Objective: In this study, we investigated the effects of calreticulin (CALR) and JAK2V617F mutational status on clinical course and disease outcomes in Turkish patients with essential thrombocythemia (ET). Materials and Methods: Seventeen centers from Turkiye participated in the study and CALR- and JAK2V617F-mutated ET patients were evaluated retrospectively. Results: A total of 302 patients were included, of whom 203 (67.2%) and 99 (32.8%) were JAK2V617F- and CALR-positive, respectively. CALR-mutated patients were significantly younger (51 years vs. 57.5 years, p=0.03), with higher median platelet counts (987x109/L vs. 709x109/L, p<0.001) and lower median hemoglobin levels (13.1 g/dL vs. 14.1 g/dL, p<0.001) compared to JAK2V617F-mutated patients. Thromboembolic events (TEEs) occurred in 54 patients (17.9%), 77.8% of which were arterial. Compared to CALR mutation, JAK2V617F was associated with a higher risk of thrombosis (8.1% vs. 22.7%, p=0.002). Rates of transformation to myelofibrosis (MF) and leukemia were 4% and 0.7%, respectively, and these rates were comparable between JAK2V617F- and CALR-mutated cases. The estimated overall survival (OS) and MF-free survival of the entire cohort were 265.1 months and 235.7 months, respectively. OS and MF-free survival durations were similar between JAK2V617F- and CALR-mutated patients. Thrombosis -free survival (TFS) was superior in CALR-mutated patients compared to JAK2V617F-positive patients (5 -year TFS: 90% vs. 71%, respectively; p=0.001). Age at diagnosis was an independent factor affecting the incidence of TEEs. Conclusion: In our ET cohort, CALR mutations resulted in higher platelet counts and lower hemoglobin levels than JAK2V617F and were associated with younger age at diagnosis. JAK2V617F was strongly associated with thrombosis and worse TFS. Hydroxyurea was the most preferred cytoreductive agent for patients with high thrombosis risk.

BACKGROUND The standard conditioning regimen for autologous stem cell transplantation (ASCT) in multiple myeloma (MM) is 200 mg/m² of melphalan (Mel200). Dosing is reduced by 30% (Mel140) in frail patients. Studies comparing the performance of these regimens report inconsistent findings, mainly confounded by non-consecutive patient inclusion, missing data, and heterogenous practices. The largest study reported an increased risk of death with Mel200 among patients with very good partial remission, or better, before ASCT. This retrospective study from a single center compared outcomes of patients with a first ASCT for myeloma treated with melphalan 140 mg/m² or 200 mg/m². MATERIAL AND METHODS This was a retrospective real-world analysis from a single center. Data from 159 consecutive, first, single ASCTs for MM between 2012 and 2021 were included. Mel200 and Mel140 were administered to 131 and 28 patients, respectively. Primary and secondary objectives were overall survival (OS) and progression-free survival (PFS), respectively. RESULTS Median follow-up was 5.8 years. Over 90% received bortezomib-based induction, and over 76% achieved at least very good partial remission (VGPR) before ASCT in either group. PFS estimates were similar between groups (P=0.49). OS was longer with Mel200 (HR=0.42, P=0.002). Mel200 maintained OS superiority in all relevant subgroups. CONCLUSIONS In a homogenous population of patients with MM, Mel200 was associated with longer OS, likely reflecting the physiological state of patients and tolerance to subsequent treatments. Concerns reported from EBMT data regarding the association of Mel200 with mortality among patients with VGPR or better before ASCT are not supported by this study's findings.

Primary immune thrombocytopenia (pITP) is an acquired bleeding disorder related with mainly decreased number of platelets due to destruction or impaired production of platelets. Clinical presentation of pITP can be multifaceted, and thrombotic events may rarely manifest. Thrombosis can develop with treatment or during the untreated period. The primary objective of the study was to examine the frequency of arterial thromboembolism (ATE) in patients with pITP. We also aimed to evaluate the risk factors in these patients and the effect of ITP treatments on ATE. The study was designed as a retrospective, multicenter, conducted under the Turkish Society of Hematology's Scientific Subcommittee on Hemostasis-Thrombosis. Patients over the age of 18 with pITP and who subsequently developed ATE while undergoing follow-up for pITP were evaluated. A total of 2,178 patients with pITP were screened, and 37 patients (1.7%) were observed to have ATE. The mean age was 62 years. Fifteen (40.5%) of the patients who developed ATE were not receiving pITP treatment at the time of thromboembolism. The patients receiving pITP treatment at the time of ATE, 9 patients (24.3%) were receiving eltrombopag and 10 patients (27%) were receiving corticosteroids. Compared to patients who did not develop ATE, multivariate analysis revealed that presence of hypertension, comorbidity, and the history of venous thromboembolism statistically significantly increased the risk of developing ATE (p: 0.008, 0.018, 0.038). It should be noted that the risk of ATE may increase in pITP patients both during and without treatment. It is important to inquire thoroughly about the presence of comorbidities, atherosclerotic risk factors, hypertension and history of thrombosis in patients at the initiation of treatment. Correctable risk factors should be addressed to minimize the number of risk factors present. The treatment of pITP shall be individualized and incorporate age-related disorders.

The aim of this study is to investigate whether there is a cut-off value for PD-L1 expression in large B-cell lymphomas that predicts prognosis, and to clarify the relationship between PD-L1 expression and histopathological as well as clinical parameters. The study included a total of 130 patients who were diagnosed with large B-cell lymphoma at Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, Pathology Department. Biopsy samples were assessed using the PD-L1 immunohistochemical antibody (Dako, 22C3 clone). The patients had a mean age of 54 ± 17 years, with a median age of 56 years. No statistically significant difference was observed between the groups in terms of survival when the 30% cut-off value was used. However, a noteworthy discrepancy in survival became apparent when the cut-off point was established at 70%. Among the diffuse large B-cell lymphoma-not otherwise specified (DLBCL-NOS) category, the activated B-cell-like (ABC-like) phenotype showed higher PD-L1 expression compared to the germinal center B-cell-like (GCB-like) phenotype. Immunohistochemical PD-L1 expression emerged as a prognostic factor, particularly significant in the ABC-like phenotype.

Purpose: Lymphocyte counts have been shown to negatively correlate with the severity in Covid-19. The aim of this study is to analyse the distribution of lymphocyte subsets in response to SARS-CoV-2 infection and its relation to the severity of the disease. Methods: Blood samples were obtained from 67 consecutive patients between April 2020 and July 2020. Data on other laboratory parameters, and clinical course were collected retrospectively from patient files and patients were defined to have as severe or non-severe (mild/moderate) disease. Leukocyte subsets to be studied were identified by using flow cytometric analysis (Beckman Coulter Navios Ex V2.0). Patients were allocated into 3 groups based on the day of blood sample collection: Days 0-7, 8-14 and >14 as Group I, Group II and Group III, respectively. In 10 of 67 patients an additional analysis was done 7-10 days after the initial sampling. Results: A total of 67 patients (30 female, 37 male) with a median age of 57 were evaluated. Lower total lymphocyte, CD3 positive, CD4 positive and B-cell counts were identified in severe infection compared to non-severe infection group which were also correlated with high serum CRP, D-dimer and ferritin levels. NK and monocyte counts were not different between the two groups. Activation markers CD38 and HLA-DR on CD4 and CD8 positive lymphocytes also were not different in either group. Conclusion: CD3 and CD4 lymphopenia were lower in accordance with previous studies and were associated with severe disease. The expectancy of high activation markers was not met. Future studies with detailed subgroup analyses at different time-points will shed more light on our general knowledge of the immune response to COVID-19.