Acquired von Willebrand Syndrome (AVWS) is a rare heterogeneous bleeding condition associated with several disorders, including monoclonal gammopathy of undeterminated significance (MGUS) 1-3. ...Successful therapy of the underlying disorder can leads to the improvement of AVWS 1. Regarding the association of AVWS and MGUS, no long-term successful therapy has been reported. Indeed, most of these patients are not treated on a curative goal 1. In a few single cases anti-CD20 targeted therapy (Rituximab) has shown no efficacy 4,5. We describe herein the case of a patient with AVWS accompanied by MGUS who was successfully treated with the proteosome inhibitor Bortezomib after failure of Rituximab.
Le facteur von Willebrand (VWF) est une glycoprotéine multimérique qui joue un rôle essentiel dans la formation du thrombus plaquettaire en présence de forces de cisaillement élevées. La maladie de ...Willebrand (MW) est une pathologie hémorragique, d’origine constitutionnelle ou acquise, résultant d’un déficit quantitatif ou qualitatif en VWF, et qui se caractérise par une grande hétérogénéité clinique et biologique, témoignant de la physiologie complexe du VWF. Si de nombreux progrès ont été réalisés concernant la compréhension des mécanismes physiopathologiques sous-jacents à la MW, son diagnostic reste difficile et justifie un avis spécialisé. Au-delà de son rôle dans l’hémostase, le VWF pourrait jouer un rôle actif dans l’inflammation, l’angiogenèse, l’apoptose et la prolifération cellulaire.
Von Willebrand factor is a multimeric glycoprotein that plays an essential role in platelet-rich thrombi formation under high shear stress. The heterogeneity of Von Willebrand disease (VWD), a constitutional or acquired bleeding diathesis secondary to a quantitative or qualitative VWF deficiency, illustrates the complex physiology of this protein. Despite significant progresses in our comprehension of the numerous pathophysiological mechanisms underlying VWD, its diagnosis remains challenging and skill demanding in clinical practice. Besides its role in haemostasis, VWF has been recently involved with inflammation, angiogenesis, apoptosis and cell-proliferation paving the way for new approaches towards this intriguing protein.
Le purpura thrombotique thrombocytopénique (PTT) est caractérisé par une anémie hémolytique, une thrombopénie et des thrombi dans les petits vaisseaux responsables de défaillances organiques ...d'origine ischémique. Depuis que la protéase de clivage du facteur Willebrand (VWF) a été identifiée comme étant l'ADAMTS-13, une avancée considérable a été réalisée dans la compréhension du processus de régulation physiologique de la taille des multimères de très haut PM (THPM) du VWF libérés par la cellule endothéliale, ainsi que des mécanismes par lesquels le déficit en ADAMTS-13 participe à la pathogenèse du PTT. Les très rares déficits constitutionnels sont de transmission autosomique récessive, associés à des mutations sur le gène de l'ADAMTS-13 de type homozygote ou hétérozygote composite. Les déficits acquis sont beaucoup plus fréquents, en général dus à des autoanticorps qui neutralisent l'activité ADAMTS-13. Plusieurs méthodes de dosage de l'activité ADAMTS-13 ont été décrites, mais elles ne sont pas encore très largement appliquées, en dehors de laboratoires très spécialisés, du fait de leur complexité technique. Le développement de techniques plus simples et rapides faciliterait la pratique de ce dosage. Les échanges plasmatiques constituent le traitement de première intention, permettant ainsi l'apport d'ADAMTS-13 et l'épuration des anticorps anti-ADAMTS-13 et des formes THPM VWF. Des traitements adjuvants de type immunosuppresseurs sont introduits dans le but de contrôler la production des autoanticorps et prévenir les récidives; plus récemment le rituximab a été utilisé avec succés.
Thrombotic thrombocytopenic purpura (TTP) is characterized by hemolytic anemia and thrombocytopenia, accompanied by microvascular thrombosis that caused ischemic organ dysfunctions. Since the von Willebrand factor (VWF)-cleaving protease implicated in TTP was identified as ADAMTS-13, considerable progress has been realized toward understanding the role of ADAMTS-13 in the normal processing of unusually large VWF multimers (ULVWF) released from endothelial cells, as well as the mechanisms by which ADAMTS-13 deficiency contributes—by the ULVWF persistence—to TTP pathogenesis. ADAMTS-13 activity is the most effective criteria for the diagnosis of TTP. The very rare congenital deficiency is an autosomal recessive condition because of compound heterozygous or homozygous mutations in the ADAMTS 13 gene. More frequent is the acquired deficiency caused by autoantibodies that neutralize ADAMTS-13 activity. Several methods have been developed to measure plasma ADAMTS-13 activity, but they are not widely used due to various difficulties. Advances with the development of more simple and rapid assays should facilate testing of ADAMTS-13 in most clinical laboratories. Plasma exchange is the first-choice therapy by supplying of ADAMTS-13 and removing of anti ADAMTS-13 antibodies and ULVWF multimers. Several therapies are used to limit the production of the autoantibodies and to prevent disease recurrence, including non selective immunosuppression, and more recently rituximab treatment.
Abstract 5313
VWD 2B and PT-VWD are rare diseases, due to mutations inducing a gain of function respectively of von Willebrand factor (VWF) and of its platelet receptor, Glycoprotein (GP)1bα
We ...report here the case of a young girl, born with an extensive purpura and a severe thrombocytopenia: platelet count: 16G/L. There was no associated biological nor clinical abnormality. A high dose of 1g/kg of immunoglobulin G infused on day 1 was unsuccessful, and a HPA-1a (−) platelet concentrate infusion led to a partial and transient increase of the platelet count up to 60G/L. Thrombocytopenia then resolved spontaneously.
Biological study showed no sign of materno-fetal allo- or auto-immunity, parents were not consanguineous.
The diagnosis of type 2B VWD was performed when she was 5 months old: VWF:RCo < 13 IU/dl, VWF:Ag 60 IU/dl, positive ristocetin induced platelet aggregation (RIPA) at a low ristocetin concentration (0.5 mg/ml). RIPA mixing studies were unconclusive.
The same biological abnormalities were found in the father, whereas the mother had normal hemostasis tests. The biological phenotype also included a study of the multimeric VWF structure, showing a marked decrease in percentage of VWF high and intermediate molecular multimers. Genetic analysis performed on VWF gene showed the heterozygous p.Pro1266Leu missense mutation in the VWF A1 domain. This mutation ( o ) is only slightly deleterious, and induces usually a mild disease, without thrombocytopenia, even in stress situations, with normal VWF multimeric distribution; therefore, it could not explain the biological phenotype severity in this family.
GPIBA was then analysed, and a candidate point mutation p.Met239Ile was evidenced. This mutation had not been described yet, but p.Met255Val had already been found in diagnosed cases of PT-VWD.
This case underlines the utmost importance to characterize precisely neonatal thrombocytopenia mechanism. Furthermore, it points out the difficulties to performing PT-VWD diagnosis, which incidence is most probably underestimated. In our case, it was the systematic and extensive biological workout performed in this case of isolated neonatal thrombocytopenia, without any obvious cause, which led to the diagnosis of a PT-VWD, inducing a severe biological phenotype, associated with type 2B VWD characterized by a mild expression. It is, to our knowledge, the first case described to date of such a morbid association.
No relevant conflicts of interest to declare.
Abstract 2438
Abnormalities of VWF have been described in WM pts, and several cases of AVWS have been reported. We aimed to describe the frequency of AVWS and the distributions of von Willebrand ...factor Ristocetin Cofactor activity (VWF:RCo) and antigen (VWF:Ag) levels along with VEGF expression in WM pts.
We systematically assessed both levels of VWF:Rco and VWF:Ag in a series of 72 WM pts (median age: 70 years, 39 to 91 years, sex ratio M/F: 1.6, symptomatic: 55). Diagnostic and treatment criteria for WM fulfilled recommendations of the 2nd international WM workshop. AVWS was suspected when VWF:RCo level was <50% (40% for blood group O pts). Immunostainings for vascular endothelial growth factor (VEGF) and VWF with assessment of microvessel density (MVD) were performed in 23 pts.
Mean levels of VWF:Ag and VWF:RCo were 167% and 152% respectively, with a significant negative relationship between both VWF:RCo and VWF:Ag and serum M-component concentration in WM pts with VWF:Ag <130% (p<1×10−4 and p=0.006, respectively).
AVWS was suspected in 10 pts with symptomatic WM (median level of VWF:RCo: 31%, Haemorrhage in 4 pts). Pts with suspected AVWS had higher serum monoclonal IgM (mIgM) concentration than remaining pts (p=0.001). Reduction of IgM with plasmapheresis (4 pts) or treatment of WM was associated with an increase in VWF:Ag and VWF:RCo levels. High level of propeptide and increase in the ratio propeptide/VWF suggested an increase in the clearance of mature VWF. However, IgM inhibitory activity was absent in all evaluated pts with suspected AVWS (n=6). VWF immunostaining on bone marrow trephine biopsy did not support an adsorption of VWF on tumoral cells.
Pspline proportional hazard regression models including VWF:Ag (p=10−4) and recursive partitioning analyses of survival showed an increase in the hazard for death with the increase in the level of VWF:Ag. Thus, 43 pts (59%) presented with VWF:Ag > 110%, and among these, 13 pts with VWF:Ag > 250%. They had higher level of propeptide (p=0.0006) than pts without abnormality of VWF (VWF:Ag < 110% and no AVWS) but the ratio propeptide/VWF:Ag was not significantly different between both subgroups, suggesting the presence of a chronic endothelial activation. Immunostainings identified a high MVD in 6 of the 23 tested pts, the presence of VEGF on mast cells in 8 pts and on tumoral cells in 13 pts. Pts with high MVD and pts expressing VEGF on mast cells had significantly higher levels of VWF:Ag than other pts (p=0.05 and 0.01 respectively). These pts more frequently had VWF:Ag levels above 250% (2-sided Fisher test: p=0.004 and 0.006 respectively). In addition, pts with high MVD more frequently (p=0.05) expressed VEGF on mast cells than other pts. The 5-year survival of pts with VWF:Ag < 110%, between 110% and 250% and >250% were 96%, 71%, and 44% respectively (p<0.0001, figure A). High VWF:Ag was also a significant adverse prognostic factor for survival after first-line therapy (p<0.0001, figure B), independently of international scoring system (p≤0.001), and for survival after sampling (p<0.0001).
Taken together, our results support a systematic assessment of VWF:RCo and VWF:Ag in WM pts. Follow-up data supported the importance of the treatment of WM in the management of suspected AVWS. Systematic assessment identified up to 59% of high-risk pts with high level VWF:Ag. The identification of this new prognostic factor raised new issues on the underlying cellular interactions between tumoral cells, mast cells and endothelial cells in WM.
Display omitted
No relevant conflicts of interest to declare.
Abstract
Abstract 2438
Introduction:
Abnormalities of VWF have been described in WM pts, and several cases of AVWS have been reported. We aimed to describe the frequency of AVWS and the distributions ...of von Willebrand factor Ristocetin Cofactor activity (VWF:RCo) and antigen (VWF:Ag) levels along with VEGF expression in WM pts.
Pts and methods:
We systematically assessed both levels of VWF:Rco and VWF:Ag in a series of 72 WM pts (median age: 70 years, 39 to 91 years, sex ratio M/F: 1.6, symptomatic: 55). Diagnostic and treatment criteria for WM fulfilled recommendations of the 2nd international WM workshop. AVWS was suspected when VWF:RCo level was <50% (40% for blood group O pts). Immunostainings for vascular endothelial growth factor (VEGF) and VWF with assessment of microvessel density (MVD) were performed in 23 pts.
Results:
Mean levels of VWF:Ag and VWF:RCo were 167% and 152% respectively, with a significant negative relationship between both VWF:RCo and VWF:Ag and serum M-component concentration in WM pts with VWF:Ag <130% (p<1×10−4 and p=0.006, respectively).
AVWS was suspected in 10 pts with symptomatic WM (median level of VWF:RCo: 31%, Haemorrhage in 4 pts). Pts with suspected AVWS had higher serum monoclonal IgM (mIgM) concentration than remaining pts (p=0.001). Reduction of IgM with plasmapheresis (4 pts) or treatment of WM was associated with an increase in VWF:Ag and VWF:RCo levels. High level of propeptide and increase in the ratio propeptide/VWF suggested an increase in the clearance of mature VWF. However, IgM inhibitory activity was absent in all evaluated pts with suspected AVWS (n=6). VWF immunostaining on bone marrow trephine biopsy did not support an adsorption of VWF on tumoral cells.
Pspline proportional hazard regression models including VWF:Ag (p=10−4) and recursive partitioning analyses of survival showed an increase in the hazard for death with the increase in the level of VWF:Ag. Thus, 43 pts (59%) presented with VWF:Ag > 110%, and among these, 13 pts with VWF:Ag > 250%. They had higher level of propeptide (p=0.0006) than pts without abnormality of VWF (VWF:Ag < 110% and no AVWS) but the ratio propeptide/VWF:Ag was not significantly different between both subgroups, suggesting the presence of a chronic endothelial activation. Immunostainings identified a high MVD in 6 of the 23 tested pts, the presence of VEGF on mast cells in 8 pts and on tumoral cells in 13 pts. Pts with high MVD and pts expressing VEGF on mast cells had significantly higher levels of VWF:Ag than other pts (p=0.05 and 0.01 respectively). These pts more frequently had VWF:Ag levels above 250% (2-sided Fisher test: p=0.004 and 0.006 respectively). In addition, pts with high MVD more frequently (p=0.05) expressed VEGF on mast cells than other pts. The 5-year survival of pts with VWF:Ag < 110%, between 110% and 250% and >250% were 96%, 71%, and 44% respectively (p<0.0001, figure A). High VWF:Ag was also a significant adverse prognostic factor for survival after first-line therapy (p<0.0001, figure B), independently of international scoring system (p≤0.001), and for survival after sampling (p<0.0001).
Conclusion:
Taken together, our results support a systematic assessment of VWF:RCo and VWF:Ag in WM pts. Follow-up data supported the importance of the treatment of WM in the management of suspected AVWS. Systematic assessment identified up to 59% of high-risk pts with high level VWF:Ag. The identification of this new prognostic factor raised new issues on the underlying cellular interactions between tumoral cells, mast cells and endothelial cells in WM.
Disclosures:
No relevant conflicts of interest to declare.
Summary
Type 2B von Willebrand disease (VWD) is characterised by an increased affinity of von Willebrand factor (VWF) for its platelet receptor glycoprotein Ib (GPIb). This feature is usually studied ...in vitro by a ristocetin‐dependent VWF platelet‐binding assay, which has some limitations as it requires e.g. (radio)‐labelled anti‐VWF antibodies and normal formaldehyde‐fixed platelets. We, here, extended the applicability of an enzyme‐linked immunosorbent assay‐based method previously described for the measurement of ristocetin co‐factor activity that used a recombinant fragment of GPIb (rfGPIbα) and horseradish peroxidase‐labelled rabbit anti‐human VWF antibodies for measuring the captured ristocetin‐VWF complexes on the rfGPIbα. Thirty‐one type 2B VWD patients from 15 families with eight different known mutations were studied. VWF in plasma from 28 of these patients bound better than normal VWF at 0·2 mg/ml ristocetin, with the ratio, optical density (OD) patient/OD normal pool plasma, higher than 1·8. For two of the three other patients with no enhanced response of plasma VWF, the platelet lysate VWF showed an enhanced binding capacity; for the last patient, the results in other members of the family are unequivocal. We conclude that, this new method for measurement of plasma or platelet VWF‐binding capacity offers great advantages for correct type 2B VWD diagnosis.
The present diagnostic assay for type 2N von Willebrand disease (VWD) is based on the in vitro measurement of the capacity of plasma von Willebrand factor (VWF) to bind exogeneous factor VIII ...(VWF:FVIIIB). We report a method using only commercially available reagents that is easy to perform. This method has been validated in a cohort of 144 patients with FVIII/VWF ratios < 0·6 using a plasma control mixture representative of intermediate VWF:FVIIIB. In total, 15 patients were diagnosed with markedly decreased VWF:FVIIIB and five patients were shown to have moderately decreased VWF:FVIIIB. Specific type 2N mutations were identified in all these patients.
STUDY OBJECTIVE: Our aim was to document the following in patients with septic shock and disseminated intravascular coagulation
(DIC): (1) the influence of DIC in the mortality rate and the ...occurrence of organ failure; (2) the comparative prognostic
value of initial antithrombin III (ATIII), protein C (PC), and protein S (PS) levels; and (3) the compared pattern of sequential
ATIII, PC, and PS levels according to clinical outcome. DESIGN: Demographic data, criteria of severity, mortality in ICU,
frequency of organ failure, hemodynamic and oxygenation parameters, and laboratory findings were compared in patients with
septic shock according to the occurrence of DIC. Initial and sequential levels of ATIII (activity), PC (antigen and activity),
PS (total and free), and C4b binding protein (C4bBP) were compared according to the outcome in patients with DIC. PATIENTS:
Sixty patients with septic shock were studied. Forty-four entered the group DIC+; 16 entered the group DIC-. RESULTS: Simplified
acute physiologic score (SAPS), frequency of acquired organ failure, blood lactate, and transaminase values were significantly
higher in the group DIC+. The mortality rate reached 77 percent in group DIC+ vs 32 percent in DIC- (p less than 0.001). In
patients with DIC, a fatal outcome was associated with higher bilirubin and transaminase levels, lower PaO2/FIo2 ratio, Vo2,
Do2 and O2 extraction. In the group DIC+, all patients but two had severe deficiencies in ATIII and PC levels. Significant
correlations were found between initial ATIII and PC levels, PC and free PS levels, and free PS and C4bBP levels. Initial
ATIII levels had the best prognostic value for prediction of subsequent death. Serial measurements were consistent with a
prolonged ATIII and PC deficiency with significantly different levels between survivors and nonsurvivors. CONCLUSIONS: DIC
is a strong predictor of death and multiple organ failure in patients with septic shock. Sequential ATIII, PC, and PS measurements
were consistent with prolonged consumption or inhibition that might account for a sustained procoagulant state and inhibition
of fibrinolysis. The initial ATIII level was the best laboratory predictor of death in these patients.
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