Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Mattheos Bobos is active.

Publication


Featured researches published by Mattheos Bobos.


Annals of Oncology | 2012

Induction chemotherapy followed by concomitant radiotherapy and weekly cisplatin versus the same concomitant chemoradiotherapy in patients with nasopharyngeal carcinoma: a randomized phase II study conducted by the Hellenic Cooperative Oncology Group (HeCOG) with biomarker evaluation

George Fountzilas; Elisabeta Ciuleanu; Mattheos Bobos; Anna Kalogera-Fountzila; Anastasia G. Eleftheraki; Georgia Karayannopoulou; Thomas Zaramboukas; Angelos Nikolaou; Konstantinos Markou; Liliana Resiga; D. Dionysopoulos; E. Samantas; H. Athanassiou; Despina Misailidou; D. Skarlos; T. Ciuleanu

BACKGROUND Concomitant administration of radiation therapy (RT) and chemotherapy with cisplatin (CCRT) is considered standard treatment in patients with locally advanced nasopharyngeal cancer (LA-NPC). The role of induction chemotherapy (IC) when followed by CCRT in improving locoregional control remains controversial. PATIENTS AND METHODS Totally, 141 eligible patients with LA-NPC were randomized to either three cycles of IC with cisplatin 75 mg/m(2), epirubicin 75 mg/m(2) and paclitaxel (Taxol) 175 mg/m(2) (CEP) every 3 weeks followed by definitive RT (70 Gy) and concomitant weekly infusion of cisplatin 40 mg/m(2) (investigational arm, 72 patients) or to the same CCRT regimen alone (control arm, 69 patients). RESULTS Sixty-two patients (86%) received three cycles of IC. No difference between the arms was observed in the number of patients who completed RT (61 versus 64, P = 018). Overall and complete response rates were very similar in the two arms and so were 3-year progression-free and overall survival rates. Grade III or IV toxic effects from IC were infrequent, apart of alopecia. Mucositis, weight loss and leukopenia were the most prominent side-effects from CCRT. CONCLUSION IC with three cycles of CEP when followed by CCRT did not significantly improve response rates and/or survival compared with that of CCRT alone.


BMC Cancer | 2008

Potential value of PTEN in predicting cetuximab response in colorectal cancer: An exploratory study

Evangelia Razis; Evangelos Briasoulis; Eleni Vrettou; Dimosthenis Skarlos; Dimitrios Papamichael; Ioannis Kostopoulos; E. Samantas; Ioannis Xanthakis; Mattheos Bobos; Eleni Galanidi; Maria Bai; Ioanna Gikonti; Alona Koukouma; Georgia Kafiri; Pavlos Papakostas; Konstantine T. Kalogeras; P. Kosmidis; George Fountzilas

BackgroundThe epidermal growth factor receptor (EGFR) is over-expressed in 70–75% of colorectal adenocarcinomas (CRC). The anti-EGFR monoclonal antibody cetuximab has been approved for the treatment of metastatic CRC, however tumor response to cetuximab has not been found to be associated with EGFR over-expression by immunohistochemistry (IHC). The aim of this study was to explore EGFR and the downstream effector phosphatase and tensin homologue deleted on chromosome 10 (PTEN) as potential predictors of response to cetuximab.MethodsCRC patients treated with cetuximab by the Hellenic Cooperative Oncology group, whose formalin-fixed paraffin-embedded tumor tissue was available, were included. Tissue was tested for EGFR and PTEN by IHC and fluorescence in situ hybridization (FISH).ResultsEighty-eight patients were identified and 72 were included based on the availability of tissue blocks with adequate material for analysis on them. All patients, except one, received cetuximab in combination with chemotherapy. Median follow-up was 53 months from diagnosis and 17 months from cetuximab initiation. At the time of the analysis 53% of the patients had died. Best response was complete response in one and partial response in 23 patients. In 16 patients disease stabilized. Lack of PTEN gene amplification was associated with more responses to cetuximab and longer time to progression (p = 0.042).ConclusionPTEN could be one of the molecular determinants of cetuximab response. Due to the heterogeneity of the population and the retrospective nature of the study, our results are hypothesis generating and should be approached with caution. Further prospective studies are needed to validate this finding.


Cancer Investigation | 2008

Gemcitabine Combined with Gefitinib in Patients with Inoperable or Metastatic Pancreatic Cancer: A Phase II Study of the Hellenic Cooperative Oncology Group with Biomarker Evaluation

George Fountzilas; Mattheos Bobos; Anna Kalogera-Fountzila; Nikolaos Xiros; Samuel Murray; Helena Linardou; Georgia Karayannopoulou; Angelos Koutras; Dimitrios Bafaloukos; Epaminondas Samantas; Christos Christodoulou; Theofanis Economopoulos; Konstantine T. Kalogeras; P. Kosmidis

The combination of gemcitabine and gefitinib was evaluated in advanced pancreatic cancer. Totally, 53 patients were treated with a 7 week cycle of gemcitabine (1,000 mg/m2 given weekly) followed by six 4 week cycles of gemcitabine given on days 1, 8 and 15. Gefitinib 250 mg was administered daily. Responses were seen in 6, and stabilization of the disease in 12 patients. The main toxicity was myelotoxicity (92%). The 6-month progression-free survival (PFS) was 30%. Median PFS was 4.1 months and median survival 7.3 months with a 1 year survival rate of 27%. The above combination demonstrated promising activity in advanced pancreatic cancer.


PLOS ONE | 2012

Differential Response of Immunohistochemically Defined Breast Cancer Subtypes to Anthracycline-Based Adjuvant Chemotherapy with or without Paclitaxel

George Fountzilas; Urania Dafni; Mattheos Bobos; Anna Batistatou; Vassiliki Kotoula; Helen Trihia; Vassiliki Malamou-Mitsi; S. Miliaras; Sofia Chrisafi; Savvas Papadopoulos; Maria Sotiropoulou; Theodoros Filippidis; Helen Gogas; Triantafyllia Koletsa; Dimitrios Bafaloukos; Despina Televantou; Konstantine T. Kalogeras; Dimitrios Pectasides; Dimosthenis Skarlos; Angelos Koutras; Meletios A. Dimopoulos

Background The aim of the present study was to investigate the efficacy of adjuvant dose-dense sequential chemotherapy with epirubicin, paclitaxel, and CMF in subgroups of patients with high-risk operable breast cancer, according to tumor subtypes defined by immunohistochemistry (IHC). Materials and Methods Formalin-fixed paraffin-embedded (FFPE) tumor tissue samples from 1,039 patients participating in two adjuvant dose-dense sequential chemotherapy phase III trials were centrally assessed in tissue micro-arrays by IHC for 6 biological markers, that is, estrogen receptor (ER), progesterone receptor (PgR), HER2, Ki67, cytokeratin 5 (CK5), and EGFR. The majority of the cases were further evaluated for HER2 amplification by FISH. Patients were classified as: luminal A (ER/PgR-positive, HER2-negative, Ki67low); luminal B (ER/PgR-positive, HER2-negative, Ki67high); luminal-HER2 (ER/PgR-positive, HER2-positive); HER2-enriched (ER-negative, PgR-negative, HER2-positive); triple-negative (TNBC) (ER-negative, PgR-negative, HER2-negative); and basal core phenotype (BCP) (TNBC, CK5-positive and/or EGFR-positive). Results After a median follow-up time of 105.4 months the 5-year disease-free survival (DFS) and overall survival (OS) rates were 73.1% and 86.1%, respectively. Among patients with HER2-enriched tumors there was a significant benefit in both DFS and OS (log-rank test; p = 0.021 and p = 0.006, respectively) for those treated with paclitaxel. The subtype classification was found to be of both predictive and prognostic value. Setting luminal A as the referent category, the adjusted for prognostic factors HR for relapse for patients with TNBC was 1.91 (95% CI: 1.31–2.80, Walds p = 0.001) and for death 2.53 (95% CI: 1.62–3.60, p<0.001). Site of and time to first relapse differed according to subtype. Locoregional relapses and brain metastases were more frequent in patients with TNBC, while liver metastases were more often seen in patients with HER2-enriched tumors. Conclusions Triple-negative phenotype is of adverse prognostic value for DFS and OS in patients treated with adjuvant dose-dense sequential chemotherapy. In the pre-trastuzumab era, the HER2-enriched subtype predicts favorable outcome following paclitaxel-containing treatment.


Oncology | 2009

Trastuzumab combined with pegylated liposomal doxorubicin in patients with metastatic breast cancer. phase II Study of the Hellenic Cooperative Oncology Group (HeCOG) with biomarker evaluation.

Christos Christodoulou; Ioannis Kostopoulos; Haralabos P. Kalofonos; Evangelos Lianos; Mattheos Bobos; Evangelos Briasoulis; Helen Gogas; E. Razis; Dimosthenis Skarlos; George Fountzilas

Objective: Combination of trastuzumab and anthracyclines in metastatic breast cancer (MBC) is precluded due to cardiotoxicity. Pegylated liposomal doxorubicin (PLD) is the least cardiotoxic among the anthracyclines. We performed a phase II study of trastuzumab and PLD with biomarker evaluation. Methods: Patients with MBC and HER2 overexpression, assessed as 3+ at local laboratories, received trastuzumab 8 mg/kg as loading dose followed by 6 mg/kg in combination with PLD 30 mg/m2, both given every 3 weeks. To be eligible, patients should have received first-line chemotherapy for MBC or should have relapsed within a year of adjuvant taxane. Tumor tissue blocks were collected for central review and exploratory biomarker evaluation. Left-ventricular ejection fraction (LVEF) was closely monitored by cardiac ultrasound. Results: Among 37 patients, an overall response rate of 22% was observed with a progression-free survival (PFS) of 6.5 months (0.8–31.1, 95% CI 2.7–10.3) and a survival of 18.7 months (1.6–40.8, 95% CI 3.7–33.7). No decline in LVEF was noticed. Overexpression of mTOR and TOP2A gene alterations were associated with better PFS. PTEN gene deletion was associated with resistance to treatment. Conclusion: Trastuzumab combined with PLD every 3 weeks is feasible, effective and safe in HER2-positive patients.


Journal of Translational Medicine | 2012

HER2 and TOP2A in high-risk early breast cancer patients treated with adjuvant epirubicin-based dose-dense sequential chemotherapy.

George Fountzilas; Christos Valavanis; Vassiliki Kotoula; Anastasia G. Eleftheraki; Konstantine T. Kalogeras; Olympia Tzaida; Anna Batistatou; Ralf Kronenwett; Ralph M. Wirtz; Mattheos Bobos; Eleni Timotheadou; Nikolaos Soupos; George Pentheroudakis; Helen Gogas; Dimitrios Vlachodimitropoulos; Genovefa Polychronidou; Gerasimos Aravantinos; Angelos Koutras; Christos Christodoulou; Dimitrios Pectasides; Petroula Arapantoni

BackgroundHER2 and TOP2A parameters (gene status, mRNA and protein expression) have individually been associated with the outcome of patients treated with anthracyclines. The aim of this study was to comprehensively evaluate the prognostic/predictive significance of the above parameters in early, high-risk breast cancer patients treated with epirubicin-based, dose-dense sequential adjuvant chemotherapy.MethodsIn a series of 352 breast carcinoma tissues from patients that had been post-operatively treated with epirubicin-CMF with or without paclitaxel, we assessed HER2 and TOP2A gene status (chromogenic in situ hybridization), mRNA expression (quantitative reverse transcription PCR), as well as HER2 and TopoIIa protein expression (immunohistochemistry).ResultsHER2 and TOP2A amplification did not share the same effects on their downstream molecules, with consistent patterns observed in HER2 mRNA and protein expression according to HER2 amplification (all parameters strongly inter-related, p values < 0.001), but inconsistent patterns in the case of TOP2A. TOP2A gene amplification (7% of all cases) was not related to TOP2A mRNA and TopoIIa protein expression, while TOP2A mRNA and TopoIIa protein were strongly related to each other (p < 0.001). Hence, TOP2A amplified tumors did not correspond to tumors with high TOP2A mRNA or TopoIIa protein expression, while the latter were characterized by high Ki67 scores (p = 0.003 and p < 0.001, respectively). Multivariate analysis adjusted for nodal involvement, hormone receptor status, Ki67 score and HER2/TOP2A parameters revealed HER2/TOP2A co-amplification (21.2% of HER2 amplified tumors) as an independent favorable prognostic factor for DFS (HR = 0.13, 95% CI: 0.02-0.96, p = 0.046); in contrast, increased HER2/TOP2A mRNA co-expression was identified as an independent adverse prognostic factor for both DFS (HR = 2.41, 95% CI: 1.31-4.42, p = 0.005) and OS (HR = 2.83, 95% CI: 1.42-5.63, p = 0.003), while high TOP2A mRNA expression was an independent adverse prognostic factor for OS (HR = 2.06, 95% CI: 1.23-3.46, p = 0.006). None of the parameters tested was associated with response to paclitaxel.ConclusionsThis study confirms the favorable prognostic value of HER2/TOP2A co-amplification and the adverse prognostic value of high TOP2A mRNA expression extending it to the adjuvant treatment setting in early high-risk breast cancer. The strong adverse prognostic impact of high HER2/TOP2A mRNA co-expression needs further validation in studies designed to evaluate markers predictive for anthracyclines.Trial registrationAustralian New Zealand Clinical Trials Registry ACTRN12611000506998.


International Journal of Food Microbiology | 2011

Detection of Helicobacter pylori in raw bovine milk by fluorescence in situ hybridization (FISH)

Apostolos S. Angelidis; Ilias Tirodimos; Mattheos Bobos; Mary S. Kalamaki; Demetrios K. Papageorgiou; Malamatenia Arvanitidou

The transmission pathways of Helicobacter pylori in humans have not been fully elucidated. Research in the last decade has proposed that foodborne transmission, among others, may be a plausible route of human infection. Owing to the organisms fastidious growth characteristics and its ability to convert to viable, yet unculturable states upon exposure to stress conditions, the detection of H. pylori in foods via culture-dependent methods has been proven to be laborious, difficult and in most cases unsuccessful. Hence, nucleic acid-based methods have been proposed as alternative methods but, to date, only PCR-based methods have been reported in the literature. In the current study, fluorescence in situ hybridization (FISH) was used for the detection of H. pylori in raw, bulk-tank bovine milk. After repeated milk centrifugation and washing steps, the bacterial flora of raw milk was subjected to fixation and permeabilization and H. pylori detection was conducted by FISH after hybridization with an H. pylori-specific 16S rRNA-directed fluorescent oligonucleotide probe. Using this protocol, H. pylori was detected in four out of the twenty (20%) raw milk samples examined. The data presented in this manuscript indicate that FISH can serve as an alternative molecular method for screening raw bovine milk for the presence of H. pylori.


Journal of Oncology | 2009

MMP9 but Not EGFR, MET, ERCC1, P16, and P-53 Is Associated with Response to Concomitant Radiotherapy, Cetuximab, and Weekly Cisplatin in Patients with Locally Advanced Head and Neck Cancer

George Fountzilas; Anna Kalogera-Fountzila; Sophia Lambaki; Ralph M. Wirtz; Angelos Nikolaou; Georgia Karayannopoulou; Mattheos Bobos; Vassiliki Kotoula; Samuel Murray; Alexandros Lambropoulos; Gerasimos Aravantinos; Konstantinos Markou; Eleni Athanassiou; Despina Misailidou; Konstantine T. Kalogeras; Demosthenis Skarlos

Concomitant administration of radiotherapy with cisplatin or radiotherapy with cetuximab appear to be the treatment of choice for patients with locally advanced head and neck cancer. In the present retrospective analysis, we investigated the predictive role of several biomarkers in an unselected cohort of patients treated with concomitant radiotherapy, weekly cisplatin, and cetuximab (CCRT). We identified 37 patients treated with this approach, of which 13 (35%) achieved a complete response and 10 (27%) achieved a partial response. Severe side effects were mainly leucopenia, dysphagia, rash, and anemia. Tumor EGFR, MET, ERCC1, and p-53 protein and/or gene expression were not associated with treatment response. In contrast, high MMP9 mRNA expression was found to be significantly associated with objective response. In conclusion, CCRT is feasible and active. MMP9 was the only biomarker tested that appears to be of predictive value in cetuximab treated patients. However, this is a hypothesis generating study and the results should not be viewed as definitive evidence until they are validated in a larger cohort.


Journal of Experimental & Clinical Cancer Research | 2012

Molecular predictors of response to tyrosine kinase inhibitors in patients with Non-Small-Cell Lung Cancer

Samuel Murray; Vasilios Karavasilis; Mattheos Bobos; Evangelia Razis; Savvas Papadopoulos; Christos Christodoulou; P. Kosmidis; George Fountzilas

IntroductionEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have become a treatment option in non-small-cell lung cancer (NSCLC) patients. However, despite their use in this disease, a significant number of patients will eventually develop resistance and relapse. In this study, we aimed to characterize several molecular events involved in potential resistance mechanisms to anti-EGFR treatment and correlate our findings with clinical outcome.Material and methodsThe medical records of patients with NSCLC who received anti-EGFR TKIs in any line within the participating centers were reviewed and available paraffin embedded tissue was retrieved. Mutational analysis for EGFR, KRAS, BRAF and intron-exon 14 deletions of MET; FISH analysis for chromosomal gain or amplification for EGFR, MET and the deletion marker D7S486 were performed. Furthermore, the expression of EGFR and MET were analysed by immunohistochemistry. All results were correlated with treatment outcomes.ResultsBetween 10/2001 and 12/2009 from an initial cohort of 72 treated patients, 59 cases (28 gefitinib/ 31 erlotinib) were included in the analysis. The majority had adenocarcinoma histology (68%), and received treatment in the second line setting (56%). Disease control rate (DCR) was 25.4% for all patients. EGFR and RAS mutational rates were 33% and 10% respectively, no other mutations were identified. High EGFR expressing tumors were found in 7 of 45 cases and pEGFR positivity (IHC) was found in 56% of the cases; MET expression was found in 48% of tumors. EGFR gene amplification was found in 4 cases, two cases showed high polysomy; overall, 13% cases were FISH positive for EGFR. High polysomy of MET gene was detected in 1/43 cases tested. D7S486 locus deletion was detected in 15/37 (40%) of cases. EGFR mutational status and gene gain were both associated with more favorable DCR. No other associations between examined biomarkers and DCR or survival were noted.ConclusionsEGFR mutational status is a predictor for disease control in patients with NSCLC treated with anti-EGFR TKIs. The predictive role of several other molecules involved in potential resistance to anti-EGFR TKIs is worthy of additional investigation.


Oncotarget | 2016

Tumors with high-density tumor infiltrating lymphocytes constitute a favorable entity in breast cancer: a pooled analysis of four prospective adjuvant trials

Vassiliki Kotoula; Kyriakos Chatzopoulos; Sotiris Lakis; Zoi Alexopoulou; Eleni Timotheadou; Flora Zagouri; George Pentheroudakis; Helen Gogas; Eleni Galani; Ioannis Efstratiou; Thomas Zaramboukas; Angelos Koutras; Gerasimos Aravantinos; E. Samantas; Amanda Psyrri; Helen P. Kourea; Mattheos Bobos; Pavlos Papakostas; P. Kosmidis; Dimitrios Pectasides; George Fountzilas

Background Tumor infiltrating lymphocytes (TILs) are considered in the prognosis of breast cancer (BC) patients. Here, we investigated the prognostic/predictive effect of TILs in patients treated in the frame of four prospective trials with adjuvant anthracycline-based chemotherapy in the pre- and post-trastuzumab era. Methods TILs density was histologically assessed as percentage of stromal area on whole routine sections of 2613 BC (1563 Luminal A/B; 477 Luminal HER2; 246 HER2-enriched; 327 triple negative [TNBC]) and were evaluated as high/low at three cut-offs (c/o; 50% [lymphocytic predominance, LP], 35% and 25%), in separate training and validation sets. Results High TILs were present in 3.5%, 6.5% and 11.5% of all tumors, using the 50%, 35% and 25% c/o, respectively. TILs status did not interact with BC subtypes or trastuzumab treatment. LPBC patient outcome was not affected by nodal status, while high TILs were favorable in TNBC with unfavorable nodal status. When adjusted for standard clinicopathological parameters and treatment, high TILs independently predicted for favorable outcome, e.g., disease-free survival with the 35% c/o in the entire cohort (HR = 0.44, 95% CI 0.28-0.69, p < 0.001) and in specific subtypes. Conclusions High TILs tumors, especially LPBC seem worthy validating as a separate entity of favorable prognosis in breast cancer.

Collaboration


Dive into the Mattheos Bobos's collaboration.

Top Co-Authors

Avatar

George Fountzilas

Aristotle University of Thessaloniki

View shared research outputs
Top Co-Authors

Avatar

Vassiliki Kotoula

Aristotle University of Thessaloniki

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Dimitrios Pectasides

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Konstantine T. Kalogeras

Aristotle University of Thessaloniki

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Helen Gogas

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Pavlos Papakostas

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Christos Christodoulou

Aristotle University of Thessaloniki

View shared research outputs
Top Co-Authors

Avatar

Ioannis Kostopoulos

Aristotle University of Thessaloniki

View shared research outputs
Researchain Logo
Decentralizing Knowledge