Patients with severe hemophilia A and factor VIII inhibitors are at increased risk for serious bleeding complications and progression to end-stage joint disease. Effective strategies to prevent bleeding in such patients have not yet been established.
We enrolled patients with hemophilia A who were older than 2 years of age, had high-titer inhibitors, and used concentrates known as bypassing agents for bleeding in a prospective, randomized, crossover study comparing 6 months of anti-inhibitor coagulant complex (AICC), infused prophylactically at a target dose of 85 U per kilogram of body weight (±15%) on 3 nonconsecutive days per week, with 6 months of on-demand therapy (AICC at a target dose of 85 U per kilogram [±15%] used for bleeding episodes). The two treatment periods were separated by a 3-month washout period, during which patients received on-demand therapy for bleeding. The primary outcome was the number of bleeding episodes during each 6-month treatment period.
Thirty-four patients underwent randomization; 26 patients completed both treatment periods and could be evaluated per protocol for the efficacy analysis. As compared with on-demand therapy, prophylaxis was associated with a 62% reduction in all bleeding episodes (P<0.001), a 61% reduction in hemarthroses (P<0.001), and a 72% reduction in target-joint bleeding (≥3 hemarthroses in a single joint during a 6-month treatment period) (P<0.001). Thirty-three randomly assigned patients received at least one infusion of the study drug and were evaluated for safety. One patient had an allergic reaction to the study drug.
AICC prophylaxis at the dosage evaluated significantly and safely decreased the frequency of joint and other bleeding events in patients with severe hemophilia A and factor VIII inhibitors. (Funded by Baxter BioScience; Pro-FEIBA ClinicalTrials.gov number, NCT00221195.).
"Once FVIII inhibitors have developed, routine supplementation with exogenous FVIII will be no longer effective and the usage of exogenous FVIII for treating on-going bleeds is restricted. In such cases, alternative agents, such as activated factor VII and activated prothrombin complex concentrate, which are more expensive and have less stable hemostatic effects, need to be used to control bleeding , . Therefore, a new agent that resolves these drawbacks of exogenous FVIII is awaited in the field of the bleeding prophylaxis of severe hemophilia A. "
[Show abstract][Hide abstract] ABSTRACT: In hemophilia A, routine prophylaxis with exogenous factor VIII (FVIII) requires frequent intravenous injections and can lead to the development of anti-FVIII alloantibodies (FVIII inhibitors). To overcome these drawbacks, we screened asymmetric bispecific IgG antibodies to factor IXa (FIXa) and factor X (FX), mimicking the FVIII cofactor function. Since the therapeutic potential of the lead bispecific antibody was marginal, FVIII-mimetic activity was improved by modifying its binding properties to FIXa and FX, and the pharmacokinetics was improved by engineering the charge properties of the variable region. Difficulties in manufacturing the bispecific antibody were overcome by identifying a common light chain for the anti-FIXa and anti-FX heavy chains through framework/complementarity determining region shuffling, and by pI engineering of the two heavy chains to facilitate ion exchange chromatographic purification of the bispecific antibody from the mixture of byproducts. Engineering to overcome low solubility and deamidation was also performed. The multidimensionally optimized bispecific antibody hBS910 exhibited potent FVIII-mimetic activity in human FVIII-deficient plasma, and had a half-life of 3 weeks and high subcutaneous bioavailability in cynomolgus monkeys. Importantly, the activity of hBS910 was not affected by FVIII inhibitors, while anti-hBS910 antibodies did not inhibit FVIII activity, allowing the use of hBS910 without considering the development or presence of FVIII inhibitors. Furthermore, hBS910 could be purified on a large manufacturing scale and formulated into a subcutaneously injectable liquid formulation for clinical use. These features of hBS910 enable routine prophylaxis by subcutaneous delivery at a long dosing interval without considering the development or presence of FVIII inhibitors. We expect that hBS910 (investigational drug name: ACE910) will provide significant benefit for severe hemophilia A patients.
PLoS ONE 02/2013; 8(2):e57479. DOI:10.1371/journal.pone.0057479 · 3.23 Impact Factor
"Uncertainty continues about the ITI product source, timing, dosing regimen, and the use of immune modulation. There is also new evidence to support the use of prophylaxis with a bypassing agent in patients with inhibitors, although it is unclear which inhibitor patients are the best candidates for this therapy [Konkle et al. 2007; Leissinger et al. 2011a; Young et al. 2011]. While significant progress has been made in the care of patients with inhibitors there remain many unanswered questions. "
[Show abstract][Hide abstract] ABSTRACT: Factor VIII (FVIII) replacement therapy is the foundation of treatment in hemophilia A and is effective unless a patient develops an alloantibody (inhibitor) against exogenous FVIII. Inhibitor development is currently the most significant treatment complication seen in patients with hemophilia and is associated with considerable morbidity and a decreased quality of life. The development of an inhibitor is the result of a complex interaction between a patient's immune system and genetic and environmental risk factors. The mainstay of treatment is the eradication of the inhibitor through immune tolerance. This review summarizes the current evidence regarding inhibitor risk factors, eradication, and hemostatic bypassing agents.
[Show abstract][Hide abstract] ABSTRACT: Intracranial haemorrhage (ICH) is the most serious bleeding symptom in haemophiliacs, resulting in high rates of mortality and disabling sequelae. The Association of Italian Haemophilia Centres carried out a retrospective survey (1987-2008) of ICH occurring in haemophiliacs with the goals to establish: (i) incidence, location of bleeding, death rate and disabling sequels; (ii) risk factors for ICH; and (iii) treatment used during the acute phase of ICH and for recurrence prevention. A total of 112 ICH episodes had occurred in 88 patients (78 haemophilia A, 10 haemophilia B), 24 of whom experienced recurrences. The cumulative hazard of ICH for the whole cohort over the entire follow-up period was 26.7 per 1000 patients, and the annualized rate of ICH was 2.50 events per 1000 patients (95% CI 1.90-3.31). The risk of ICH was higher in the youngest children (24.4 per 1000, 95% CI 12.7-47.0 in the first year of age and 14.9, 95% CI 7.1-31.4 in the second year of age) and then progressively rose again after the age of 40. Univariate, bivariate (age-adjusted) and multivariate analysis investigating the effects of patient characteristics on ICH occurrence showed that haemophilia severity and inhibitor status were strongly associated with ICH [severe vs. mild, HR 3.96 (2.39-6.57); inhibitor vs. non-inhibitor 2.52 (1.46-4.35)]. HCV infection was also associated with the risk of ICH [HR 1.83 (1.25-2.69)]. Therapeutic suggestions based upon our experience to control ICH recurrence are provided.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.