Comprehensive response to Usutu virus following first isolation in blood donors in the Friuli Venezia Giulia region of Italy: Development of recombinant NS1-based serology and sensitivity to antiviral drugs.

Surveillance of Usutu virus is crucial to prevent future outbreaks both in Europe and in other countries currently naïve to the infection, such as the Americas. This goal remains difficult to achieve, notably because of the lack of large-scale cohort studies and the absence of commercially available diagnostic reagents for USUV. This work started with the first identification of USUV in a blood donor in the Friuli Venezia Giulia (FVG) Region in Northern-Eastern Italy, which is endemic for West Nile virus. Considering that only one IgG ELISA is commercially available, but none for IgM, a novel NS1 antigen based IgG/M ELISA has been developed. This assay tested successfully for the detection of Usutu virus in blood donors with the identification of a second case of transmission and high levels of exposure. Furthermore, two pan-flavivirus antiviral drugs, that we previously characterized to be inhibitors of other flavivirus infectivity, were successfully tested for inhibition of Usutu virus with inhibitory concentrations in the low micromolar range. To conclude, this work identifies North-Eastern Italy as endemic for Usutu virus with implications for the screening of transfusion blood. A novel NS1-based ELISA test has been implemented for the detection of IgM/G that will be of importance as a tool for the diagnosis and surveillance of Usutu virus infection. Finally, Usutu virus is shown to be sensitive to a class of promising pan-flavivirus drugs.

Predictive value of pretransplantation molecular minimal residual disease assessment by WT1 gene expression in FLT3-positive acute myeloid leukemia.

The FMS-like tyrosine kinase 3 (FLT3) mutation in acute myeloid leukemia (AML) is a negative prognostic factor and, in these cases, allogeneic stem cell transplantation (allo-SCT) can represent an important therapeutic option, especially if performed in complete remission (CR). However, it is increasingly clear that not all cytological CRs (cCRs) are the same and that minimal residual disease (MRD) before allo-SCT could have an impact on AML outcome. Unfortunately, FLT3, due its instability of expression, is still not considered a good molecular MRD marker. We analyzed the outcome of allo-SCT in a population of FLT3-positive AML patients according to molecular MRD at the pretransplantation workup, assessed by the quantitative expression evaluation of the panleukemic marker Wilms' tumor (WT1) gene. Sixty-two consecutive AML FLT3-positive patients received allo-SCT between 2005 and 2016 in our center. The median age at transplantation was 55 years. The quantitative analysis of the WT1 gene expression (bone marrow samples) was available in 54 out of 62 (87%) cases, both at diagnosis (100% overexpressing WT1 with a mean of 9747 ± 8064 copies) and before allo-SCT (33 WT1-negative and 21 WT1-positive cases at the pretransplantation workup). Of these cases, 33/54 (61%) were both in cCR and molecular remission (WT1-negative) at the time of transplantation, 13/54 (24%) were in cCR but not in molecular remission (WT1-positive), and 8/54 (15%) showed a cytological evidence of disease (relapsed or refractory). Both post-allo-SCT overall survival (OS) and disease-free survival (DFS) were significantly better in patients who were WT1-negative (WT1 <250 copies) at the time of transplantation compared with those who were WT1-positive (WT1 >250 copies), with a median OS and DFS not reached in the WT1-negative group and 10.2 and 5.5 months, respectively, in the WT1-positive group (OS log-rank p = 0.0005; hazard ratio [HR] = 3.7, 95% confidence interval [95% CI] = 1.5-9; DFS log-rank p = 0.0001; HR = 4.38, 95% CI = 1.9-10). Patients with cCR who were WT1-positive had the same negative outcome as those with a cytological evidence of disease. The relapse rate after allo-SCT was 9% (3/33) in pre-allo-SCT WT1-negative cases and 54% (7/13) in WT1-positive cases (p = 0.002). At multivariate analysis, WT1 negativity before allo-SCT and grade <2 acute graft versus host disease were the only independent prognostic factors for improved OS and DFS. These data show that pre-allo-SCT molecular MRD evaluation through WT1 expression is a powerful predictor of posttransplantation outcomes (OS, DFS, relapse rate). Patients with both cCR and a WT1-negative marker before allo-SCT have a very good outcome with very low relapse rate; conversely, patients with positive molecular MRD and refractory/relapsed patients have a negative outcome. The WT1 MRD stratification in FLT3-positive AML is a valuable tool with which to identify patients who are at high risk of relapse and that could be considered from post-allo-SCT prophylaxis with FLT3 inhibitors or other strategies (donor lymphocyte infusion, tapering of immunosuppression, azacitidine).

The role of MDR-related proteins in the prognosis of adult acute myeloid leukaemia (AML) with normal karyotype.

Cytogenetic abnormalities are among the most important factors affecting the outcome of patients with acute myeloid leukaemia (AML), but approximately 40-50% of AML cases display a normal karyotype at diagnosis. Multidrug resistance (MDR) proteins overexpression is associated with worse prognosis in acute leukaemias, but its role in normal karyotype AML is less defined. We analysed the expression of P-glycoprotein (PGP), MDR-related protein (MRP) and lung resistance protein (LRP) in 135 adult patients with normal karyotype AML and its correlation with other biological features of the disease, to evaluate the impact of MDR proteins on response to therapy and on survival. Increased PGP expression was associated with lower rate of complete remission (CR; p = 0.006), similarly to advanced age. Cases overexpressing PGP displayed also a shorter event-free survival (EFS; 4 vs. 10 months, p = 0.035) and the increased expression of at least one MDR protein was associated with a reduced overall survival (OS; p = 0.038). Also age was predictive of worse prognosis. Our data confirm the prognostic role of MDR proteins, in particular of PGP, also in AML patients with normal karyotype at diagnosis. This finding could be used to stratify patients with different prognosis and to design risk-adapted therapeutic strategies.

The prognostic value of P-glycoprotein (ABCB) and breast cancer resistance protein (ABCG2) in adults with de novo acute myeloid leukemia with normal karyotype.

Multidrug resistance is a major cause of treatment failure in acute myeloid leukemia (AML). P-glycoprotein (PGP) over-expression has an unfavorable prognostic significance, while the role of breast cancer resistance protein (BCRP) is less clear, especially in AML patients with a normal karyotype. We studied 73 consecutive AML patients with a normal karyotype. BCRP was over-expressed in 24 patients (33%) and was significantly co-expressed with PGP (13/24 vs 11/49, p=0.006) and with CD56. Only PGP, along with age and CD34, affected the achievement of complete remission (p=0.02), while BCRP-positive cases showed an increased risk of relapse (p=0.005) and a shorter disease-free survival (p=0.027). BCRP over-expression did not influence the achievement of remission, but significantly affected the duration of complete remissions. BCRP may, therefore, be regarded as a prognostic factor in patients with normal karyotype AML, for the design of risk-adapted post-remission therapy.