Circulating Tumor Cells and Thromboembolic Events in Patients with Glioblastoma.

Patients with glioblastoma (GBM) are at increased risk for arterial and venous thromboembolism (TE). Risk factors include surgery, the use of corticosteroids, radiation, and chemotherapy, but also prothrombotic characteristics of the tumor itself such as expression of tissue factor, vascular endothelial growth factor, or podoplanin. Although distant metastases are extremely rare in this tumor entity, circulating tumor cells (CTCs) have been detected in a significant proportion of GBM patients, potentially linking local tumor growth characteristics to systemic hypercoagulability. We performed post hoc analysis of a study, in which GBM patients had been investigated for CTCs. Information on TE was retrieved from electronic patient charts. In total, 133 patients (median age, 63 years; interquartile range, 53-70 years) were analyzed. During follow-up, TE was documented in 14 patients (11%), including 8 venous and 6 arterial events. CTCs were detected in 26 patients (20%). Four (15%) patients with CTCs had a TE compared with 10 (9%) patients without CTCs. There was no difference in the frequency of TE events between patients with and those without detectable CTCs (p = 0.58). In summary, although our study confirms a high risk of TE in GBM patients, it does not point to an obvious association between CTCs and vascular thrombosis.

Regulation of coagulation activation in newly diagnosed AML by the heme enzyme myeloperoxidase.

INTRODUCTION: Patients with acute myeloid leukemia (AML) are at increased risk of thrombohemorrhagic complications. Overexpressed tissue factor (TF) on AML blasts contributes to systemic coagulation activation. We have recently shown that the heme enzyme myeloperoxidase (MPO) negatively regulates TF procoagulant activity (PCA) on myelomonocytic cells in vitro. We now aimed to further characterize the functional interaction of MPO and TF in AML in vivo. METHODS: We prospectively recruited 66 patients with newly diagnosed AML. TF PCA of isolated peripheral blood mononuclear cells (PBMC) was assessed by single-stage clotting assay in the presence or absence of inhibitors against MPO catalytic activity (ABAH) or against MPO-binding integrins (anti-CD18). MPO in plasma and in AML blasts was measured by ELISA, and plasma D-dimers and prothrombin fragment F1+2 were quantified by automated immunoturbidimetric and chemiluminescence assays, respectively. RESULTS: Patients with AML had significantly higher MPO plasma levels compared to healthy controls and exhibited increased levels of D-dimers and F1+2. In vivo thrombin generation was mediated by TF PCA on circulating PBMC. Ex vivo incubation of isolated PBMC with ABAH or anti-CD18 antibody resulted in either increased or decreased TF PCA. The strong and robust correlation of F1+2 with TF PCA of circulating PBMC was abrogated at MPO plasma levels higher than 150 ng/mL, indicating a modulatory role for MPO on TF-mediated in vivo thrombin generation above this threshold. CONCLUSION: Our study indicates that catalytically active MPO released by circulating myeloblasts regulates TF-dependent coagulation in patients with newly diagnosed AML in a CD18-dependent manner.

Inhibition of protein disulfide isomerase with PACMA-31 regulates monocyte tissue factor through transcriptional and posttranscriptional mechanisms.

INTRODUCTION: Protein disulfide isomerase (PDI) contributes to tissue factor (TF) regulation in monocytes. While bacitracin and quercetin-3-rutinoside mitigate myeloid TF production, the effect of PACMA-31, a more specific PDI inhibitor with distinct pharmacologic properties, remains unclear. MATERIALS AND METHODS: Lipopolysaccharide (LPS) stimulation of peripheral blood mononuclear cells (PBMCs) or citrate-anticoagulated whole blood was carried out in the presence of PACMA-31 or DMSO vehicle before monocytes were analyzed for TF expression, including antigen, procoagulant activity (PCA) and mRNA, release of IL-6 and TNFα, and LPS-induced signaling pathways. RESULTS: While PACMA-31 alone had no effect, coincubation with LPS and PACMA-31 (25 µM) enhanced LPS-induced monocyte TF production in whole blood. The effect was at least partially regulated on the transcriptional level and could not be explained by increased phosphatidylserine membrane exposure. In contrast, the same PACMA-31 concentrations were cytotoxic in isolated PBMCs. A lower dose of PACMA-31, however, restored the stimulating effect by enhancing IκB-NFκB signaling that also increased the release of IL-6 and TNFα. The protease-activated receptor 2 (PAR2) inhibitor ENMD547 but not TF antibody 10H10 or factor Xa inhibitor rivaroxaban prevented the stimulatory effect of PACMA-31 on inflammatory monocytes. In sharp contrast, short time incubation of LPS-stimulated PBMCs with 25 µM PACMA-31 was non-cytotoxic and significantly inhibited cellular TF PCA but not surface antigen expression. CONCLUSIONS: PACMA-31 regulates monocyte TF in a concentration-dependent manner by opposing transcriptional and posttranscriptional mechanisms. While low concentrations of PACMA-31 augment monocyte TF production by amplifying LPS-dependent PAR2 signaling, high concentrations convert monocyte TF into its non-coagulant state.

Retrospective analysis of three induction chemotherapy regimens in acute myeloid leukemia including CPX-351, cytarabine/daunorubicin with and without the addition of cladribine.

Recently new treatments for acute myeloid leukemia (AML) emerged, including regimens like CPX-351 and cladribine with cytarabine and daunorubicin (DA + C), demonstrating improved survival in patient subsets. This retrospective analysis is comparing the outcome of 124 patients treated with cytarabine and daunorubicin (DA; n = 54), CPX-351 (n = 26) and DA + C (n = 44). Complete response rate following one cycle of therapy was increased in DA + C (62%) compared to CPX-351 (42%) and DA (50%). CPX-351 demonstrated a significant increased survival post allogenic stem cell transplantation against DA (hazard ratio (HR): 4.9; 95% confidence interval (95%CI): 1.1-21, p = 0.03). Median survival was reached for DA (5.6 years) but not for DA + C or CPX-351. Subgroup analysis showed that AML with myelodysplasia-related changes and therapy-related AML treated with CPX-351 had increased survival compared to DA (HR: 5.2; 95%CI: 1.2-22; p = 0.03). Our findings point twoards a CPX-351 superiority. However, the use of DA + C should be further evaluated in comparative studies.

Bacitracin and Rutin Regulate Tissue Factor Production in Inflammatory Monocytes and Acute Myeloid Leukemia Blasts.

Aberrant expression of tissue factor (TF) by transformed myeloblasts and inflammatory monocytes drives coagulation activation in acute myeloid leukemia (AML). Although regulation of TF procoagulant activity (PCA) involves thiol-disulfide exchange reactions, the specific role of protein disulfide isomerase (PDI) and other thiol isomerases in AML-associated TF biology is unclear. THP1 cells and peripheral blood mononuclear cells (PBMCs) from healthy controls or AML patients were analyzed for thiol isomerase-dependent TF production under various experimental conditions. Total cellular and membrane TF antigen, TF PCA and TF mRNA were analyzed by ELISA, flow cytometry, clotting or Xa generation assay and qPCR, respectively. PBMCs and THP1 cells showed significant insulin reductase activity, which was inhibited by bacitracin or rutin. Co-incubation with these thiol isomerase inhibitors prevented LPS-induced TF production by CD14-positive monocytes and constitutive TF expression by THP1 cells and AML blasts. Downregulation of the TF antigen was mainly restricted to the cryptic pool of TF, efficiently preventing phosphatidylserine-dependent TF activation by daunorubicin, and at least partially regulated on the mRNA level in LPS-stimulated monocytes. Our study thus delineates a complex role of thiol isomerases in the regulation of myeloid TF PCA, with PDI being a promising therapeutic target in the management of AML-associated coagulopathies.

Pilot study using intraoperative fluorescence angiography during arteriovenous hemodialysis access surgery.

INTRODUCTION:: In this pilot study, we used indocyanine green fluorescence angiography during hemodialysis access surgery. The aim was to evaluate its relevance as a diagnostic tool to visualize changes in hand microperfusion. PATIENTS AND METHODS:: In this prospective single-center study, 47 adult patients (33 male, 14 female) with renal disease (24 preemptive, 23 endstage) were enrolled. Surgical creation of an arteriovenous fistula was performed (22 forearm, 25 upper arm). Microperfusion of the ipsilateral hand and fingers was evaluated intraoperatively using indocyanine green fluorescence angiography. We compared the cumulated microperfusion parameters ingress (In) and ingress rate (InR) before and after opening of the anastomosis. To compare the dimension of microcirculatory decline, we calculated the ratios of the parameters (RatioIn and RatioInR) after to those before anastomosis opening. RESULTS:: The cumulated microperfusion parameters In and InR showed a significant decrease after completion of anastomosis and declamping. This effect has been seen in all patients for the hand and for each finger consecutively. During follow-up (mean 4.6, range 3-11 months), 5 patients (10.6%) complained about hemodialysis access-induced distal ischemia. The ratio of intraoperative microperfusion in those five hemodialysis access-induced ischemia patients was significantly lower compared to asymptomatic patients (RatioIn 0.23 vs 0.58, p = 0.001, and RatioInR 0.25 vs 0.62, p = 0.003). CONCLUSION:: Intraoperative fluorescence angiography could visualize the deterioration of ipsilateral hand microperfusion after surgical creation of an arteriovenous fistula. It seems to be a promising tool to detect patients at risk for hemodialysis access-induced distal ischemia early in the peri- or even intraoperative stage.

Immune checkpoints PVR and PVRL2 are prognostic markers in AML and their blockade represents a new therapeutic option.

Immune checkpoints are promising targets in cancer therapy. Recently, poliovirus receptor (PVR) and poliovirus receptor-related 2 (PVRL2) have been identified as novel immune checkpoints. In this investigation we show that acute myeloid leukemia (AML) cell lines and AML patient samples highly express the T-cell immunoreceptor with Ig and ITIM domains (TIGIT) ligands PVR and PVRL2. Using two independent patient cohorts, we could demonstrate that high PVR and PVRL2 expression correlates with poor outcome in AML. We show for the first time that antibody blockade of PVR or PVRL2 on AML cell lines or primary AML cells or TIGIT blockade on immune cells increases the anti-leukemic effects mediated by PBMCs or purified CD3+ cells in vitro. The cytolytic activity of the BiTE® antibody construct AMG 330 against leukemic cells could be further enhanced by blockade of the TIGIT-PVR/PVRL2 axis. This increased immune reactivity is paralleled by augmented secretion of Granzyme B by immune cells. Employing CRISPR/Cas9-mediated knockout of PVR and PVRL2 in MV4-11 cells, the cytotoxic effects of antibody blockade could be recapitulated in vitro. In NSG mice reconstituted with human T cells and transplanted with either MV4-11 PVR/PVRL2 knockout or wildtype cells, prolonged survival was observed for the knockout cells. This survival benefit could be further extended by treating the mice with AMG 330. Therefore, targeting the TIGIT-PVR/PVRL2 axis with blocking antibodies might represent a promising future therapeutic option in AML.