Stephan Garbe

Residual tumor cells are unique cellular targets in glioblastoma.

Residual tumor cells remain beyond the margins of every glioblastoma (GBM) resection. Their resistance to postsurgical therapy is considered a major driving force of mortality, but their biology remains largely uncharacterized. In this study, residual tumor cells were derived via experimental biopsy of the resection margin after standard neurosurgery for direct comparison with samples from the routinely resected tumor tissue. In vitro analysis of proliferation, invasion, stem cell qualities, GBM‐typical antigens, genotypes, and in vitro drug and irradiation challenge studies revealed these cells as unique entities. Our findings suggest a need for characterization of residual tumor cells to optimize diagnosis and treatment of GBM. ANN NEUROL 2010;68:264–269

Interference with Activator Protein-2 transcription factors leads to induction of apoptosis and an increase in chemo- and radiation-sensitivity in breast cancer cells

BackgroundActivator Protein-2 (AP-2) transcription factors are critically involved in a variety of fundamental cellular processes such as proliferation, differentiation and apoptosis and have also been implicated in carcinogenesis. Expression of the family members AP-2α and AP-2γ is particularly well documented in malignancies of the female breast. Despite increasing evaluation of single AP-2 isoforms in mammary tumors the functional role of concerted expression of multiple AP-2 isoforms in breast cancer remains to be elucidated. AP-2 proteins can form homo- or heterodimers, and there is growing evidence that the net effect whether a cell will proliferate, undergo apoptosis or differentiate is partly dependent on the balance between different AP-2 isoforms.MethodsWe simultaneously interfered with all AP-2 isoforms expressed in ErbB-2-positive murine N202.1A breast cancer cells by conditionally over-expressing a dominant-negative AP-2 mutant.ResultsWe show that interference with AP-2 protein function lead to reduced cell number, induced apoptosis and increased chemo- and radiation-sensitivity. Analysis of global gene expression changes upon interference with AP-2 proteins identified 139 modulated genes (90 up-regulated, 49 down-regulated) compared with control cells. Gene Ontology (GO) investigations for these genes revealed Cell Death and Cell Adhesion and Migration as the main functional categories including 25 and 12 genes, respectively. By using information obtained from Ingenuity Pathway Analysis Systems we were able to present proven or potential connections between AP-2 regulated genes involved in cell death and response to chemo- and radiation therapy, (i.e. Ctgf, Nrp1, Tnfaip3, Gsta3) and AP-2 and other main apoptosis players and to create a unique network.ConclusionsExpression of AP-2 transcription factors in breast cancer cells supports proliferation and contributes to chemo- and radiation-resistance of tumor cells by impairing the ability to induce apoptosis. Therefore, interference with AP-2 function could increase the sensitivity of tumor cells towards therapeutic intervention.

Enrichment and terminal differentiation of striated muscle progenitors in vitro

Enrichment and terminal differentiation of mammalian striated muscle cells is severely hampered by fibroblast overgrowth, de-differentiation and/or lack of functional differentiation. Herein we report a new, reproducible and simple method to enrich and terminally differentiate muscle stem cells and progenitors from mice and humans. We show that a single gamma irradiation of muscle cells induces their massive differentiation into structurally and functionally intact myotubes and cardiomyocytes and that these cells can be kept in culture for many weeks. Similar results are also obtained when treating skeletal muscle-derived stem cells and progenitors with Mitomycin C.

An efficient method for fractionated whole rodent brain radiation

Abstract Objective: In order to test for mechanisms of whole brain radio therapy side effects and possible neuroprotective measures, a rodent model is desirable. In many models, a high single dose of 8–20 Gray (Gy) of whole brain irradiation is used. These experimental radiation protocols do not closely reflect the clinical situation, where the cumulative dosage is applied in smaller fractions. We describe an efficient method to perform repetitive, fractionated whole brain radio therapy to the rat brain. Methods: Fifteen-week-old rats were irradiated with a dose of 5 or 10 Gy on four consecutive days, resulting in a cumulative dose in opposing fields of 20 Gy (n = 15) and 40 Gy (n = 17), respectively. Sham-irradiated rats (n = 14) received the same procedure but without application of cranial irradiation. Four collimators with a diameter of 3 cm each were used to place four rats and an ionization chamber simultaneously in the dose field for monitoring. Results: Fourteen days after the procedure, irradiated animals showed decreased open-field activity (two-tailed t-test, sham versus 20 Gy, P<0·001; sham versus 40 Gy, P = 0·002), but no cognitive deficit as indicated by latencies in the Morris water maze test. Six weeks after the irradiation, no group showed alterations of histopathology such as vascular changes, demyelination, or white matter necrosis. Discussion: The proposed model represents an efficient and safe method to perform fractioned high-dose irradiation of the rodent brain. Speculatively, it is possible to increase the cumulative dosage and dose per fraction used in this model to achieve a higher degree of radiation-induced toxicity.

Volumetric changes of the breast during radiotherapy. Is a replanning necessary for the electron boost

Hintergrund und Ziel:Eine Radiotherapie der Mamma induziert eine Gewebereaktion mit daraus resultierendem Ödem. Dieses Ödem führt zu einer Volumenzunahme der Mamma. Ziel der Studie war es, diese Volumenzunahme zu quantifizieren und deren Einfluss auf die Planung des Elektronenboosts zu analysieren.Patienten und Methodik:Bei 140 Patientinnen mit Mammakarzinom nach brusterhaltender Therapie erfolgte vor, während und/oder nach der Bestrahlung eine CT-Planung, um die Volumenveränderungen während der Bestrahlung zu evaluieren. Die ermittelten CT-Daten wurden unter Verwendung des HELAX-TMS-Planungssystems zur Bestimmung der Dosisverteilung ausgewertet. Die Bestimmung des Brustvolumens erfolgte mittels Interpolationsalgorithmus. Gemessen am Ausgangsvolumen wurden die Patientinnen in drei Subgruppen unterteilt: Gruppe 1 (n = 47): ≤ 670 cm3, Gruppe 2 (n = 46): 671–999 cm3 und Gruppe 3 (n = 47): ≥ 1 000 cm3 Brustvolumen.Ergebnisse:Initial zeigte sich ein mittleres Brustvolumen von 907 cm3 (100–3 073 cm3). Nach Radiotherapie kam es zu einem Anstieg des Brustvolumens um durchschnittlich 81 cm3 auf 988 cm3 (109–3 185 cm3). Signifikant messbare Volumenzunahmen traten ab einer Zielvolumendosis von 40 Gy auf. Bezogen auf die drei Subgruppen ergaben sich folgende mittlere Volumenzunahmen: Gruppe 1: 53 cm3 (3–120 cm3), Gruppe 2: 85 cm3 (20–200 cm3) und Gruppe 3: 105 cm3 (5–340 cm3). Der Zuwachs war in allen drei Gruppen mit einem p-Wert von p < 0,001 hochsignifikant. Je nach Volumenzunahme der Brust resultierte eine Änderung der Herdtiefe um bis zu 1,0 cm.Schlussfolgerung:Aufgrund der interkurrenten Volumenänderungen unter Bestrahlung erscheint eine zweite CT-Untersuchung zur Nachplanung vor Boostbestrahlung sinnvoll. Die zweite CT-Planung sollte ab 40 Gy erfolgen, um das Ödem ausreichend erfassen zu können.Background and Purpose:Radiotherapy can induce tissue reactions with an edema leading to increased breast volume. The aim of the present study was to quantify this increase and analyze its effect on the electron boost technique.Patients and Methods:140 patients with breast cancer treated with breast-conserving surgery underwent CT planning before, during and/or after radiotherapy in order to evaluate breast volume changes due to radiotherapy. CT data were analyzed using the HELAX planning system and dose distribution was assessed. Determination of the breast volume was achieved using an interpolation algorithm. Three subgroups were analyzed: group 1 (n = 47): ≤ 670 cm3, group 2 (n = 46): 671–999 cm3, and group 3 (n = 47): ≥ 1000 cm3 breast volume.Results:The mean initial breast volume was 907 cm3 (100–3073 cm3). After radiotherapy, mean breast volume increased by 81 cm3 to 988 cm3 (109–3185 cm3). Significant changes in volume were observed after a dose of 40 Gy. According to the subgroups mean volume increase was as follows: group 1: 53 cm3 (3–120 cm3), group 2: 85 cm3 (20–200 cm3), and group 3: 105 cm3 (5–340 cm3). This difference was statistically significant for all subgroups (p < 0.001). Corresponding to the volume increase, depth of the boost target volume changed up to 1.0 cm.Conclusion:As radiotherapy may lead to a significant increase in breast volume, it seems appropriate to perform a second planning CT after about 40 Gy in order to optimize dose distribution for boost irradiation.

Magnetic resonance imaging analysis of anterior and posterior eye segment displacement during ocular gaze shifts.

Purpose To determine the relationship between movements of the posterior and anterior eye segments during arbitrary gaze shifts and to obtain information for monitoring fixation during radiotherapy for ocular diseases. Methods We examined eye movements of ten emmetropic volunteers in a 1.5 T magnetic resonance system. Using a T2-weighted ultrafast turbo-spin echo sequence (UTSE), the eyes were examined within 21 seconds. Sagittal and transversal eye slices were obtained in five passages in five gaze directions (straight ahead, 15° above, 15° below, 15° right and 15° left of the primary position). Displacement of the posterior eye segment was analyzed in relation to the movement of the anterior segment in all directions. Results The relationship between the movements of the anterior and posterior eye segment was 1:0.8 (± 0.06 SD) during horizontal gaze shifts and 1:1.16 (± 0.11 SD) during vertical gaze shifts. Conclusions Magnetic resonance imaging showed that the relationship between anterior and posterior eye segments was different during horizontal and vertical eye movements, indicating the presence of more than one center of rotation. Compared to the anterior eye segment, there was less displacement of the posterior eye segment during horizontal eye movements and more displacement during vertical eye movements.

Volumetrische Veränderungen der Mamma während der Radiotherapie

Hintergrund und Ziel:Eine Radiotherapie der Mamma induziert eine Gewebereaktion mit daraus resultierendem Ödem. Dieses Ödem führt zu einer Volumenzunahme der Mamma. Ziel der Studie war es, diese Volumenzunahme zu quantifizieren und deren Einfluss auf die Planung des Elektronenboosts zu analysieren.Patienten und Methodik:Bei 140 Patientinnen mit Mammakarzinom nach brusterhaltender Therapie erfolgte vor, während und/oder nach der Bestrahlung eine CT-Planung, um die Volumenveränderungen während der Bestrahlung zu evaluieren. Die ermittelten CT-Daten wurden unter Verwendung des HELAX-TMS-Planungssystems zur Bestimmung der Dosisverteilung ausgewertet. Die Bestimmung des Brustvolumens erfolgte mittels Interpolationsalgorithmus. Gemessen am Ausgangsvolumen wurden die Patientinnen in drei Subgruppen unterteilt: Gruppe 1 (n = 47): ≤ 670 cm3, Gruppe 2 (n = 46): 671–999 cm3 und Gruppe 3 (n = 47): ≥ 1 000 cm3 Brustvolumen.Ergebnisse:Initial zeigte sich ein mittleres Brustvolumen von 907 cm3 (100–3 073 cm3). Nach Radiotherapie kam es zu einem Anstieg des Brustvolumens um durchschnittlich 81 cm3 auf 988 cm3 (109–3 185 cm3). Signifikant messbare Volumenzunahmen traten ab einer Zielvolumendosis von 40 Gy auf. Bezogen auf die drei Subgruppen ergaben sich folgende mittlere Volumenzunahmen: Gruppe 1: 53 cm3 (3–120 cm3), Gruppe 2: 85 cm3 (20–200 cm3) und Gruppe 3: 105 cm3 (5–340 cm3). Der Zuwachs war in allen drei Gruppen mit einem p-Wert von p < 0,001 hochsignifikant. Je nach Volumenzunahme der Brust resultierte eine Änderung der Herdtiefe um bis zu 1,0 cm.Schlussfolgerung:Aufgrund der interkurrenten Volumenänderungen unter Bestrahlung erscheint eine zweite CT-Untersuchung zur Nachplanung vor Boostbestrahlung sinnvoll. Die zweite CT-Planung sollte ab 40 Gy erfolgen, um das Ödem ausreichend erfassen zu können.Background and Purpose:Radiotherapy can induce tissue reactions with an edema leading to increased breast volume. The aim of the present study was to quantify this increase and analyze its effect on the electron boost technique.Patients and Methods:140 patients with breast cancer treated with breast-conserving surgery underwent CT planning before, during and/or after radiotherapy in order to evaluate breast volume changes due to radiotherapy. CT data were analyzed using the HELAX planning system and dose distribution was assessed. Determination of the breast volume was achieved using an interpolation algorithm. Three subgroups were analyzed: group 1 (n = 47): ≤ 670 cm3, group 2 (n = 46): 671–999 cm3, and group 3 (n = 47): ≥ 1000 cm3 breast volume.Results:The mean initial breast volume was 907 cm3 (100–3073 cm3). After radiotherapy, mean breast volume increased by 81 cm3 to 988 cm3 (109–3185 cm3). Significant changes in volume were observed after a dose of 40 Gy. According to the subgroups mean volume increase was as follows: group 1: 53 cm3 (3–120 cm3), group 2: 85 cm3 (20–200 cm3), and group 3: 105 cm3 (5–340 cm3). This difference was statistically significant for all subgroups (p < 0.001). Corresponding to the volume increase, depth of the boost target volume changed up to 1.0 cm.Conclusion:As radiotherapy may lead to a significant increase in breast volume, it seems appropriate to perform a second planning CT after about 40 Gy in order to optimize dose distribution for boost irradiation.

Extraretinal Induced Visual Sensations during IMRT of the Brain

BACKGROUND We observed visual sensations (VSs) in patients undergoing intensity modulated radiotherapy (IMRT) of the brain without the beam passing through ocular structures. We analyzed this phenomenon especially with regards to reproducibility, and origin. METHODS AND FINDINGS Analyzed were ten consecutive patients (aged 41-71 years) with glioblastoma multiforme who received pulsed IMRT (total dose 60Gy) with helical tomotherapy (TT). A megavolt-CT (MVCT) was performed daily before treatment. VSs were reported and recorded using a triggered event recorder. The frequency of VSs was calculated and VSs were correlated with beam direction and couch position. Subjective patient perception was plotted on an 8x8 visual field (VF) matrix. Distance to the orbital roof (OR) from the first beam causing a VS was calculated from the Dicom radiation therapy data and MVCT data. During 175 treatment sessions (average 17.5 per patient) 5959 VSs were recorded and analyzed. VSs occurred only during the treatment session not during the MVCTs. Plotting events over time revealed patient-specific patterns. The average cranio-caudad extension of VS-inducing area was 63.4mm (range 43.24-92.1mm). The maximum distance between the first VS and the OR was 56.1mm so that direct interaction with the retina is unlikely. Data on subjective visual perception showed that VSs occurred mainly in the upper right and left quadrants of the VF. Within the visual pathways the highest probability for origin of VSs was seen in the optic chiasm and the optic tract (22%). CONCLUSIONS There is clear evidence that interaction of photon irradiation with neuronal structures distant from the eye can lead to VSs.

Volumetrische Veränderungen der Mamma während der Radiotherapie@@@Volumetric Changes of the Breast during Radiotherapy. Is a Replanning Necessary for the Electron Boost?: Ist vor Boostbestrahlung mit Elektronen eine Nachplanung erforderlich?

Hintergrund und Ziel:Eine Radiotherapie der Mamma induziert eine Gewebereaktion mit daraus resultierendem Ödem. Dieses Ödem führt zu einer Volumenzunahme der Mamma. Ziel der Studie war es, diese Volumenzunahme zu quantifizieren und deren Einfluss auf die Planung des Elektronenboosts zu analysieren.Patienten und Methodik:Bei 140 Patientinnen mit Mammakarzinom nach brusterhaltender Therapie erfolgte vor, während und/oder nach der Bestrahlung eine CT-Planung, um die Volumenveränderungen während der Bestrahlung zu evaluieren. Die ermittelten CT-Daten wurden unter Verwendung des HELAX-TMS-Planungssystems zur Bestimmung der Dosisverteilung ausgewertet. Die Bestimmung des Brustvolumens erfolgte mittels Interpolationsalgorithmus. Gemessen am Ausgangsvolumen wurden die Patientinnen in drei Subgruppen unterteilt: Gruppe 1 (n = 47): ≤ 670 cm3, Gruppe 2 (n = 46): 671–999 cm3 und Gruppe 3 (n = 47): ≥ 1 000 cm3 Brustvolumen.Ergebnisse:Initial zeigte sich ein mittleres Brustvolumen von 907 cm3 (100–3 073 cm3). Nach Radiotherapie kam es zu einem Anstieg des Brustvolumens um durchschnittlich 81 cm3 auf 988 cm3 (109–3 185 cm3). Signifikant messbare Volumenzunahmen traten ab einer Zielvolumendosis von 40 Gy auf. Bezogen auf die drei Subgruppen ergaben sich folgende mittlere Volumenzunahmen: Gruppe 1: 53 cm3 (3–120 cm3), Gruppe 2: 85 cm3 (20–200 cm3) und Gruppe 3: 105 cm3 (5–340 cm3). Der Zuwachs war in allen drei Gruppen mit einem p-Wert von p < 0,001 hochsignifikant. Je nach Volumenzunahme der Brust resultierte eine Änderung der Herdtiefe um bis zu 1,0 cm.Schlussfolgerung:Aufgrund der interkurrenten Volumenänderungen unter Bestrahlung erscheint eine zweite CT-Untersuchung zur Nachplanung vor Boostbestrahlung sinnvoll. Die zweite CT-Planung sollte ab 40 Gy erfolgen, um das Ödem ausreichend erfassen zu können.Background and Purpose:Radiotherapy can induce tissue reactions with an edema leading to increased breast volume. The aim of the present study was to quantify this increase and analyze its effect on the electron boost technique.Patients and Methods:140 patients with breast cancer treated with breast-conserving surgery underwent CT planning before, during and/or after radiotherapy in order to evaluate breast volume changes due to radiotherapy. CT data were analyzed using the HELAX planning system and dose distribution was assessed. Determination of the breast volume was achieved using an interpolation algorithm. Three subgroups were analyzed: group 1 (n = 47): ≤ 670 cm3, group 2 (n = 46): 671–999 cm3, and group 3 (n = 47): ≥ 1000 cm3 breast volume.Results:The mean initial breast volume was 907 cm3 (100–3073 cm3). After radiotherapy, mean breast volume increased by 81 cm3 to 988 cm3 (109–3185 cm3). Significant changes in volume were observed after a dose of 40 Gy. According to the subgroups mean volume increase was as follows: group 1: 53 cm3 (3–120 cm3), group 2: 85 cm3 (20–200 cm3), and group 3: 105 cm3 (5–340 cm3). This difference was statistically significant for all subgroups (p < 0.001). Corresponding to the volume increase, depth of the boost target volume changed up to 1.0 cm.Conclusion:As radiotherapy may lead to a significant increase in breast volume, it seems appropriate to perform a second planning CT after about 40 Gy in order to optimize dose distribution for boost irradiation.