Does Outcome/Survival of Patients With Myelodysplastic Syndromes Should Be Predicted by Reduced Levels of ADAMTS-13? Results From a Pilot Study

ADAMTS13, von Willebrand Factor, Platelet Microparticles, Factor VIII, and Impact of Somatic Mutations in the Pathogenesis of Splanchnic Vein Thrombosis Associated with BCR-ABL-Negative Myeloproliferative Neoplasms

BACKGROUND

Myeloproliferative neoplasms (MPNs) are often associated with splanchnic vein thrombosis (SVT). Not all the factors involved in the thrombotic tendency are currently known.

OBJECTIVES

This study aims to evaluate a possible association between ADAMTS13, von Willebrand factor (VWF), platelet microvesicles (MV), and factor VIII activity (FVIII:C) with thrombotic events in MPN patients.

MATERIALS AND METHODS

In total, 36 consecutive MPN patients with SVT were enrolled. The MPNs were diagnosed based on clinical characteristics and one or more gene mutations among JAK-2, CALR, and MPL. As controls, 50 randomly selected patients with MPN without thrombosis, 50 patients with deep vein thrombosis without MPNs, and 50 healthy blood donors were evaluated. Complete blood count, ADAMTS13, VWF, MV, and FVIII:C in plasma were measured in all the subjects.

RESULTS

The JAK-2 mutation was found in 94% of the patients with SVT, but none were triple-negative for genetic mutations (JAK2 V617F, CALR, MPL, and exon 12). Compared to the normal subjects, in all the MPN patients (with or without SVT), the levels of ADAMTS13 were found to be significantly lower (p < 0.001) and the MV concentrations were significantly higher (p < 0.001). Among the MPN patients, the VWF and FVIII:C levels were significantly higher in the patients with SVT than those without thrombosis (p = 0.007 and p = 0.04, respectively). Splenomegaly was present in 78% of MPN patients with SVT and in 30% of those without SVT (p < 0.001). The ADAMTS13/VWF ratio was reduced in all the patients, but not in the healthy blood donors (p < 0.001).

CONCLUSIONS

The significant increase in circulating MV, VWF, and FVIII:C in the MPN patients and in the patients with thrombosis supports the role of endothelium damage in promoting thrombotic events. In particular, a significant increase in VWF and FVIII:C levels was found in the MPN patients with SVT.

Hyperfibrinogenemia as a Poor Prognostic Indicator in Myelodysplastic Syndrome

Background

Myelodysplastic syndrome (MDS) is a group of heterogeneous myeloid clonal diseases originating from hematopoietic stem cells. It has been demonstrated that fibrinogen (FIB) is associated with disease risk in several cancer types. Coagulation and fibrinolysis problems are widespread in MDS patients. Therefore, FIB might be one of these indicators. We thus examined the role of FIB levels in the prognosis of MDS.

Methods

A cohort of 198 MDS patients were retrospectively analyzed to explore the prognostic value of the plasma FIB levels at diagnosis. Patients were divided into the high FIB group and low FIB group. The prognostic significance of FIB was determined by univariate and multivariate Cox hazard models.

Results

In our cohort, the FIB levels in 198 MDS patients were higher than those in 100 healthy donors (3.9 g/L vs 2.9 g/L, P < 0.0001). MDS patients with high FIB levels had significantly shorter overall survival (OS; P = 0.001) and decreased leukemia-free survival (LFS; P = 0.036). Multivariate cox proportional hazards regression analysis indicated that, in addition to older age, gender, lower HB, poorer karyotype for OS, lower NE, and higher bone marrow blast percentage for OS and LFS, elevated FIB level was also an independent adverse prognostic factor for OS (P = 0.045) but not for LFS (P = 0.188).

Conclusion

Elevated FIB levels may be associated with mortality risk among MDS patients and could predict disease progress and patient prognosis. Thus, assessment of FIB levels may promote the determination of the prognosis of MDS patients.

The Intriguing Connections between von Willebrand Factor, ADAMTS13 and Cancer

von Willebrand factor (VWF) is a complex and large protein that is cleaved by ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and together they serve important roles in normal hemostasis. Malignancy can result in both a deficiency or excess of VWF, leading to aberrant hemostasis with either increased bleeding or thrombotic complications, as respectively seen with acquired von Willebrand syndrome and cancer-associated venous thromboembolism. There is emerging evidence to suggest VWF also plays a role in inflammation, angiogenesis and tumor biology, and it is likely that VWF promotes tumor metastasis. High VWF levels have been documented in a number of malignancies and in some cases correlate with more advanced disease and poor prognosis. Tumor cells can induce endothelial cells to release VWF and certain tumor cells have the capacity for de novo expression of VWF, leading to a proinflammatory microenvironment that is likely conducive to tumor progression, metastasis and micro-thrombosis. VWF can facilitate tumor cell adhesion to endothelial cells and aids with the recruitment of platelets into the tumor microenvironment, where tumor/platelet aggregates are able to form and facilitate hematogenous spread of cancer. As ADAMTS13 moderates VWF level and activity, it too is potentially involved in the pathophysiology of these events. VWF and ADAMTS13 have been explored as tumor biomarkers for the detection and prognostication of certain malignancies; however, the results are underdeveloped and so currently not utilized for clinical use. Further studies addressing the basic science mechanisms and real word epidemiology are required to better appreciate the intriguing connections between VWF, ADAMTS13 and malignancy. A better understanding of the role VWF and ADAMTS13 play in the promotion and inhibition of cancer and its metastasis will help direct further translational studies to aid with the development of novel cancer prognostic tools and treatment modalities.