Pattern of bleeding in a large prospective cohort of haemophilia A patients: A three-year follow-up of the AHEAD (Advate in HaEmophilia A outcome Database) study.

INTRODUCTION: Outcome data on treatment of patients with haemophilia A spanning several years of real-world evidence collection are currently very limited. AIM AND METHODS: The global prospective long-term Advate® Haemophilia A Outcome Database (AHEAD) cohort study collects real-world data from patients with severe and moderate haemophilia. We report an interim data read-out after three years of observation. RESULTS: A total of 522 patients were enrolled from 21 countries: 334 completed year 1 follow-up, 238 completed year 2 and 136 completed year 3, with an overall follow-up of 811 patient-years. Median annual bleeding rates (ABR) were 1.7 in the prophylaxis group and 8.9 in the on-demand group at year 1 visit, 1.6 and 13.0, respectively, at year 2 visit and 2.2 and 10.3, respectively, at year 3 visit. Moreover, about 42% of patients on prophylaxis vs 12% of patients on on-demand had zero annual joint bleeding rates (AJBR). Effectiveness of prophylaxis and on-demand treatment was deemed excellent/good in the majority of cases. Octocog alfa (Advate® ) was well tolerated. The inhibitors that developed in nine patients all disappeared spontaneously. Three patients had been previously exposed to FVIII for ≤50 exposure days (EDs), 3 for >50 EDs and 3 showed a borderline positive inhibitory activity (≤0.6 BU/mL). CONCLUSIONS: These data confirm that the goal of zero bleeds is achievable, although not yet achieved in all patients. Understanding reasons behind the lower response to standard prophylaxis regimens in some patients and personalizing prophylactic treatment may further improve outcome in patients with haemophilia A.

Correlation between FIX genotype and pharmacokinetics of Nonacog alpha according to a multicentre Italian study.

INTRODUCTION: Pharmacokinetic (PK) studies on recombinant FIX concentrate, Nonacog alpha, were conducted with different sampling time designs which gave rise to not complete and homogenous outcomes. In addition, patient's FIX genotype/PK relationship has never been investigated. AIM: Investigate how different sampling times may affect PK parameters and try to find a FIX genotype/PK relationship. PATIENTS AND METHODS: A cohort pharmacokinetic, Nonacog Alpha single-dose, open-label, non-comparative study was conducted in eight Comprehensive Care Haemophilia Centres in Italy. Seventeen previously treated moderate or severe haemophilia B patients were enrolled. Factors IX:C one-stage clotting assay, FIX genotype and PK analysis were centralized. RESULTS: The evaluation of PK outcomes showed a quite long half-life, smaller clearance and volume of distribution of Nonacog Alpha in comparison with the results from previously reported studies, where blood sampling was stopped too early. The relationship between PK outcomes and FIX genotype showed that small deletions displayed the higher clearance and shorter half-life, the nonsense mutations (the lower and the longer respectively), and missense mutations were in between. CONCLUSIONS: It is evident that area under the curve (AUC) and other PK parameters depend from the sampling time design. In order to have a complete evaluation of clotting factors in vivo decay, blood samples must be collected until the baseline factor concentration has been achieved again. Due to the relationship between FIX genotype and clearance, tailored prophylaxis of HB patients could be partially predicted by genotyping.

Bleeding phenotype and correlation with factor XI (FXI) activity in congenital FXI deficiency: results of a retrospective study from a single centre.

Bleeding phenotype in factor XI (FXI)-deficient patients is variable, and not related to baseline FXI:Act. Aims of our study were to describe the characteristics and the management of surgery and deliveries in FXI-deficient patients, and to investigate the relationship between the haemorrhagic phenotype and the baseline FXI:Act. Ninety-five patients were diagnosed and followed in our centre for a median follow-up of 0.9 years (0.1-36.2); median FXI:Act of all patients: 38% (0.5-69%). Fifty-six patients (59%) experienced bleeding episodes not surgery-related. Prior to diagnosis, 64 patients underwent 132 surgeries, and after diagnosis, 23 patients underwent 36 surgeries. Globally 26 of 168 surgeries were prophylactically treated, whereas 142 of 168 were not. As regard as surgeries performed without prophylaxis, 30 bleeding events (21%) occurred in 21 patients. At diagnosis, the median FXI:Act of bleeding and non-bleeding patients was 28% and 37%, respectively, without statistically significant difference between the two groups (P = 0.26). As regard as surgeries performed under prophylactic treatment just 1 bleeding event occurred. Prior to diagnosis, 31 spontaneous deliveries (SD) and eight caesarian sections (CS) were performed without prophylaxis: 4 postpartum haemorrhages (10.5%) occurred (patients FXI:Act: 2%, 6%, 27%, 52.3% respectively). After diagnosis, four SD and five CS were performed with prophylaxis: no postpartum haemorrhages occurred. We confirm the wide bleeding phenotype variability in FXI-deficient patients, not related to the baseline FXI:Act levels. We highlight the importance of performing a correct diagnosis and follow-up, because a good management of prophylactic treatment, dramatically reduces the bleeding rate in case of surgery or deliveries.

Efficacy and safety of highly purified, doubly virus-inactivated VWF/FVIII concentrates in inherited von Willebrand's disease: results of an Italian cohort study on 120 patients characterized by bleeding severity score.

The efficacy of highly purified VWF/FVIII concentrates with standardized ristocetin cofactor content (VWF:RCo) has been already proven in patients with von Willebrand's disease (VWD). Aim of this retrospective study is to confirm efficacy and safety of two highly purified, doubly virus-inactivated VWF/FVIII concentrates in a large cohort of patients with VWD who were characterized at enrolment by bleeding severity score. Study drugs Alphanate or Fanhdi were given to 120 cases (51 males, 69 females, median age 50 years, range 6-83 years). Patients had VWD3 (10), VWD2A (19), VWD2B (25), VWD2M (10) and DDAVP-unresponsive VWD1 (56) and a median bleeding severity score of 8 (range 0-27). A total of 114 bleeding episodes in 55 cases and 131 surgical procedures in 85 cases could be analysed. Excellent-good clinical responses were seen in 97% of bleeding episodes and in 99% of surgical procedures. To prevent recurrent gastrointestinal (GI) bleeding, cerebral (CNS) haemorrhage, haemarthroses, urogenital or multisite bleeding in more severe patients, secondary prophylaxis was also carried out in 15 cases with VWD3 (3), VWD2A (3), VWD2B (2), VWD1 (7). A median dose of 42 IU VWF:RCo kg(-1) given every other day or twice a week over a median period of 334 days (range 24-799) prevented bleeding completely in 13 cases and reduced its incidence in the remaining two. These results confirm the efficacy and safety of the study concentrates, not only in the management of bleeding and surgery but also in secondary prophylaxis of severe VWD.

Prevalence of allo-immunization anti-HLA and anti-integrin alphaIIbbeta3 in Glanzmann Thromboasthenia patients.

SUMMARY: Platelet transfusions, main therapy of Glanzmann Thromboasthenia (GT), can induce an allo-immunization against human leucocyte antigen and integrin alphaIIbbeta3. We have investigated in our GT patients the rate of allo-immunization and of refractoriness to platelet transfusions. From 1975 until December 2005, we have followed 17 GT patients: 14 type 1, 3 variant type; nine females, eight males; median age at diagnosis 9.8 years (range 1-44.5); median age at the time of the study 35.5 years (range 23.6-68.5). In our patients, 121 bleeding episodes occurred (24 severe, 37 moderate, and 60 mild). Ten major and 22 minor surgical procedures have been performed. Two spontaneous deliveries and three caesarian sections with five live births were performed; moreover, one late foetal loss occurred, and one voluntary abortion was performed. Sixteen of 17 patients have been transfused at least once in life with platelets and/or red blood cells (RBC). All transfused patients have been investigated for the presence of anti-HLA and anti-integrin alphaIIbbeta3 allo-antibodies. The positiveness of allo-antibodies has been demonstrated in 4/16 transfused patients (25%): isolated for anti-HLA in two; isolated for anti-integrin alphaIIbbeta3 in one; and combined in one. In spite of the presence of allo-antibodies, platelet transfusions have always been effective and the haemostasis was not compromised.

Mortality and causes of death in Italian persons with haemophilia, 1990-2007.

Although a number of studies have analysed so far the causes of death and the life expectancy in haemophilic populations, no investigations have been conducted among Italian haemophilia centres. Thus, the aim of this study was to investigate mortality, causes of deaths, life expectancy and co-morbidities in Italian persons with haemophilia (PWH). Data pertaining to a total of 443 PWH who died between 1980 and 2007 were retrospectively collected in the 30 centres who are members of the Italian Association of Haemophilia Centres that chose to participate. The mortality rate ratio standardized to the male Italian population (SMR) was reduced during the periods 1990-1999 and 2000-2007 such that during the latter, death rate overlapped that of the general population (SMR 1990-1999: 1.98 95% CI 1.54-2.51; SMR 2000-2007: 1.08 95% CI 0.83-1.40). Similarly, life expectancy in the whole haemophilic population increased in the same period (71.2 years in 2000-2007 vs. 64.0 in 1990-1999), approaching that of the general male population. While human immunodeficiency virus infection was the main cause of death (45%), 13% of deaths were caused by hepatitis C-associated complications. The results of this retrospective study show that in Italian PWH improvements in the quality of treatment and global medical care provided by specialized haemophilia centres resulted in a significantly increased life expectancy.

Performance of recalibrated ReFacto laboratory standard in the measurement of FVIII plasma concentration via the chromogenic and one-stage assays after infusion of recalibrated ReFacto (B-domain deleted recombinant factor VIII).

The use of ReFacto Laboratory Standard (RLS) in the one-stage clotting assay was proposed to reduce the underestimation of factor VIII (FVIII) plasma concentration after the infusion of 'ReFacto' (B-domain deleted recombinant FVIII) in haemophilia A patients. Both ReFacto and RLS were recently recalibrated, with the resulting materials containing approximately 20% more protein than the previous products. The aim of this study was to evaluate the performance of recalibrated RLS in the measurement of FVIII plasma concentration after the infusion of recalibrated ReFacto. In 13 severe haemophilia A patients, 25 IU kg(-1) of ReFacto were injected intravenously. Venous blood samples were collected at 0.25, 0.5, 1, 3, 6, 9, 24, 28 and 32 h after the end of the infusion. Pharmacokinetic parameters were measured for the chromogenic and one-stage assays using International Plasma Standard (IPS) and RLS for both assays and assuming a non-compartmental drug disposition. Comparisons among assays and standards were performed using anova. Pharmacokinetic estimates obtained with the chromogenic method were in agreement with those published in the literature. The one-stage method was confirmed to be more sensitive to lower plasma concentrations of FVIII. The measured maximum plasma concentration (C(max)) was slightly higher than theoretical values and independent of the assay used. C(max), area under the curve (AUC) and volume of distribution at steady state (V(ss)) presented non-significant differences among the methods and standards used. The clinical utility of RLS in the evaluation of FVIII concentration after the infusion of ReFacto seems to be reduced since recalibration of the product.

Patients with type 3 severe von Willebrand disease are not protected against atherosclerosis: results from a multicenter study in 47 patients.

BACKGROUND: The results of a number of studies in pigs and mice suggest that absence of von Willebrand factor (vWF) protects against the development of atherosclerosis. We studied whether patients with a complete deficiency of vWF (type 3 von Willebrand disease [vWD]) develop fewer atherosclerotic vessel wall changes than healthy controls. METHODS AND RESULTS: This study included 47 individuals with type 3 vWD and 84 healthy controls. Early atherosclerotic changes were assessed by measuring the thickness of the intima-media in the carotid and femoral arteries by B-mode ultrasonography. Advanced atherosclerotic changes were quantified by summing the maximal thickness of atherosclerotic plaques in the carotid and femoral arteries and were expressed as a plaque score. Established risk factors were determined to adjust for possible differences between the groups. We found no substantial difference in intima-media thickness between vWD patients and controls (adjusted difference for carotid artery 0.007 mm, 95% CI -0.022 to 0.036 mm; femoral artery 0.069 mm, 95% CI -0.056 to 0.19 mm). Similar proportions of patients and controls had atherosclerotic plaques (19% and 17%, respectively). No difference was found in the plaque score between groups (adjusted difference -0.22 mm, 95% CI -0.69 to 0.26). Among vWD patients, we found no effect of treatment with vWF concentrates on intima-media thickness or plaque score. CONCLUSIONS: The results of this study indicate that vWF does not play a substantial role in human atherogenesis.

Clonal hemopoiesis and risk of thrombosis in young female patients with essential thrombocythemia.

OBJECTIVE: Several studies demonstrated a high prevalence of nonrandom X-chromosome inactivation pattern (X-CIP) in essential thrombocythemia (ET). This study explored the incidence of clonal hemopoiesis in myeloid precursors and endogenous erythroid colonies (EECs) in ET patients and its correlation with thrombotic manifestations. MATERIALS AND METHODS: Clonal analysis of hemopoiesis using X-CIP was performed in 40 female patients with ET. Median age was 40.5 years (range 20-64), and median platelet count at testing time was 700 x 10(9)/L (range 220-1300 x 10(9)/L). Patients older than 65 years were excluded to reduce age-related skewing. Clonality was assessed on neutrophils, platelets, EECs, and bone marrow CD34(+) cells. RESULTS: Eight (20%) of 40 patients developed thrombosis mainly at diagnosis. Clonal hemopoiesis was found in 17 (42.5%) patients, 15 (37.5%) had polyclonal hemopoiesis, and 8 (20%) were considered uninterpretable due to constitutive skewing. Clonality was confirmed on purified CD34(+) subpopulations from bone marrow, documenting that clonality does not appear lineage-restricted. There were no statistical differences in age at diagnosis, median platelet count at testing time, and length of follow-up. Thrombotic episodes were significantly more frequent in the monoclonal group (p = 0.04, Fisher exact test). CONCLUSIONS: Young female patients with ET exhibiting a clonal pattern of hemopoiesis by X-CIP analysis are at higher risk for thrombosis. X-CIP analysis may contribute to defining the individual risk leading to appropriate treatment. X-CIP will allow a correct diagnosis in patients with latent myeloproliferative disorders and thrombosis in unusual sites. Clonal hemopoiesis is easily recognized by X-CIP, but its applicability is limited to the female sex and is hampered by the presence of age-related or constitutive skewing.

Inhibitor development and mortality in non-severe hemophilia A.

BACKGROUND: The life expectancy of non-severe hemophilia A (HA) patients equals the life expectancy of the non-hemophilic population. However, data on the effect of inhibitor development on mortality and on hemophilia-related causes of death are scarce. The development of neutralizing factor VIII antibodies in non-severe HA patients may dramatically change their clinical outcome due to severe bleeding complications. OBJECTIVES: We assessed the association between the occurrence of inhibitors and mortality in patients with non-severe HA. METHODS: In this retrospective cohort study, clinical data and vital status were collected for 2709 non-severe HA patients (107 with inhibitors) who were treated between 1980 and 2011 in 34 European and Australian centers. Mortality rates for patients with and without inhibitors were compared. RESULTS: During 64,200 patient-years of follow-up, 148 patients died (mortality rate, 2.30 per 1000 person-years; 95% confidence interval (CI), 1.96-2.70) at a median age of 64 years (interquartile range [IQR], 49-76). In 62 patients (42%) the cause of death was hemophilia related. Sixteen inhibitor patients died at a median age of 71 years (IQR, 60-81). In ten patients the inhibitor was present at time of death; seven of them died of severe bleeding complications. The all-cause mortality rate in inhibitor patients was > 5 times increased compared with that for those without inhibitors (age-adjusted mortality rate ratio, 5.6). CONCLUSION: Inhibitor development in non-severe hemophilia is associated with increased mortality. High rates of hemophilia-related mortality in this study indicate that non-severe hemophilia is not mild at all and stress the importance of close follow-up for these patients.

Recombinant alpha-interferon 2b in the treatment of HIV-related thrombocytopenia.

OBJECTIVE: To assess the efficacy and the mechanism of action of alpha-interferon (alpha-IFN) in the treatment of HIV-related thrombocytopenia. METHODS: Thirteen HIV-positive subjects [nine men and four women with severe thrombocytopenia (platelets, < or = 30 x 10(9)/l)] were treated with alpha-IFN 2b alone at a dose of 3 x 10(6) U three times a week for 5 weeks. Haematological parameters, platelet kinetic and bone-marrow myeloid progenitor cultures [megakaryocyte colony-forming units (CFU-MK); granulocyte macrophage CFU (CFU-GM) and erythroid burst-forming units (BFU-E)] were evaluated before and after treatment in responsive subjects. RESULTS: Seven out of 13 subjects showed a partial response (platelets, 50-149 x 10(9)/l) after alpha-IFN 2b therapy. Platelet survival as evaluated by 111In-oxine significantly increased, while platelet turnover showed a slight but not statistically significant increase after treatment. The growth of bone-marrow myeloid progenitor cells decreased after alpha-IFN 2b therapy, again without statistical significance. CONCLUSION: alpha-IFN 2b may increase the platelet count in HIV-positive subjects with severe symptomatic thrombocytopenia by prolonging platelet survival. The immunomodulatory and antiviral action of this drug may be responsible for prolonged platelet survival.

Natural history and risk factors for thrombosis in 360 patients with antiphospholipid antibodies: a four-year prospective study from the Italian Registry.

PURPOSE: To assess the natural history and risk factors for thrombosis in a large cohort of unselected patients with antiphospholipid antibodies. PATIENTS AND METHODS: Three hundred sixty consecutive patients (118 males, 242 females, median age 39 years [range 2 to 78]) fulfilling the currently accepted criteria for diagnosis of lupus anticoagulant (LAC) (n = 326) and/or raised immunoglobulin G anticardiolipin antibodies (IgG ACA) (n = 185) were collected from 16 Italian institutions and prospectively observed for a median of 3.9 years (range 0.5 to 5). Main endpoints were the occurrence of arterial or venous thrombosis, the outcome of pregnancies, and any severe complications leading to hospitalization or death. RESULTS: Thirty-four patients developed a thrombotic complication, with a total incidence of 2.5% patient-years. Multivariate logistic regression analysis identified two independent risk factors for thrombotic events: a previous thrombosis (RR 4.9; 95% CI, 1.76 to 13.7; P < 0.005) and IgG ACA titer above 40 units (RR 3.66; 95% CI, 1.24 to 10.8; P < 0.01). A total of 28 pregnancies were observed in 25 women and 11 (39%) were abortive. Adverse pregnancy outcomes were significantly more frequent in women with a history of miscarriage or vascular occlusion (9/16, 56%) than in asymptomatic women (2/12, 17%) (P = 0.035). Four patients developed non-Hodgkin's lymphoma during the follow-up. Eighteen patients died. Vascular events and hematological malignancies represented the most frequent causes of death (n = 5 for each). CONCLUSIONS: The present study shows that: (a) previous thrombosis and ACA titer > 40 U are independent predictors of thrombosis; (b) history of miscarriage or vascular disease is significantly associated with adverse pregnancy outcome; (c) hematological malignancies can develop during follow-up in patients with antiphospholipid antibodies.

Treatment of congenital factor VII deficiency with a new concentrate.

A new factor VII concentrate, made from ACD plasma by a process involving successive absorptions of cryoprecipitate supernatant on DEAE Sephadex and of the resulting supernatant on A1(OH)3, was administered to 10 patients with severe factor VII deficiency. 5 patients received only one dose for treatment of a single bleeding episode, the remaining 5 were given multiple infusions (47) for spontaneous hemorrhages or for the prevention of surgical bleeding. In vivo factor VII recovery ranged from 43 to 126% (average 88%) of the assayed in vitro activity of the concentrate. A dose of 0.5 u/kg was found to produce a 1% rise of the plasma factor VII levels. The mean half-life on injected factor VII as assessed in 7 kinetic studies was 205 min (range 168--234). Spontaneous bleeding was easily controlled by the concentrate and major surgical procedures (two tonsillectomies) could be performed without complications. 1 patient developed HBSAg positive hepatitis, but otherwise no serious side effects were observed. Factor VII concentrate reduced the risk of precipitating circulatory overload associated with the use of plasma and avoids the unnecessary rise of factor II, IX and X which follows prothrombin complex concentrates.

Factor VII activity and antigen in haemophilia B variants.

Twenty three patients belonging to 18 different pedigrees of Haemophilia B were studied with regard to ox-brain prothrombin time and its correlation to factor VII. Eleven among them were B-negative (no detectable factor IX antigen), five were B-reduced (factor IX antigen detectable but below the normal values) and seven were B-positive (normal levels of factor IX antigen). Ox-brain prothrombin time was found prolonged (greater than or equal to mean + 2.5 SD:99% confidence limits) in nine patients. Factor VII Activity (VII:C) was found reduced in 1/11 B-negative, in 2/5 B-reduced and in 4/7 B-positive patients. Factor VII Antigen (VII:Ag) was found normal in all but one patient. The ratio VII:C/VII:Ag was abnormal in eight patients independently from the variant of Haemophilia B. The underlying defect which causes the prolongation of Ox-brain prothrombin time due to factor VII:C mild deficiency is heterogeneous. Age, a mild Vitamin K deficiency, the presence of an inhibitor of Factor VII activation and other unknown causes, may be responsible for this pattern.

Clinical factors associated with progression to AIDS in the Italian cohort of HIV-positive hemophiliacs. G.I.C.C. Gruppo Italiano Coagulopatie Congenite.

This study updates estimates of the cumulative incidence of AIDS among Italian patients with congenital coagulation disorders (mostly hemophiliacs), and elucidates the role of age at seroconversion, type and amount of replacement therapy, and HBV co-infection in progression. Information was collected both retrospectively and prospectively on 767 HIV-1 positive patients enrolled in the on-going national registry of patients with congenital coagulation disorders. The seroconversion date was estimated as the median point of each patient's seroconversion interval, under a Weibull distribution applied to the overall interval. The independence of factors associated to faster progression was assessed by multivariate analysis. The cumulative incidence of AIDS was estimated using the Kaplan-Meier survival analysis at 17.0% (95% CI = 14.1-19.9%) over an 8-year period for Italian hemophiliacs. Patients with age greater than or equal to 35 years exhibited the highest cumulative incidence of AIDS over the same time period, 32.5% (95% CI = 22.2-42.8%). Factor IX recipients (i.e. severe B hemophiliacs) had higher cumulative incidence of AIDS (23.3% vs 14.2%, p = 0.01) than factor VIII recipients (i.e. severe A hemophiliacs), as did severe A hemophiliacs on less-than-20,000 IU/yearly of plasma-derived clotting factor concentrates, as opposed to A hemophiliacs using an average of more than 20,000 IU (18.8% vs 10.9%, p = 0.02). No statistically significant difference in progression was observed between HBsAg-positive vs HBsAg-negative hemophiliacs (10.5% vs 16.4%, p = 0.10). Virological, immunological or both reasons can account for such findings, and should be investigated from the laboratory standpoint.

Identification and three-dimensional structural analysis of nine novel mutations in patients with prothrombin deficiency.

Prothrombin deficiency is an autosomal recessive disorder associated with a moderately severe bleeding tendency. In this study, 13 patients with prothrombin deficiency were screened for the presence of alterations in the prothrombin gene, and nine novel candidate mutations were identified. Of 11 patients with hypoprothrombinemia, ten are homozygous for five mutations and one patient is a compound heterozygote. The two patients with dysprothrombinemia are homozygous for two mutations. Eight of nine mutations are missense ones associated with single amino acid substitutions in the propeptide (Arg-1Gln, Arg-2Trp), the kringle-1 (Asp118Try) and kringle-2 (Arg220Cys) domains and the catalytic serine protease domain (Gly330Ser, Ser354Arg. Arg382His and Arg538Cys). The ninth mutation is an in-frame deletion of 3 bp that results in the omission of one amino acid (del Lys 301/302). The combination of these missense mutations with crystal structures for alpha-thrombin and the prothrombin fragments 1 and 2 resulted in new insight into the function of alpha-thrombin. The hypoprothrombinemia mutations were inferred to affect either the cleavage of the propeptide from the Gla domain, the stability of the kringle-1 and -2 domains, or the close association of the A and B chains of the serine protease domain. The dysprothrombinemia mutations were inferred to directly affect catalytic function through their location at the active site crevice or exosite 1 within the serine protease domain.

Markers of procoagulant imbalance in patients with inherited thrombophilic syndromes.

In 107 asymptomatic and untreated patients with inherited syndromes associated with thrombophilia (antithrombin III, protein C and protein S deficiencies), we compared in parallel two plasma peptides which reflect activation of the common coagulation pathway: the prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FPA). Both F1 + 2 and FPA were measured with simple, commercially available ELISA methods. High levels of F1 + 2 or FPA were found in about one fourth of the patients as a whole. When patients were divided according to the type of inherited thrombophilic syndrome, it appeared that F1 + 2 was more frequently elevated in protein C and protein S deficiencies than in antithrombin deficiency; and that, in general, it was no more frequently elevated than FPA. Although our data confirm the existence of a procoagulant imbalance in inherited thrombophilic syndromes due to defects of natural anticoagulant proteins, they do not confirm that such imbalance can be more frequently diagnosed by measuring F1 + 2 levels, particularly in patients with antithrombin deficiency.

Pharmacokinetics of monoclonally-purified and recombinant factor VIII in patients with severe von Willebrand disease.

A monoclonally-purified factor VIII (FVIII) concentrate, containing little von Willebrand factor (vWF), was infused to 11 patients with severe von Willebrand disease and unmeasurable levels of plasma vWF. In comparison with the historical data obtained infusing hemophiliacs in the same conditions, monoclonally-purified FVIII had a significantly shorter half-life and faster clearance from plasma but similar in vivo recovery and volume of distribution. Two additional patients with severe von Willebrand disease were also infused with recombinant FVIII totally devoid of vWF. Half-life was very short and in vivo recovery low, with a larger volume of distribution than for monoclonally-purified FVIII. We conclude that in patients with severe von Willebrand disease the small amounts of vWF contained in the monoclonally-purified FVIII concentrate are not sufficient to stabilize infused FVIII, nor to support the normal circulation of endogenous FVIII that these patients produce at a normal rate.