and Application, Inc. (CSA) accelerometer, and a Tritrac accelerometer. Correlations between accelerometer counts and energy cost were examined. In addition, individual equations to predict METs from counts were developed from the walking data and applied to the other activities to compare the relationships between counts and energy cost.

RESULTS

Observed MET levels differed from values reported in the Compendium of Physical Activities, although all activities fell in the moderate intensity range. Relationships between counts and METs were stronger for walking (CSA, r = 0.77; Tritrac, r = 0.89) than for all activities combined (CSA, r = 0.59; Tritrac, r = 0.62). Metabolic costs of golf and the household activities were underestimated by 30-60% based on the equations derived from level walking.

CONCLUSION

The count versus METs relationship for accelerometry was found to be dependent on the type of activity performed, which may be due to the inability of accelerometers to detect increased energy cost from upper body movement, load carriage, or changes in surface or terrain. This may introduce error in attempts to use accelerometry to assess point estimates of physical activity energy expenditure in free-living situations.

Neural mechanisms of orientation selectivity in the visual cortex

The origin of orientation selectivity in the responses of simple cells in cat visual cortex serves as a model problem for understanding cortical circuitry and computation. The feed-forward model posits that this selectivity arises simply from the arrangement of thalamic inputs to a simple cell. Much evidence, including a number of recent intracellular studies, supports a primary role of the thalamic inputs in determining simple cell response properties, including orientation tuning. This mechanism alone, however, cannot explain the invariance of orientation tuning to changes in stimulus contrast. Simple cells receive push-pull inhibition: ON inhibition in OFF subregions and vice versa. Addition of such inhibition to the feed-forward model can account for this contrast invariance, provided the inhibition is sufficiently strong. The predictions of "normalization" and "feedback" models are reviewed and compared with the predictions of this modified feed-forward model and with experimental results. The modified feed-forward and the feedback models ascribe fundamentally different functions to cortical processing.

Phase II Study of Sunitinib Malate, an Oral Multitargeted Tyrosine Kinase Inhibitor, in Patients With Metastatic Breast Cancer Previously Treated With an Anthracycline and a Taxane

Purpose

Sunitinib is an oral, multitargeted tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor, stem cell factor receptor (KIT), and colony-stimulating factor-1 receptor. This phase II, open-label, multicenter study evaluated sunitinib monotherapy in patients with metastatic breast cancer (MBC).

Patients and Methods

Sixty-four patients previously treated with an anthracycline and a taxane received sunitinib 50 mg/d in 6-week cycles (4 weeks on, then 2 weeks off treatment). The primary end point was objective response rate. Plasma samples were obtained for pharmacokinetic and biomarker analysis.

Results

Seven patients achieved a partial response (median duration, 19 weeks), giving an overall response rate of 11%. Three additional patients (5%) maintained stable disease for ≥ 6 months. Median time to progression and overall survival were 10 and 38 weeks, respectively. Notably, responses occurred in triple negative tumors and HER2-positive, trastuzumab-treated patients. Thirty-three patients (52%) required dose interruption during ≥ 1 cycle, and 25 patients required dose reduction (39%). Thirty-six patients (56%) had dose modifications due to adverse events (AEs). Treatment was associated with increases in plasma VEGF and decreases in soluble VEGFRs and KIT. The most common AEs were fatigue, nausea, diarrhea, mucosal inflammation, and anorexia. Most AEs were mild to moderate (grade 1 to 2) in severity and were effectively managed with dose delays or reductions.

Conclusion

Sunitinib is active in patients with heavily pretreated MBC. Most AEs were of mild-to-moderate severity and manageable with supportive treatment and/or dose modification. Further studies in breast cancer are warranted.

Kinase activity controls the sorting of the epidermal growth factor receptor within the multivesicular body

We compared the internalization and intracellular sorting of epidermal growth factor receptor (EGF-R) and point mutant kinase-negative EGF-R separately expressed in NIH 3T3 cells lacking endogenous receptor. Both EGF-Rs internalized rapidly, but kinase-negative receptor was surface down-regulated only with monensin or at 20 degrees C. Furthermore, EGF internalized by mutant receptor alone was, in significant proportion, returned to the cell surface undegraded. Hence unlike wild-type receptor, kinase-negative EGF-R recycles. By electron microscopy the early pathways of endocytosis for the two receptors were identical; however, after 10-20 min the pathways diverged at the multivesicular body (MVB). Wild-type EGF-R, destined for degradation, localized to internal vesicles, while kinase-negative EGF-R, destined for recycling, localized to surface membranes of the MVBs and moved to small tubulovesicles. We conclude that sorting of internalized receptor for degradation or recycling can occur through spatial segregation within the MVB, and sorting of EGF-R is controlled by tyrosine kinase activity.

Ocular dominance column development: analysis and simulation

The visual cortex of many adult mammals has patches of cells that receive inputs driven by the right eye alternating with patches that receive inputs driven by the left eye. These ocular dominance patches (or "columns") form during early life as a consequence of competition between the activity patterns of the two eyes. A mathematical model of several biological mechanisms that can account for this development is presented. Analysis of this model reveals the conditions under which ocular dominance segregation will occur and determines the resulting patch width. Simulations of the model also exhibit other phenomena associated with early visual development, such as topographic refinement of cortical receptive fields, the confinement of input cell connections to patches, monocular deprivation plasticity including a critical period, and the effect of artificially induced strabismus. The model can be used to predict the results of proposed experiments and to discriminate among various mechanisms of plasticity.

Enzalutamide for the Treatment of Androgen Receptor-Expressing Triple-Negative Breast Cancer

Purpose Studies suggest that a subset of patients with triple-negative breast cancer (TNBC) have tumors that express the androgen receptor (AR) and may benefit from an AR inhibitor. This phase II study evaluated the antitumor activity and safety of enzalutamide in patients with locally advanced or metastatic AR-positive TNBC. Patients and Methods Tumors were tested for AR with an immunohistochemistry assay optimized for breast cancer; nuclear AR staining > 0% was considered positive. Patients received enzalutamide 160 mg once per day until disease progression. The primary end point was clinical benefit rate (CBR) at 16 weeks. Secondary end points included CBR at 24 weeks, progression-free survival, and safety. End points were analyzed in all enrolled patients (the intent-to-treat [ITT] population) and in patients with one or more postbaseline assessment whose tumor expressed ≥ 10% nuclear AR (the evaluable subgroup). Results Of 118 patients enrolled, 78 were evaluable. CBR at 16 weeks was 25% (95% CI, 17% to 33%) in the ITT population and 33% (95% CI, 23% to 45%) in the evaluable subgroup. Median progression-free survival was 2.9 months (95% CI, 1.9 to 3.7 months) in the ITT population and 3.3 months (95% CI, 1.9 to 4.1 months) in the evaluable subgroup. Median overall survival was 12.7 months (95% CI, 8.5 months to not yet reached) in the ITT population and 17.6 months (95% CI, 11.6 months to not yet reached) in the evaluable subgroup. Fatigue was the only treatment-related grade 3 or higher adverse event with an incidence of > 2%. Conclusion Enzalutamide demonstrated clinical activity and was well tolerated in patients with advanced AR-positive TNBC. Adverse events related to enzalutamide were consistent with its known safety profile. This study supports additional development of enzalutamide in advanced TNBC.

A phase I/II dose-escalation trial of bevacizumab in previously treated metastatic breast cancer

Vascular endothelial growth factor promotes angiogenesis, an important mediator of growth and metastasis in human breast cancer. Bevacizumab, a monoclonal antibody to vascular endothelial growth factor, is under investigation as an anti-angiogenic agent. This phase I/II trial evaluated the safety and efficacy of bevacizumab in patients with previously treated metastatic breast cancer. Seventy-five patients were treated with escalating doses of bevacizumab ranging from 3 mg/kg to 20 mg/kg administered intravenously every other week. Tumor response was assessed before the sixth (70 days) and 12th (154 days) doses. Safety was evaluated during every cycle. Eighteen patients were treated at 3 mg/kg, 41 at 10 mg/kg, and 16 at 20 mg/kg. Four patients discontinued study treatment because of an adverse event. Hypertension was reported as an adverse event in 17 patients (22%). The overall response rate was 9.3% (confirmed response rate, 6.7%). The median duration of confirmed response was 5.5 months (range, 2.3 to 13.7 months). At the final tumor assessment on day 154, 12 of 75 patients (16%) had stable disease or an ongoing response. The optimal dose of bevacizumab in this trial was 10 mg/kg every other week and toxicity was acceptable. These data support the initiation of trials in metastatic breast cancer combining bevacizumab with chemotherapy.

Randomized phase II, double-blind, placebo-controlled study of exemestane with or without entinostat in postmenopausal women with locally recurrent or metastatic estrogen receptor-positive breast cancer progressing on treatment with a nonsteroidal aromatase inhibitor

PURPOSE

Entinostat is an oral isoform selective histone deacetylase inhibitor that targets resistance to hormonal therapies in estrogen receptor-positive (ER+) breast cancer. This randomized, placebo-controlled, phase II study evaluated entinostat combined with the aromatase inhibitor exemestane versus exemestane alone.

PATIENTS AND METHODS

Postmenopausal women with ER+ advanced breast cancer progressing on a nonsteroidal aromatase inhibitor were randomly assigned to exemestane 25 mg daily plus entinostat 5 mg once per week (EE) or exemestane plus placebo (EP). The primary end point was progression-free survival (PFS). Blood was collected in a subset of patients for evaluation of protein lysine acetylation as a biomarker of entinostat activity.

RESULTS

One hundred thirty patients were randomly assigned (EE group, n = 64; EP group, n = 66). Based on intent-to-treat analysis, treatment with EE improved median PFS to 4.3 months versus 2.3 months with EP (hazard ratio [HR], 0.73; 95% CI, 0.50 to 1.07; one-sided P = .055; two-sided P = .11 [predefined significance level of .10, one-sided]). Median overall survival was an exploratory end point and improved to 28.1 months with EE versus 19.8 months with EP (HR, 0.59; 95% CI, 0.36 to 0.97; P = .036). Fatigue and neutropenia were the most frequent grade 3/4 toxicities. Treatment discontinuation because of adverse events was higher in the EE group versus the EP group (11% v 2%). Protein lysine hyperacetylation in the EE biomarker subset was associated with prolonged PFS.

CONCLUSION

Entinostat added to exemestane is generally well tolerated and demonstrated activity in patients with ER+ advanced breast cancer in this signal-finding phase II study. Acetylation changes may provide an opportunity to maximize clinical benefit with entinostat. Plans for a confirmatory study are underway.

Immunohistochemistry of matrix metalloproteinases in reperfusion injury to rat brain: activation of MMP-9 linked to stromelysin-1 and microglia in cell cultures

Reperfusion damages the blood-brain barrier (BBB). Matrix metalloproteinases (MMPs) are associated with the opening of the BBB, but their cellular localization and activation mechanisms are uncertain. We used immunohistochemistry to determine the cellular localization of the MMPs in reperfused rat brain, and cell cultures to study their activation. Spontaneously hypertensive rats (SHR) had a 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion for times from 3 h to 21 days. Frozen sections were immunostained with antibodies to gelatinase A (MMP-2), stromelysin-1 (MMP-3), and gelatinase B (MMP-9). Sham-operated control rats showed MMP-2 immunostaining in astrocytic processes next to blood vessels. After 3 h of the onset of reperfusion MMP-2 immunostaining increased in astrocytes. At 24 h immunoreactivity for MMP-3 and MMP-9 appeared. MMP-3 co-localized with activated microglia (Ox-42+) and ischemic neurons (NeuN+). MMP-9 immunostaining was seen at 48 h in endothelial cells, neutrophils, and neurons. At 5 and 21 days intense MMP-2 staining was seen in reactive astrocytes around the ischemic core. Studies of activation of the MMP were done in lipopolysaccharide (LPS)-stimulated astrocyte and microglia cultures. Stimulated astrocytes produced an activated form of MMP-2. When microglia were stimulated, they activated MMP-9. Immunostaining showed MMP-3 in cultures of enriched microglial cells. The hydroxymate-type, MMP inhibitor, BB-1101, blocked the activation of MMP-2 and MMP-9 by LPS in mixed glial cultures. We propose that MMP-2 is normally present in astrocytic end feet, and that during ischemia MMP-9 and MMP-3 are produced. MMP-3 in microglia/macrophages may be activating proMMP-9. Our results show that a differential expression of MMPs by astrocytes, microglia, and endothelial cells at the blood vessels is involved in the proteolytic disruption of the BBB.

Movement of internalized ligand-receptor complexes along a continuous endosomal reticulum

Complexes of cell-surface receptors and their ligands are commonly internalized by endocytosis and enter a prelysosomal endosomal pathway for further processing. Fluorescence microscopy and video recording of living cells to trace the passage of ligand-receptor complexes has identified the endosomal compartment as an extensive network of tubular cisternae. Endocytosed material entering this reticulum enters discrete swellings, identified as multivesicular bodies by electron microscopy, which move along the reticulum towards the pericentriolar area.

Comparison of Abbreviated Breast MRI vs Digital Breast Tomosynthesis for Breast Cancer Detection Among Women With Dense Breasts Undergoing Screening

IMPORTANCE

Improved screening methods for women with dense breasts are needed because of their increased risk of breast cancer and of failed early diagnosis by screening mammography.

OBJECTIVE

To compare the screening performance of abbreviated breast magnetic resonance imaging (MRI) and digital breast tomosynthesis (DBT) in women with dense breasts.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study with longitudinal follow-up at 48 academic, community hospital, and private practice sites in the United States and Germany, conducted between December 2016 and November 2017 among average-risk women aged 40 to 75 years with heterogeneously dense or extremely dense breasts undergoing routine screening. Follow-up ascertainment of cancer diagnoses was complete through September 12, 2019.

EXPOSURES

All women underwent screening by both DBT and abbreviated breast MRI, performed in randomized order and read independently to avoid interpretation bias.

MAIN OUTCOMES AND MEASURES

The primary end point was the invasive cancer detection rate. Secondary outcomes included sensitivity, specificity, additional imaging recommendation rate, and positive predictive value (PPV) of biopsy, using invasive cancer and ductal carcinoma in situ (DCIS) to define a positive reference standard. All outcomes are reported at the participant level. Pathology of core or surgical biopsy was the reference standard for cancer detection rate and PPV; interval cancers reported until the next annual screen were included in the reference standard for sensitivity and specificity.

RESULTS

Among 1516 enrolled women, 1444 (median age, 54 [range, 40-75] years) completed both examinations and were included in the analysis. The reference standard was positive for invasive cancer with or without DCIS in 17 women and for DCIS alone in another 6. No interval cancers were observed during follow-up. Abbreviated breast MRI detected all 17 women with invasive cancer and 5 of 6 women with DCIS. Digital breast tomosynthesis detected 7 of 17 women with invasive cancer and 2 of 6 women with DCIS. The invasive cancer detection rate was 11.8 (95% CI, 7.4-18.8) per 1000 women for abbreviated breast MRI vs 4.8 (95% CI, 2.4-10.0) per 1000 women for DBT, a difference of 7 (95% CI, 2.2-11.6) per 1000 women (exact McNemar P = .002). For detection of invasive cancer and DCIS, sensitivity was 95.7% (95% CI, 79.0%-99.2%) with abbreviated breast MRI vs 39.1% (95% CI, 22.2%-59.2%) with DBT (P = .001) and specificity was 86.7% (95% CI, 84.8%-88.4%) vs 97.4% (95% CI, 96.5%-98.1%), respectively (P < .001). The additional imaging recommendation rate was 7.5% (95% CI, 6.2%-9.0%) with abbreviated breast MRI vs 10.1% (95% CI, 8.7%-11.8%) with DBT (P = .02) and the PPV was 19.6% (95% CI, 13.2%-28.2%) vs 31.0% (95% CI, 17.0%-49.7%), respectively (P = .15).

CONCLUSIONS AND RELEVANCE

Among women with dense breasts undergoing screening, abbreviated breast MRI, compared with DBT, was associated with a significantly higher rate of invasive breast cancer detection. Further research is needed to better understand the relationship between screening methods and clinical outcome.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02933489.

Constitutive modelling of brain tissue: experiment and theory

Recent developments in computer-integrated and robot-aided surgery--in particular, the emergence of automatic surgical tools and robots--as well as advances in virtual reality techniques, call for closer examination of the mechanical properties of very soft tissues (such as brain, liver, kidney, etc.). The ultimate goal of our research into the biomechanics of these tissues is the development of corresponding, realistic mathematical models. This paper contains experimental results of in vitro, uniaxial, unconfined compression of swine brain tissue and discusses a single-phase, non-linear, viscoelastic tissue model. The experimental results obtained for three loading velocities, ranging over five orders of magnitude, are presented. The applied strain rates have been much lower than those applied in previous studies, focused on injury modelling. The stress-strain curves are concave upward for all compression rates containing no linear portion from which a meaningful elastic modulus might be determined. The tissue response stiffened as the loading speed increased, indicating a strong stress-strain rate dependence. The use of the single-phase model is recommended for applications in registration, surgical operation planning and training systems as well as a control system of an image-guided surgical robot. The material constants for the brain tissue are evaluated. Agreement between the proposed theoretical model and experiment is good for compression levels reaching 30% and for loading velocities varying over five orders of magnitude.

Redefining the target: chemotherapeutics as antiangiogenics

Angiogenesis, or new blood vessel formation, is now known to play an important role in both growth and metastasis of many cancers. The central importance of angiogenesis and the understanding of how new blood vessels are formed, has led to novel therapies designed to interrupt this process. Though specific antiangiogenic compounds have only recently entered the clinic, they herald a new era, one in which biology is the basis for therapy. The intense interest in angiogenesis has also lead to a re-examination of the activity of many established cytotoxic agents. Claims of antiangiogenic activity abound, unfortunately, with no common criteria and often little evidence of clinical relevance. What are we to think? Have oncologists unknowingly been administering antiangiogenic therapy all these years? If chemotherapeutics are really antiangiogenics in disguise, why have they failed to cure most solid tumors? Might the hard-learned lessons of chemotherapy resistance pertain to the novel antiangiogenics as well? Though we can offer no certain answers to these important questions, we do offer a framework on which to order the rapidly burgeoning literature. We suggest criteria by which a cytotoxic agent might reasonably be considered to have meaningful antiangiogenic activity. Finally, we describe potential mechanisms of resistance to antiangiogenic chemotherapies-some of which may apply to the pure antiangiogenics currently in development.

Mechanical properties of brain tissue in-vivo: experiment and computer simulation

Realistic computer simulation of neurosurgical procedures requires incorporation of the mechanical properties of brain tissue in the mathematical model. Possible applications of computer simulation of neurosurgery include non-rigid registration, virtual reality training and operation planning systems and robotic devices to perform minimally invasive brain surgery. A number of constitutive models of brain tissue, both single-phase and bi-phasic, have been proposed in recent years. The major deficiency of most of them, however, is the fact that they were identified using experimental data obtained in vitro and there is no certainty whether they can be applied in the realistic in vivo setting. In this paper we attempt to show that previously proposed by us hyper-viscoelastic constitutive model of brain tissue can be applied to simulating surgical procedures. An in vivo indentation experiment is described. The force-displacement curve for the loading speed typical for surgical procedures is concave upward containing no linear portion from which a meaningful elastic modulus might be determined. In order to properly analyse experimental data, a three-dimensional, non-linear finite element model of the brain was developed. Magnetic resonance imaging techniques were used to obtain geometric information needed for the model. The shape of the force-displacement curve obtained using the numerical solution was very similar to the experimental one. The predicted forces were about 31% lower than those recorded during the experiment. Having in mind that the coefficients in the model had been identified based on experimental data obtained in vitro, and large variability of mechanical properties of biological tissues, such agreement can be considered as very good. By appropriately increasing material parameters describing instantaneous stiffness of the tissue one is able, without changing the structure of the model, to reproduce experimental curve almost perfectly. Numerical studies showed also that the linear, viscoelastic model of brain tissue is not appropriate for the modelling brain tissue deformation even for moderate strains.