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Introduction. Myelodysplastic syndromes (MDS), a group of clonal hematological diseases, are characterized by ineffective hematopoiesis, progressive peripheral blood (PB) cytopenia(s), and increased risk of developing acute myeloid leukemia (AML). Classification and risk stratification are constantly under revision for a better estimation of prognosis in those patients. Investigation of immune biomarkers is needed, because immune dysregulation also plays an important role in dysplastic hemopoiesis and immunological escape of neoplastic clones. Here, we studied frequency of low-density granulocytes (LDGs), a neutrophil subset with immunoregulatory functions, in MDS and AML at diagnosis and during treatments. Methods. A total of 17 patients (M/F, 14/12; median age, 69 years old; range, 21-84 years) and seven healthy subjects were enrolled at the Hematology and Transplant Center, University Hospital "San Giovanni di Dio e Ruggi d'Aragona", Salerno, Italy, between October 2020 and July 2021. Patients were diagnosed with AML (N = 7), or MDS (N = 10) according to the 2016 World Health Organization criteria. For immunophenotyping, fresh EDTA whole PB was stained with the ollowing antibodies: CD45; HLA-DR; CD15; CD3; CD56; CD19; CD11b; CD33; CD34; CD14; and CD16 (all from Beckman Coulter, Brea, CA). Acquisition was carried out using a Navios EX flow cytometer, and Navios software v1.3 (Beckman Coulter). Post-acquisition compensation and analysis were performed using FlowJo software (v.10.7.1, Becton Dickinson). LDGs were identified as CD3-CD56-CD19-CD11b+CD33+CD14-CD15+ cells, following previously published gating strategies (Rahman S, et al. Ann Rheum Dis. 2019). Data were analyzed using Prism (GraphPad software, La Jolla, CA). A P < 0.05 was considered statistically significant. Results. Frequencies of circulating LDGs were significantly reduced in AML patients at diagnosis compared to controls (P = 0.0018) and MDS (P = 0.0077) and were slightly decreased compared to AML in complete remission (P = 0.1605). MDS patients were then divided based on Revised International Prognostic Scoring System (IPSS-R), and very-low and low-risk MDS patients displayed significantly higher circulating LDG frequencies compared to AML at diagnosis (P = 0.0083), while no differences were described between AML at baseline and intermediate-risk MDS (P = 0.1103). Subsequently, LDGs were correlated with clinical and phenotypic features by correlation analysis showing significant negative correlations between LDGs and blasts identified by flow cytometry (r = -0.5463; P = 0.0057) but not by cytology (P = 0.1346), between LDGs and lymphocytes (r = -0.4407; P = 0.0311) or flow cytometric normalized blast count (NBC; r = -0.5283; P = 0.0096) as previously defined (Giudice V, et al. Biomedicines. 2021). A slight negative correlation was described between LDGs and WT1 expression levels (r = -0.5369; P = 0.0719), particularly evident in MDS patients (r = -0.9980; P = 0.0402), supporting our previous findings of negative prognostic impact of WT1 expression in MDS and AML. Finally, we investigated CD16 expression on LDGs, because CD16 is essential for neutrophil degranulation. Despite no differences were described between percentage of LDG subsets among patients' groups, various correlations were identified by Pearson analysis. In particular, CD16+ LDGs negatively correlated with blasts (P = 0.0229), while positively correlated with lymphocytes (P = 0.0404) detected by flow cytometry. Conversely, CD16int and CD16- LDGs negatively correlated with lymphocytes (P = 0.0109 and P = 0.0021, respectively) and positively correlated with granulocytes identified by flow cytometry (P = 0.0024 and P = 0.0008, respectively). In addition, CD16int LDGs negatively correlated with blasts detected by flow cytometry (r = -0.65; P = 0.0414). Conclusions. Our preliminary results suggested a possible role of LDGs in prognostic definition of AML and MDS patients especially when combined with other biomarkers, such as WT1 expression levels or NBC. Moreover, our data supported the hypothesis of biological heterogeneity of granulocytes, as LDG subsets variously correlated with lymphocytes and leukemic cells suggesting different roles in suppression or activation of immune responses. However, our findings need further validation in larger cohorts and in in vitro studies. Disclosures No relevant conflicts of interest to declare.

Wilm’s tumor 1 (WT1), a zinc-finger transcription factor and an epigenetic modifier, is frequently overexpressed in several hematologic disorders and solid tumors, and it has been proposed as diagnostic and prognostic marker of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, the exact role of WT1 in leukemogenesis and disease progression remains unclear. In this real-world evidence retrospective study, we investigated prognostic role of WT1-mRNA expression levels in AML and MDS patients and correlations with complete blood counts, flow cytometry counts, and molecular features. A total of 71 patients (AML, n = 46, and MDS, n = 25) were included in this study, and WT1 levels were assessed at diagnosis, during treatment and follow-up. We showed that WT1 expression levels were inversely correlated with normal hemopoiesis in both AML and MDS, and positively associated with blast counts. Flow cytometry was more sensitive and specific in distinguishing normal myeloid cells from neoplastic counterpart even just using linear parameters and CD45 expression. Moreover, we showed that a simple integrated approach combining blast counts by flow cytometry, FLT3 mutational status, and WT1 expression levels might be a useful tool for a better prognostic definition in both AML and MDS patients.

Cytomegalovirus (CMV) reactivation is one of the most frequent complication after hematopoietic stem cell transplantation (HSCT). Pre-transplant CMV-positive recipient serostatus is the most significant independent variable for viral reactivation. Oral valgancyclovir (VGCV) is a prodrug of intravenous gancyclovir (GCV) and is an effective and safety alternative for the management of CMV reactivation prophylaxis and preemptive therapy. However, VGCV at standard dose (900 mg twice a day) increases risk of myelosuppression in HSCT recipients. The efficacy of low dose (LD, 450 mg daily) oral VGCV was retrospectively evaluated in 30 allogeneic HLA-matched related patients and 2 unrelated, with a median age of 40 years (range, 18-59) and a median follow-up of 30 months (range, 3-56). Primary diseases were acute myeloid leukemia (AML, n=19), acute lymphoblastic leukemia (n=4), non-Hodgkin’s lymphoma (n=3), multiple myeloma (n=3) and myelodysplastic syndrome (n=3). Seventeen of twenty-three acute leukemia (AL) patients were transplanted in first complete remission (CR), while the remaining (n=6) were transplanted in 2nd CR. Five patients suffered from AML secondary to long-lasting MDS (n=3) or Hodgkin disease and breast cancer (n=2). Based upon CMV serostatus (D/R, donor/recipient), thirty (94%) of HSCT recipients were classified as high risk (D-/R+ = 3 and D+/R+ = 27) for CMV reactivation and only 6% as low risk (D-/R- = 2); none of the patients was in the intermediate risk group (D+/R-). Fifteen and 17 patients received a myeloablative and RIC regimens, respectively. Twenty-one patients received GvHD prophylaxis with cyclosporin A (CsA, 1 mg/kg intravenously from day -1 to +21, then 8 mg/kg orally for at least 6 months) and short-course methotrexate (MTX, 10 mg/kg on days +1, +3, +6 and +11). The others (n=11) received CsA with MTX and antithymocyte globulin (ATG, as a part of the conditioning regimen at 10 mg/kg at days -3, -2 and -1). According to the Glucksberg scoring system, thirteen patients experienced grade I-II and two grade III-IV acute GvHD, while 7 patients developed limited (n=6, 18%) and extensive (n=3, 10%) chronic GvHD. Starting from time of engraftment, LD oral VGCV was given prophylactically for at least 6 months. CMV infection was monitored weekly using polymerase chain reaction (PCR) in high risk seropositive recipients and we started preemptive therapy when the peak viral load exceeding 1000 copies/mL in two consecutive plasma samples. Six patients (4 early and 2 late) developed a positive PCR after a mean of 59 days post-HSCT successfully treated with 900 mg of VGCV twice a day for at least when PCR negative (in a median of 12 days). Only one patient developed late fatal gastrointestinal CMV disease. Indeed, asymptomatic early and late CMV-DNA PCR reactivation occurred only in 17% (n=5) of high risk seropositive HSCT recipients, in contrast to 37% and 18% of early and late CMV reactivation observed in matched gender, disease phase, graft source and CMV serostatus cohort of 32 HSCT recipients treated prophylactically with oral acyclovir (ACV, 15 mg/kg daily) and high dose intravenous immunoglobulins (IVIG, 0.4 gr/kg weekly for at least 6 months) . Seven patients presented hematological toxicity do not requiring drug discontinuation. The rate of non CMV-related infections was 25% and was similar in both groups with and without CMV reactivation. At the end of the follow-up, 18 of 32 (56%) patients were alive with a median follow-up of 31 months (range, 2-56). Relapsed-related mortality was 20%, transplant-related mortality was 9% and did not differ between group with and without CMV reactivation. Our data provide evidence that LD-VGCV is safe and effective as CMV reactivation prophylaxis in allogeneic HSCT recipients. These results require further validation in randomized studies. Disclosures: No relevant conflicts of interest to declare.

Primary hepatic lymphoma is an extremely rare malignancy accounting for 0.016% of all cases of non-Hodgkin lymphomas. Approximately 1-4% of histologies described show a follicular pattern. We report a case of primary hepatic non-Hodgkin lymphoma that developed in a middle-aged woman three years after radical treatment (neoadjuvant chemoradiotherapy and surgery) for a rectal adenocarcinoma. Abdomen ultrasound showed a single nodule in the liver, which raised the issue of differential diagnosis with a metastasis from rectal cancer. After surgical removal of the nodule, histology revealed a primary B cell, stage IE follicular non-Hodgkin lymphoma, confined to the liver; indeed, no foci of lymphoma were found elsewhere in the body.