Methodologies for data collection in congenital haemophilia with inhibitors (CHwI): critical assessment of the literature and lessons learned from recombinant factor VIIa

AIMS

To systematically review the effectiveness of on-demand treatment with recombinant coagulation factor VIIa (rFVIIa) in congenital haemophilia with inhibitors and, if feasible, perform a meta-analysis of the data.

MATERIALS AND METHODS

Publications from Embase^® , MEDLINE^® , MEDLINE^® In-Process and the Cochrane Central Register of Controlled Trials were searched. Selected publications were reviewed for inclusion by two independent expert reviewers. Discrepancies were reconciled by a third independent reviewer. Data from selected studies were extracted using a predefined grid to ensure uniform and comparable results were captured.

RESULTS

A systematic search (cut-off date of 2 May 2016) identified 20 studies (13 observational; seven randomized controlled trials). All studies were of sufficient quality to include in this analysis and comprised 1221 participants, with 5981 bleeds in 746 individuals treated with rFVIIa. Haemostatic overall effectiveness of the individual studies identified ranged from 68% to 100% at ≤12 hours, 86% to 96% at 13-24 hours and 76% to 99% at 24-48 hours with rFVIIa <100 μg/kg, with similar rates reported for the ≥250 μg/kg dose. However, heterogeneity between the studies precluded pooling of results.

CONCLUSIONS

Data from the individual studies confirmed that rFVIIa is an effective therapy for the on-demand treatment of bleeds in congenital haemophilia with inhibitors. However, the high levels of heterogeneity between studies precluded pooling of results for a valid, reliable or precise summary measure. There remains a need to implement standardized clinical definitions and measurements for the effectiveness and safety of haemophilia therapies in future clinical trials.

Lenalidomide as a novel therapy for gastrointestinal angiodysplasia in von Willebrand disease

INTRODUCTION

Lenalidomide is a thalidomide analog with anti-angiogenic properties. Previous case reports suggest its efficacy in preventing gastrointestinal bleeding (GIB) secondary to angiodysplasia (AD) in hereditary haemorrhagic telangiectasia and potentially in reversing AD. We present the first case series to explore lenalidomide as a treatment for AD-related GIB in patients with von Willebrand disease (VWD).

METHODS

A retrospective chart review was conducted to include patients with VWD, who were evaluated from 2010 to 2013 and who had received lenalidomide to treat recurrent GIB secondary to AD. All patients had failed single-agent use of antifibrinolytic agents. Patients were observed for at least 2 years on therapy.

RESULTS

Five patients (3 males; 68.2 ± 4.9 years) with VWD (3 with type 3 and 1 each with types 1 and 2a) and AD were found. Sites of AD included the stomach, duodenum, jejunum and colon. Lenalidomide was started at 5 mg oral daily. Uptitration to 10 and 15 mg in 1 patient each was necessary due to recurrence of GIB. The mean number of endoscopies performed for control of GIB post lenalidomide was significantly lower compared to pretherapy (0.25 vs 5.50; P = .001). Mean bleed-free duration on lenalidomide was 12.6 ± 4.7 months. Three patients have reported no GIB on lenalidomide.

CONCLUSION

This case series demonstrates significantly reduced number of endoscopies and increased bleed-free duration with lenalidomide treatment in selected patients with VWD and recurrent GIB from AD. Prospective multicenter trials are needed to further define the role of lenalidomide in the management of GIB from angiodysplasia and VWD.

Efficacy and safety of Nuwiq® (human-cl rhFVIII) in patients with severe haemophilia A undergoing surgical procedures

INTRODUCTION

Haemophilia A patients are at a high risk of excess bleeding during surgeries. The aim of haemostatic therapy during the perioperative period is to normalize FVIII level perioperatively and postoperatively to maintain normal haemostasis until wound healing is complete.

AIMS/METHODS

To examine the efficacy of Nuwiq^® (simoctocog alfa, human-cl rhFVIII), a 4^th generation recombinant FVIII produced in a human cell line, for surgical prophylaxis in patients with severe haemophilia A. This analysis assessed the efficacy of Nuwiq^® during surgical procedures and in the postoperative period in seven clinical studies of previously treated patients (PTPs) with severe haemophilia A.

RESULTS

Thirty-six patients, aged 3-55 years, received surgical prophylaxis with Nuwiq^® for 60 surgeries (28 major and 32 minor). Efficacy was evaluated for 52 surgeries (25 major and 27 minor). The success rate of Nuwiq^® treatment was 98.1% (51 of 52 evaluated surgeries); haemostatic efficacy was assessed as "excellent" or "good" in all but one major surgery (assessed as "moderate"). The number of infusions ranged from 1 to 19 for minor surgeries and from 3 to 76 for major surgeries. The median (range) daily doses were 42.0 (28.2-100.9) IU kg^-1 for minor surgeries and 69.3 (43.3-135.6) IU kg^-1 for major surgeries. There were no serious treatment-related adverse events, and none of the patients developed FVIII inhibitors.

CONCLUSIONS

The results of this pooled analysis show that Nuwiq^® was efficacious in maintaining haemostasis during and after major and minor surgical procedures in PTPs with severe haemophilia A.

Acquired haemophilia in cancer: A systematic and critical literature review

AIM

There is a paucity of data on the clinical presentation and management of cancer patients with acquired haemophilia (AH), we here report a systematic literature review on acquired haemophilia in the context of cancer.

METHODS

Treatment outcomes of AH were defined as complete response (CR), partial response (PR) or no response (NR), based on inhibitor eradication, coagulation factor VIII levels and bleeding control. Reported deaths were either related to cancer or bleeding.

RESULTS

Overall, 105 cases were collected and analyzed according to classification of cancer and efficacy of treatments for inhibitor and malignancy. The mean age was 68 years for both males (range 37-86 years) and females (range 43-89 years), 39 patients were female subjects and 66 were males. A solid cancer was diagnosed in 60 subjects, while 45 patients suffered a haematological malignancy. Solid cancers affected mainly males; however, the incidence of solid tumours vs haematological malignancies was not statistically significant (P = .09). Not all patients were treated for their underlying cancer, bleeding and/or inhibitor, in two cases outcome is unavailable. CR was reported in 62.1% (64/103) cases, PR in 9.7% (10/103) cases, NR with or without death was reported in 28.1% (29/103) cases.

CONCLUSION

CR was best achieved when successful and complete elimination of autoantibodies occurred contemporaneously with the successful treatment of the underlying malignancy. In some cases, recurrent autoantibodies were harbingers of relapsed cancer. Type of cancer, inhibitor titer, treatments administered for bleeding control and inhibitor eradication did not significantly affect clinical outcome of analyzed cases.

Multicenter randomized controlled trial on Duration of Therapy for Thrombosis in Children and Young Adults (the Kids-DOTT trial): pilot/feasibility phase findings

BACKGROUND

Randomized controlled trials (RCTs) on pediatric venous thromboembolism (VTE) treatment have been challenged by unsubstantiated design assumptions and/or poor accrual. Pilot/feasibility (P/F) studies are critical to future RCT success.

METHODS

The Kids-DOTT trial is a multicenter RCT investigating non-inferiority of a 6-week (shortened) versus 3-month (conventional) duration of anticoagulation in patients aged < 21 years with provoked venous thrombosis. Primary efficacy and safety endpoints are symptomatic recurrent VTE at 1 year and anticoagulant-related, clinically relevant bleeding. In the P/F phase, 100 participants were enrolled in an open, blinded-endpoint, parallel-cohort RCT design.

RESULTS

No eligibility violations or randomization errors occurred. Of the enrolled patients, 69% were randomized, 3% missed the randomization window, and 28% were followed in prespecified observational cohorts for completely occlusive thrombosis or persistent antiphospholipid antibodies. Retention at 1 year was 82%. Interobserver agreement between local and blinded central determination of venous occlusion by imaging at 6 weeks after diagnosis was strong (k-statistic = 0.75; 95% confidence interval [CI] 0.48-1.0). The primary efficacy and safety event rates were 3.3% (95% CI 0.3-11.5%) and 1.4% (95% CI 0.03-7.4%).

CONCLUSIONS

The P/F phase of the Kids-DOTT trial has demonstrated the validity of vascular imaging findings of occlusion as a randomization criterion, and defined randomization, retention and endpoint rates to inform the fully powered RCT.

Treatment of venous thromboembolism in cancer patients with dalteparin for up to 12 months: the DALTECAN Study

BACKGROUND

Treatment of venous thromboembolism (VTE) in patients with cancer has a high rate of recurrence and bleeding complications. Guidelines recommend low-molecular-weight heparin (LMWH) for at least 3-6 months and possibly indefinitely for patients with active malignancy. There are, however, few data supporting treatment with LMWH beyond 6 months. The primary aim of the DALTECAN study (NCT00942968) was to determine the safety of dalteparin between 6 and 12 months in cancer-associated VTE.

METHODS

Patients with active cancer and newly diagnosed VTE were enrolled in a prospective, multicenter study and received subcutaneous dalteparin for 12 months. The rates of bleeding and recurrent VTE were evaluated at months 1, 2-6 and 7-12.

FINDINGS

Of 334 patients enrolled, 185 and 109 completed 6 and 12 months of therapy; 49.1% had deep vein thrombosis (DVT); 38.9% had pulmonary embolism (PE); and 12.0% had both on presentation. The overall frequency of major bleeding was 10.2% (34/334). Major bleeding occurred in 3.6% (12/334) in the first month, and 1.1% (14/1237) and 0.7% (8/1086) per patient-month during months 2-6 and 7-12, respectively. Recurrent VTE occurred in 11.1% (37/334); the incidence rate was 5.7% (19/334) for month 1, 3.4% (10/296) during months 2-6, and 4.1% (8/194) during months 7-12. One hundred and sixteen patients died, four due to recurrent VTE and two due to bleeding.

CONCLUSION

Major bleeding was less frequent during dalteparin therapy beyond 6 months. The risk of developing major bleeding complications or VTE recurrence was greatest in the first month of therapy and lower over the subsequent 11 months.

Factor VIII alloantibody inhibitors: cost analysis of immune tolerance induction vs. prophylaxis and on-demand with bypass treatment

Development of inhibitors (alloantibodies to exogenous factor VIII) is the most significant treatment complication in patients with haemophilia A. The only proven way to eradicate inhibitors is through immune tolerance induction (ITI), while bypassing agents are typically employed to treat or prevent bleeds in patients with high titre inhibitors. Costs of these approaches have not been well studied. The aim of this study was to compare lifetime costs of treating patients with severe haemophilia A with inhibitors using on-demand or prophylaxis treatment with bypassing agents and ITI. A decision-analytic model was developed to compare the treatment costs and outcomes. Quantitation of the reduction in bleeding events for patients on prophylaxis and after eradication of inhibitors when on ITI and relapse of inhibitors was derived from published studies. Costs were obtained from standard US costing sources and are reported in 2014 US dollars. Costs and outcomes were discounted 3% per annum. Lifetime costs of treating patients with inhibitors are lower for ITI vs. on-demand or prophylaxis. Patients are also projected to live longer, have greater quality-adjusted life-years, and have fewer bleeding events than patients treated on-demand. Treating patients via ITI to eradicate inhibitors may result in lower lifetime costs and greater life-years and quality-adjusted life-years than treating with bypassing agents.

Prophylaxis in real life scenarios

Prophylaxis has become the standard mantra of care for those individuals with severe haemophilia A and B. Primary prophylaxis is advocated to prevent the occurrence of symptomatic acute spontaneous haemarthroses and to preserve joint structure and function. Typically, twice or thrice weekly infusions of factor VIII or IX concentrates are integral to this treatment approach. Secondary prophylaxis is initiated after the relentless cycle of progressive joint damage has been triggered by prior haemarthroses and is intended to preserve existing joint health by preventing additional spontaneous bleeding events. Event-driven prophylaxis involves the administration of clotting factor concentrates to prevent acute traumatic bleeds, which are anticipated to occur in association with surgical or physical trauma. This regimen enhances the effectiveness of primary or secondary prophylaxis protocols or on-demand approaches to replacement therapy. Besides the marked reduction in the so-called annual bleed rate, prophylaxis regimens frequently increase personal self-confidence to embark on a more active and physical lifestyle; however, in reality, prophylaxis must be individualized in accordance with bleeding phenotypes, with the unique pharmacokinetic profile of administered replacement clotting factor concentrates, with the specific clinical scenario, and with the degree of intensity anticipated for any physical activity. The introduction of extended half-life replacement products will also influence how these prophylaxis regimens will be accomplished. The following scenarios will discuss how prophylaxis regimens can be implemented to protect the individual from developing spontaneous and activity-induced acute bleeding complications and to maintain an improved quality of life.

MASAC Consensus Conference: impediments to conducting clinical research in persons with haemophilia, von Willebrand's disease and rare bleeding disorders

A consensus conference conducted by the Medical and Scientific Advisory Council of the National Hemophilia Foundation was held in New Orleans, LA, on November 11, 2010, to discuss the impediments to conducting clinical research in persons with haemophilia, von Willebrand's disease and rare bleeding disorders. The conference combined presentations providing academic, non-profit and industry perspectives with periods of open discussion. The objective of this conference was to identify the many challenges involved in facilitating U.S. Food and Drug Administration approval of innovative products for these patient populations.

Health care expenditures for Medicaid-covered males with haemophilia in the United States, 2008

Although haemophilia is an expensive disorder, no studies have estimated health care costs for Americans with haemophilia enrolled in Medicaid as distinct from those with employer-sponsored insurance (ESI). The objective of this study is to provide information on health care utilization and expenditures for publicly insured people with haemophilia in the United States in comparison with people with haemophilia who have ESI. Data from the MarketScan Medicaid Multi-State, Commercial and Medicare Supplemental databases were used for the period 2004-2008 to identify cases of haemophilia and to estimate medical expenditures during 2008. A total of 511 Medicaid-enrolled males with haemophilia were identified, 435 of whom were enrolled in Medicaid for at least 11 months during 2008. Most people with haemophilia qualified for Medicaid based on 'disability'. Average Medicaid expenditures in 2008 were $142,987 [median, $46,737], similar to findings for people with ESI. Average costs for males with haemophilia A and an inhibitor were 3.6 times higher than those for individuals without an inhibitor. Average costs for 56 adult Medicaid enrollees with HCV or HIV infection were not statistically different from those for adults without the infection, but median costs were 1.6 times higher for those treated for blood-borne infections. Haemophilia treatment can lead to high costs for payers. Further research is needed to understand the effects of public health insurance on haemophilia care and expenditures, to evaluate treatment strategies and to implement strategies that may improve outcomes and reduce costs of care.

Healthcare expenditures for males with haemophilia and employer-sponsored insurance in the United States, 2008

Although hemophilia has a potentially high economic impact, published estimates of health care costs for Americans with hemophilia are sparse and non-specific as to the non-bleeding complications of the disease. The objective of this study is to estimate average annual health care expenditures for people with hemophilia covered by employer-sponsored insurance, stratified according to the influence of age, type of hemophilia [A (factor VIII deficiency) versus B (factor IX)], presence of neutralizing alloantibody inhibitors and exposure to blood-borne viral infections. Data from the MarketScan Commercial and Medicare Research Databases were used for the period 2002-2008 to identify cases of hemophilia and to estimate mean and median medical expenditures during 2008. A total of 1,164 males with hemophilia were identified with continuous enrollment during 2008, 933 with hemophilia A and 231 with hemophilia B. Mean health care expenditures were $155,136 [median $73,548]. Mean costs for 30 (3%) males with an inhibitor were 5 times higher than for males without an inhibitor, approximately $697,000 [median $330,835] and $144,000 [median $73,321], respectively. Clotting factor concentrate accounted for 70%-82% of total costs. Average costs for 207 adults with HCV or HIV infection were 1.5 times higher than those for adults without infection. Hemophilia treatment is costly, particularly for individuals with neutralizing alloantibody inhibitors who require bypassing agents. Efforts to understand the cause of inhibitors are needed so that prevention strategies can be implemented and the excess costs resulting from this serious complication of hemophilia care can be avoided.

Outcomes of mentored, grant-funded fellowship training in haemostasis /thrombosis: findings from a nested case-control survey study

Successful strategies by which to effectively recruit and retain academic subspecialists in benign haematology have not been established. To evaluate the effectiveness of a grant-funded, mentored fellowship with respect to retention and early career goals in haemostasis/thrombosis, we sought to compare outcomes for graduates of a grant-funded, mentored fellowship training programme in haemostasis/thrombosis [the National Hemophilia Foundation (NHF)-Baxter Clinical Fellowship Award] during conventional haematology/oncology fellowship training (cases), vs. their training peers who were graduates of conventional haematology/oncology fellowship training alone (controls), via a nested case-control survey study. Survey response rate was 85% (11/13) for cases and 90% (9/10) for controls. All respondents had pursued careers in academic haematology/oncology. Median (range) percent time spent in benign haematology postfellowship was 98% (70-100%) for cases vs. 0% (0-20%) for controls. Time spent in research was significantly greater among cases than controls (median 80% [range: 42-90%] vs. 55% [10-80%], respectively; P = 0.01). By years 3-4 postfellowship, median annual number of peer-reviewed publications was higher for cases than controls (3.5 vs. 1.0; P = 0.01). Cases were also more successful in grant funding (including K-awards). These data suggest that a grant-funded, mentored fellowship training programme in haemostasis/thrombosis may be superior to conventional haematology/oncology fellowship training alone with respect to outcomes of retention in clinical care/research, early-career grant funding and publication productivity.

Survey of current prophylaxis practices and bleeding characteristics of children with severe haemophilia A in US haemophilia treatment centres

Every other day (qod) factor VIII prophylaxis prevents joint bleeds in children with severe haemophilia A. Although three times weekly or qod prophylaxis is recommended by the National Hemophilia Foundation (NHF), how widely these practices have been adopted is not known. We sought to define current prophylaxis practices at US haemophilia treatment centres (HTCs). An email survey was distributed to US HTCs, utilizing web-based membership rosters of the Centers for Disease Control (CDC) and the Hemostasis Thrombosis Research Society (HTRS). Of 62 HTCs responding, prophylaxis is initiated on a three times weekly schedule in 29 (46.8%), twice weekly in 13 HTCs (21.0%) and once weekly in 20 HTCs (32.2%). Central venous catheters are used to infuse factor prophylactically at 55 HTCs (88.7%), including in 100% of children initiating prophylaxis at 19 HTCs (30.6%) and in 50% of those at 41 HTCs (66.1%), but avoided altogether at seven HTCs (11.3%). Prophylaxis is initiated after one or more bleeds in 56 HTCs (90.3%), but after the first bleed in only 28 HTCs (25.2%). Among 226 newborns with severe haemophilia A in 62 HTCs, 1.82 births/HTC/year, the median age at first bleed, excluding circumcision, is 7 months. Of the 113 (53.5%) newborns who underwent circumcision, 62 (54.9%) bled. Despite a recommended standard of three times weekly prophylaxis, over half of surveyed HTCs do not follow these guidelines, and nearly one-third begin prophylaxis on a once weekly schedule to delay or avoid the need for central venous access.

Improved performance characteristics of the von Willebrand factor ristocetin cofactor activity assay using a novel automated assay protocol

BACKGROUND, OBJECTIVES AND METHODS: An accurate, sensitive and precise assay for reliable determination of the ristocetin cofactor activity of von Willebrand factor (VWF:RCo) in plasma and von Willebrand Factor (VWF)-containing concentrates has been evaluated. The assay is based on a commercially available automated protocol with modifications including a combination of adding additional ristocetin and the use of two calibration curves for the high and low measuring ranges.

RESULTS

 Addition of extra ristocetin resulted in improved measurement of VWF recoveries from various VWF-containing concentrates that were underestimated using the standard automated protocol. The modifications resulted in improved assay performance over an extended measuring range (2.00-0.03 IUmL(-1) ). Accuracy was tested using VWF deficiency plasma spiked with the 1st international standard (IS) for VWF concentrate. Seven dilutions, ranging from 1.80 to 0.05IUmL(-1) , were analyzed and resulted in measured concentrations between 80% and 100% of the assigned potency of the standard. Linearity was determined from the regression plot of the same concentrate dilutions and resulted in a correlation coefficient of 0.998. The repeatability, expressed as coefficient of variation, was 2% in the normal range (0.90IUmL(-1) ) and 8% at the level of 0.05IUmL(-1) . The corresponding reproducibility results were 2% and 15% at the normal and low measuring ranges, respectively.

CONCLUSIONS

 Analysis of patients with von Willebrand disease (VWD) indicates that the modified automated BCS(®) protocol has a superior discrimination power compared with the standard protocol. This is especially true in samples with low VWF, as in patients with type 3 VWD.

Infectious complications associated with alemtuzumab treatment

13504

Introduction: We report our single institutional experience of ICs associated with alemtuzumab treatment. Methods: Patients (pts) who received alemtuzumab were identified by review of the GUH pharmacy database. All ICs occurring from initiation of alemtuzumab until death or end of follow up as of January 3, 2007 were reviewed and categorized as opportunistic (OI) or non- opportunistic (NOIs). Pts who received hematopoetic stem cell or solid organ transplantation subsequent to alemtuzumab (n=33) or who could not tolerate test doses of alemtuzumab (n=1) were excluded from analysis. Results: Data were reviewed for 16 pts treated with alemtuzumab from February 2003 to September 2006. Median age was 60 years (range 40–78); with 4 females and 12 males. Fifteen pts had chronic lymphocytic leukemia (CLL), and 1 had acute lymphoblastic leukemia (ALL). Median follow-up after starting alemtuzumab treatment was 462 days. Pts with CLL had an average of 2.4 prior treatments (range 1–6). The pt with ALL received alemtuzumab as part of multi-agent intensification chemotherapy regimen. Alemtuzumab was administered subcutaneously, 30 mg three times a week. Median of 29 doses (range 7- 45) were given. Among CLL pts there was 1CR, 8 PRs and 6 PDs (RR 60%). Pneumocystis jirovenci (PCP) and herpersvirus (HSV) prophylaxis was given to 15 (93%) pts. Cytomegalovirus (CMV) surveillance was performed for all. Absolute lymphocyte count (ALC) <1000/μL developed within 5 weeks in 12 (75%) pts. Median ALC at 8 weeks was 155/μL (range 0–18,612). Thirteen OIs were diagnosed in 9 (56%) pts including asymptomatic CMV viremia (n=5), PCP (n=2, one pt did not received PCP prophylaxis), invasive pulmonary aspergillosis (n=2), disseminated histoplasmosis (n=1), localized HSV (n=1), disseminated herpes zoster (n=1), and cerebral acanthamebiasis (n=1). Seven NOIs were noted in 6 pts including bacterial pneumonia, sinusitis, endocarditis and pseudo-membranous colitis. Mortality secondary to ICs was 31%. There was no correlation between ICs and age, duration of lymphoproliferative disorder, number of prior treatments, cumulative dose, response to alemtuzumab, or ALC. Conclusion: Despite adequate prophylaxis, ICs secondary to alemtuzumab are more frequent and diverse than previously reported in clinical trials.

No significant financial relationships to disclose.

D-dimer, factor VIII coagulant activity, low-intensity warfarin and the risk of recurrent venous thromboembolism

BACKGROUND

Elevated plasma D-dimer and factor VIII coagulant activity (FVIIIc) may be associated with the risk of recurrent venous thromboembolism (VTE).

OBJECTIVES

To evaluate D-dimer and FVIIIc as risk factors for recurrent VTE and assess the efficacy of extended low-intensity warfarin (target International Normalized Ratio 1.5-2.0) in preventing recurrence by biomarker level.

PATIENTS AND METHODS

In the Prevention of Recurrent Venous Thromboembolism trial, 508 idiopathic VTE patients treated for > or = 3 months with full-intensity warfarin, and who had stopped warfarin for 7 weeks on average, were randomized to low-intensity warfarin or placebo and followed for 2.1 years for recurrent VTE. Prerandomization blood samples were analysed for D-dimer and FVIIIc.

RESULTS

One-third of participants had elevated baseline D-dimer (> or = 500 ng mL(-1)) and one-fourth, elevated FVIIIc (> or = 150 IU dL(-1)). Adjusting for other risk factors, the hazard ratios (HRs) for recurrent VTE with elevated D-dimer or FVIIIc were 2.0 [95% confidence interval (CI) 1.2-3.4] and 1.5 (95% CI 0.8-2.8), respectively. The association of elevated D-dimer with recurrence was larger among patients with one prior VTE (HR 3.2, 95% CI 1.3-8.0) than in patients with more than one event (HR 1.4, 95% CI 0.7-2.2). For patients with one prior VTE on placebo, the annual recurrence incidence was 10.9% with elevated D-dimer and 2.9% with normal values. Low-intensity warfarin was equally effective in recurrence risk reduction in those with normal or elevated biomarkers.

CONCLUSIONS

Among patients with idiopathic VTE, measurement of D-dimer, but not FVIIIc, might be useful for risk stratification. The efficacy of extended low-intensity warfarin therapy did not vary by biomarker level.

Dose effect and efficacy of rFVIIa in the treatment of haemophilia patients with inhibitors: analysis from the Hemophilia and Thrombosis Research Society Registry

Recombinant activated factor VII (rFVIIa), licensed in 1999 for treatment of haemophilia patients with inhibitors (HI), represents an important advance in the therapeutic armamentarium. Standard bolus dosing ranges from 90 to 120 mcg kg(-1) every 2-3 h until arrest of bleeding. As licensure, clinical use of rFVIIa has increased and broadened. Clinicians now use a wide dose range, 90-300 mcg kg(-1). High-dose regimens may optimize thrombin generation or burst, and may allow for prolonged dose interval. The Hemophilia and Thrombosis Research Society (HTRS) maintains a registry database to study haemophilia treatment and related disorders, particularly treatment of acute bleeding in HI, acquired haemophilia, FVII deficiency and von Willebrand's disease (VWD). To assess the effect of rFVIIa dose on efficacy and safety in the treatment of acute bleeding in HI, data from the HTRS database from January 2000 through June 2002 were analysed. Bleeding episodes were grouped by bolus rFVIIa dose range: <100, 100-150, 150-200 and >200 mcg kg(-1). Investigator-reported efficacy for the first 72 h of treatment was evaluated. Thirty-eight congenital HI patients were treated for 555 bleeding episodes. Patient age range was 1-55 years (median: 14). Bleeding episodes were spontaneous (45%), caused by trauma (38%), or because of surgery, dental, diagnostic, or medical procedures (17%); bleeding occurred in joint, muscle, and intra/extracranial sites. Treatment location included: 80% at home, 12% at other facilities (treatment centres, ER, inpatient and OR), and 8% at both home/other facilities. Median total dose given over 72 h was 360 mcg kg(-1) (range: 40-4281, mean: 537). Bleeding stopped in 87% of the episodes. Bleeding cessation rate was 84% for the three lower dose groups, and 97% for the highest dose group (P < 0.001). Five patients experienced nine adverse events (AEs). AE rates were <1% for <100, 5% for 100-150, 0% for 150-200, <1% for >200 mcg kg(-1) dose group. Decreased therapeutic response accounted for eight of the nine AEs. These data, which represent the most comprehensive report of rFVIIa use since the USA licensure, demonstrate that bleeding episodes in HI patients can be treated safely and effectively at home and that doses up to 346 mcg kg(-1) appear to be well-tolerated. Additionally, rFVIIa doses >200 mcg kg(-1) appear to significantly increase efficacy (97% in the high-dose group, compared with 84% in the lower dose groups). Optimal dosing remains to be determined; specifically, what the lowest effective dose is and whether a single high-dose bolus eliminates the need for repeated dosing. Recombinant FVIIa appears to have a wide safety margin that may allow dose escalation to address these questions.

B-domain deleted recombinant factor VIII preparations are bioequivalent to a monoclonal antibody purified plasma-derived factor VIII concentrate: a randomized, three-way crossover study

BACKGROUND

Deletion of the B-domain of recombinant blood coagulation factor VIII (BDDrFVIII) increases the manufacturing yield of the product but does not impair in vitro or in vivo functionality. BDDrFVIII (ReFacto) has been developed with the additional benefit of being formulated without human albumin.

OBJECTIVE

The primary objective of this three-way crossover-design study was to compare the pharmacokinetic (PK) parameters of two BDDrFVIII formulations (one reconstituted with 5 mL of sterile water, the other reconstituted with 4 mL sodium chloride 0.9% USP) with those of a plasma-derived, full-length FVIII preparation (Hemofil M) in patients with haemophilia A to determine bioequivalence.

METHODS

A series of blood samples were collected over a period of 48 h after i.v. administration of each of the FVIII preparations. Plasma FVIII activity was determined using a validated chromogenic substrate assay. Plasma FVIII activity vs. time curves was characterized for a standard set of PK parameter estimates. Two parameter estimates, the maximum plasma concentration (Cmax) and the area under plasma concentration vs. time curves (AUCs), were used to evaluate bioequivalence. The two preparations were considered bioequivalent if the 90% confidence intervals for the ratio of geometric means for Cmax and AUCs fell within the bioequivalence window of 80% to 125%.

RESULTS/CONCLUSION

Results show that each BDDrFVIII formulation is bioequivalent to Hemofil M and the two formulations of BDDrFVIII are bioequivalent to each other.

Liver biopsy in patients with inherited disorders of coagulation and chronic hepatitis C

Liver biopsy plays a pivotal role in the management of patients with a variety of liver diseases, including chronic hepatitis C virus. The major risk of the procedure is the potential for significant haemorrhagic complications. Although the data are limited, the procedure does not appear to pose excessive risk to the patient with inherited disorders of coagulation, provided that adequate haemostasis can be achieved prior to the liver biopsy. This requires close coordination of care between the hepatologist and the haematologist. Indications for liver biopsy should be the same in patients with haemophilia as in other populations.

The safety and efficacy of B-domain deleted recombinant factor VIII concentrate in patients with severe haemophilia A

BACKGROUND

B-domain-deleted recombinant factor VIII (BDDrFVIII) was developed when the B-domain was found to be redundant for maintaining haemostasis. This allows formulation of the final product without albumin added as a stabilizer.

METHODS

Three multicentre clinical studies and one pharmacokinetic study were conducted in 218 patients to evaluate the safety and haemostatic efficacy of BDDrFVIII.

RESULTS

Previously treated patients (n = 113; median duration, 1711 days; median exposure days, 385; total 98,096,287 IU infused) rated 97-99% of all infusions as good or excellent efficacy. FVIII inhibitor was noted in one patient in the previously treated patient cohort after 113 exposure days. Among 101 previously untreated patients, responses to BDDrFVIII were rated as excellent or good in 92-95% of infusions (median duration, 1413 days; median exposure days, 148; total 12,636,458 IU infused). Thirty-two previously untreated patients developed inhibitors after a median duration of 12 exposure days (range, 3-49). Sixteen of 32 (50%) patients had low levels (< or = 5 Bethesda units) and 16 had high levels of inhibitors. Inhibitors disappeared in six of 14 (43%) of the high-level and six of eight (75%) of the low-level patients who underwent immune tolerance induction therapy. A total of 42 patients underwent surgery and the overall efficacy of BDDrFVIII was rated as excellent or good for 99.6% of infusions.

CONCLUSIONS

The results of these clinical studies indicate that BBDrFVIII is safe and effective and has haemostatic activity similar to that of full-length FVIII concentrates.

Viral pharmacovigilance study of haemophiliacs receiving porcine factor VIII

Porcine factor VIII (FVIII; Hyate:C; Speywood Biopharm Ltd, UK) has been used since 1980 for the treatment both of patients with acquired haemophilia and those with congenital haemophilia and inhibitory antibodies. Each batch is extensively screened using cell-culture techniques to confirm the absence of viruses. The production process does not incorporate specific virucidal treatment steps, such as heat treatment or the addition of a solvent/detergent mixture. Low levels of porcine parvovirus were detected in some batches of the product in late 1996 and supply was suspended. In this retrospective study, sera from 81 recipients of porcine FVIII and 125 other volunteers were screened for evidence of antibodies against a range of porcine viruses: porcine parvovirus (PPV), encephalomyocarditis virus (EMCV), and porcine respiratory and reproductive syndrome virus (PRRSV). The 125 volunteer controls included subjects from six categories: healthy control subjects, pig abattoir personnel, personnel involved in the manufacture of porcine FVIII, recipients of porcine heparin, recipients of porcine insulin, and haemophiliacs treated only with human FVIII. No antibodies to PPV or PRRSV were detected in any subject. Four patients and two volunteers were found to have antibodies to EMCV, but this incidence is similar to that observed in the general population. In conclusion, there was no evidence of transmission of PPR or other marker porcine virus associated with the use of porcine FVIII concentrate (Hyate: C).

Human recombinant factor IX: safety and efficacy studies in hemophilia B patients previously treated with plasma-derived factor IX concentrates

Human plasma-derived factor IX (pdFIX) concentrates are routinely used to treat patients with hemophilia B, an X-linked bleeding disorder that affects 1 in 30 000 males, but concerns remain regarding transmission of blood-borne pathogens. Therefore, the safety and efficacy of recombinant human factor IX (rFIX) were evaluated. A 20-center international trial was conducted in previously treated patients with severe or moderate (< 5 IU/dL factor IX activity) hemophilia B. Participants received rFIX for pharmacokinetic studies, treatment of or prophylaxis against hemorrhage, or surgical hemostasis, and were assessed at 3-month intervals for 2 years. Fifty-six subjects were treated. Mean incremental rFIX recovery was 0.75 IU/dL per IU/kg, 30% lower than expected for pdFIX, although the mean half-life was similar. Pharmacokinetic parameters were stable over time. Somewhat lower recoveries were seen in subjects younger than 15 years of age and in those with no detectable factor IX antigen. A total of 7362 infusions of rFIX were administered. All 1796 hemorrhages were controlled, 80.9% of which required only one rFIX infusion. Effective hemostasis was also achieved in prophylactic and surgical settings. One individual developed a low titer (1.2 Bethesda unit) transient inhibitor that spontaneously resolved. rFIX was not associated with serious adverse events, thrombogenicity, or virus transmission. rFIX is safe and effective for the treatment of hemophilia B. Despite a lower recovery compared with pdFIX, rFIX controlled hemorrhage in a wide variety of settings and may provide a safety advantage in terms of risk from blood-borne pathogens.

D-dimer testing: the role of the clinical laboratory in the diagnosis of pulmonary embolism

Pulmonary embolism is a common, yet often unsuspected and unrecognised disease associated with a high mortality. New, objective, "user friendly" and cost effective diagnostic strategies are being explored. D-dimers, the fibrinolytic degradation products of crosslinked fibrin, have emerged as the most useful of the procoagulant activity and ongoing fibrinolysis markers. D-dimer measurements are very sensitive in excluding a diagnosis of pulmonary embolism in the setting of normal values, a low clinical suspicion, and non-diagnostic lung scans. Several assays have been developed and are reviewed.

Management of von Willebrand disease: a survey on current clinical practice from the haemophilia centres of North America

The optimal treatment of patients with von Willebrand's disease (vWD) remains to be defined. Moreover, it has not been firmly established which, if any, commonly measured parameters of von Willebrand factor (vWF) protein in the plasma are useful in guiding treatment. To better understand what guidelines physicians follow in the management of vWD, we surveyed 194 North American physicians who are members of the Hemophilia Research Society. Ninety-nine per cent of responding physicians depend on factor VIII (FVIII):C, vWF:RCo activity and vWF:AG to diagnose vWD, while only 49% use the bleeding time. The minimal goals of treatment for patients undergoing major surgery/trauma or central nervous system haemorrhage were FVIII:C and vWF:RCo activity greater than 80% while levels of more than 50% for minor surgery and dental extractions were considered adequate. Treatment of vWD was based on the type of vWD with type 1 patients being treated most often with desmopressin acetate (DDAVP) alone, types 2A and 2B patients with a combination of DDAVP and a vWF-containing FVIII product, type 3 patients with vWF-containing concentrate. Viral infections, including human immunodeficiency virus, hepatitis A, B and C viruses, and parvovirus have been seen in vWD and the efficacy of viral attenuation processes is a major criterion for the selection of treatment by physicians. Based on this survey, prospective studies need to be designed to address the clinical efficacy, safety and predictive value of laboratory monitoring of patients with vWD.

Both atenolol and propranolol blunt the fibrinolytic response to exercise but not resting fibrinolytic potential

This randomized, double-blind trial found that tissue plasminogen activator activity increased and plasminogen activator inhibitor-1 activity decreased significantly more with exercise during placebo treatment than during treatment with beta blockade. These results suggest that beta blockade blunts the fibrinolytic response to maximal exercise.

New products for managing inhibitors to coagulation factors: a focus on recombinant factor VIIa concentrate

The treatment of alloantibody and autoantibody inhibitors directed against the factor VIII coagulant protein is one of the most challenging and expensive problems in hematology. Because the currently available plasma replacement products used in this context do not control the bleeding complications in all patients, and because of the usual emergent quality of the bleeding complications, there has been a definite need to have a uniformly reliable product for instant use, which possesses a high degree of hemostatic reliability and safety. The recent introduction of recombinant factor VIIa (rFVIIa) has been a welcome addition to the pharmacologic armamentarium for the treatment of neutralizing antibodies against coagulation factors. The mechanisms of action of rFVIIa have also been interesting and have provided insight into how the coagulation pathway accomplishes adequate hemostasis. This review will discuss this new medication and place into the context of coagulation inhibitor therapy.

Hemostatic responses to maximal exercise in oral contraceptive users

OBJECTIVE

This study examined the effect of exercise on markers of fibrinolysis and coagulation in users and nonusers of oral contraceptives.

STUDY DESIGN

Fourteen oral contraceptive users and 14 nonusers performed a maximal exercise test on a cycle ergometer. Blood samples were collected before and immediately after the completion of the test. A repeated-measures analysis of variance was used for statistical analysis with values considered significant at P =.05.

RESULTS

Acute maximal exercise resulted in significant increases in tissue plasminogen activator activity in both groups. There was a trend toward a smaller increase in tissue plasminogen activator activity in oral contraceptive users, but the difference between groups was not statistically significant. Plasminogen activator inhibitor 1 activity was reduced with exercise in both groups but with a significantly greater decrease observed in the nonusers (P <.0001). Prothrombin fragment 1+2 was significantly higher (P <.0001) in the oral contraceptive group but did not change with exercise. Epinephrine levels before and after exercise were similar between the 2 groups, but postexercise norepinephrine concentrations were significantly lower (P =.026) in the oral contraceptive users.

CONCLUSION

These data suggest that oral contraceptive use blunts the fibrinolytic response to exercise. This, together with increased coagulation activation in oral contraceptive users, may alter the hemostatic balance during exercise.

Phenotypic expressions of CCR5-delta32/delta32 homozygosity

OBJECTIVE

As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-delta32/delta32 homozygous genotype has phenotypic expressions other than those related to HIV-1.

DESIGN

Study subjects were white homosexual men or men with hemophilia who were not infected with HIV-1. In this study, 15 CCR5-delta32/delta32 homozygotes were compared with 201 CCR5 wild-type (+/+) subjects for a wide range of clinical conditions and laboratory assay results ascertained during prospective cohort studies and routine clinical care. CCR5-delta32 genotype was determined by polymerase chain reaction, followed by single-stranded conformational polymorphism analysis.

RESULTS

Hypertension and conditions attributable to hemophilia were the only diagnoses frequently found in clinical records of CCR5-delta32/delta32 study subjects. Based on blood pressure measurement and treatment history, CCR5-delta32/delta32 homozygotes had a 2.8-fold higher prevalence of hypertension than age-matched CCR5-+/+ study subjects (95% confidence interval [CI], 1.2-6.4; p = .01); none of the homozygotes had severe hypertension. Hematologic measures were generally similar across the genotypes, but total lymphocyte counts were approximately 20% higher in CCR5-delta32/delta32 study subjects than in CCR5-+/+ study subjects (p < .05). Among patients with hemophilia who were infected with hepatitis C virus (HCV), mean alanine aminotransferase levels were 117% higher among CCR5-delta32/delta32 homozygotes (p < .05), but serum HCV levels did not differ by CCR5-delta32 genotype. CCR5-delta32/delta32 homozygous study subjects had a lower prevalence of antibodies to measles virus than those with other genotypes, but this association was not confirmed in a group of blood donors. The prevalence of antibodies to nine other common viruses, HBV, and HCV was not related to CCR5 genotype.

CONCLUSIONS

CCR5-delta32/delta32 homozygotes are generally similar to wild-type persons. Confirmatory investigations are required to determine whether hypertension, increased lymphocyte counts, and higher hepatic enzyme levels in the presence of HCV infection represent true phenotypic expressions of this genotype. CCR5-delta32/delta32 homozygosity does not provide broad protection against viral infections.