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Chemoradiotherapy with nimorazole: Factors influencing local tumor control

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Polo-like kinase 1 (PLK1) plays an important role in mitotic progression, is frequently overexpressed and associated with a poor prognosis of cancer patients, thus providing a promising target in anticancer treatment. Aim of the current project was to evaluate the effect of the novel PLK1 inhibitor BI 6727 in combination with irradiation.In vitro proliferation and radiation cell survival assays as well as in vivo local tumour control assays after single treatment and combined radiation and drug application were carried out using the squamous cell carcinoma models A431 and FaDu. In addition, cell cycle phases were monitored in vitro and in vivo.BI 6727 showed a dose-dependent antiproliferative effect and an increase in the mitotic fraction. BI 6727 alone reduced clonogenic cell survival, while radiosensitivity in vitro (SF2) and in vivo (single-dose TCD(50) under clamped hypoxia) was not affected. In contrast, local tumour control was significantly improved after application of BI 6727 simultaneously to fractionated irradiation (A431: TCD(50) = 60.5 Gy [95% C.I. 57; 63] after IR alone and30 Gy after combined treatment; FaDu: 49.5 Gy [43; 56 Gy] versus 32.9 Gy [26; 40]).Despite the lack of direct cellular radiosensitisation, PLK1 inhibition with BI 6727 during fractionated irradiation significantly improves local tumour control when compared to irradiation alone. This result is likely explained by a considerable effect on cell cycle and an independent cytotoxic potential of BI 6727.

Lactate was previously shown to be a prognostic but not a predictive pre-therapeutic marker for radiation response of tumor xenografts. We hypothesize that metabolic changes during fractionated irradiation may restrict the predictiveness of lactate regarding tumor radiosensitivity. Tumor xenografts were generated in nude mice by implanting 4 head and neck squamous cell carcinoma lines with different sensitivities to fractionated irradiation. Tumors were irradiated with up to 15 fractions of 2 Gy over a period of 3 weeks, and ATP and lactate levels were measured in vital tumor areas with induced metabolic bioluminescence imaging. Corresponding changes in mRNA expression of glycolysis-related genes were determined by quantitative RT-PCR. Lactate content decreased significantly in 3 out of 4 cell lines in the course of irradiation showing no correlation with cell line-specific radiosensitivity. Radiation-induced changes in ATP levels and glycolysis-related mRNA expression, however, only occurred in radiosensitive or intermediately radioresistant xenografts, whereas these parameters remained unchanged in radioresistant tumors. Sensitivity-related differences in the transcriptional response of tumors to radiotherapy may be exploited in the clinic for better individualization of tumor treatment.

Purpose Evaluation of micromilieu-dependent quantified γH2AX foci as a potential predictive biomarker in well-oxygenated tumour areas in 9 HNSCC xenograft models in vivo. Materials & methods GammaH2AX foci were quantified in perfused tumour areas 30 min (initial γH2AX foci) and 24 h (residual γH2AX foci) after exposure to a single dose of 4 Gy. The initial and residual normalised γH2AX foci were correlated with TCD50 after single dose irradiation under clamped blood flow (SDclamp) or a fractionated irradiation setting under ambient blood flow (fx). Results A significant negative correlation between initial and residual normalised γH2AX foci and TCD50 SDclamp and TCD50 fx for 9 HNSCC tumour xenograft models in vivo was found. Residual normalised γH2AX foci showed higher intertumoural variability and their correlation with TCD50 was more robust. Conclusions For the first time a significant negative correlation between γH2AX foci and local tumour control after irradiation has been demonstrated. Our results underline the potential of residual γH2AX foci as a predictive biomarker for local tumour control after radiotherapy.

Purpose: Polo-like kinase 1 (PLK1) plays an important role in mitotic progression, is frequently overexpressed and associated with a poor prognosis of cancer patients, thus providing a promising target in anticancer treatment. Aim of the current project was to evaluate the effect of the novel PLK1 inhibitor BI 6727 in combination with irradiation. Material and methods: In vitro proliferation and radiation cell survival assays as well as in vivo local tumour control assays after single treatment and combined radiation and drug application were carried out using the squamous cell carcinoma models A431 and FaDu. In addition, cell cycle phases were monitored in vitro and in vivo. Results: BI 6727 showed a dose-dependent antiproliferative effect and an increase in the mitotic fraction. BI 6727 alone reduced clonogenic cell survival, while radiosensitivity in vitro (SF2) and in vivo (single-dose TCD50 under clamped hypoxia) was not affected. In contrast, local tumour control was significantly improved after application of BI 6727 simultaneously to fractionated irradiation (A431: TCD50 = 60.5 Gy [95% C.I. 57; 63] after IR alone and

Purpose: Evaluation of micromilieu-dependent quantified gamma H2AX foci as a potential predictive biomarker in well-oxygenated tumour areas in 9 HNSCC xenograft models in vivo. Materials & methods: GammaH2AX foci were quantified in perfused tumour areas 30 min (initial gamma H2AX foci) and 24 h (residual gamma H2AX foci) after exposure to a single dose of 4 Gy. The initial and residual normalised gamma H2AX foci were correlated with TCD50 after single dose irradiation under clamped blood flow (SDclamp) or a fractionated irradiation setting under ambient blood flow (fx). Results: A significant negative correlation between initial and residual normalised gamma H2AX foci and TCD50 SDclamp and TCD50 fx for 9 HNSCC tumour xenograft models in vivo was found. Residual normalised gamma H2AX foci showed higher intertumoural variability and their correlation with TCD50 was more robust. Conclusions: For the first time a significant negative correlation between gamma H2AX foci and local tumour control after irradiation has been demonstrated. Our results underline the potential of residual gamma H2AX foci as a predictive biomarker for local tumour control after radiotherapy

Purpose: To evaluate the impact of fractionation schedule on the size of the gross tumour volume (GTV) effect on tumour control after radiotherapy of NSCLC. Material and methods: A subgroup analysis on 163 patients treated in a randomized phase III trial of CHARTWEL (continuous hyperfractionated accelerated radiotherapy-weekend less) vs conventional radiotherapy was performed. The influence of GTV and other baseline factors on local failure (LF), disease-free survival (DFS), distant metastases (DM), and overall survival (OS) was estimated using the Cox Proportional Hazards model. Results: Superior local control was achieved by CHARTWEL compared to conventional radiotherapy (HR 0.54, p = 0.015). The hazard of LF increased with increasing GTV for both conventional fractionation and CHARTWEL, however the increase for the latter was less pronounced and not significant. Conclusion: Highly accelerated CHARTWEL treatment was significantly more effective than conventional radiotherapy for locoregional control of NSCLC. GTV had a significant effect on locoregional control after conventional fractionation, an effect that was not significant with CHARTWEL. This is the first study to demonstrate that the magnitude of the time factor of fractionated radiotherapy increases with tumour volume. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

Purpose To evaluate the impact of fractionation schedule on the size of the gross tumour volume (GTV) effect on tumour control after radiotherapy of NSCLC. Material and methods A subgroup analysis on 163 patients treated in a randomized phase III trial of CHARTWEL (continuous hyperfractionated accelerated radiotherapy-weekend less) vs conventional radiotherapy was performed. The influence of GTV and other baseline factors on local failure (LF), disease-free survival (DFS), distant metastases (DM), and overall survival (OS) was estimated using the Cox Proportional Hazards model. Results Superior local control was achieved by CHARTWEL compared to conventional radiotherapy (HR 0.54, p =0.015). The hazard of LF increased with increasing GTV for both conventional fractionation and CHARTWEL, however the increase for the latter was less pronounced and not significant. Conclusion Highly accelerated CHARTWEL treatment was significantly more effective than conventional radiotherapy for locoregional control of NSCLC. GTV had a significant effect on locoregional control after conventional fractionation, an effect that was not significant with CHARTWEL. This is the first study to demonstrate that the magnitude of the time factor of fractionated radiotherapy increases with tumour volume.

Hypoxia and reoxygenation are important determinants of outcome after radiotherapy. HIF-1α is a key molecule involved in cellular response to hypoxia. HIF-1α expression levels have been shown to change after irradiation. The objective of the present study was to explore the prognostic value of HIF-1α expression during fractionated irradiation.Six human squamous cell carcinoma models xenografted in nude mice were analysed. Tumours were excised after 3, 5 and 10 fractions. HIF-1α expression was quantified by western blot. For comparative analysis, previously published data on local tumour control data and pimonidazole hypoxic fraction was used.HIF-1α expression in untreated tumours exhibited intertumoural heterogeneity and did not correlate with pimonidazole hypoxic fraction. During fractionated irradiation the majority of tumour models exhibited a decrease in HIF-1α expression, whereas in UT-SCC-5 no change was observed. Neither kinetics nor expression levels during fractionated irradiation correlated with local tumour control.Our data do not support the use of HIF-1α determined during treatment as a biomarker to predict outcome after fractionated irradiation.

Radiotherapy is today used in about 50% of all cancer patients, often in multidisciplinary approaches. With major advance in radiotherapy techniques, increasing knowledge on tumor genetics and biology and the continuous introduction of specifically targeted drugs into combined radio-oncological treatment schedules, individualization of radiotherapy is of high priority to further improve treatment outcomes, i.e. to increase long-term tumor cure and/or to reduce chronic treatment toxicity. This review gives an overview on the importance of predictive biomarkers for the field of radiation oncology. The current status of knowledge on potential biomarkers of tumor hypoxia, tumor cell metabolism, DNA repair, cancer stem cells and biomarkers for combining radiotherapy with inhibition of the epidermal growth factor receptor using monoclonal antibodies is described.

High pretreatment tumor lactate content is associated with poor outcome after fractionated irradiation in human squamous cell carcinoma (hSCC) xenografts. Therefore, decreasing lactate content might be a promising approach for increasing tumor radiosensitivity. As the basis for such experiments, the effects of the biochemical inhibitors pyruvate dehydrogenase kinase dichloroacetate (DCA), lactate dehydrogenase oxamate, and monocarboxylic acid transporter-1 α-cyano-4-hydroxycinnamate (CHC) on tumor micromilieu and growth were investigated.Oxygen consumption (OCR) and extracellular acidification rates (ECAR) were measured in FaDu and UT-SCC-5 hSCC in response to DCA in vitro. Mice bearing FaDu, UT-SCC-5, and WiDr colorectal adenocarcinoma received either DCA in drinking water or DCA injected twice a day, or CHC injected daily. WiDr was also treated daily with oxamate. FaDu and UT-SCC-5 were either excised 8 days after treatment for histology or tumor growth was monitored. WiDr tumors were excised at 8 mm. Effect of inhibitors on ATP, lactate, hypoxia, and Ki67 labeling index (LI) was evaluated.DCA increased OCR and decreased ECAR in vitro. None of the treatments with inhibitors significantly changed lactate content, hypoxia levels, and Ki67 LI in the three tumor lines in vivo. ATP concentration significantly decreased after only daily twice injections of DCA in FaDu accompanied by a significant increase in necrotic fraction. Tumor growth was not affected by any of the treatments.Overall, tumor micromilieu and tumor growth could not be changed by glycolysis modifiers in the three tumor cell lines in vivo. Further studies are necessary to explore the impact of metabolic targets on radiation response.

Purpose To compare functional effects of combined irradiation and EGFR inhibition in different HNSCC tumour models in vivo with the results of molecular evaluations, aiming to set a basis for the development of potential biomarkers for local tumour control. Material and methods In five HNSCC tumour models, all wild-type for EGFR and KRAS, the effect of radiotherapy alone (30 fractions/6weeks) and with simultaneous cetuximab or erlotinib treatment on local tumour control were evaluated and compared with molecular data on western blot, immunohistochemistry and fluorescence-in situ-hybridisation (FISH). Results Erlotinib and cetuximab alone significantly prolonged tumour growth time in 4/5 tumour models. Combined irradiation and cetuximab treatment significantly improved local tumour control in 3/5 tumour models, whereas erlotinib did not alter local tumour control in any of the tumour models. The amount of the cetuximab-effect on local tumour control significantly correlated with the EGFR/CEP-7 ratios obtained by FISH. Conclusion Both drugs prolonged growth time in most tumour models, but only application of cetuximab during irradiation significantly improved local tumour control in 3/5 tumour models. The significant correlation of this curative effect with the genetic EGFR expression measured by FISH will be further validated in preclinical and clinical studies.

Purpose Bone marrow derived CD11b+ myelomonocytes have been shown to be recruited by the tumour and to promote tumour regrowth after irradiation. Here we investigated in a panel of well characterised hSCC tumour models the number of tumour-infiltrating CD11b+ cells and the association with response to clinically relevant fractionated irradiation. Methods Six hSCC tumour models (UT-SCC-5, -14, -15, XF354, FaDu, SAS) xenografted in nude mice were excised after injection of pimonidazole hypoxia marker before irradiation and after 5 and 10 fractions. In parallel, TCD 50 (dose to cure 50% of the tumours) assays were performed to determine the response to 30 fractions within 6weeks. The TCD 50 values have been previously published [1]. Double staining of CD11b and pimonidazole was performed using immunofluorescence. CD11b+ cells were counted in viable pimonidazole-negative areas (non-hypoxic) and pimonidazole-positive areas (hypoxic) of whole tumour cross-sections. Results The median number of tumour-infiltrating CD11b+ cells either decreased or remained unchanged after 5 and 10 fractions in most of the tumour models. The density of CD11b+ cells in hypoxic areas was similar or lower than in non-hypoxic regions independently on treatment in majority of the tumour models. After 10 fractions the median CD11b+ cell density was significantly associated with the TCD 50 values after 30 fractions. Conclusion The data from our exploratory study suggest that tumour-infiltrating CD11b+ cells may contribute to local tumour control after fractionated irradiation, which supports to further study their prognostic value and to evaluate specific myelomonocyte targeting strategies to overcome radiation resistance.

Radiobiological and cell biological knowledge is increasingly used to further improve local tumour control or to reduce normal tissue damage after radiotherapy. Important research areas are evolving which need to be addressed jointly by nuclear medicine and radiation oncology. For this differences of the biological distribution of diagnostic and therapeutic nuclides compared with the more homogenous dose-distribution of external beam radiotherapy have to be taken into consideration. Examples for interdisciplinary biology-based cancer research in radiation oncology and nuclear medicine include bioimaging of radiobiological parameters characterizing radioresistance, bioimage-guided adaptive radiotherapy, and the combination of radiotherapy with molecular targeted drugs.

Image-guided radiotherapy (IGRT) represents a novel method to precisely deliver radiation to tumours while sparing surrounding normal tissues. Integration of biological imaging using PET or MRI appears to be a promising concept to improve radiotherapy (Bio-IGRT). For this it is essential that biological imaging provides radiobiologically relevant information. Preclinical and clinical investigations into validation of PET tracers and MR methods in the context of curative radiotherapy and of concepts for biology-based escalation of radiation dose as well as other therapeutic interventions are an important task for further cancer research.

Purpose To explore the prognostic value of microenvironmental parameters for local tumor control determined before and during fractionated irradiation. Methods and Materials Six human squamous cell carcinoma (hSCC) lines were transplanted subcutaneously into the right hind leg of nude mice. Tumors were irradiated with 30 fractions within 6 weeks. Local tumor control was determined 120 days after irradiation. Radiation response was quantified as dose to cure 50% of tumors (TCD50). In parallel, untreated and irradiated tumors were excised after injection of pimonidazole (hypoxia marker) and Hoechst 33342 (perfusion marker) for histological evaluation. Results Pimonidazole hypoxia decreased during fractionated irradiation in the majority of tumor lines. Fraction of perfused vessels and vascular area showed modest changes during fractionated irradiation. Histological parameters before treatment and after three and five fractions did not significantly correlate with TCD50 after irradiation with 30 fractions within 6 weeks (p > 0.05). Hypoxic volume and perfused vessels after 10 fractions showed a significant association with local tumor control after fractionated irradiation (p = 0.018 and p = 0.019, respectively). None of these parameters remained statistically significant when the p value was adjusted for multiple comparisons. Conclusions The results from this exploratory study suggest that determination of microenvironmental parameters during treatment provides better prognostic information for the outcome after fractionated radiotherapy than pretreatment parameters, which warrants further investigation and confirmation in experimental and clinical studies.

Previous experiments showed that the fraction of radiobiologically hypoxic tumor cells (rHF) in un-treated tumors did not accurately predict local tumor control after fractionated irradiation. Thus, the prognostic value of rHF determined during fractionated irradiation was investigated. Six human squamous cell carcinoma lines were transplanted into nude mice and then irradiated with 15 fractions over 3 weeks. Thereafter, single dose irradiation under normal and clamped blood flow was given. Local tumor control rates were used to calculate the rHF and the TCD50, i.e., the radiation dose necessary to control 50% of the tumors, after single dose irradiation. These values were compared with the in parallel determined TCD50 after 30 fractions in 6 weeks. The rHF after 15 fractions varied between 28% and 100%. No correlation was found with the TCD50 after 30 fractions in 6 weeks. Single dose top-up TCD50 under ambient and clamp conditions after 15 fractions significantly correlated with TCD50 after 30 fractions in 6 weeks. rHF after 15 fractions is not a prognostic parameter for the outcome after fractionated irradiation. In contrast, the radiobiological parameters number of tumor stem cells, intrinsic radiosensitivity, and number of radiobiologically hypoxic tumor cells appear promising to predict outcome after fractionated irradiation.

Contains fulltext : 88794.pdf (Publisher’s version ) (Closed access) BACKGROUND AND PURPOSE: Previous experiments have shown that application of the anti-EGFR monoclonal antibody C225 (cetuximab) improves local tumour control after irradiation in FaDu human squamous cell carcinoma (hSCC) due to the combined effect of decreased repopulation and improved reoxygenation. The present study investigates early changes of the pimonidazole hypoxic fraction of FaDu tumours and the expression and phosphorylation of the EGFR and its downstream signal transduction molecules after treatment with C225 alone or in combination with irradiation. MATERIAL AND METHODS: FaDu tumour xenografts were irradiated with up to 3x3Gy with or without additional C225 treatment and excised at different time points. Tumour hypoxia was evaluated using pimonidazole. EGFR expression and phosphorylation and intratumoural distribution of C225 were assessed by immunofluorescence analysis. Western blots were performed to evaluate expression and phosphorylation of EGFR, ErbB2, AKT and MAPK (ERK1/2). RESULTS: Hypoxia did not change during the 4days of treatment in the tumours treated with C225 alone or combined with irradiation. C225 treatment led to downregulation of the total EGFR in FaDu tumours, accompanied by a change of the spatial distribution of the receptor favouring the membranous expression. An induction of phosphorylation of the EGFR (tyr992, tyr1173) was observed with C225 alone or combined with irradiation. AKT phosphorylation was decreased, whereas MAPK phosphorylation remained unchanged. C225 membrane staining was homogeneously distributed over the whole tumour with no differences between hypoxic and non-hypoxic tumour cells. CONCLUSION: Pimonidazole-hypoxia of FaDu tumours during the initial part of fractionated irradiation is not influenced by C225, indicating that external hypoxia markers may not be promising as biomarkers for tumour response to combined treatment. The downregulation of the total EGFR, but at the same time higher membrane staining, as well as the changes in downstream signal transduction molecules, warrants further investigation in other tumour models. 01 november 2010

Background and purpose To study whether pre-therapeutic lactate or pyruvate predict for tumour response to fractionated irradiation and to identify possible coherencies between intermediates of glycolysis and expression levels of selected proteins. Materials and methods Concentrations of lactate, pyruvate, glucose and ATP were quantified via bioluminescence imaging in tumour xenografts derived from 10 human head and neck squamous cell carcinoma (HNSCC) lines. Tumours were irradiated with 30 fractions within 6weeks. Expression levels of the selected proteins in tumours were measured at the mRNA and protein level. Tumour-infiltrating leucocytes were quantified after staining for CD45. Results Lactate but not pyruvate concentrations were significantly correlated with tumour response to fractionated irradiation. Lactate concentrations in vivo did not reflect lactate production rates in vitro . Metabolite concentrations did not correlate with GLUT1, PFK-L or LDH-A at the transcriptional or protein level. CD45-positive cell infiltration was low in the majority of tumours and did not correlate with lactate concentration. Conclusions Our data support the hypothesis that the antioxidative capacity of lactate may contribute to radioresistance in malignant tumours. Non-invasive imaging of lactate to monitor radiation response and testing inhibitors of glycolysis to improve outcome after fractionated radiotherapy warrant further investigations.

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Tumour hypoxia measured by biochemical markers such as pimonidazole and parameters of the glucose metabolism such as lactate concentration have been shown to correlate with outcome after fractionated radiotherapy in experimental and clinical tumours and might serve as potential candidates for treatment individualization. High resolution imaging of tumour pathophysiology allows to study not only average values per tumour but also to investigate the spatial variations in hypoxia, perfusion, and energy metabolism. To examine relationships between hypoxia marker pimonidazole, perfusion marker Hoechst and the parameters of metabolic micromilieu such as glucose and lactate at the microregional level serial histological sections were explored for co-localization in 3 different human squamous cell carcinomas (hSCC) growing in nude mice

Purpose: This study investigated the uptake of [18F]2-fluoro-2-deoxy-glucose ([18F]FDG) in the human tumour xenograft FaDu at early time points after single dose irradiation with Positron-Emission-Tomography (PET), autoradiography and functional histology. Materials and methods: [18F]FDG-PET of FaDu hSCC xenografts on nude mice was performed before 25 Gy or 35 Gy single dose irradiation and one, seven or 11 days post irradiation (p.irr.). Before the second PET, mice were injected with pimonidazole (pimo) and bromodeoxyuridine (BrdU). After the PET tumours were excised, sliced and subjected to autoradiography and functional histology staining (pimo, BrdU, Ki67). [18F]FDG tumour uptake was quantified in the PET scans by maximal standard uptake value (SUVmax) and in the autoradiography after co-registration to the histology slices. Results: No differences in the overall [18F]FDG uptake between the two dose groups and time points were found with PET or autoradiography. Comparing! autoradiography and histology, the [18F]FDG uptake was constant in tumour necrosis over time, while it decreased in vital tumour areas and particularly in hypoxic regions. No differences in the [18F]FDG uptake between positive and negative areas of Ki67 and BrdU were found. Conclusions: The decline of [18F]FDG uptake in vital tumour and in pimopositive areas as seen in autoradiography, was not reflected by evaluation of SUVmax determined by PET. These findings suggest that the SUVmax does not necessarily reflect changes in tumour biology after irradiation.

Purpose: To examine relationships between tumour hypoxia, perfusion and metabolic microenvironment at themicroregional level in three different human squamous cell carcinomas (hSCC). Materials and methods: Nude mice bearing FaDu, UT-SCC-15, and UT-SCC-5 hSCC were injected with pimonidazole hypoxia and Hoechst perfusion markers. Bioluminescence imaging was used to determine spatial distribution of glucose and lactate content in serial tumour sections. Metabolite levels were grouped in 10 concentration ranges. Images were co-registered and at each concentration range the proportion of area stained for pimonidazole and Hoechst was determinedin 11–13 tumours per tumour line. Results: The spatial distribution of metabolites in pimonidazole hypoxic and Hoechst perfused areas is characterised by pronounced heterogeneity. In all three tumour lines glucose concentration decreased with increasing pimonidazole hypoxic fraction and increased with increasing perfused area at the microregional level. A weak albeit significant positive correlation between lactate concentration and pimonidazole hypoxic fraction was found only in UT-SCC-5. Lactate concentration consistently decreased with increasing perfused area in all three tumour lines. Conclusions: Both glucose consumption and supply may contribute to the microregional glucose levels. Microregional lactate accumulation in tumours may be governed by clearance potential. The extent of microregional hypoxia cannot be predicted from the lactate concentration indicating that both parameters need to be measured independently.

Purpose: To assess the potential of using the residual phosphorylation of histone H2AX (γH2AX) after irradiation as a marker of radiosensitivity invitro. Material and methods: Confluent cell cultures of FaDu and SKX human squamous cell carcinoma lines were irradiated with graded single doses. Twenty-four hours after irradiation cells were seeded for standard colony forming assay (CFA). In parallel, staining for γH2AX was performed to visualise the residual foci. Results: In the CFA, FaDu showed a higher radioresistance than SKX. After analysis of the residual foci data, we constructed ‘predicted’ survival curves using two different methods. First, the proportion of nuclei with

Hintergrund: Präklinische und klinische Untersuchungen haben gezeigt, dass das Ausmaß der prätherapeutischen Tumorhypoxie das Ergebnis einer Strahlentherapie solider Tumoren beeinflusst. Derzeit werden strahlentherapeutische Interventionen wie z.B. Dosis-Eskalation partieller hypoxischer Subvolumina untersucht. In dieser Studie wurde in einer einzelnen, in Nacktmäusen transplantierten humanen Tumorzelllinie untersucht, ob das prätherapeutische [18F]FMISO hypoxische Tumorvolumen (HV) oder die Intensität des Tracer-uptakes (maximaler Standard uptake value SUVmax) mit der lokalen Tumorkontrolle nach Einzeldosisbestrahlung korreliert. Methoden: Die hSCC Zelllinie FaDu wurde subkutan auf das rechte Hinterbein von NMRI Nacktmäusen transplantiert. 70 Tiere wurden bei einem Tumorvolumen von 165-343 mm³ in das Experiment aufgenommen. Jedes Tier erhielt am Tag 0 eine PET-Untersuchung (MicroPET® P4, CTI Molecular Imaging Inc) mit dem Hypoxie-Marker 18F]FMISO ([18F]Fluormisonidazol) unter Anästhesie. Die Auswertung erfolgte mittels 3D-regions of interest über dem Tumor (ROVER software, ABX GmbH, Radeberg, Germany). Bestimmt wurde das [18F]FMISO hypoxische Volumen (HV) und der SUVmax. Anschließend wurden die Tumoren entsprechend des medianen hypoxischen Volumens für Einzeldosisbestrahlungen mit 25 Gy oder 35 Gy unter normalem Blutfluss randomisiert. Die Einzeldosisbestrahlungen erfolgten mit 200 kV Röntgenstrahlen (0.5 mm Cu, ~ 1 Gy min-1). Der experimentelle Endpunkt war die lokale Tumorkontrolle am Tag 120 nach Bestrahlung. Ergebnisse: Die lokalen Tumorkontrollraten nach Bestrahlung mit 25 Gy waren niedriger als nach Bestrahlung mit 35 Gy (22% vs. 69%, Logrank-Test p< 0.0001). Die Spanne der HV reichte von 38-353 mm³, der Median HV betrug 112 mm³ (95%CI: 92; 128 mm³). Für Tumoren < Median HV betrug die lokale Kontrollrate 33% nach 25 Gy vs. 82% nach 35 Gy (p=0.001). In Tumoren > Median HV betrug die lokale Kontrollrate 15% nach 25 Gy vs. 53% nach 35 Gy (p=0.0005). In der multivariaten Cox-Analyse konnte nach Korrektur für Dosis und Tumorvolumeneffekte ein signifikanter Effekt des HV als kontinuierliche Variable (p=0.009) oder dichotome Variable (Stratifikation entsprechend des Median HV) (p=0.039) nachgewiesen werden. Der SUVmax war bezüglich der Prognose der Heilungswahrscheinlichkeit nicht relevant. Schlussfolgerungen: Das [18F]FMISO hypoxische Tumorvolumen ist ein signifikanter unabhängiger Prädiktor für das Ergebnis einer Bestrahlung mit hohen Einzeldosen in FaDu hSCC. Diese Ergebnisse unterstützen die Hypothese, dass ein prätherapeutisches [18F]FMISO-PET wichtige Informationen für die Verschreibung einer heterogenen Bestrahlungsdosis in hypoxischen Subvolumina individueller Tumoren liefern kann. Weitere Experimente mit anderen Tumormodellen und fraktionierter Bestrahlung sind notwendig. Gefördert im Rahmen des EU-Projektes „BioCare“ Molecular Imaging for Biologically Optimized Cancer Therapy proposal# 505785 und DFG Projekt Ba 1433.

Background and purpose: To test the effect of BIBF 1120, a novel small molecule inhibitor of multiple angiogenic receptor tyrosine kinases, on the hypoxia and radiation response of tumours. Materials and methods: Poorly differentiated human squamous cell carcinoma FaDu growing in nude mice was treated with BIBF 1120 and investigated by functional histology. To test the effect of BIBF 1120 on the radiobiological hypoxic fraction (rHF), the number and intrinsic radiation sensitivity of tumour stem cells and the outcome after fractionated irradiation, a series of local tumour control assays were performed. Results: BIBF 1120 significantly reduced the vessel area, vessel area with a perfusion signal and tumour growth rate but did not affect tumour hypoxia or the number and intrinsic radiation sensitivity of tumour stem cells. Concurrent BIBF 1120 had no effect on local tumour control after fractionated irradiation. Conclusion: Triple angiokinase inhibition resulted in a clear-cut decrease of angiogenesis, vessel area with a perfusion signal and tumour growth but did not change tumour hypoxia or radiation response of tumour stem cells. Further experiments into mechanisms of interaction between anti-angiogenic strategies and irradiation appear to be necessary to better define and exploit the potential of this strategy to improve local tumour control after fractionated radiotherapy.