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Query: "author" (Srdjan Novaković) .

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Prevalence of BRAF, NRAS and c-KIT mutations in Slovenian patients with advanced melanoma
Maja Ebert Moltara, Srdjan Novaković, Marko Boc, Marina Bučić, Martina Reberšek, Vesna Zadnik, Janja Ocvirk, 2018, original scientific article

Abstract: BRAF, NRAS and c-KIT mutations are characteristics of tumour tissues that influence on treatment decisions in metastatic melanoma patients. Mutation frequency and their correlation with histological characteristics in Slovenian population have not been investigated yet. Patients and methods. In our retrospective analysis we analysed mutational status of BRAF, NRAS and c-KIT in 230 pathological samples of patients who were intended to be treated with systemic therapy due to metastatic disease at the Institute of Oncology Ljubljana between 2013 and 2016. We collected also histological characteristics of primary tumours and clinical data of patients and correlated them with mutational status of tumour samples. Results. The study population consisted of 230 patients with a mean age 59 years (range 25%85). 141 (61.3%) were males and 89 (38.7%) females. BRAF mutations were identified in 129 (56.1%), NRAS in 31 (13.5%) and c-KIT in 3 (1.3%) tissue samples. Among the 129 patients with BRAF mutations, 114 (88.4%) patients had V600E mutation and 15 (11.6%) had V600K mutation. Patients with BRAF mutations tended to be younger at diagnosis (52 vs. 59 years, p < 0.05), patients with NRAS mutations older (61 vs. 55 years, p < 0.05). Number of c-KIT mutations were too low for any statistical correlation, but there was one out of 3 melanoma located in mucus membranes. Conclusions. The analysis detected high rate of BRAF mutations, low NRAS mutations and low c-KIT mutations compared to previously published studies in Europe and North America. One of the main reasons for this observation is specific characteristics of study population.
Keywords: BRAF, NRAS, c-KIT, melanoma
Published in DiRROS: 10.06.2024; Views: 52; Downloads: 37
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Genetic counselling, BRCA1/2 status and clinico-pathologic characteristics of patients with ovarian cancer before 50 years of age
Mirjam Cvelbar, Marko Hočevar, Srdjan Novaković, Vida Stegel, Andraž Perhavec, Mateja Krajc, 2017, original scientific article

Abstract: In Slovenia like in other countries, till recently, personal history of epithelial ovarian cancer (EOC) has not been included among indications for genetic counselling. Recent studies reported up to 17% rate of germinal BRCA1/2 mutation (gBRCA1/2m) within the age group under 50 years at diagnosis. The original aim of this study was to invite to the genetic counselling still living patients with EOC under 45 years, to offer gBRCA1/2m testing and to perform analysis of gBRCA1/2m rate and of clinico-pathologic characteristics. Later, we added also the data of previously genetically tested patients with EOC aged 45 to 49 years. Patients and methods. All clinical data have to be interpreted in the light of many changes happened in the field of EOC just in the last few years: new hystology stage classification (FIGO), new hystology types and differentiation grades classification, new therapeutic possibilities (PARP inhibitors available, also in Slovenia) and new guidelines for genetic counselling of EOC patients (National Comprehensive Cancer Network, NCCN), together with next-generation sequencing possibilities. Results. Compliance rate at the invitation was 43.1%. In the group of 27 invited or previously tested patients with EOC diagnosed before the age of 45 years, five gBRCA1/2 mutations were found. The gBRCA1/2m detection rate within the group was 18.5%. There were 4 gBRCA1 and 1 gBRCA2 mutations detected. In the extended group of 42 tested patients with EOC diagnosed before the age of 50 years, 14 gBRCA1/2 mutations were found. The gBRCA1/2m detection rate within this extended, partially selected group was 33.3%. There were 11 gBRCA1 and 3 gBRCA2 mutations detected. Conclusions. The rate of gBRCA1/2 mutation in tested unselected EOC patients under the age of 50 years was higher than 10%, namely 18.5%. Considering also a direct therapeuthic benefit of PARP inhibitors for BRCA positive patients, there is a double reason to offer genetic testing to all EOC patients younger than 50 years. Regarding clinical data, it is important to perform their re-interpretation in everyday clinical practice, because this may influence therapeutic possibilities to be offered.
Keywords: ovarian cancer, BRCA 1/2, genetic counseling
Published in DiRROS: 24.05.2024; Views: 138; Downloads: 99
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Clonality analysis of lymphoid proliferations using the BIOMED-2 clonality assays : a single institution experience
Ira Koković, Barbara Jezeršek Novaković, Petra Škerl, Srdjan Novaković, 2014, original scientific article

Abstract: Background. Clonality determination in patients with lymphoproliferative disorders can improve the final diagnosis.The aim of our study was to evaluate the applicative value of standardized BIOMED-2 gene clonality assay protocolsfor the analysis of clonality of lymphocytes in a group of different lymphoid proliferations.Materials and methods. With this purpose, 121 specimens from 91 patients with suspected lymphoproliferationssubmitted for routine diagnostics from January to December 2011 were retrospectively analyzed. According to thefinal diagnosis, our series comprised 32 cases of B-cell lymphomas, 38 cases of non-Hodgkins T-cell lymphomas and51 cases of reactive lymphoid proliferations. Clonality testing was performed using the BIOMED-2 clonality assays.Results. The determined sensitivity of the TCR assay was 91.9%, while the sensitivity of the IGH assay was 74.2%. Thedetermined specificity of the IGH assay was 73.3% in the group of lymphomas and 87.2% in the group of reactivelesions. The determined specificity of the TCR assay was 62.5% in the group of lymphomas and 54.3% in the group ofreactive lesions.Conclusions. In the present study, we confirmed the utility of standardized BIOMED-2 clonality assays for the detectionof clonality in a routine diagnostical setting of non-Hodgkins lymphomas. Reactions for the detection of thecomplete IGH rearrangements and reactions for the detection of the TCR rearrangements are a good choice forclonality testing of a wide range of lymphoid proliferations and specimen types while the reactions for the detectionof incomplete IGH rearrangements have not shown any additional diagnostic value.
Keywords: Biomed-2, clonality analysis, lymphomas, IGH rearrangement, TCR rearrangement
Published in DiRROS: 11.04.2024; Views: 194; Downloads: 49
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Breast cancer risk prediction using Tyrer-Cuzick algorithm with an 18-SNPs polygenic risk score in a European population with below-average breast cancer incidence
Tjaša Oblak, Petra Škerl, Benjamin J. Narang, Rok Blagus, Mateja Krajc, Srdjan Novaković, Janez Žgajnar, 2023, original scientific article

Abstract: Goals: To determine whether an 18 single nucleotide polymorphisms (SNPs) polygenic risk score (PRS18) improves breast cancer (BC) risk prediction for women at above-average risk of BC, aged 40-49, in a Central European population with BC incidence below EU average. Methods: 502 women aged 40-49 years at the time of BC diagnosis completed a questionnaire on BC risk factors (as per Tyrer-Cuzick algorithm) with data known at age 40 and before BC diagnosis. Blood samples were collected for DNA isolation. 250 DNA samples from healthy women aged 50 served as a control cohort. 18 BC-associated SNPs were genotyped in both groups and PRS18 was calculated. The predictive power of PRS18 to detect BC was evaluated using a ROC curve. 10-year BC risk was calculated using the Tyrer-Cuzick algorithm adapted to the Slovenian incidence rate (S-IBIS): first based on questionnaire-based risk factors and, second, including PRS18. Results: The AUC for PRS18 was 0.613 (95 % CI 0.570-0.657). 83.3 % of women were classified at above-average risk for BC with S-IBIS without PRS18 and 80.7 % when PRS18 was included. Conclusion: BC risk prediction models and SNPs panels should not be automatically used in clinical practice in different populations without prior population-based validation. In our population the addition of an 18SNPs PRS to questionnaire-based risk factors in the Tyrer-Cuzick algorithm in general did not improve BC risk stratification, however, some improvements were observed at higher BC risk scores and could be valuable in distinguishing women at intermediate and high risk of BC.
Keywords: early breast cancer, polygenic risk score, risk prediction
Published in DiRROS: 21.03.2024; Views: 178; Downloads: 50
.pdf Full text (1,54 MB)

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Testing of mechanisms of action of rituximab and clinical results in high-risk patients with aggressive CD20+ lymphoma
Barbara Jezeršek Novaković, Vladimir Kotnik, Tanja Južnič Šetina, Marjeta Vovk, Srdjan Novaković, 2007, original scientific article

Abstract: Background. Rituximab has been applied successfully in the treatment of indolent and aggressive CD20 positive B cell lymphomas, yet the exact in vivo mechanisms of its action have not been unambiguously explained. This study wastherefore aimed to confirm the presumed major mechanisms of action of rituximab and concomitantly to assess the effectiveness of first-line chemoimmunotherapy in high-risk patients with aggressive CD20 lymphomas. Patients, materials and methods. The activity of rituximab was tested in vitroon Raji and SU-DHL-4 cells using the cell proliferation assay and flow cytometry. In the clinical part of the study, 20 high-risk patients with aggressive CD 20 lymphomas were treated with R-CHOP. Results. Only complement-mediated cytotoxicity was observed under the in vitro applied experimental conditions. Neither the direct apoptotic effect nor the antibody-dependent cell-mediated cytotoxicity was detected probably due to a too low concentration of rituximab and a too low ratio of cytotoxic lymphocytes to tumor cells. The treatment outcome in patients was excellent since complete remissions were achieved in 90% of poor-risk patients at the end of primary treatment and 80% of patients were disease free at 18.5 months median observation period. Conclusions. According to our results, the complement-dependent cytotoxicity is an important mechanism of rituximab action in vitro. To achieve direct apoptosis, higher concentrations than 20 micro g/ml of rituximab should be used, while for an effective antibody-dependent cell-mediated cytotoxicity, the ratio of cytotoxic lymphocytes to tumor cells should be higher than 1:1. In the high- risk patients with aggressive CD20 lymphomas, the addition of rituximab to CHOP substantially improves the therapeutic results.
Published in DiRROS: 22.02.2024; Views: 221; Downloads: 61
.pdf Full text (232,23 KB)

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Rapid detection of most frequent Slovenian germ-line mutations in BRCA1 gene using real-time PCR and melting curve analysis
Srdjan Novaković, Vida Stegel, 2005, original scientific article

Abstract: Background. Detection of inherited mutations in cancer susceptibility genes isof great importance in some types of cancers including the colorectal cancer(mutations of APC gene in familial adenomatous polyposis -FAP, mutationsin mismatch repair genes in hereditary nonpolyposis colorectal cancer- HNPCC), malignant melanoma (mutations in CDKN2A and CDK4 genes) and breast cancer (mutations in BRCA1 and BRCA2 genes). Methods. This article presents the technical data for the detection of five mutations in BRCA1 gene in breast cancer patients and their relatives. The mutations - 1806C>T, 300T>G, 300T>A, 310G>A, 5382insC -were determined by the real-time PCR and themelting curve analysis. Results and conclusion. In comparison to direct sequencing, this method proved to be sensitive and rapid enough for the routine daily determination of mutations in DNA isolated from the peripheral blood.
Published in DiRROS: 14.02.2024; Views: 212; Downloads: 53
.pdf Full text (254,79 KB)

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