Browsing by Author "Uygun, Vedat"

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Different Kinetics and Risk Factors for Isolated Extramedullary Relapse After Allogeneic Hematopoietic Stem Cell Transplantation in Children With Acute Leukemia
(Elsevier Science inc, 2021) Hazar, Volkan; Ozturk, Gulyuz; Yalcin, Koray; Uygun, Vedat; Aksoylar, Serap; Kupesiz, A.; Pekpak, Esra
Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the most frequent cause of post-transplantation mortality. Isolated extramedullary (EM) relapse (iEMR) after HSCT is relatively rare and not well characterized, particularly in pediatric patients. We retrospectively analyzed 1527 consecutive pediatric patients with acute leukemia after allo-HSCT to study the incidence, risk factors, and outcome of iEMR compared with systemic relapse. The 5 -year cumulative incidence of systemic relapse (either bone marrow [BM] only or BM combined with EMR) was 24.8%, and that of iEMR was 5.5%. The onset of relapse after allo-HSCT was significantly longer in EM sites than in BM sites (7.19 and 5.58 months, respectively; P =.013). Complete response (CR) 2 +/active disease at transplantation (hazard ratio [HR], 3.1; P <.001) and prior EM disease (HR, 2.3; P =.007) were independent risk factors for iEMR. Chronic graft-versus-host disease reduced the risk of systemic relapse (HR, 0.5; P=.043) but did not protect against iEMR. The prognosis of patients who developed iEMR remained poor but was slightly better than that of patients who developed systemic relapse (3 -year overall survival, 16.5% versus 15.3%; P =.089). Patients experiencing their first systemic relapse continued to have further systemic relapse, but only a minority progressed to iEMR, whereas those experiencing their iEMR at first relapse developed further systemic relapse and iEMR at approximately similar frequencies. A second iEMR was more common after a first iEMR than after a first systemic relapse (58.8% versus 13.0%; P =.001) and was associated with poor outcome. iEMR has a poor prognosis, particularly after a second relapse, and effective strategies are needed to improve outcomes. (C) 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.
Effect of Genetic Mutations on Outcomes of Stem Cell Transplantation in Children With Hemophagocytic Lymphohistiocytosis
(Springernature, 2025) Ozturk, Gulyuz; Yesilipek, Mehmet Akif; Akcay, Arzu; Uygun, Vedat; Ozek, Gulcihan; Karasu, Gulsun; Antmen, Bulent
Primary hemophagocytic lymphohistiocytosis (p-HLH) can be cured with allogeneic haematopoietic stem cell transplantation (allo-HSCT). It remains unclear whether HSCT outcomes are affected by the presence of different genetic mutations. We used data obtained from children who underwent allo-HSCT for HLH to examine the effects of genetic mutations on HSCT outcomes. Data from 153 paediatric patients in 18 paediatric stem cell centres were retrospectively evaluated. Patients were divided into four groups: 1) with PRF1 mutation (n = 46), 2) with UNC13D mutation (n = 38), 3) with STX11/STXBP2 mutation (n = 25) and 4) with Griscelli syndrome type 2/ Chediak-Higashi syndrome (GS2/CHS) diagnosis (n = 44). Statistical analysis showed no difference between the subgroups in terms of engraftment, VOD, acute GVHD, chronic GVHD, TRM, OS and EFS rates. The most important factor affecting OS and EFS in all genetic subgroups was remission status before HSCT. The 5-year EFS values for children with mutations in PRF1, UNC13D, STX11/STXBP2 and GS2/CHS were 71%, 66.6%, 74% and 66.7, respectively (log-rank >0.05). However, with prospective studies covering more patients, and creating different genetic subgroups by performing more detailed genetic analyses, special approaches for different genetic subgroups can be revealed in the future.
Role of a Second Transplantation for Children With Acute Leukemia Following Posttransplantation Relapse: a Study by the Turkish Bone Marrow Transplantation Study Group
(Taylor & Francis Ltd, 2020) Hazar, Volkan; Karasu, Gulsun Tezcan; Uygun, Vedat; Ozbek, Namik; Karakukcu, Musa; Ozturk, Gulyuz; Aksoylar, Serap
We examined outcomes of 51 pediatric patients with relapsed acute leukemia (AL) who underwent a second allogeneic hematopoietic stem cell transplantation (alloHSCT). After a median follow-up of 941 days (range, 69-2842 days), leukemia-free survival (LFS) and overall survival (OS) at 3 years were 26.6% and 25.6%, respectively. The nonrelapse mortality rate (NMR) and cumulative incidence of relapse (CIR) were 36.4% and 42.4%, respectively. The Cox regression analysis demonstrated that the risk factors at second transplantation for predicting limited LFS were active disease (hazard ratio (HR) = 5.1), reduced intensity conditioning (RIC) (HR = 5.0), matched unrelated donor (MUD) (HR = 3.4) and performance score <80 (HR = 3.2). Pediatric patients with AL who relapsed after their first alloHSCT may survive with a second alloHSCT. Disease status, conditioning intensity, donor type, and performance score at the second transplantation are the relevant risk factors. A score based on these factors may predict the results of the second transplantation.