Structural determinants of allosteric antagonism at metabotropic glutamate receptor 2: mechanistic studies with new potent negative allosteric modulators

BACKGROUND AND PURPOSE

Altered glutamatergic neurotransmission is linked to several neurological and psychiatric disorders. Metabotropic glutamate receptor 2 (mGlu₂) plays an important role on the presynaptic control of glutamate release and negative allosteric modulators (NAMs) acting on mGlu₂/₃ receptors are under assessment for their potential as antidepressants, neurogenics and cognitive enhancers. Two new potent mGlu₂/₃ NAMs, RO4988546 and RO5488608, are described in this study and the allosteric binding site in the transmembrane (TM) domain of mGlu₂ is characterized.

EXPERIMENTAL APPROACH

Site directed mutagenesis, functional measurements and β₂-adrenoceptor-based modelling of mGlu₂ were employed to identify important molecular determinants of two new potent mGlu₂/₃ NAMs.

KEY RESULTS

RO4988546 and RO5488608 affected both [³H]-LY354740 agonist binding at the orthosteric site and the binding of a tritiated positive allosteric modulator (³H-PAM), indicating that NAMs and PAMs could have overlapping binding sites in the mGlu₂ TM domain. We identified eight residues in the allosteric binding pocket that are crucial for non-competitive antagonism of agonist-dependent activation of mGlu₂ and directly interact with the NAMs: Arg³·²⁸, Arg³·²⁹, Phe³·³⁶, His(E2.52) , Leu⁵·⁴³, Trp⁶·⁴⁸, Phe⁶·⁵⁵ and Val⁷·⁴³. The mGlu₂ specific residue His(E2.52) is likely to be involved in selectivity and residues located in the outer part of the binding pocket are more important for [³H]-LY354740 agonist binding inhibition, which is independent of the highly conserved Trp⁶·⁴⁸ residue.

CONCLUSIONS AND IMPLICATIONS

This is the first complete molecular investigation of the allosteric binding pocket of mGlu₂ and Group II mGluRs and provides new information on what determines mGlu₂ NAMs selective interactions and effects.

Applicability of tableside flat panel detector CT parenchymal cerebral blood volume measurement in neurovascular interventions: preliminary clinical experience

BACKGROUND AND PURPOSE

CBV is a vital perfusion parameter in estimating the viability of brain parenchyma (eg, in cases of ischemic stroke or after interventional vessel occlusion). Recent technologic advances allow parenchymal CBV imaging tableside in the angiography suite just before, during, or after an interventional procedure. The aim of this work was to analyze our preliminary clinical experience with this new imaging tool in different neurovascular interventions.

MATERIALS AND METHODS

FPD-CBV measurement was performed on a biplane FPD angiographic system. Eighteen patients (11 women, 7 men) were examined (age range, 18-86 years; median, 58.7 years). In the 10 patients with stroke, the extent of intracranial hypoperfusion was evaluated. The remaining 8 patients had an intracranial hemorrhage; periprocedural CBV was evaluated during the course of interventional treatment.

RESULTS

In the 18 cases studied, 23 CBV measurements were performed. Twenty acquisitions were of sufficient diagnostic quality. The remaining 3 acquisitions failed technically, 1 due to motion artifacts and 2 due to injection technique and/or hardware failure.

CONCLUSIONS

FPD-CBV measurement in the angiography suite provides a feasible and helpful tool for peri-interventional neuroimaging. It extends the intraprocedural imaging modalities to the level of tissue perfusion. However, the technique has technical limitations and shows room for improvement in the future.

Outbreak of Hot-Foot Syndrome – Caused by Pseudomonas Aeruginosa

Infections with Pseudomonas aeruginosa can cause the hot-foot syndrome, presenting with painful plantar erythematous nodules. Particularly, the mechanically stressed areas of the foot are affected after contact with contaminated water from saunas, swimming pools, hot tubs, etc. We report an outbreak of hot-foot syndrome caused by Pseudomonas in 10 patients. The therapeutic regimens applied reached from local antiseptic therapy to systemic antibiotics.

High-dynamic-range magnetometry with a single nuclear spin in diamond

Sensors based on the nitrogen-vacancy defect in diamond are being developed to measure weak magnetic and electric fields at the nanoscale. However, such sensors rely on measurements of a shift in the Lamor frequency of the defect, so an accumulation of quantum phase causes the measurement signal to exhibit a periodic modulation. This means that the measurement time is either restricted to half of one oscillation period, which limits accuracy, or that the magnetic field range must be known in advance. Moreover, the precision increases only slowly (as T(-0.5)) with measurement time T (ref. 3). Here, we implement a quantum phase estimation algorithm on a single nuclear spin in diamond to combine both high sensitivity and high dynamic range. By achieving a scaling of the precision with time to T(-0.85), we improve the sensitivity by a factor of 7.4 for an accessible field range of 16 mT, or, alternatively, we improve the dynamic range by a factor of 130 for a sensitivity of 2.5 µT Hz(-1/2). Quantum phase estimation algorithms have also recently been implemented using a single electron spin in a nitrogen-vacancy centre. These methods are applicable to a variety of field detection schemes, and do not require quantum entanglement.

Comparison of six different specimen types for Epstein-Barr viral load quantification in peripheral blood of pediatric patients after heart transplantation or after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Epstein-Barr Virus (EBV) a gamma-herpes virus is associated with a spectrum of lymphoid and epithelial malignancies including posttransplant lymphoproliferative disorders (PTLD). EBV-load measurement has been shown to be important for the monitoring of these patients. However, in contrast to the viral quantification of human immunodeficiency virus or human hepatitis C virus, the EBV-load measurement has not been completely standardized as yet.

OBJECTIVES

In this study, we compared the EBV DNA levels in whole blood (WB), plasma, peripheral mononuclear cells (PBMC) and B-cells (BC) in children and adolescents after heart transplantations (HTx) and allogeneic hematopoietic stem cell transplantations (HSCT).

STUDY DESIGN

In a period of 2 years (from May 2007 to May 2009) we collected 547 samples of 96 cardiac transplant recipients and 248 samples of 37 patients who underwent HSCT. For EBV DNA quantification we used a duplex real-time PCR (ABI Prism 7500, Applied Biosystems). Additionally, EBV-load of PBMC and BC were normalized with respect to endogenous cell DNA.

RESULTS

In both patient populations we found no significant difference of test sensitivity for the EBV detection. In PBMC as well as BC, there was a high correlation between the analysis of cells with and without normalization in both populations. Spearman's correlation coefficient ρ between PBMC without and PBMC with normalization was ρ=0.98 (P<0.0001) in patients after HTx and ρ=0.99 (P<0.0001) in patients after HSCT. Correlation between BC with and without normalization was ρ=0.98 (P<0.0001) in patients after HTx and ρ=0.995 (P<0.0001) in patients after HSCT. When comparing the different blood compartments for EBV quantification in both populations, the strongest correlations were found between the EBV DNA levels in WB and PBMC (HTx: ρ=0.93, P<0.0001; HSCT: ρ=0.81, P<0.0001) followed by PBMC and BC (HTx: ρ=0.87, P<0.0001; HSCT: ρ=0.81, P<0.0001) as well as WB and BC (HTx: ρ=0.86, P<0.0001; HSCT: ρ=0.75, P<0.0001). In contrast, the correlation coefficients between plasma and the other blood compartments (WB as well as PBMC or BC) were lower. Six patients developed seven episodes of PTLD (five patients after HTx and one after renal transplantation). Analyzing the different blood compartments, we found that a threshold of WB ≥20,000EBV-copies/ml and plasma ≥1000EBV-copies/ml had the highest sensitivities and specificities (WB: sensitivity 100%, specificity 87% and plasma: sensitivity 88%, specificity 98%).

CONCLUSION

Normalization towards an endogenous control does not seem to be necessary for EBV quantification in peripheral blood. The analysis of whole blood correlates well with B-cells and PBMC. Routine screening of EBV DNA in whole blood appeared to be a useful tool supplemented by EBV-load measurement in plasma to discriminate chronic high EBV-load carrier without risk for PTLD from those who are at risk for PTLD. Values in whole blood higher than 20,000EBV-copies/ml WB and plasma values higher than 1000EBV-copies/ml plasma indicated PTLD in our series.

P1-18-01: Z-ACT1: Zometa Combined with Standard Therapy in Patients with Metastatic Breast Cancer Further Decreases the Proportion of Patients with CTC Counts of 5 or above

Introduction: Zoledronic acid (ZOL) has been shown to reduce the risk of recurrence and residual tumor size in the adjuvant/neoadjuvant setting in patients with early/intermediate-stage breast cancer (BC). In addition, ZOL combined with neoadjuvant chemotherapy reduced numbers of disseminated-tumor cells in the bone marrow compared with chemotherapy alone. However, the activity of ZOL on disseminated- or circulating-tumor cells (CTCs) in patients with metastatic breast cancer (MBC) is not well defined. Cristofanilli M, et al (J Clin Oncol. 2005; 23: 1420–30) reported that CTCs in MBC are an independent predictor of overall survival (OS) and progressionfree survival (PFS). Accordingly, this study is evaluating the potential anticancer benefit of adding ZOL to standard therapy in patients with newly diagnosed MBC as assessed by the change in CTC count from baseline to 3–5 weeks.

Methods: Eligible patients had HER2−negative MBC, newly diagnosed or at first relapse after adjuvant therapy with or without bone metastases. In this open-label 3-arm study, patients without bone metastases were randomized to standard therapy + ZOL every 3–4 weeks for the first 6 months (Arm A) or standard therapy + ZOL during month 6–12 after standard therapy initiation (Arm B). All patients with bone metastases received ZOL every 3–4 weeks (Arm C). The primary endpoint is PFS. Secondary endpoints include the proportion of patients with CTCs ≥5 or &lt;5 per 7.5 mL of peripheral blood 3–5 weeks after standard therapy initiation. Data were compared with historical controls (patients with MBC receiving first-line standard treatment alone; Cristofanilli M, et al. 2005). CTCs were quantified using CellSearch™.

Results: In Z-ACT1, 29 previously untreated MBC patients with bone metastases were enrolled in Arm C, all of whom had ≥1 CTC at study entry (range, 1–117). 53% received hormonal therapy alone, 42% chemotherapy alone, and 5% received various combinations. In patients receiving standard therapy + ZOL, the percentage of patients with CTC ≥5 decreased from 55% to 25% at 3–5 weeks. At baseline, the median uNTX level was 46.5 (n = 10) in patients with &lt; 5 CTCs and 57 in patients with ≥5 CTC (n = 13). At 3–5 weeks, the median decrease from baseline in uNTX was 74% (n = 10) in the &lt; 5 CTC group and 25% (n = 5) in the ≥5 CTC group. At 3–5 weeks, the median uNTX levels in the &lt;5 and ≥5 CTC groups were 12 and 22 nmol bce/mmol, respectively. This study has now been modified to a 2-arm study (standard therapy +/− ZOL) in MBC patients with no bone metastases. CTC, uNTX, and PFS data will be presented from this new head-to-head analysis. Changes in CTCs out to 6 months and correlation with uNTX and PFS in this original bone metastasis cohort will also be presented.

Conclusions: This preliminary analysis suggests that the addition of ZOL to standard therapy in women with bone metastases from MBC results in a further decrease in CTC numbers at 3–5 weeks after initiation of therapy.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-18-01.

Familial Alzheimer's disease and inherited prion disease in the UK are poorly ascertained

AIMS

To ascertain the frequency and geographical distribution of patients diagnosed with known genetic causes of Alzheimer's disease (AD) and inherited prion disease (IPD) in the UK 2001-2005. By comparison with frequencies predicted from published population studies, to estimate the proportion of patients with these conditions who are being accurately diagnosed.

METHODS

All the positive diagnostic test results (from both genetic testing centres) were identified for mutations in presenilin-1 (PSEN1), presenilin-2 (PSEN2), amyloid precursor protein (APP) and prion protein genes (PRNP) for patients resident in the UK in a 5 year period. The variation in the incidence of mutation detection between UK regions was assessed with census population data. Published studies of the genetic epidemiology of familial early onset AD (EOAD) were reviewed to produce estimates of the number of patients in the UK that should be detected.

RESULTS

The rate of detection of EOAD and IPD varied very significantly and consistently between regions of the UK with low rates of detection in Northern and Western Britain (72% less detection in these regions compared with Central and Southeast Britain). The estimates from population studies further suggest a greater number of patients with EOAD than are diagnosed by genetic testing throughout the UK.

CONCLUSIONS

It is likely that patients with EOAD and IPD are not being recognised and referred for testing. With the prospect of meaningful disease modifying therapeutics for these diseases, this study highlights an issue of relevance to neurologists and those planning for provision of National Health Services.

[The anterolateral thigh flap: its versatility in oncological soft tissue reconstruction of the head and neck region]

The anterolateral thigh flap (ATL) has become a standard procedure in reconstructive microsurgery. In this study the results with the ALT for reconstruction in the head and neck area after tumor resection in 33 patients were retrospectively analyzed. Patients included 28 men and 5 women aged 47-70 years who suffered from intraoral and extraoral tumors. Satisfactory soft tissue coverage could be achieved in all patients and no flaps were lost. The ALT is a versatile free flap enabling reliable soft tissue reconstruction of complex defects in the head and neck region. Flap dissection and preparation of the recipient area can usually be performed simultaneously. Additional advantages include the long and strong caliber vascular pedicle, the low donor site morbidity and the different possibilities of tissue composition, making the ALT a workhorse flap in modern reconstructive microsurgery.

Dark states of single nitrogen-vacancy centers in diamond unraveled by single shot NMR

The nitrogen-vacancy (NV) center in diamond is supposed to be a building block for quantum computing and nanometer-scale metrology at ambient conditions. Therefore, precise knowledge of its quantum states is crucial. Here, we experimentally show that under usual operating conditions the NV exists in an equilibrium of two charge states [70% in the expected negative (NV-) and 30% in the neutral one (NV0)]. Projective quantum nondemolition measurement of the nitrogen nuclear spin enables the detection even of the additional, optically inactive state. The nuclear spin can be coherently driven also in NV0 (T1≈90  ms and T2≈6  μs).

Final results of the European Advanced Renal Cell Carcinoma Sorafenib (EU-ARCCS) expanded-access study: a large open-label study in diverse community settings

BACKGROUND

The European Advanced Renal Cell Carcinoma Sorafenib (EU-ARCCS) expanded-access study provided sorafenib to advanced renal cell carcinoma (RCC) patients in whom previous systemic therapy had failed. The study assessed the safety and use of sorafenib for the treatment of advanced RCC in a large community-based patient population across 11 countries in Europe.

PATIENTS AND METHODS

EU-ARCCS was a single-arm, open-label trial of sorafenib in advanced RCC patients. End points included safety, time to progression, progression-free survival (PFS), and disease control rate (DCR). Subgroup analyses included age, Eastern Cooperative Oncology Group performance status, histology, prior therapy, and number and sites of metastases.

RESULTS

About 1159 advanced RCC patients were enrolled. Most patients (94%) experienced drug-related adverse events (AEs) of any grade, with the most common grade ≥3 AEs including hand-foot skin reaction (13%), diarrhea (7%), fatigue (7%), hypertension (6%), and rash/desquamation (5%). The incidence of AEs in the subgroups was similar to that in the overall population. Median PFS was 6.6 months; DCR at ≥8 and ≥12 weeks was 85% and 78%, respectively.

CONCLUSIONS

The sorafenib safety profile in European community-based practice settings was similar to that reported in clinical trials. The heterogeneous advanced RCC patient population in EU-ARCCS permitted assessment of sorafenib in important subpopulations of advanced RCC patients.

Relationship of a dominant advanced glycation end product, serum carboxymethyl-lysine, and abnormal glucose metabolism in adults: the Baltimore Longitudinal Study of Aging

BACKGROUND AND OBJECTIVES

Although hyperglycemia is thought to increase the generation of advanced glycation end products (AGEs), studies have not shown a consistent relationship between abnormal glucose metabolism and serum AGEs. We investigated the relationship between a dominant serum AGE, N-carboxymethyl-lysine (CML), and glucose metabolism.

SUBJECTS AND METHODS

Serum CML, fasting plasma glucose, and glucose tolerance were measured in 755 adults in the Baltimore Longitudinal Study of Aging. Fasting plasma glucose was categorized as normal (< or = 99 mg/dL), impaired (100-125 mg/dL), and diabetic (> 125 mg/dL). Two-hour plasma glucose on oral glucose tolerance testing was categorized as normal (< or = 139 mg/dL), impaired (140-199 mg/dL), and diabetic (> or = 200 mg/dL).

RESULTS

The proportion of adults with normal, impaired, and diabetic fasting plasma glucose was 73.8%, 22.9%, and 2.9%, respectively, and the proportion with normal, impaired, and diabetic 2-hour plasma glucose was 73.1%, 19.2%, and 7.7%, respectively. Serum CML (microg/mL) was not associated with abnormal fasting plasma glucose (Odds Ratio [O.R.] 0.60, 95% Confidence Interval [C.I.] 0.15-2.36, P = 0.47) in a multivariate, ordered logistic regression model, adjusting for age, race, gender, body mass index, and chronic diseases. Serum CML (microg/mL) was associated with abnormal 2-hour plasma glucose on glucose tolerance testing (O.R. 0.15, 95% C.I. 0.04-0.63, P = 0.009) in a multivariate, ordered logistic regression model, adjusting for the same covariates.

CONCLUSIONS

Elevated CML, a dominant AGE, was not associated with elevated fasting plasma glucose and was associated with a reduced odds of abnormal glucose tolerance in older community-dwelling adults.

A clinical phase I/II trial with the monoclonal antibody cG250 (RENCAREX®) and interferon-alpha-2a in metastatic renal cell carcinoma patients

PURPOSE

To evaluate the efficacy and safety of WX-G250, a chimeric monoclonal antibody that binds to carboxy anhydrase IX, combined with low-dose interferon-alpha (LD-IFNα) in patients with progressive metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

Thirty-one patients, nephrectomized for the primary tumor, clear cell progressive mRCC, were enrolled to receive weekly infusions of WX-G250 (20 mg i.v.; week 2-12) combined with LD-IFNα (3 MIU s.c. 3 times/week; week 1-12). At week 16, patients were evaluated for response and stratified into two groups: (a) responders into the extended treatment group for an additional 6 weeks of treatment or (b) the progressive group with no further study treatment.

RESULTS

Of the 31 treated patients, 26 were evaluable for response to treatment. Two patients showed partial remission and 14 patients had stable disease as assessed in week 16. One patient experienced partial remission resulting in a complete remission lasting at least 17 months. Nine patients had durable stable disease of 24 weeks or longer. Clinical benefit was obtained in 42% (11/26) patients. The median overall survival achieved was 30 months and the 2-year survival was 57%. Patients receiving extended treatment showed a significantly longer 2-year survival rate than discontinued patients (79 vs. 30%; P=0.0083). In general, treatment was well tolerated with little toxicity.

CONCLUSION

Treatment with the antibody WX-G250 in combination with LD-IFNα is safe, well tolerated, led to clinically meaningful disease stabilization and demonstrated clinical benefit in this progressive mRCC patient population.