OS06.6.A Real-World Pattern of Care Study on Glioblastoma in the Austrian Population. Final results from 2014-2020

Background

The Austrian ABTR-SANO Glioblastoma Registry is the first population-based assessment of patterns of care for patients with Glioblastoma across Austrian healthcare institutions. The primary aim is to assess the real world effectiveness of administered therapies.

Material and Methods

Clinical data are collected via a common web-based IT platform “ABTR-SANO Net” since 2014. The database and the ongoing evaluation of clinical parameters, as well as interims analysis are provided in cooperation with a review board. First Outcome analysis, including patients from 2014-2020, was performed at the end of 2021.

Results

Eleven centers across Austria are involved, and the data of 1416 patients (m/f ratio: 1,35, median age: 66 years) were recently analyzed in detail. Age, extent of resection, as well as ECOG was associated with improved survival. Methylated MGMT Status also showed a moderate survival benefit. Patients with re-resection and re-radiation also exhibited improved survival, which however may be attributed to a selection bias.Second line treatment manly comprised of antiangiogenic treatment, followed by alkylated agents, re-radiation and re-surgery. Median overall survival of all patients was 344 days and clearly age dependent (best for <50 years, worse for>80 years).

Conclusion

This is the first population based outcome analysis of Glioblastoma in Austria. Results regarding prognostic markers and outcome are mostly comparable with international data. Robust population based data are important in order to monitor quality of health care, and to match the data with results from clinical studies.

P11.44.A The impact of heme biosynthesis regulation on glioma aggressiveness: correlations with most recent diagnostic molecular markers

Background

The prognosis of patients with diffusely infiltrating gliomas is dismal but varies greatly between individuals. While characterization of gliomas was primarily relied on typical histopathological features, specific molecular markers increasingly gained importance and play a key role in the recently published 5th edition of the World Health Organization (WHO) classification. Heme biosynthesis represents a crucial pathway due to its key role in oxygen transport, energy production or drug metabolism. Recently, we described a “heme biosynthesis mRNA expression signature” that correlates with histopathological glioma grades and patient survival. The aim of the current study was to correlate the heme biosynthesis mRNA expression signature with the most recent diagnostic molecular markers for glioma stratification.

Material and Methods

In this study, patient data were derived from the “The Cancer Genome Atlas” (TCGA) lower-grade glioma and glioblastoma cohorts. We identified diffusely infiltrating gliomas correlating molecular tumor diagnosis according to the most recent WHO classification with heme biosynthesis mRNA expression. The following molecular markers were analyzed: EGFR amplification, TERT promoter mutation, CDKN2A/B homozygous loss, concurrent chromosome 7 gain/10 loss, MGMT methylation, IDH mutation, ATRX loss, p53 mutation and 1p19q co-deletion. Subsequently, we calculated the heme biosynthesis mRNA expression signature and correlated this signature with distinct molecular glioma markers as well as the resulting molecular subgroups.

Results

A total of 649 patients with available data on up-to-date molecular markers and heme biosynthesis mRNA expression were included. According to analysis of individual molecular markers, we found a significantly higher heme biosynthesis mRNA expression signature in gliomas with IDH wildtype (p<0.0005), without 1p19q co-deletion (p<0.0005), with homozygous CDKN2A/B loss (p<0.0005) and with EGFR amplification (p=0.001). Furthermore, we observed that the heme biosynthesis mRNA expression signature increased with the aggressiveness of the molecular subgroups (p<0.0005), being lowest in WHO grade 2 oligodendrogliomas and highest in WHO grade 4 glioblastomas.

Conclusion

Our data demonstrate a significant correlation between diagnostic molecular markers and heme biosynthesis regulation in diffusely infiltrating gliomas. Consequently, heme biosynthesis expression is a promising biomarker for glioma aggressiveness and might constitute a potential target for novel therapeutic approaches.

P11.55.B Postoperative MRI is able to detect an unexpected residual tumor after surgery of brain metastases: experience from 5 specialized centers

Background

Brain metastases (BM) constitute the most common central nervous system tumors. The treatment options of BM consist of surgery, radiotherapy, radiosurgery, chemotherapy, and immunotherapy. Regarding surgery in BM, the extent of resection (EOR) represents a crucial factor for patient prognosis. However, first studies using postoperative MRI demonstrated that an unexpected residual tumor after surgery of BM is not uncommon despite these tumors were considered to be well-demarcated. The aim of this study was thus to investigate in a large cohort including multiple neurosurgical centers the EOR following BM resection, potential risk factors for incomplete resection and postsurgical follow-up data.

Material and Methods

In the current retrospective study conducted at 5 specialized neurosurgical centers in Austria, we included patients with BM resection and available postoperative MRI. The EOR following BM resection was determined by postoperative MRI (complete vs incomplete resection). Additionally, the data on the intraoperative judgement of the EOR of the performing neurosurgeon were collected. Moreover, potential factors for incomplete resection including tumor localization, tumor volume, primary tumor, pattern of contrast media enhancement on imaging and tumor eloquence were investigated. Finally, the rate of local progression of BM after initial surgery was analyzed in the follow-up period and overall survival data were collected.

Results

Altogether, 548 patients with 649 surgically treated BM were included. According to postoperative MRI, complete resection was achieved in 407 (66%) of 649 BM and incomplete resection in 176 (29%) of 649 BM. Misjudgment of the EOR by the neurosurgeon was found in 25% of cases and resulted in an unexpected residual tumor which was evident on postoperative MRI in 122 (22%) BM. Preoperative tumor volume was significantly larger in incompletely resected BM. Moreover, local progression was significantly more common in cases with incompletely resected BM and was also associated with shorter overall survival.

Conclusion

Our data of this study including multiple centers indicate that postoperative MRI is capable to detect a relatively high rate of unexpected residual tumors following resection of BM. Since local progression was more common in BM with residual tumors and this was associated with shorter survival, special attention should be paid to achieve a complete tumor resection.

Predicting the wettability of quartz surfaces exposed to dense nonaqueous phase liquids

A model incorporating electrostatic and van der Waals forces was used to predict the wetting behavior of several systems containing a quartz surface, water, and a dense nonaqueous phase liquid (DNAPL). The disjoining pressure between the quartz/water and a water/DNAPL interface as a function of their separation was calculated from a full solution of the nonlinear Poisson-Boltzmann equation allowing for charge regulation. For the pH regime associated with a positive pressure barrier, the quartz surface was predicted to be water wetting. The model takes into account the charging behavior of an isolated DNAPL/water interface as inferred from electrophoretic mobility data. It provides excellent predictions for four coal tar and creosote samples tested, where the quartz was oil-wetting below pH 5 and water-wetting at higher pH values. In a fifth sample, the transition occurred above pH 7, which indicates that mechanisms other than electrostatic interaction control the wetting behavior in this sample.

Exact Poisson-Boltzmann solution for the interaction of dissimilar charge-regulating surfaces

An efficient method is proposed to calculate the electric double layer force between two flat surfaces of dissimilar composition and ionization properties. The approach is based on explicit expressions for the solution of the (nonlinear) Poisson-Boltzmann equation and allows for boundary conditions of charge regulation, i.e., chemical equilibrium of both surfaces with a bulk electrolyte at all surface separations. As an illustration, we discuss in some detail the interaction between a weakly acidic and a strongly acidic latex surface, and between an acidic (silica) surface and an amphoteric (rutile) surface.

Colloidal Particles at Water-Glass Interface: Deposition Kinetics and Surface Heterogeneity

Videomicroscopy in combination with evanescent field illumination is applied to study the sorption of colloidal particles from flow in a parallel plate channel on a glass surface. The experiments, carried out in the presence of a repulsive electrostatic barrier, reveal surprisingly complex results: The glass surface, though optically flat and well cleaned, is not homogeneous, but rather the sorption occurs at a limited number of preferred sites. Moreover, these sites are not static: new sites keep appearing at random positions on the observed surface and disappearing at a rate of kd = 1.3 x 10(-5) s-1. These findings can be understood within a simple model that takes into account slow but inevitable dissolution of the glass surface. The bulk glass contains potential adsorbers, which are continuously being exposed by the dissolution process and act as transient adsorption sites, before being washed off by the flowing buffer solution. Copyright 1998 Academic Press.

Absolute Aggregation Rate Constants of Hematite Particles in Aqueous Suspensions: A Comparison of Two Different Surface Morphologies

Measurements of absolute aggregation rate constants were performed for two samples of well-characterized spheroidal hematite particles with rather different surface morphology. At high ionic strength, the system is in the fast aggregation regime with pH independent rate constants around (1-4) x 10(-18) m3/s. At low ionic strengths, the rate constant is a function of pH and goes through a flat maximum around the point of zero charge (PZC) where fast aggregation conditions are reached. With increasing pH the rate constants increase gradually below the PZC while they decrease very rapidly above the PZC. Above the PZC the rate constants are rather well predicted by the classical DLVO theory. Below the PZC, however, it is necessary to assume a distribution in the surface potentials with a coefficient of variation around 30% to account for the observed behavior. In spite of the pronounced differences in the surface roughness of both hematite samples, their aggregation rate constants are rather similar. Copyright 1997 Academic Press.

Measurement of Absolute Coagulation Rate Constants for Colloidal Particles: Comparison of Single and Multiparticle Light Scattering Techniques

The absolute coagulation rate constants of monodisperse spherical colloids in aqueous suspension were measured at the early stage of the coagulation processes by using two different techniques: single particle light scattering (SPLS) and simultaneous static and dynamic light scattering (SLS + DLS). Single particle light scattering determines the cluster-size distribution directly by counting the number of different clusters during the coagulation process and therefore can be used to test the kinetic growth model used for obtaining the coagulation rate constants. The simultaneous static and dynamic light-scattering method is an in-situ experiment, where the average cluster size is estimated by simultaneous static and dynamic light-scattering measurements at different angles on a multiangle fiber-optics-based setup. A combined evaluation of the static and dynamic light-scattering data permits the determination of the absolute rate constants without the explicit use of light scattering form factors and hydrodynamic properties for dimers. In this paper, we compare results obtained with both techniques. Good agreement was found for the absolute coagulation rate constants of two different latex particle suspensions. Furthermore, we show that the two techniques complement one another and the limitations of the first are overcome by the second and vice versa. Copyright 1997Academic Press

Interpretation of Competitive Adsorption Isotherms in Terms of Affinity Distributions

In the present study we evaluate affinity distributions for competitive adsorption isotherms which involve several components. In such a multicomponent situation, the affinity distribution becomes a function of several affinity constants, and already in the case of two components, little is known about their features. In the two-component situation, we have calculated the affinity distributions from the adsorption isotherms with a numerical inversion technique. This technique is based on a constrained least-squares algorithm and uses a regularization function which biases the resulting affinity distribution toward a smooth function. The applicability of the procedure was tested with a newly derived isotherm, which is based on a fully uncorrelated affinity distribution, and with the generalized Langmuir-Freundlich (LF) isotherm, which is known to have a perfectly correlated distribution. The present study demonstrates that the extended Henderson-Hasselbalch (HH) isotherm has an underlying affinity distribution, which displays a partial correlation, while the non-ideal competitive adsorption (NICA) isotherm has an affinity distribution with a varying degree of correlation. In the competitive situation, the affinity distribution thus provides an interesting means to characterize the corresponding isotherms. As an illustration of the present techniques, experimental data of metal ion binding for a humic acid are analyzed in the same context.

On the difference in ionization properties between planar interfaces and linear polyelectrolytes

Ionizable planar interfaces and linear polyelectrolytes show markedly different proton-binding behavior. Planar interfaces protonate in a single broad step, whereas polyelectrolytes mostly undergo a two-step protonation. Such contrasting behavior is explained using a discrete-charge Ising model. This model is based on an approximation of the ionizable groups by point charges that are treated within a linearized Poisson-Boltzmann approximation. The underlying reason as to why planar interfaces exhibit mean-field-like behavior, whereas linear polyelectrolytes usually do not, is related to the range of the site-site interaction potential. For a planar interface, this interaction potential is much more long ranged if compared with that of the cylindrical geometry as appropriate to a linear polyelectrolyte. The model results are in semi-quantitative agreement with experimental data for fatty-acid monolayers, water-oxide interfaces, and various linear polyelectrolytes.

A self-report diagnostic measure of generalized anxiety disorder

The present study tested the reliability of a self-report diagnostic measure of generalized anxiety disorder (GAD) based on DSM criteria. Among two samples of undergraduate students, 47-80% of the GAD diagnoses by questionnaire were confirmed by diagnostic interview, with the higher rate being associated with DSM-IV criteria. Categorization of a participant as Non-GAD by questionnaire was found to be 100% reliable by interview. Given these findings as well as prior empirical support for the validity of the measure, this questionnaire has utility for identifying analogue GAD and Non-GAD participants from undergraduate populations for use in preliminary investigations of the mechanisms and functions associated with chronic worry and GAD.

Phenomenological theories of globular microemulsions

Simple phenomenological theory of noninteracting microemulsion water droplets dispersed in an oil phase (or vice versa) is presented. Several characteristics quantities such as radii, polydispersities, shape fluctuation amplitudes and interfacial tensions are evaluated. In particular, the different features of a one phase microemulsion and a two phase coexistence of the microemulsion with an excess water phase are emphasized. We discuss the relations to most existent theories of microemulsion droplets, micelles and nucleating droplets and briefly review recent experimental techniques to access the relevant parameters.