The polo-like kinase 1 (PLK1) inhibitor NMS-P937 is effective in a new model of disseminated primary CD56+ acute monoblastic leukaemia

CD56 is expressed in 15–20% of acute myeloid leukaemias (AML) and is associated with extramedullary diffusion, multidrug resistance and poor prognosis. We describe the establishment and characterisation of a novel disseminated model of AML (AML-NS8), generated by injection into mice of leukaemic blasts freshly isolated from a patient with an aggressive CD56+ monoblastic AML (M5a). The model reproduced typical manifestations of this leukaemia, including presence of extramedullary masses and central nervous system involvement, and the original phenotype, karyotype and genotype of leukaemic cells were retained in vivo. Recently Polo-Like Kinase 1 (PLK1) has emerged as a new candidate drug target in AML. We therefore tested our PLK1 inhibitor NMS-P937 in this model either in the engraftment or in the established disease settings. Both schedules showed good efficacy compared to standard therapies, with a significant increase in median survival time (MST) expecially in the established disease setting (MST = 28, 36, 62 days for vehicle, cytarabine and NMS-P937, respectively). Importantly, we could also demonstrate that NMS-P937 induced specific biomarker modulation in extramedullary tissues. This new in vivo model of CD56+ AML that recapitulates the human tumour lends support for the therapeutic use of PLK1 inhibitors in AML

Drug resistance and minimal residual disease in multiple myeloma

Great progress has been made in improving survival in multiple myeloma (MM) patients over the last 30 years. New drugs have been introduced and complete responses are frequently seen. However, the majority of MM patients do experience a relapse at a variable time after treatment, and ultimately the disease becomes drug-resistant following therapies. Recently, minimal residual disease (MRD) detection has been introduced in clinical trials utilizing novel therapeutic agents to measure the depth of response. MRD can be considered as a surrogate for both progression-free and overall survival. In this perspective, the persistence of a residual therapy-resistant myeloma plasma cell clone can be associated with inferior survivals. The present review gives an overview of drug resistance in MM, i.e., mutation of β5 subunit of the proteasome; upregulation of pumps of efflux; heat shock protein induction for proteasome inhibitors; downregulation of CRBN expression; deregulation of IRF4 expression; mutation of CRBN, IKZF1, and IKZF3 for immunomodulatory drugs and decreased target expression; complement protein increase; sBCMA increase; and BCMA down expression for monoclonal antibodies. Multicolor flow cytometry, or next-generation flow, and next-generation sequencing are currently the techniques available to measure MRD with sensitivity at 10-5. Sustained MRD negativity is related to prolonged survival, and it is evaluated in all recent clinical trials as a surrogate of drug efficacy

PATHOGENETIC ASPECTS OF MYELODISPLASTIC SYNDROMES

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Prognostic value of CD47 overexpression measured by flow cytometry in acute myeloid leukemia

The glycoprotein CD47 is an innate immune checkpoint ubiquitously expressed on all healthy cells to prevent themselves from phagocytosis. CD47 binds to its receptor SIRP alpha on macrophages, thus producing a signal transduction cascade which inhibits phagocytosis. CD47 is overexpressed on various solid and hematologic malignancies in order to escape the immune system. High expression of CD47 in patients with AML has been associated with poor prognosis, however, there is no standard technique to assess CD47 expression on AML blasts in clinical practice and the real prognostic value of CD47 overexpression varies among studies in the current literature. In this study, CD47 expression was evaluated by flow cytometry on AML blasts from bone marrow samples at diagnosis and reported in terms of median fluorescence intensity (MFI). Flow cytometry analysis demonstrated the expression of CD47 in all AML patients with a median MFI on leukemic blasts of 16.8 (range 2-693.63). CD47 levels on AML blasts correlated with WBC count (rs 0.403, p = 0.016), BM blasts percentage (rs 0.494, p = 0.003), PB blasts percentage (rs 0.482, p = 0.003) and LDH levels (rs 0.382, p = 0.028) and higher expression of CD47 was associated with reduced survival with a hazard ratio of 1.04 (CI: 1.01-1.08, p = 0.047). Further studies with larger sample sizes are necessary to better define the real prognostic value of CD47 overexpression in the complexity of AML tumor microenvironment and, possibly, to identify a subgroup of patients who could derive maximum benefit from emerging CD47-SIRP alpha blocking therapies

SELECTIVE INFLUENCES IN THE B-CELL RECEPTOR IMMUNOGLOBULIN HEAVY AND LIGHT CHAIN IN HAIRY CELL LEUKEMIA

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Straight aortic endograft in abdominal aortic disease

Background: We describe our 8-year experience with the use of endovascular techniques (ET) for the treatment of abdominal aortic aneurysms (AAA) through a straight endograft. Methods: We retrospectively reviewed data of all patients who were treated for AAA using ET in two centres from 1998 to 2012 and who received a single straight endograft (group A) or a double straight tube (group B). Outcomes were analyzed to assess survival, absence of endoleak and absence of reintervention for both groups. Log-rank and Chi-Square were used as appropriate to make comparison between the two groups. P values <.05 were considered statistically significant. Results: Fifty-three patients from 1998 to May 2012 were treated for AAA using a straight endograft. In 28 cases (52.8%) a single aortic straight tube was used (Group A), while in the remaining cases a "double trombone technique" was used (Group B). Primary success was obtained in 52 cases (98.1%). In one patient of group A immediately after the operation we observed a type Ia endoleak, which was correct with a proximal aortic cuff. Fluoroscopy time, operation time, amount of intraprocedural contrast medium and blood loss were slightly higher for group B, even if not significantly. Mortality at 30 days was nil for both groups. Mean follow-up was 49 months (range 2-153 months). Five patients died in group A, four of them for a neoplastic disease and the remaining for aortic rupture. No patients died in group B. Endoleaks occurred more frequently in patients of group A (5 type I endoleaks and 1 type II endoleak from a lumbar artery). Reintervention were more frequent for patients of group A, being type I endoleak the main cause. A stent fracture was observed in a patient who received EVAR by "trombone technique" 3 months later. Reintervention was then necessary and a third stent was successfully placed to cover the lesion. Conclusions: In our experience the endovascular repair of AAA using straight aortic endografts was a safe and effective technique. Reintervention and endoleaks were slightly more frequent in patients who had received a single endograft compared to patients who were treated using the "trombone technique"

Residual peripheral blood CD26+ leukemic stem cells in chronic myeloid leukemia patients during TKI therapy and during treatment-free remission

Chronic myeloid leukemia (CML) patients in sustained "deep molecular response" may stop TKI treatment without disease recurrence; however, half of them lose molecular response shortly after TKI withdrawing. Well-defined eligibility criteria to predict a safe discontinuation up-front are still missing. Relapse is probably due to residual quiescent TKI-resistant leukemic stem cells (LSCs) supposedly transcriptionally low/silent and not easily detectable by BCR-ABL1 qRT-PCR. Bone marrow Ph+ CML CD34+/CD38- LSCs were found to specifically co-express CD26 (dipeptidylpeptidase-IV). We explored feasibility of detecting and quantifying CD26+ LSCs by flow cytometry in peripheral blood (PB). Over 400 CML patients (at diagnosis and during/after therapy) entered this cross-sectional study in which CD26 expression was evaluated by a standardized multiparametric flow cytometry analysis on PB CD45+/CD34+/CD38- stem cell population. All 120 CP-CML patients at diagnosis showed measurable PB CD26+ LSCs (median 19.20/μL, range 0.27-698.6). PB CD26+ LSCs were also detectable in 169/236 (71.6%) CP-CML patients in first-line TKI treatment (median 0.014 cells/μL; range 0.0012-0.66) and in 74/112 (66%), additional patients studied on treatment-free remission (TFR) (median 0.015/μL; range 0.006-0.76). Notably, no correlation between BCR-ABL/ABLIS ratio and number of residual LSCs was found both in patients on or offTKIs. This is the first evidence that "circulating" CML LSCs persist in the majority of CML patients in molecular response while on TKI treatment and even after TKI discontinuation. Prospective studies evaluating the dynamics of PB CD26+ LSCs during TKI treatment and the role of a "stem cell response" threshold to achieve and maintain TFR are ongoing

Effect of a thymic factor on T lymphocytes in B cell chronic lymphocytic leukemia: in vitro and in vivo studies

Abstract Abnormalities of T lymphocytes in B cell chronic lymphocytic leukemia (B-CLL) have been extensively documented by several immunologic investigations. Following recent studies pointing to the favorable effect of TP-1, a partially purified extract of calf thymus, on the T cell-mediated immunity of several diseases, including Hodgkin's disease, we have used monoclonal antibodies and the enriched T lymphocytes of 16 untreated B-CLL patients to evaluate the proportion of T cell subsets before and after the administration of TP-1. In addition, the proliferative response to phytohemagglutinin (PHA) and the helper function in a pokeweed mitogen (PWM) system were assessed. In ten cases, the effect of TP-1 was also studied in vitro by evaluating the same parameters before and after incubation of B-CLL T cells with the drug. The study demonstrated that in vivo administration of TP-1 increases significantly (P less than .001) the proportion of the defective helper/inducer T cell population (OKT4-positive cells) in B-CLL, leading to a near normal OKT4/OKT8 ratio. Furthermore, the improved phenotypic profile was accompanied by an increased proliferative response to PHA and, in particular, by a significant increase (P less than .01) of T helper capacity; this increase was, however, insufficient to enable the normalization of the serum immunoglobulin levels. The in vitro incubation of B-CLL T lymphocytes did not succeed in producing significant modifications in distribution and function.</jats:p