Next generation sequencing in bleeding disorders: two novel variants in the F5 gene (Valencia-1 and Valencia-2) associated with mild factor V deficiency.

Inherited bleeding coagulation disorders (IBCDs) have a powerful diagnostic tool in next generation sequencing (NGS) that not only offers confirmation of diagnosis but also aids in genetic counselling, prenatal diagnosis and helps to predict the clinical course and follow-up of a disease. In our group, targeted-NGS using a Custom SureSelect QXT Panel (Agilent Technologies, Inc., Santa Clara, CA, USA) was designed to screen for causal variants in 40 genes related with the coagulation cascade. In this work, we used NGS for screening all the coding and intronic boundary regions of F5 gene in two patients affected by factor V (FV) deficiency (parahemophilia). Two new mutations were found: c.4745A>G (p.Tyr1582Cys, NM_000130.4) and c.1999_2002dupAATT (p.Ser668ter; NM_000130.4), both located in exon 13 of the F5 gene. We designated them Valencia-1 and Valencia-2 respectively. Valencia-1 could provoke loss of the fifth cupredoxin domain of the FV, and would be responsible for its defective activity. Valencia-2 prematurely stops the translation of mRNA, resulting in a truncated FV protein which lacks completely the B domain and the light chain. NGS has permitted to describe an increasing number of FV deficiency-causing mutations and a better understanding of FV's structure and function. The description of deficiency-causing mutations will continue to increase our knowledge of the functional residues of FV, as well as those which are involved in the correct folding of the protein. In this sense, NGS is a useful tool for studying IBCDs, as permits studying the whole coagulation cascade at once and gives a global view of the patient's genetic background.

Bayesian pharmacokinetic-guided prophylaxis with recombinant factor VIII in severe or moderate haemophilia A.

INTRODUCTION: Personalised pharmacokinetics (PK) using Bayesian analysis with limited sampling is assumed to help to optimise prophylaxis in haemophilia A (HA) patients. MATERIALS AND METHODS: Our prospective, observational study analysed the influence of PK parameters on clinical variables (bleeding rates, joint status, adherence, and consumption) using myPKFiT® in a cohort of twenty-one severe and moderate HA patients on prophylaxis with recombinant FVIII (Advate®) in two periods of one year, the first before PK-based tailoring and the second after PK-guided prophylaxis. Intra-individual and inter-individual coefficients of variation (CV) of half-life (t1/2) were calculated. RESULTS: A total of 73 PK estimations were performed in both periods, resulting in 17.2% inter-individual CV in mean t1/2, and 4.9% intra-individual CV. Before PK-based tailoring a significant association between joint bleeds and t1/2 was found (P = 0.010), especially in patients with short t1/2. This finding was reproduced (P = 0.013) after withdrawal of two patients with bleeding phenotype related to their advanced arthropathy but normal t1/2 and trough levels. Patients with joint bleeds weighed less (P = 0.039) and required higher doses (P = 0.032) than patients with zero joint bleeds. These associations were not observed in the second period after the adoption of PK-guided prophylaxis. There were no differences between the two periods, although a tendency to fewer spontaneous bleeds was suggested after PK-based tailoring. CONCLUSIONS: PK-guided prophylaxis facilitates an adequate level of bleeding control in patients with HA, maintaining clinical variables and patient convenience in an integrative manner, without increasing FVIII consumption.

Phase 3 study of recombinant von Willebrand factor in patients with severe von Willebrand disease who are undergoing elective surgery.

Essentials Recombinant von Willebrand factor (rVWF) is effective in von Willebrand disease (VWD). A phase 3 study of rVWF, with/without recombinant factor VIII (rFVIII) before surgery in VWD. Overall rVWF's efficacy was rated excellent/good; rVWF was administered alone in most patients. rVWF was well-tolerated and hemostasis was achieved in patients with severe VWD undergoing surgery. SUMMARY: Background Recombinant von Willebrand factor (rVWF) has demonstrated efficacy for on-demand treatment of bleeding in severe von Willebrand disease (VWD), warranting evaluation in the surgical setting. Objectives This study (NCT02283268) evaluated the hemostatic efficacy/safety profile of rVWF, with/without recombinant factor VIII (rFVIII), in patients with severe VWD undergoing surgery. Patients/Methods Patients received rVWF 40-60 IU kg-1 , VWF ristocetin cofactor activity was measured 12-24 h before surgery. If endogenous FVIII activity (FVIII:C) target levels were achieved 3 h before surgery, rVWF was administered alone 1 h before surgery; rVWF was co-administered with rFVIII if target endogenous FVIII levels were not achieved. rVWF was infused postoperatively to maintain target trough levels. Overall and intraoperative hemostatic efficacy, the pharmacodynamics of rVWF administration and the incidence of adverse events (AEs) were assessed. Results All patients treated with rVWF for major (n = 10), minor (n = 4) and oral (n = 1) surgery had overall and intraoperative hemostatic efficacy ratings of excellent (73.3% and 86.7%) or good (26.7% and 13.3%). Most rVWF infusions (89.4%) were administered alone, resulting in hemostatically effective levels of endogenous FVIII within 6 h, which were sustained for 72-96 h; 70% (n = 7/10) of major surgeries were performed without rFVIII co-administration. Six patients reported 12 treatment-emergent AEs. Two patients each had one serious AE: diverticulitis (not treatment related) and deep vein thrombosis (sponsor-assessed as possibly treatment related). No severe allergic reactions or inhibitory antibodies were reported. Conclusions These data support the efficacy and safety profile of rVWF in patients with severe VWD undergoing elective surgery.

Comparison of a new chemiluminescent immunoassay for von Willebrand factor activity with the ristocetin cofactor-induced platelet agglutination method.

Measuring von Willebrand factor (VWF) activity is essential for the diagnosis of von Willebrand disease (VWD). The VWF activity is usually assessed based on measurement of the ristocetin cofactor (VWF:RCo). However, that test is technically challenging and has high intra- and inter-assay variabilities. A new automated chemiluminescent immunoassay VWF activity has recently become commercially available (HemosIL AcuStar von Willebrand Factor Ristocetin Cofactor Activity). The main objective of this study was to evaluate this new method and to compare it with the VWF:RCo assay as the reference method. We studied 91 samples, 18 healthy volunteers samples and 73 samples from patients (VWF:RCo level <50 IU dL(-1) ): 29 type 1 VWD, 13 type 2A, 5 type 2B, 5 type 2M, 3 type 2N, 5 type 3, 4 type 3 under treatment, 5 type 3 carriers and 4 samples with other pathologies. The HemosIL AcuStar VWF:RCo assay was 96% sensitive and 100% specific for detecting VWF abnormalities. The good analytical performance, and the sensitivity and specificity of HemosIL AcuStar VWF:RCo to detect VWF deficiency renders it a suitable method for VWD screening.

One-stage and chromogenic FVIII:C assay discrepancy in mild haemophilia A and the relationship with the mutation and bleeding phenotype.

The discrepancy of the levels of factor VIII activity (FVIII:C) by different assays in some mild and moderate haemophilic A patients has been long known. Specific mutations affecting FVIII:C discrepancies have been described. No consensus exit as to which method most accurately represents the FVIII cofactor function in vivo and which has a better correlation with the haemorrhagic clinical expression. We studied 163 mild A haemophiliacs, and detected discrepancies in 20% of the patients, most of whom presented higher levels of FVIII:C with the one-stage assay. In nine families, the FVIII mutation was found, while three showed mutations not previously described (Leu1978Phe and Ser1791Pro associated with higher levels of FVIII:C by one-stage method; Arg1639His in a patient with low level of FVIII:C by the one-stage, but normal, chromogenic assay). Assessing the level of FVIII:C by different methods could help to learn the possible haemorrhagic expressions of patients.

Clinical and echographical control protocol of haemarthrosis in haemophilia patients with inhibitors: evaluation of the efficacy of recombinant factor VIIa in the evolution process (EFFISEVEN protocol).

The intention of the 'clinical and echographical protocol of evaluation the efficacy of recombinant activated factor VII in the haemarthrosis' (EFFISEVEN protocol) was to provide an extensive study of the evolution of haemarthrosis, and second, of its repercussions on the degenerative process of joints. The clinical evaluation of haemarthroses and their evolution is based on a well-established methodology, although very few studies have sought to determine the correlation between pain, mobility and the objective data regarding the haemorrhage. We believe that it is necessary to unify criteria and that the EFFISEVEN protocol may contribute data that improve standards which, in turn, will influence the degenerative process of joints, and consequently affect the quality of life of haemophilia patients with inhibitors. Echographical control of haemarthrosis is an objective method that allows control over how the haemorrhage evolves and also helps in the identification of rebleeding. Therefore, its use adds a new dimension to patient management strategies. Techniques used to monitor recombinant activated factor VII (rFVIIa) treatment require further study, although preliminary results guarantee their efficacy.

Inhibitor development in one patient and laboratory discrepancies in several families with both mild haemophilia and Arg531Cys mutation.

Certain mutations in mild haemophilia A have been associated with a greater risk of inhibitor development, especially when associated with intense treatment. We present a patient with both mild haemophilia A and Arg531Cys mutation, which developed lowtitre inhibitors and was not seen to be related to the intense substitute treatment. The inhibitor has a greater effect on the exogenous factor VIII, permiting an adequate response to treatment with desmopressin. A discrepancy exists in the factor VIII activity in this our patient and in the haemophiliacs of another two families with the same mutation when determination is performed with one-stage or chromogenic method.

Inhibitors in haemophilia A: current management and open issues.

The incidence of inhibitors in haemophilia A is 21-33%. The development of inhibitors to factor VIII (FVIII) is one of the most serious complications in haemophilia therapy and is an important challenge in haemophilia care. The main short-term objective of the treatment of haemophilic patients with inhibitors is to control bleeding episodes, and the long-term one is to eradicate the inhibitor by means of immune tolerance induction (ITI). The choice of treatment for bleeding in inhibitor patients is dictated by the current inhibitor titre, the severity of the bleed and the previous anamnesic response to FVIII. In low responder inhibitor patients the best treatment is large doses of concentrates of FVIII to attain haemostatic levels of the factor infused. The same approach can also be considered in high responders who have a temporarily low inhibitor level and major haemorrhage. High responders patients with high inhibitors titre or with minor haemorrhage must be treated with bypassing agents, such as FEIBA (factor VIII inhibitor bypassing activity) or recombinant activated FVII (rVIIa); there is no agreement which of both agents should be chosen in the different clinical situations. Only in patients waiting to start ITI treatment the rFVIIa use is clearly recommended, in order to avoide an anamnesic responce. In case of failure with this agents, extracorporeal immunoadsortion may be considered. All haemophiliac children who develop an inhibitor should be considered for ITI. The start of ITI should be deferred until the inhibitor has declined below 10 Bethesda units/mL (BU ml(-1)) where possible. Starting the treatment when inhibitor titre is below 10 BU ml(-1) is the strongest predictor of success. However, there are many other points to clarify: recommended FVIII doses in the ITI; if the results can be affected by concomitant infections during ITI; if there are any differences using plasma derived or recombinant concentrates, even more if the plasma-derived concentrate contains large amounts von willebrand factor or not; age of starting the ITI and the delay in beginning it; if using immunosupresors can help in the treatment of patients with a bad prognosis; and when the treatment must be left in patients without a clear failure.

Modelo agregométrico aplicado al estudio de la estabilidad de los concentrados de plaquetas conservados en solución aditiva PAS-2 / Aggregometric model applied to the study of platelet concentrates stability preserved in additive solution PAS-2

La demanda creciente de concentrados de plaquetas (CP) ha impulsado el desarrollo de investigación dirigidas al estudio de sustancias sintéticas que puedan sustituir al plasma en el proceso de producción de los CP. Nuestro objetivo es establecer una metodología que nos permita llevar a cabo un prorama de calidad en los CP y estudiar la influencia del PAS-2 sobre la función plaquetar a lo largo de su almacenamiento. Este programa de calidad se basa en la medida de la reacción plaquetar sobre plaquetas de los CP resuspendidos en plasma fresco congelado de un donante y la utilización de colágeno, ionóforo de calcio y ADP más epinefrina a unas concentraciones de: 16,6 µg/ml, 20 µM y 3 µM más 20 µM, respectivamente. Los resultados de la agregación plaquetar fueron algo superiores en CP-P que en CP-PAS. Sin embargo, la actividad plaquetar al sexto día de almacenamiento se mantiene en los CP-PAS con colágeno e ionóforo de calcio y desciente discretamente en los CP-P cuando utilizamos colágeno y ADP más epinefrina. Estos resultados sugieren que el PAS-2 es un buen medio sintético para utilizarlo como conservante en los CP. Este estudio in vitro se complementará con otro en desarrollo sobre la valoración del rendimiento in vivo de los CP producidos con medios sintéticos (AU)

A comparison of FVII:C and FVIIa assays for the monitoring of recombinant factor VIIa treatment.

The use of recombinant factor VIIa (rFVIIa) is on the increase, not only to treat haemophilic patients with inhibitors, but also patients with other clotting disorders. However, the most appropriate method of monitoring this treatment remains a question that has yet to be resolved. We studied 24 plasma samples from patients receiving rFVIIa treatment (three had haemophilia A with inhibitors, and three a congenital FVII deficiency) and compared the results obtained from the FVII:C and FVIIa assays. Although a good correlation between the two methods was obtained (r = 0.91), the values of the FVII:C method were 1.63 higher than those of the FVIIa method, with a relatively wide margin in the interval of the FVII:C/FVIIa ratios obtained [95% confidence interval (CI) 1.38--1.88, range 0.68--3.68]. This interval became wider when we compared values of over 6 IU mL(-1), which led us to conclude that the two methods cannot be considered equivalent. As the FVIIa method specifically measures FVIIa, and FVII:C assay is known to have a wide interlaboratory variability, we believe that the FVIIa assay would be more suitable for the monitoring of rFVIIa treatment.

Influence of methylene blue photoinactivation treatment on coagulation factors from fresh frozen plasma, cryoprecipitates and cryosupernatants.

OBJECTIVE: To study the influence of virus photoinactivation with methylene blue (MB) on the coagulation factors of fresh frozen plasma (FFP) and the corresponding cryoprecipitates and cryosupernatants derived from it. MATERIALS AND METHODS: The photoinactivation procedure of the German Red Cross (Springe) was applied using Biomat (Grifols, Spain). Twenty isogroup pools of three plasma units were made from 60 U of FFP. The pools were split into three bags. One of them was photoinactivated, and pre- and postinactivation samples (MB-plasma) were obtained. The second bag was treated in the same way, followed by the preparation of MB-cryoprecipitate and MB-cryosupernatant. The third bag was not photoinactivated, and was processed in the same way to obtain control cryoprecipitate and cryosupernatant. The prothrombin time and activated partial thromboplastin time were analysed, as well as fibrinogen, factors (F) II, V, VII, VIII, IX, XI and XIII, antithrombin III, von Willebrand (vW) F:RCo, vWF:Ag and the multimeric structure of vWF. RESULTS: In plasma, the proteins most sensitive to photoinactivation were fibrinogen, FV, FVIII, FIX and FXI (24, 32, 28, 23 and 27% loss, respectively). In the MB-cryoprecipitate, the losses were higher for FVIII (23%), moderate for fibrinogen, FXIII and vWF:RCo (18, 14 and 13%, respectively) and minimal (only 3%) for vWF:Ag. In MB-cryosupernatants, the losses were higher for FV (26%) and moderate for fibrinogen (16%), FIX (18%) and FXI (19%), as well as for FII and FXIII (15%). The multimeric structure of vWF was not modified in MB-plasma or in MB-cryoprecipitates. The supernatants (both MB treated as well as controls) showed an absence of multimers of very high and high molecular weight. CONCLUSIONS: The quantitative and qualitative conservation of coagulation factors achieved in MB-plasma-derived products suggest that they are useful for the global replacement of coagulation factors and for deficiencies in FV and FXI. In countries lacking the economic resources to obtain virally inactivated concentrates, MB-cryoprecipitates could be useful in von Willebrand's disease and fibrinogen and FXIII deficiencies. MB-cryosupernatants could be employed in thrombotic thrombocytopenic purpura, in the correction of total or partial deficiencies of prothrombin complex factors and in specific deficiencies of FV and FXI.

Response to plasma exchange and steroids as combined therapy for patients with thrombotic thrombocytopenic purpura.

We describe our experience in the management of 11 consecutive patients with thrombotic thrombocytopenic purpura (TTP) treated with a combined therapy of plasma exchange (PE) and steroids. Nine patients (82%) achieved complete remission (CR) after a median of 6 rounds of PE (range 2-22). There were 3 early relapses managed in the same way as the initial episode. One patient relapsed 23 months after diagnosis achieving CR with standard therapy; another patient suffered several relapses, and splenectomy was performed after the last one. Three patients died, 2 of them with resistant disease 9 and 38 days after diagnosis, and the remaining one died due to AIDS-related complications while he was in CR. Eight patients are alive in CR with a median follow-up of 38 months (range 8-74). The combination of PE and steroids is a well-tolerated and effective treatment of TTP, but improvements in therapy are needed to manage refractory patients.