1. The influence of cytotoxic drugs on the immunophenotype of blast cells in paediatric B precursor acute lymphoblastic leukaemiaTomaž Prelog, Simon Buček, Andreja Brožič, Jakob Peterlin, Marko Kavčič, Maša Omerzel, Boštjan Markelc, Tanja Jesenko, Veronika Kloboves-Prevodnik, 2024, original scientific article Abstract: Flow cytometry plays is important in the diagnosis of acute lymphoblastic leukaemia (ALL) and when antigen-specific immunotherapy is indicated. We have investigated the effects of prednisolone, vincristine, daunorubicin, asparaginase and methotrexate on the antigen expression on blast cells that could influence the planning of antigen-specific therapy as well as risk-based treatment assignment. Patients and methods. Patients aged ≤ 17 years with de novo B-cell ALL (B-ALL) were enrolled in the study. Blast cells were isolated and exposed in vitro to 5 individual cytotoxic drugs in logarithmically increasing concentrations. Then, the expression of CD10, CD19, CD20, CD27, CD34, CD45, CD58, CD66c and CD137 antigens was determined by quantitative flow cytometry. Results. Cytotoxic drugs caused dose-dependent or dose-independent modulation of antigen expression. Daunorubicin caused a dose-dependent down-modulation of CD10, CD19, CD34, CD45 and CD58 and an up-modulation of CD137. Vincristine caused a dose-dependent down-modulation of CD19 and CD58 and an up-modulation of CD45. Daunorubicin also caused dose-independent down-modulation of CD27 and prednisolone down-modulation of CD10, CD19, CD27, CD34 and CD58. Down-modulation of CD20 was detected only in relation to the specific dose of daunorubicin. Conclusions. The results of the study have shown that cytotoxic drugs can alter the expression of antigens that are important for immunotherapy. Importantly, daunorubicin, prednisolone and vincristine caused down-modulation of CD19 and CD58, suggesting that these drugs are better avoided during bridging therapy prior to bispecific antibodies or CAR-T cell therapy. In addition, immunophenotypic changes on blast cells induced by different drugs could also influence risk-based treatment assignment. Keywords: immunophenotypic changes, chemotherapy, immunotherapy Published in DiRROS: 26.06.2026; Views: 82; Downloads: 43
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2. Genetic profiling of NUDT15 in the Slovenian populationAlenka Šmid, Dunja Urbančič, Jaka Vrevc Žlajpah, Natalia Stollarova, Tomaž Prelog, Marko Kavčič, Janez Jazbec, Irena Mlinarič-Raščan, Nataša Karas Kuželički, 2024, original scientific article Abstract: Determining variant TPMT alleles to predict patient response to thiopurine therapy represents one of the first successful implementations of pharmacogenomics in clinical practice. However, despite the TPMT-adjusted thiopurine dosing, some TPMT wild-type patients still exhibit toxicity at standard doses. Over the past decade, the pharmacogene NUDT15 has emerged as a significant co-modulator of thiopurine therapy. Initially, NUDT15 was considered important predominantly in Asian populations, but recent studies have highlighted its relevance in European populations as well. To evaluate the pharmacogenetic significance of NUDT15 in the Slovenian population, we sequenced extended regions of exon 1 and exon 3 in 109 healthy individuals and 37 patients with acute lymphoblastic leukemia. We identified eight variants, including one with established clinical significance (allele *3) and one extremely rare variant (Chr13 at 48045861; GRCh38, NC_000013.11). The frequencies of most previously described variants in both the general population and in the ALL cohort were consistent with those reported in other European populations, except for rs45465203, which was less frequent in the Slovenian population. None of the variants, except for NUDT15*3, were associated with cumulative thiopurine doses in ALL patients. However, these variants warrant further investigation in larger ALL cohorts. Keywords: 6-mercaptopurine, acutelymphoblastic leukemia, dose reduction, minorallele frequency, NUDT15, population genetics, thiopurines Published in DiRROS: 16.06.2026; Views: 158; Downloads: 154
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3. PAX5 alterations in a consecutive childhood B-Cell acute lymphoblastic leukemia cohort treated using the ALL IC-BFM 2009 protocolKlementina Črepinšek, Nika Klobučar, Tine Tesovnik, Robert Šket, Barbara Jenko Bizjan, Jernej Kovač, Marko Kavčič, Tomaž Prelog, Lidija Kitanovski, Janez Jazbec, Maruša Debeljak, 2024, original scientific article Keywords: childhood B-cell acute lymphoblastic leukemia, PAX5 genetic alterations, prognostic significance Published in DiRROS: 04.06.2026; Views: 200; Downloads: 132
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4. Risk factors for venous thromboembolism in Slovenian children and adolescents : a single center experienceMineja Leban, Marko Kavčič, Jakob Peterlin, Janez Jazbec, Barbara Faganel Kotnik, 2026, original scientific article Abstract: Venous thromboembolism (VTE) are rare but potentially life-threatening conditions in children, usually associated with underlying medical conditions. Some children with diagnosed VTE have genetic risk factors for the development of VTE, as well as for recurrent complications. This study reports risk factors for developing VTE in a homogeneous population of children and adolescents. A total of 155 children and adolescents, aged 0–21 years, who were diagnosed with VTE at the University Children's Hospital, UMC Ljubljana, between July 2006 and October 2021, were included. The median age at the time of the VTE diagnosis was 12.0 years (interquartile range: 1–7 years). Associated medical conditions were present in 75.5% of patients, and thrombophilia was diagnosed in 43.2% of patients. Oncological disease accounted for 27.7% of cases, while infections were found to be the most significant acquired risk factor (17.4%), followed by the presence of a central venous catheter (15.5%). Genetic thrombophilia markers were identified in 27.1% of patients, with the highest frequency in adolescents (62.5%). Factor V (FV) Leiden heterozygote was the most common marker (9.6% of patients), followed by elevated factor VIII (FVIII) activity (5.8%) and elevated Lp(a) levels (5.2%). Combined thrombophilia markers were found in 52.2% of patients. In addition to inherited thrombophilia, 83.3% of patients had acquired risk factors. Compared to previously reported prevalence, a lower occurrence of FV Leiden heterozygote, elevated Lp(a) levels, elevated FVIII activity and antiphospholipid syndrome was observed in our population. Keywords: acquired risk factors, genetic thrombophilia markers, inherited thrombophilia, pediatrics, venous thromboembolism Published in DiRROS: 13.03.2026; Views: 336; Downloads: 221
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5. Bridging the gap in pediatric relapsed acute lymphoblastic leukemia treatment : isights and outcomes from the ALL-IC REL 2016 guidelinesMarko Kavčič, Dániel J. Erdélyi, Volkan Hazar, Mirella Ampatzidou, Boryana Avramova, Anca Colita, Tomaž Prelog, Janez Jazbec, 2025, original scientific article Abstract: Background: The Acute Lymphoblastic Leukemia InterContinental (ALL-IC) Study Group exemplifies the potential of broad international collaboration. Patient outcomes have improved by standardizing therapeutic options and employing flow cytometry-based minimal residual disease (MRD) for treatment stratification. Nevertheless, relapse occurs in 10%–20% of cases, with survival rates falling short of benchmarks set by top-tier published studies. Objectives: We aimed to unify treatment guidelines for children with first relapse of ALL across the ALL-IC network, analyze post-relapse outcomes, and report findings from an observational registry. Methods: Patients were stratified as standard-risk (SR) or high-risk (HR) based on relapse features and genetics. HR criteria included T-cell immunophenotype, very early or early isolated bone marrow relapse, and relapse post-stem cell transplant (SCT). SR was assigned to all others. SCT was indicated in the whole HR group and in SR patients with poor responses (MRD ≥ 0.1% on Day 29). Results: Among 370 patients (mean age 9 years; 33.2% female) diagnosed with first relapse between 2017 and 2021, 90.5% had received ALL-IC-Berlin-Frankfurt-Münster (BFM) 2009 treatment initially. Upon relapse, 46.8% were classified as SR and 53.2% as HR. Complete remission rates post-induction were 84% (SR) and 56% (HR). MRD < 0.1% was achieved by 53% (SR) and 29% (HR). Five-year overall survival was 50.5% (74% SR, 32% HR). HR outcomes were hindered by disease progression, treatment toxicity, and posttransplant complications. Conclusions: This inaugural ALL-IC REL Consortium report demonstrates promising SR outcomes, akin to the International Study for the Treatment of Childhood Relapsed ALL (IntReALL) findings, but highlights poor HR outcomes with standard chemotherapy. Novel therapeutic strategies are urgently needed in upcoming ALL-IC-BFM REL protocols. Keywords: acute lymphoblastic leukemia intercontinental, ALL-IC, acute lymphoblastic leukemia, relapse, treatment guidelines Published in DiRROS: 24.02.2026; Views: 468; Downloads: 269
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6. Prognostic factors and survival outcomes of first CNS relapse in childhood acute lymphoblastic leukemia : results from the ALL-IC REL 2016 studyVolkan Hazar, Monika Makiya, Koray Yalçın, Juan Tadecilla Cadiu, Federico Manni, Andrea Reyes Barragan, Marko Kavčič, Tomaž Prelog, Janez Jazbec, 2026, original scientific article Abstract: Acute lymphoblastic leukemia (ALL) is among the most curable pediatric cancers, yet relapse involving the central nervous system (CNS) remains a major therapeutic obstacle. In this prospective cohort, 97 children (aged 1.1–18.2 years) experiencing their first CNS relapse were enrolled in the ALL-IC REL study. Relapses were classified as isolated CNS (i-CNS, n = 43) or combined CNS (c-CNS, n = 54), and patients received treatment through standard- or high-risk regimens, encompassing chemotherapy, cranial irradiation, and allogeneic stem cell transplantation. The estimated 2-year event-free survival was 40.0%, and overall survival 49.4%, closely matching outcomes reported internationally. Survival rates were comparable across i-CNS and c-CNS relapses, while induction failure occurred more frequently in c-CNS. Multivariable analysis identified female sex, T-cell phenotype, and very early relapse as independent predictors of poor prognosis. These results underscore the critical necessity for risk-adapted therapy techniques and the incorporation of innovative medicines into forthcoming procedures. Keywords: childhood, acute lymphoblastic leukemia, central nervous system relapse, prognostic factors, survival, hematopoietic stem cell transplantation Published in DiRROS: 24.02.2026; Views: 520; Downloads: 284
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7. Vključevanje staršev v zdravstveno oskrbo hospitaliziranega otroka z rakom : model v družino usmerjena zdravstvena oskrbaMojca Horvat, Jadranka Stričević, Marko Kavčič, Petra Klanjšek, 2025, original scientific article Abstract: Uvod: Uspešna implementacija koncepta družini usmerjene zdravstvene oskrbe v klinično okolje je velik izziv za multidisciplinarni tim pri zdravljenju otrok z rakom in njihovih družin. Namen raziskave je bil preučiti percepcijo in prakso tima v slovenskem okolju.Metode: Raziskava je bila izvedena z anketnim vprašalnikom o oskrbi, osredotočeni na družino v pediatrični onkologiji (angl. Family-Centered Care Questionnaire-Revised). Vzorec je vključeval 80 članov multidisciplinarnega tima, od katerih je 63 vrnilo izpolnjene anketne vprašalnike. Podatki so bili analizirani s programom SPSS, uporabljeni so bili deskriptivni in interferenčni statistični postopki, vključno z Mann-Whitneyjevim U-testom in Kruskal-Wallisovim testom.Rezultati: Raziskava je pokazala, da se multidisciplinarni tim, ki obravnava otroke z rakom, v veliki meri zaveda pomena oskrbe, osredinjene na otroka in družino (x = 2,28, s = 0,550). Obstajajo odstopanja v zavedanju pomena skrbi za celotno družino (x = 2,60, s = 0,670). Razlike so bile ugotovljene glede vključevanja staršev v oskrbo, predvsem med strokovnjaki z različnimi delovnimi izkušnjami (p = 0,024) ter med negovalnimi timi intenzivne terapije in onkologije (p < 0,001).Diskusija in zaključek: Moramo si prizadevati za kakovostno sodobno zdravstveno oskrbo, ki zadostuje potrebam otroka in staršem ter vodi do boljših rezultatov zdravljenja, krajših hospitalizacij, večjega zadovoljstva in nižjih stroškov. To razumevanje mora biti vključeno v organizacijo, oblikovanje smernic, postopke ter v vsak stik strokovnjakov z družino. Keywords: starši, hospitalizacija, zdravstvena nega, v družino usmerjena skrb, otrok, rak Published in DiRROS: 28.01.2026; Views: 440; Downloads: 439
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8. Gene therapy of rare diseases as a milestone in medicine : overview of the field and report on initial experiences in SloveniaUrh Grošelj, Marko Kavčič, Ana Drole Torkar, Jan Kafol, Duško Lainšček, Roman Jerala, Matjaž Sever, Samo Zver, Gregor Serša, Maja Čemažar, Primož Strojan, Aleš Grošelj, Mojca Žerjav-Tanšek, Špela Miroševič, Simona Ivančan, Tomaž Prelog, David Gosar, Jasna Oražem, Matej Mlinarič, Sara Bertok, Jernej Kovač, Jana Kodrič, Saba Battelino, Marko Pokorn, Alojz Ihan, Janez Jazbec, Tadej Battelino, Damjan Osredkar, 2025, review article Abstract: Gene therapy has transitioned from a long-awaited promise to a clinical reality, offering transformative treatments for rare congenital diseases and certain cancers, which have a significant impact on patients’ lives. Current approaches focus on gene replacement therapy, either in vivo or ex vivo, mostly utilizing viral vectors to deliver therapeutic genes into target cells. However, refining these techniques is essential to overcome challenges and complications associated with gene therapy to ensure long-term safety and efficacy. Slovenia has witnessed significant advancements in this field since 2018, marked by successful gene therapy trials and treatments for various rare diseases. Significant strides have been made in the field of gene therapy in Slovenia, treating patients with spinal muscular atrophy and rare metabolic disorders, including the pioneering work on CTNNB1 syndrome. Additionally, immune gene therapy, exemplified by IL-12 adjuvant therapy for cancer, has been a focus of research in Slovenia. Through patient-centred initiatives and international collaborations, researchers in Slovenia are advancing preclinical research and clinical trials, paving the way for accessible gene therapies. Establishing clinical infrastructure and genomic diagnostics for rare diseases is crucial for gene therapy implementation. Efforts in this regard in Slovenia, including the establishment of a Centre for Rare Diseases, Centre for the Technologies of Gene and Cell Therapy, and rapid genomic diagnostics, demonstrate a commitment to comprehensive patient care. Despite the promises of gene therapy, challenges remain, including cost, distribution, efficacy, and long-term safety. Collaborative efforts are essential to address these challenges and ensure equitable access to innovative therapies for patients with rare diseases. Keywords: gene therapy, rare genetic diseases, Slovenia, CAR-T cells, cancer, immune gene therapy Published in DiRROS: 04.12.2025; Views: 668; Downloads: 407
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