Quantitative MRI findings indicate diffuse white matter damage in Susac Syndrome

Background

Susac Syndrome (SuS) is an autoimmune endotheliopathy impacting the brain, retina and cochlea that can clinically mimic multiple sclerosis (MS).

Objective

To evaluate non-lesional white matter demyelination changes in SuS compared to MS and healthy controls (HC) using quantitative MRI.

Methods

3T MRI including myelin water imaging and diffusion basis spectrum imaging were acquired for 7 SuS, 10 MS and 10 HC participants. Non-lesional white matter was analyzed in the corpus callosum (CC) and normal appearing white matter (NAWM). Groups were compared using ANCOVA with Tukey correction.

Results

SuS CC myelin water fraction (mean 0.092) was lower than MS(0.11, p = 0.01) and HC(0.11, p = 0.04). Another myelin marker, radial diffusivity, was increased in SuS CC(0.27μm2/ms) compared to HC(0.21μm2/ms, p = 0.008) and MS(0.23μm2/ms, p = 0.05). Fractional anisotropy was lower in SuS CC(0.82) than HC(0.86, p = 0.04). Fiber fraction (reflecting axons) did not differ from HC or MS. In NAWM, radial diffusivity and apparent diffusion coefficient were significantly increased in SuS compared to HC(p < 0.001 for both measures) and MS(p = 0.003, p < 0.001 respectively).

Conclusions

Our results provided evidence of myelin damage in SuS, particularly in the CC, and more extensive microstructural injury in NAWM, supporting the hypothesis that there are widespread microstructural changes in SuS syndrome including diffuse demyelination.

Diffusely abnormal white matter in clinically isolated syndrome is associated with parenchymal loss and elevated neurofilament levels

We characterized the frequency of diffusely abnormal white matter (DAWM) across a broad spectrum of multiple sclerosis (MS) participants. 35% of clinically isolated syndrome (CIS), 57% of relapsing remitting and 64% of secondary progressive MS participants demonstrated DAWM. CIS with DAWM had decreased cortical thickness, higher lesion load and a higher concentration of serum neurofilament light chain compared to CIS without DAWM. DAWM may be useful in identifying CIS patients with greater injury to their brains. Larger and longitudinal studies are warranted.

Machine learning for predicting AF ablation outcomes using daily heart rhythm data at baseline

Background

While numerous studies have shown that catheter ablation is superior to antiarrhythmic drug (AAD) in treating atrial fibrillation (AF), the long term outcomes have been limited by arrhythmia recurrence. Reliable data and methods to predict ablation outcomes will thus be valuable for treatment planning.

Objective

To evaluate the utility of machine learning and various types of input variables, viz. patient characteristics at baseline, and daily heart rhythm data recorded prior to ablation for outcome prediction.

Methods

We acquired permission to analyze data collected from a randomized clinical trial that recorded daily biomeasures from &gt;345 patients who were referred for first catheter ablation due to AF refractory to at least one AAD. After standardizing the dataset, each patient sample is characterized by a set of daily measures, viz. heart rate variability (HRV) and AF burden (AFB), which is the total minutes in AF per day. We next performed comparative analyses on 19 candidate model variants to evaluate each model's ability in identifying patients who were to experience at least one episode of AF recurrence during post-ablation period starting from day 91 up to day 365 post-ablation, per standard guidelines. We examined: i) use of a set of daily biomeasures jointly with baseline sex and age; and ii) observation lengths of the pre-ablation period. We also examined the use of baseline CHA2DS2-VASc scores, left-atrial volume (LAV), atrial diameter, medical history. We conducted multiple sets of 3-fold cross validation (CV) experiments, each fold independently trained a candidate model with 236 samples (two thirds of the dataset) and performed evaluation on the left-out samples. About 50% of cohort belongs to one class. Each fold scored a model and its input variables in terms of sensitivity (SEN), specificity (SPEC), area under receiver operating characteristic curve (AUC), etc. To circumvent risks of overfitting highly parameterized models to our training subset, we shortlisted 19 models that have few hyper-parameters, e.g. stepwise regression, random forest (RF), linear discriminant analysis (LDA).

Results

CV results demonstrated that LDA and RF gave comparable performances, with RF achieving highest AUC of 0.68±0.06 using 30 days of rhythm data prior to ablation (SEN of 65.9±7.82; SPEC of 66.3±0.57). When observation period extended to 90 days prior, AUC improved to 0.691±0.02. In contrast, use of LAV alone was not adequate to predict outcome (AUC∼0.5), and when combined with all aforementioned baseline variables, the best model achieved AUC of 0.58±0.05. Feature analyses from the trained models suggest that AFB had highest relevance in predicting outcome. Using only daily AFB, RF and LDA respectively achieved AUC of 0.608±0.04 and 0.652±0.04.

Conclusions

Our results suggest the value of pre-ablation rhythm data for improving outcome-prediction. Future work will validate these findings using large public datasets.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Huawei-Data Science Institute Research Program; Natural Sciences and Engineering Research Council of Canada (NSERC)

Gadolinium Deposition in Deep Brain Structures: Relationship with Dose and Ionization of Linear Gadolinium-Based Contrast Agents

BACKGROUND AND PURPOSE

Dose-dependent association between hyperintensity in deep brain structures on unenhanced T1WIs and gadolinium-based contrast agent administrations has been demonstrated with subsequent histopathological confirmation of gadolinium deposition. Our aim was to determine whether greater exposure to linear gadolinium-based contrast agent administration is associated with higher signal intensity in deep brain structures on unenhanced T1-weighted MR imaging. Secondary objective was to compare signal intensity differences between ionic and nonionic linear gadolinium-based contrast agents.

MATERIALS AND METHODS

Subjects with secondary-progressive MS originally enrolled in a multicenter clinical trial were studied retrospectively. Eighty subjects (high-exposure cohort) received 9 linear gadolinium-based contrast agent administrations (30 nonionic/50 ionic) between week -4 and year 1 and a tenth administration by year 2. One hundred fifteen subjects (low-exposure cohort) received 2 administrations (40 nonionic/75 ionic) between week -4 and year 1 and a third administration by year 2. Signal intensities were measured on unenhanced T1WIs by placing sample-points on the dentate nucleus, globus pallidus, caudate, thalamus, pons, and white matter, and they were normalized using the following ratios: dentate/pons, globus pallidus/white matter, caudate/white matter, and thalamus/white matter.

RESULTS

Between week -4 and year 1, subjects in the high-exposure cohort showed increased signal intensity ratios in all regions (P < .01), while the low-exposure cohort showed only an increase in the dentate nucleus (P = .003). Between years 1 and 2, when both cohorts received only 1 additional gadolinium-based contrast agent, no significant changes were observed. In the high-exposure cohort, significantly higher changes in signal intensity ratios were observed in subjects receiving linear nonionic than in those receiving linear ionic gadolinium-based contrast agents.

CONCLUSIONS

Hyperintensity in deep brain structures from gadolinium deposition is related to the number of doses and the type of linear gadolinium-based contrast agent (nonionic greater than ionic) administration.

Vasoconstrictor stimulus determines the functional contribution of myoendothelial feedback to mesenteric arterial tone

KEY POINTS

In isolated resistance arteries, endothelial modulation of vasoconstrictor responses to α₁ -adrenoceptor agonists occurs via a process termed myoendothelial feedback: localized inositol trisphosphate (InsP₃ )-dependent Ca²⁺ transients activate intermediate conductance Ca²⁺ -activated K⁺ (IK_Ca ) channels, hyperpolarizing the endothelial membrane potential to limit further reductions in vessel diameter. We demonstrate that IK_Ca channel-mediated myoendothelial feedback limits responses of isolated mesenteric arteries to noradrenaline and nerve stimulation, but not to the thromboxane A₂ mimetic U46619 or to increases in intravascular pressure. In contrast, in the intact mesenteric bed, although responses to exogenous noradrenaline were limited by IK_Ca channel-mediated myoendothelial feedback, release of NO and activation of endothelial small conductance Ca²⁺ -activated K⁺ (SK_Ca ) channels in response to increases in shear stress appeared to be the primary mediators of endothelial modulation of vasoconstriction. We propose that (1) the functional contribution of myoendothelial feedback to arterial tone is determined by the nature of the vasoconstrictor stimulus, and (2) although IK_Ca channel-mediated myoendothelial feedback may contribute to local control of arterial diameter, in the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction.

ABSTRACT

Constriction of isolated resistance arteries in response to α₁ -adrenoceptor agonists is limited by reciprocal engagement of inhibitory endothelial mechanisms via myoendothelial feedback. In the current model of feedback, agonist stimulation of smooth muscle cells results in localized InsP₃ -dependent Ca²⁺ transients that activate endothelial IK_Ca channels. The subsequent hyperpolarization of the endothelial membrane potential then feeds back to the smooth muscle to limit further reductions in vessel diameter. We hypothesized that the functional contribution of InsP₃ -IK_Ca channel-mediated myoendothelial feedback to limiting arterial diameter may be influenced by the nature of the vasoconstrictor stimulus. To test this hypothesis, we investigated the functional role of myoendothelial feedback in modulating responses of rat mesenteric resistance arteries to the adrenoceptor agonist noradrenaline, the thromboxane A₂ mimetic U46619, increases in intravascular pressure and stimulation of perivascular sympathetic nerves. In isolated arteries, responses to noradrenaline and stimulation of sympathetic nerves, but not to U46619 and increases in intravascular pressure, were modulated by IK_Ca channel-dependent myoendothelial feedback. In the intact mesenteric bed perfused under conditions of constant flow, responses to exogenous noradrenaline were modulated by myoendothelial feedback, but shear stress-induced release of NO and activation of endothelial SK_Ca channels appeared to be the primary mediators of endothelial modulation of vasoconstriction to agonists and nerve stimulation. Thus, we propose that myoendothelial feedback may contribute to local control of diameter within arterial segments, but at the level of the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction.

Subcutaneous interferon β-1a three times weekly and the natural evolution of gadolinium-enhancing lesions into chronic black holes in relapsing and progressive multiple sclerosis: Analysis of PRISMS and SPECTRIMS trials

Background

Evolution of gadolinium-enhancing lesions into chronic black holes (CBH) may be reduced by interferon (IFN) therapy.

Objective

The objective of this paper is to assess the effect of IFN β-1a and placebo on CBH evolution and disability in patients with relapsing–remitting multiple sclerosis (RRMS), as well as CBH evolution in patients with secondary progressive multiple sclerosis (SPMS).

Methods

A post hoc, exploratory analysis of patients with RRMS and SPMS with monthly MRI scans (months –1 to 9) from two separate placebo-controlled clinical trials of IFN β-1a was conducted.

Results

In RRMS patients, the risk of ≥1 evolved CBH was lower for IFN β-1a versus placebo (odds ratio 0.42; p = 0.024); volume of newly evolved CBH was numerically reduced. A numerically higher proportion of patients with ≥1 evolving CBH vs no evolving CBH had confirmed three-month disability progression (four-year rate 55.8% vs 43.1%, respectively). Proportion of lesions evolving into CBH (patient level: 34.7% vs 12.6%, p < 0.0001; lesion level: 28.8% vs 11.0%, p < 0.0001) and evolved CBH volume (median 33.5 mm³ (Quartile 1, 0.0; Quartile 3, 173.4) vs 0.0 mm³ (0.0; 52.4); p = 0.0008) was higher for SPMS than RRMS patients treated with IFN β-1a.

Conclusion

In RRMS, IFN β-1a significantly decreased the proportion of new T1 Gd+ lesions evolving into CBH and the risk of developing a CBH. In patients with SPMS, more lesions develop to CBH, indicating reduced repair capacity, and the natural history of lesion development appears to be unaffected by IFN β-1a treatment.

WNT antagonists exhibit unique combinatorial antitumor activity with taxanes by potentiating mitotic cell death

The WNT pathway mediates intercellular signaling that regulates cell fate in both normal development and cancer. It is widely appreciated that the WNT pathway is frequently dysregulated in human cancers through a variety of genetic and epigenetic mechanisms. Targets in the WNT pathway are being extensively pursued for the development of new anticancer therapies, and we have advanced two WNT antagonists for clinical development: vantictumab (anti-FZD) and ipafricept (FZD8-Fc). We examined the antitumor efficacy of these WNT antagonists in combination with various chemotherapies in a large set of patient-derived xenograft models. In responsive models, WNT blockade led to profound synergy with taxanes such as paclitaxel, and the combination activity with taxanes was consistently more effective than with other classes of chemotherapy. Taxane monotherapy increased the frequency of cells with active WNT signaling. This selection of WNT-active chemotherapy-resistant tumorigenic cells was prevented by WNT-antagonizing biologics and required sequential dosing of the WNT antagonist followed by the taxane. The WNT antagonists potentiated paclitaxel-mediated mitotic blockade and promoted widespread mitotic cell death. By blocking WNT/β-catenin signaling before mitotic blockade by paclitaxel, we found that this treatment effectively sensitizes cancer stem cells to taxanes. This combination strategy and treatment regimen has been incorporated into ongoing clinical testing for vantictumab and ipafricept.

HAN DOVER BETWEEN ANAESTHETISTS AND POST-ANAESTHETIC CARE UNIT NURSING STAFF USING ISBAR PRINCIPLES: A QUALITY IMPROVEMENT STUDY

A structured approach to communication between health care professionals contains introduction/identification; situation; background; assessment and request/recommendation (ISBAR). ISBAR was introduced into the post anaesthetic care unit (PACU) of a large Victorian health service in 2013. The aim of this study was to measure the effect of an education program on ISBAR compliance.

METHOD

A pre/post-test design using a 14-item audit tool was used to measure compliance to ISBAR before and after an education intervention in two acute hospitals in Melbourne, Victoria. The intervention consisted of one 30-minute education session to anaesthetists, and two 30-minute education sessions to PACU nurses, combined with visual cues using ISBAR wall posters.

RESULTS

In Hospital A, significant improvement from pre- to post-audit was found in the items of cardiovascular assessment and actions (Fisher's exact test p < .05) and (X² (1) = 4.06, p < .05), respiratory assessment (X² (1) = 12.85, p < .01), analgesia assessment and responsibility + referral (X² (1) = 4.44, p < .05. For Hospital B significant improvement was found in communication difficulties (X² (2)= 13.55, p-< .01) and significant decreased performance was found in respiratory assessment (X² (1) = 8.98, p < .01) and responsibility + referral (X² (1) = 13.26, p < .01).

IMPLICATION FOR PRACTICE

The results from this study cohort suggest an augmented education program may produce mixed results for ISBAR compliance. More than education and visual tools may be required to improve PACU ISBAR compliance.

Abstract A42: Using a PDX tumor bank to screen for cancer stem cell therapies

OncoMed Pharmaceuticals is focused on discovering novel therapies that target cancer stem cells (CSCs), specifically those which depend on the Notch or Wnt pathways. Since Patient Derived Xenografts (PDXs) recapitulate both tumor cell heterogeneity and maintain the histopathological characteristics of the original tumor, they represent an important preclinical model for CSC drug discovery and can be used to effectively screen for new therapeutic candidates. To this end, OncoMed has established a fully characterized PDX Tumor Bank for its monoclonal antibody discovery and developmental efforts and has used PDX models to advance seven candidates into clinical trials. The goal of this study is to: 1) review the operational steps needed to propagate PDX's; 2) define the quality controls necessary to maintain these tumors; 3) assess how the Tumor Bank has helped in the selection and advancement of these targeted biologics into the clinic; and 4) review the role of the Tumor Bank in defining biomarkers for clinical use.

Tumor specimens were received from surgery and processed into fragments, cell clumps, or dissociated cells. Tumor tissue or cells were either implanted into NOG or Nod/scid mice or frozen for later implantation. Primary tumors that grew were serially transplanted to establish working stocks for drug screening experiments. Every tumor was characterized for a variety of molecular, cellular, and tumor endpoints. All pertinent data and samples were captured into a custom designed database which included lineage diagrams to easily track tumor propagation and characterization endpoints.

The quality control of the established PDXs must be carefully monitored throughout the process. We have used DNA fingerprinting to ensure the identification of each tumor and subsequent passages, but the larger problem of identifying and monitoring the development of spontaneous lymphomas (both human and murine) that can infiltrate and contaminate the PDX required a rigorous monitoring strategy. The infection of mice with Lactate Dehydrogenase Elevating Virus from contaminated reagents can severely affect animal health and, therefore the screening process. Surprisingly, the misdiagnosis of tumors received from surgery was higher than expected and resulted in tumors being correctly reclassified before being used.

The strategy employed to effectively screen selected targets in the Notch and Wnt pathways was to first review the molecular characterization data from our PDX models, and then select appropriate models for in vivo efficacy testing. In order to assess how the Tumor Bank has helped both in the screening process and the identification of biomarkers, we will review both pre-clinical and clinical data for selected OncoMed antibodies. As an example, one anti-CSC agent, OMP-59R5 (Tarextumab), which targets Notch2/3 was tested in ten pancreatic PDX models. Six pancreatic PDX tumors were responders to anti-NOTCH2/3 while four were non-responders. Bioinformatic analysis of the responder/non-responder data sets identified tumors that had high Notch3 gene expression as responders to OMP-59R5 treatment. Based on this preclinical data, Notch3 levels were evaluated in a Phase 1b pancreatic trial as a potential predictive biomarker. In this trial, higher response rate and longer survival was noted in patients with Notch3 high tumors receiving GEM/Nab-P/ Tarextumab (at 5-15mg/kg). These observations are being tested in a placebo-controlled, randomized Ph2 setting.

The creation of a working PDX Tumor Bank across multiply human solid tumor types has allowed us to implement an effective preclinical screening program to select candidate biologics and potential predictive biomarkers for targets in the Notch and Wnt pathways.

Citation Format: James Evans, Chun Zhang, Angie InKyung Park, Alayne Brunner, Min Wang, Cristina Dee-Hoskins, Roger Lopez, Xiaomei Song, Kellie Pickell, Wan-Cheng Yen, Marcus Fischer, Raymond Tam, Gilbert O'Young, Jakob Dupont, Lei Zhou, Austin Gurney, John Lewicki, Tim Hoey, Ann M. Kapoun, Belinda Cancilla. Using a PDX tumor bank to screen for cancer stem cell therapies. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A42.

Abstract 4652: Effects of anti-DLL4 treatment on non-small cell lung cancer (NSCLC) human xenograft tumors

Background: Non-small cell lung cancer (NSCLC) accounts for the vast majority of lung cancers, the leading cause of cancer-related deaths. Notch signaling has been shown to play an important role in lung cancer initiation and progression. Delta-like ligand 4 (DLL4) activates the Notch pathway and is important for cancer stem cell (CSC) survival. Demcizumab (OMP-21M18) is a humanized IgG2 anti-DLL4 antibody currently being tested in a Phase 2 trial in combination with pemetrexed and carboplatin for first-line treatment of patients with NSCLC. Previously, OMP-21M18 in combination with its mouse anti-DLL4 surrogate has been shown to inhibit tumor growth, decrease cancer stem cell frequency, and cause dysfunctional sprouting of new vessels resulting in an anti-angiogenic effect in patient-derived tumor xenograft (PDX) models in breast, colon, ovarian, and pancreatic cancers. Here we show results from NSCLC PDX models.

Methods and Results: Anti-DLL4 treatment was tested in a series of NSCLC PDX models. Because DLL4 inhibition has been shown to have effects on the tumor as well as the vasculature, the combination of OMP-21M18 (targeting human DLL4) and 21R30 (antibody targeting mouse DLL4) treatment in the PDX models was used to model demcizumab treatment in humans. Treatment with anti-DLL4 in combination with chemotherapy inhibited tumor growth in a series of NSCLC PDX models. Additionally, a tumorigenicity assay showed a decrease in the frequency of tumor-initiating cells following treatment with anti-DLL4 and chemotherapy. Gene expression analysis of tumor samples provided insights into the mechanism of action.

Conclusions: Anti-DLL4 treatment in a panel of NSCLC PDX tumor models in vivo showed inhibition of tumor growth and a decrease in the frequency of tumor-initiating cells. Mechanism of action and gene expression analysis of these models treated with anti-DLL4 will be presented. These findings provide additional evidence supporting demcizumab as an effective treatment for NSCLC patients.

Citation Format: Alayne Brunner, Fiore Cattaruzza, Wan-Ching Yen, Pete Yeung, Marcus Fischer, Belinda Cancilla, Gilbert O’Young, Raymond Tam, Yu-Wang Liu, Austin Gurney, John Lewicki, Tim Hoey, Min Wang, Ann M. Kapoun. Effects of anti-DLL4 treatment on non-small cell lung cancer (NSCLC) human xenograft tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4652.

Activation of endothelial IKCa channels underlies NO-dependent myoendothelial feedback

Agonist-induced vasoconstriction triggers a negative feedback response whereby movement of charged ions through gap junctions and/or release of endothelium-derived (NO) limit further reductions in diameter, a mechanism termed myoendothelial feedback. Recent studies indicate that electrical myoendothelial feedback can be accounted for by flux of inositol trisphosphate (IP3) through myoendothelial gap junctions resulting in localized increases in endothelial Ca(2+) to activate intermediate conductance calcium-activated potassium (IKCa) channels, the resultant hyperpolarization then conducting back to the smooth muscle to attenuate agonist-induced depolarization and tone. In the present study we tested the hypothesis that activation of IKCa channels underlies NO-mediated myoendothelial feedback. Functional experiments showed that block of IP3 receptors, IKCa channels, gap junctions and transient receptor potential canonical type-3 (TRPC3) channels caused endothelium-dependent potentiation of agonist-induced increase in tone which was not additive with that caused by inhibition of NO synthase supporting a role for these proteins in NO-mediated myoendothelial feedback. Localized densities of IKCa and TRPC3 channels occurred at the internal elastic lamina/endothelial-smooth muscle interface in rat basilar arteries, potential communication sites between the two cell layers. Smooth muscle depolarization to contractile agonists was accompanied by IKCa channel-mediated endothelial hyperpolarization providing the first demonstration of IKCa channel-mediated hyperpolarization of the endothelium in response to contractile agonists. Inhibition of IKCa channels, gap junctions, TRPC3 channels or NO synthase potentiated smooth muscle depolarization to agonists in a non-additive manner. Together these data indicate that rather being distinct pathways for the modulation of smooth muscle tone, NO and endothelial IKCa channels are involved in an integrated mechanism for the regulation of agonist-induced vasoconstriction.

Abstract 255: Dual targeting of Delta-like ligand 4 (DLL4) and programmed death 1(PD1) inhibits tumor growth and generates enhanced long-term immunological memory

Blocking DLL4, a Notch ligand, effectively inhibits tumor growth by increasing non-functional angiogenesis and decreasing the cancer stem cells (CSC) population. We are currently testing an anti-DLL4 antibody, demcizumab, in Phase1B trials in NSCLC, pancreatic, and ovarian cancer. DLL4 is also known to modulate immune responses. In the current study we examine the impact of anti-DLL4 on anti-tumor immune responses as a single agent and in combination with the key immune checkpoint inhibitor Programmed Cell Death Protein 1 (PD1). While the recent clinical success of PD1 inhibitors represents a new and promising cancer immunotherapeutic approach, high initial response rates are often associated by a lack of long-term, durable effects in a significant number of patients. Therefore, we hypothesized that dual blockade of DLL4 and PD1 might further impact tumor growth by further enhancing anti-tumor immune immunity. Our data demonstrates that dual blockade of DLL4 and PD1 using antibodies not only reduces tumor growth, but also led to tumor rejection in ∼50% in CT26WT tumor-bearing mice, similar to those treated with anti-PD1 alone (no tumor rejection was observed with anti-DLL4 alone). Anti-PD1 increased specific CD8+ T cell-mediated IFN-γ production while decreasing IL6. Anti-DLL4 treatment reduced IL17 production. Interestingly, only the dual blockage led to increased production of IL2 by splenocytes. Since IL2 is required for secondary population expansion of CD8+ memory T cells, increased IL2 in the combination group suggests potential for increased T cell activation, maintenance and memory T cell function, as compared to single agent anti-DLL4 and anti-PD1. While anti-PD1 reduced inhibition of CD4+ T cell proliferation by Tregs, the dual blockade significantly reduced Treg-mediated CD8+ T cell suppression. Furthermore, both effector and memory CD8+ T cell frequencies were increased within the total CD8+ T cell population. Interestingly, anti-PD1 decreased granulocytic MDSCs, while anti-DLL4 reduced monocytic MDSCs. Mice cured with single-agent anti-PD1 and anti-DLL4/anti-PD1 combination treatments were protected from series of re-challenge with tumor cells, suggesting the existence of immunologic memory. Interestingly, more mice were protected from tumor re-challenge when both DLL4 and PD1 were blocked, as compared to PD1 alone. Surprisingly, mice previously treated with the anti-DLL4/anti-PD1 combination produced more IL2, clearly indicating the role of DLL4 blockade in enhancing anti-tumor immunity. Therefore, these results show that dual targeting of DLL4 and PD1 may be an effective and durable cancer therapy by increasing anti-tumor immune response and promoting long-term immunological memory.

Citation Format: Minu Srivastava, Christopher L. Murriel, Julie Roda, Hyun-Bae Jie, Fumiko Axelrod, Ming-Hong Xie, Rui Yun, Erin Mayes, Trevor Bentley, Belinda Cancilla, Raymond Tam, Tracy Tang, Ann Kapoun, John Lewicki, Tim Hoey, Austin Gurney, Angie Inkyung Park. Dual targeting of Delta-like ligand 4 (DLL4) and programmed death 1(PD1) inhibits tumor growth and generates enhanced long-term immunological memory. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 255. doi:10.1158/1538-7445.AM2015-255

Abstract 1549: Development and validation of a biomarker for prospective selection of Notch1 activation in patients with certain advanced solid tumors in a first-in-human phase1 study of the cancer stem cell targeting antibody OMP-52M51 (anti-Notch1)

The Notch pathway plays a key role in embryonic development, the regulation of stem and progenitor cells, and is implicated centrally in many forms of human cancer. Notch1 is known to be frequently activated in certain solid tumor types. OMP-52M51 is a humanized IgG2 antibody that inhibits the signaling function of the Notch1 receptor. Mouse xenograft studies using minimally-passaged, patient-derived xenografts have shown that OMP-52M51 impedes tumor growth and selectively eliminates CSCs in a range of tumor types particularly in tumors with activated Notch1 signaling.

We previously reported the frequency of Notch pathway activation across a large panel of human tumors (n&gt;600) by an Immunohistochemistry (IHC) assay that detects the activated form of Notch1 using an antibody that specifically recognizes the Notch1 intracellular domain (ICD). Using this test and a rigorous H-score cut-off, we found elevated Notch1 ICD in 7-53% of the following cancers: chemo-resistant breast (29%), gastric (13%), cholangiocarcinoma (20%), esophageal (27%), hepatacellular carcinoma (HCC, 7%), small cell lung cancer (SCLC, 12%), pancreatic (12%) and colorectal cancer (53%).

Here we developed a specific CLIA-validated IHC assay capable of identifying patients with Notch1 activation. The assay has a rapid turn-around time and shows robust precision, reproducibility and accuracy. The sensitivity of the method was confirmed by comparing results obtained on xenograft tumor tissue samples with known levels of Notch1 expression and response to anti-Notch1 therapy. From these results, the cut-off of the assay was set. This predictive biomarker was specifically designed to screen patients for prospective selection in the first-in-human Phase1 study of OMP-52M51 (anti-Notch1) in certain advanced solid tumors (NCT01778439). Detailed assay validation data and its application to the analysis of clinical trial samples will be highlighted.

Citation Format: Belinda Cancilla, Raymond Tam, Chun Zhang, Steve Anderson, John Lewicki, Tim Hoey, Bryan McCune, Lori Johnson, Esohe Idusogie, Ann M. Kapoun. Development and validation of a biomarker for prospective selection of Notch1 activation in patients with certain advanced solid tumors in a first-in-human phase1 study of the cancer stem cell targeting antibody OMP-52M51 (anti-Notch1). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1549. doi:10.1158/1538-7445.AM2015-1549

Lysine Residues Are Not Required for Proteasome-Mediated Proteolysis of the Auxin/Indole Acidic Acid Protein IAA1

Although many ubiquitin-proteasome substrates have been characterized in plants, very little is known about the corresponding ubiquitin attachment(s) underlying regulated proteolysis. Current dogma asserts that ubiquitin is typically covalently attached to a substrate through an isopeptide bond between the ubiquitin carboxy terminus and a substrate lysyl amino group. However, nonlysine (non-Lys) ubiquitin attachment has been observed in other eukaryotes, including the N terminus, cysteine, and serine/threonine modification. Here, we investigate site(s) of ubiquitin attachment on indole-3-acetic acid1 (IAA1), a short-lived Arabidopsis (Arabidopsis thaliana) Auxin/indole-3-acetic acid (Aux/IAA) family member. Most Aux/IAA proteins function as negative regulators of auxin responses and are targeted for degradation after ubiquitination by the ubiquitin ligase SCF(TIR1/AFB) (for S-Phase Kinase-Associated Protein1, Cullin, F-box [SCF] with Transport Inhibitor Response1 [TIR1]/Auxin Signaling F-box [AFB]) by an interaction directly facilitated by auxin. Surprisingly, using a Histidine-Hemaglutinin (HIS(6x)-HA(3x)) epitope-tagged version expressed in vivo, Lys-less IAA1 was ubiquitinated and rapidly degraded in vivo. Lys-substituted versions of IAA1 localized to the nucleus as Yellow Fluorescent Protein fusions and interacted with both TIR1 and IAA7 in yeast (Saccharomyces cerevisiae) two-hybrid experiments, indicating that these proteins were functional. Ubiquitination on both HIS(6x)-HA(3x)-IAA1 and Lys-less HIS(6x)-HA(3x)-IAA1 proteins was sensitive to sodium hydroxide treatment, indicative of ubiquitin oxyester formation on serine or threonine residues. Additionally, base-resistant forms of ubiquitinated IAA1 were observed for HIS(6x)-HA(3x)-IAA1, suggesting additional lysyl-linked ubiquitin on this protein. Characterization of other Aux/IAA proteins showed that they have diverse degradation rates, adding additional complexity to auxin signaling. Altogether, these data indicate that Aux/IAA family members have protein-specific degradation rates and that ubiquitination of Aux/IAAs can occur on multiple types of amino residues to promote rapid auxin-mediated degradation.

Progressive multiple sclerosis exhibits decreasing glutamate and glutamine over two years

Background:

Few biomarkers of progressive multiple sclerosis (MS) are sensitive to change within the two-year time frame of a clinical trial.

Objective:

To identify biomarkers of MS disease progression with magnetic resonance spectroscopy (MRS) in secondary progressive MS (SPMS).

Methods:

Forty-seven SPMS subjects were scanned at baseline and annually for two years. Concentrations of N-acetylaspartate, total creatine, total choline, myo-inositol, glutamate, glutamine, and the sum glutamate+glutamine were measured in a single white matter voxel.

Results:

Glutamate and glutamine were the only metabolites to show an effect with time: with annual declines of (95% confidence interval): glutamate −4.2% (−6.2% to −2.2%, p < 10−4), glutamine −7.3% (−11.8% to −2.9%, p = 0.003), and glutamate+glutamine −5.2% (−7.6% to −2.8%, p < 10−4). Metabolite rates of change were more apparent than changes in clinical scores or brain atrophy measures.

Conclusions:

The high rates of change of both glutamate and glutamine over two years suggest they are promising new biomarkers of MS disease progression.

Oncolytic activity of reovirus in HPV positive and negative head and neck squamous cell carcinoma

BACKGROUND

The management of patients with advanced stages of head and neck cancer requires a multidisciplinary and multimodality treatment approach which includes a combination of surgery, radiation, and chemotherapy. These toxic treatment protocols have significantly improved survival outcomes in a distinct population of human papillomavirus (HPV) associated oropharyngeal cancer. HPV negative head and neck squamous cell carcinoma (HNSCC) remains a challenge to treat because there is only a modest improvement in survival with the present treatment regimens, requiring innovative and new treatment approaches. Oncolytic viruses used as low toxicity adjunct cancer therapies are novel, potentially effective treatments for HNSCC. One such oncolytic virus is Respiratory Orphan Enteric virus or reovirus. Susceptibility of HNSCC cells towards reovirus infection and reovirus-induced cell death has been previously demonstrated but has not been compared in HPV positive and negative HNSCC cell lines.

OBJECTIVES

To compare the infectivity and oncolytic activity of reovirus in HPV positive and negative HNSCC cell lines.

METHODS

Seven HNSCC cell lines were infected with serial dilutions of reovirus. Two cell lines (UM-SCC-47 and UM-SCC-104) were positive for type 16 HPV. Infectivity was measured using a cell-based ELISA assay 18 h after infection. Oncolytic activity was determined using an alamar blue viability assay 96 h after infection. Non-linear regression models were used to calculate the amounts of virus required to infect and to cause cell death in 50% of a given cell line (EC50). EC50 values were compared.

RESULTS

HPV negative cells were more susceptible to viral infection and oncolysis compared to HPV positive cell lines. EC50 for infectivity at 18 h ranged from multiplicity of infection (MOI) values (PFU/cell) of 18.6 (SCC-9) to 3133 (UM-SCC 104). EC50 for cell death at 96 h ranged from a MOI (PFU/cell) of 1.02×10(2) (UM-SCC-14A) to 3.19×10(8) (UM-SCC-47). There was a 3×10(6) fold difference between the least susceptible cell line (UM-SCC-47) and the most susceptible line (UM-SCC 14A) EC50 for cell death at 96 h.

CONCLUSIONS

HPV negative HNSCC cell lines appear to demonstrate greater reovirus infectivity and virus-mediated oncolysis compared to HPV positive HNSCC. Reovirus shows promise as a novel therapy in HNSCC, and may be of particular benefit in HPV negative patients.

Triton X-100 inhibits L-type voltage-operated calcium channels

Triton X-100 (TX-100) is a nonionic detergent frequently used at millimolar concentrations to disrupt cell membranes and solubilize proteins. At low micromolar concentrations, TX-100 has been reported to inhibit the function of potassium channels. Here, we have used electrophysiological and functional techniques to examine the effects of TX-100 on another class of ion channels, L-type voltage-operated calcium channels (VOCCs). TX-100 (30 nmol·L(-1) to 3 μmol·L(-1)) caused reversible concentration-dependent inhibition of recombinant L-type VOCC (CaV 1.2) currents and of native L-type VOCC currents recorded from rat vascular smooth muscle cells and cardiac myocytes, and murine and human pancreatic β-cells. In functional studies, TX-100 (165 nmol·L(-1) to 3.4 μmol·L(-1)) caused concentration-dependent relaxation of rat isolated mesenteric resistance arteries prestimulated with phenylephrine or KCl. This effect was independent of the endothelium. TX-100 (1.6 μmol·L(-1)) inhibited depolarization-induced exocytosis in both murine and human isolated pancreatic β-cells. These data indicate that at concentrations within the nanomolar to low micromolar range, TX-100 significantly inhibits L-type VOCC activity in a number of cell types, an effect paralleled by inhibition of cell functions dependent upon activation of these channels. This inhibition occurs at concentrations below those used to solubilize proteins and may compromise the use of solutions containing TX-100 in bioassays.

Endothelial calcium-activated potassium channels as therapeutic targets to enhance availability of nitric oxide

The vascular endothelium plays a critical role in vascular health by controlling arterial diameter, regulating local cell growth, and protecting blood vessels from the deleterious consequences of platelet aggregation and activation of inflammatory responses. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as nitric oxide (NO), and to elicit hyperpolarization of the endothelial cell membrane potential, which can spread to the surrounding smooth muscle cells via gap junctions. Endothelial hyperpolarization, mediated by activation of calcium-activated potassium (K(Ca)) channels, has generally been regarded as a distinct pathway for smooth muscle relaxation. However, recent evidence supports a role for endothelial K(Ca) channels in production of endothelium-derived NO, and indicates that pharmacological activation of these channels can enhance NO-mediated responses. In this review we summarize the current data on the functional role of endothelial K(Ca) channels in regulating NO-mediated changes in arterial diameter and NO production, and explore the tempting possibility that these channels may represent a novel avenue for therapeutic intervention in conditions associated with reduced NO availability such as hypertension, hypercholesterolemia, smoking, and diabetes mellitus.

How feelings of stereotype threat influence older adults' memory performance

The purpose of the present research was to explore the role of stereotype threat as a mediator of older people's memory performance under different instructional sets. In three studies, younger and older participants completed a memory test that was either framed as a memorization or as an impression formation task. Across these studies, memory performance was greater for younger than for older adults and was higher in the impression formation than memorization condition, but was not different for older adults in the two instruction conditions. These results also showed that age differences in memory performance were mediated by participants' feelings of stereotype threat, such that age was positively related to stereotype threat and stereotype threat was negatively related to memory performance. These data demonstrate that concerns about being negatively stereotyped influence age differences in memory performance, and that the effects of these feelings on performance are not easily reduced by reframing the task instructions.

Electroconvulsive therapy in chinese patients: a case series

Although a growing body of literature suggests that ethnic differences affect individuals' response to psychotropic medication, there are little data describing ethnic differences in response to electroconvulsive therapy (ECT). In this report, the charts of 12 Chinese patients given ECT in a New York City inpatient Asian psychiatric unit during an 18-month period were reviewed. No significant differences in response to ECT compared with typical response to ECT in the United States were found. The average number of treatments administered, response rate, and relapse rate were approximately consistent with American data. The only difference observed was the presence of delusions in all the patients referred for ECT.

Fabrication of strong long-period gratings in hydrogen-free fibers with 157-nm F2-laser radiation

Long-period gratings were fabricated in standard telecommunication fiber (Corning SMF-28) by use of what is believed to be record short-wavelength light from a 157-nm F(2) laser. Strong loss peaks were formed without the need for enhancement techniques such as hydrogen loading. The magnitude of the attenuation peak was sensitive to the single-pulse laser fluence, decreasing with increasing pulse fluence as a result of nonuniform 157-nm laser interaction with both the fiber cladding and core. The long-period fiber gratings have good wavelength stability (Dlambda~7 nm) under thermal annealing at 150 degrees C.

Neuroleptic dosing in Hispanic and Asian Inpatients with schizophrenia

This study is the second in a series examining the prescribing of antipsychotic medication to patients with schizophrenia in cross-cultural clinical programs. A computer search identified all patients with the diagnosis of "schizophrenia" treated during a 1-year period in an inpatient Hispanic and Asian psychiatric unit(s); second computer search identified a matched (admission date) sample of Anglo patients from the general inpatient psychiatry services. The medication variables included type of neuroleptic drug used, the maximum dose, the stabilized dose (i.e., neuroleptic dose at discharged and the dose associated with first report of extrapyramidal symptoms. Neuroleptic doses were converted to chlorpromazine (CPZ) equivalents and corrected for body weight to a standard of 68 kg. Oneway analysis of variance procedures were used to compare both actual and standardized neuroleptic CPZ across the three samples, these statistical comparisons were completed for both maximum and stabilized dose(s). The analysis with maximum dose revealed a significant main effect for both actual (p < 0.05) and standardized CPZ (p < 0.05). Similar results were also found for stabilized dose with both actual (p < 0.05) and standardized CPZ (p < 0.05). Examination of the direction of mean differences for both medication dosing variables using both CPZ comparisons revealed that the patients in general sample received significantly larger doses of antipsychotic medication than either Asian or Hispanic patients.

The SMR family: a novel family of multidrug efflux proteins involved with the efflux of lipophilic drugs

The sequenced members of a novel family of small, hydrophobic, bacterial multidrug-resistance efflux proteins, which we have designated the small multidrug resistance (SMR) protein family, are identified and analysed. Two distinct clusters of proteins were identified within this family: (i) small multidrug efflux systems; and (ii) Sug proteins, potentially involved in the suppression of groEL mutations. Hydropathy and residue distribution analyses of this family suggest a structural model in which the polypeptide chain spans the membrane four times as mildly amphipathic alpha-helices. The roles of specific residues, a possible mechanistic model of drug efflux, and the primary physiological role(s) of the SMR proteins are discussed.

Chlamydia infection in street youth: Need for more aggressive screening programs

OBJECTIVES

To determine, first, the sexual practices among street youth in the Ottawa-Carleton, Ontario region; second, the percentage of street youth who report previous sexually transmitted disease (STD) screening; and third, the rate of previous infection with Chlamydia trachomatis in this population.

METHODS

This prospective street youth pilot study was cross-sectional in design. Street youth aged 15 to 20 years were recruited through a drop-in centre or shelter in Ottawa, Ontario between August and October 1993. Information on demographics, substance use, current sexual practices and STD screening and infection history were obtained through a structured face to face interview and a 75-item questionnaire. Past C trachomatis infection was determined by microimmunofluorescence assay with purified antigens of C trachomatis (serovars A to K), Chlamydia psittaci (avian strain 6BC) and Chlamydia pneumoniae (TW-183 strain).

RESULTS

Ninety-eight per cent of the youth approached participated. Of the 100 street youth (61 males, mean age 17.8 years; 39 females, mean age 17.1 years), 94% were sexually active, with 21% of males and 26% of females having had four or more different sexual partners in the previous year. Only 27% of males and 8% of females reported consistent condom use with all partners all of the time. Thirty per cent of males and 50% of females reported previous STD testing. Of the 100 street youth, 22 (16 males and six females) had had previous C trachomatis infection by serotesting, but only three of 16 (19%) of these males and three of six (50%) of these females reported previous STD testing. None of the 22 recalled previous diagnosis or treatment for any STD.

CONCLUSIONS

These street youth reported a high prevalence of risky sexual behaviour, and this supports the national STD guidelines for targeted screening in this population. The current screening guidelines for C trachomatis in this population do not reach the majority of street youth.

Lessons learned from Hurricane Andrew: recommendations for care of the elderly in long-term care facilities

We report on the experience of a 500-bed, long-term care facility in Miami, Fla, which provides housing and nursing care units for patients--ranging from those who are independently ambulatory to those who are acutely ill and feeble--in preparing for, during, and in the immediate aftermath of Hurricane Andrew, which struck on August 24, 1992. The problems encountered included a massive influx of evacuated elderly to the facility, facility isolation, loss of electrical power, loss of running water, special dietary needs, and limited professional staffing due to personal property losses or loss of transportation. Overwhelmed county emergency medical services, limited access to hospitals and patient care, and difficulty in procuring supplies exacerbated the already complicated situation resulting from the storm. As a result of these catastrophic conditions, a number of challenges specific to the care of the elderly were identified. In conjunction with the Florida Department of Elder Affairs, we drafted a comprehensive blueprint that could serve as a disaster plan for other long-term care facilities facing a similar threat during the hurricane season.