Recombinant and plasma-derived factor VIII products conferred similar risks of inhibitor development, and the content of von Willebrand factor in the products and switching among products were not associated with the risk of inhibitor development. Second-generation full-length recombinant products were associated with an increased risk, as compared with third-generation products. (Funded by Bayer Healthcare and Baxter BioScience.).

In this population-based material from the five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), 2860 children below 15 years of age were diagnosed with acute lymphoblastic leukemia (ALL) from July 1981 to June 1998. The annual incidence was 3.9/100 000 children and was stable throughout the study period. The development from regional or national protocols to common Nordic treatment protocols for all risk groups was completed in 1992 through a successive intensification with multidrug chemotherapy, including pulses of methotrexate in high doses and avoidance of cranial irradiation in most children. The overall event-free survival (EFS) at 5 years has increased from 56.5 ± 1.7% in the early 1980s to 77.6 ± 1.4% during the 1990s. The main improvements were seen in children with non-high risk leukemia. In high-risk patients, progress has been moderate, especially in children with high WBC (у100 × 10 9 /l) at diagnosis. During the last time period (January 1992-June 1998), only 10% of the patients have received cranial irradiation in first remission, while 90% of the patients have received pulses of high dose methotrexate (5-8 g/m 2 ) isolated or combined with high-dose cytosine arabinoside (total dose 12 g/m 2 ) plus multiple intrathecal injections of methotrexate as CNS-targeted treatment, not translating into increased cumulative incidence of CNS relapse. Leukemia (2000) 14, 2267-2275.

Key Points• The inhibitor incidence in nonsevere hemophilia A patients with certain F8 mutations approaches the inhibitor incidence in severe patients.• These findings are highly relevant for clinical practice, as they facilitate identification of high-risk patients based on F8 genotype.Neutralizing antibodies (inhibitors) toward factor VIII form a severe complication in nonsevere hemophilia A, profoundly aggravating the bleeding pattern. Identification of high-risk patients is hampered by lack of data that take exposure days to therapeutic factor VIII concentrates into account. In the INSIGHT study, we analyzed the association between F8 mutation and inhibitor development in patients with nonsevere hemophilia A (factor VIII 2-40 IU/dL). This analysis included 1112 nonsevere hemophilia A patients from 14 centers in Europe and Australia that had genotyped at least 70% of their patients. Inhibitor risk was calculated as KaplanMeier incidence with cumulative number of exposure days as the time variable. During 44 800 exposure days (median, 24 exposure days per patient; interquartile range [IQR], 7-90), 59 of the 1112 patients developed an inhibitor; cumulative incidence of 5.3% (95% confidence interval [CI], 4.0-6.6) after a median of 28 exposure days (IQR,. The inhibitor risk at 50 exposure days was 6.7% (95% CI, 4.5-8.9) and at 100 exposure days the risk further increased to 13.3% (95% CI, 9.6-17.0). Among a total of 214 different F8 missense mutations 19 were associated with inhibitor development. These results emphasize the importance of F8 genotyping in nonsevere hemophilia A. (Blood. 2013; 122(11):1954-1962 IntroductionPatients with hemophilia A who are treated with factor VIII concentrates are at risk of developing factor VIII neutralizing alloantibodies (inhibitors).1,2 Inhibitor development is one of the most challenging complications in the treatment of hemophilia A, as it increases the bleeding tendency while it renders treatment with therapeutic factor VIII concentrates ineffective. Although inhibitor development is less frequently observed in patients with nonsevere hemophilia A (baseline factor VIII activity of 2-40 IU/dL), the clinical impact can be profound. In these patients, inhibitors may also interact with their endogenous factor VIII, resulting in a decrease of the factor VIII plasma level below 1 IU/dL 1 and major bleeding complications. 4 Identification of patients at risk of developing inhibitors may help to prevent this serious complication. However, currently there are no tools available to predict individual inhibitor risk in nonsevere hemophilia patients.The type of mutation in the factor VIII gene (F8) is an important risk factor for inhibitor development. [5][6][7] Nonsevere hemophilia A is generally caused by F8 missense mutations.8 Despite information on large numbers of F8 mutations associated with nonsevere hemophilia A that is collected in international databases, 9,10 it is not possible to calculate the inhibitor risk for specific F8 mutations, as data on exposure days to thera...

Adding pharmacologically guided treatment intensification to dose adjustments by blood counts may not be warranted for girls, whereas new approaches to optimize maintenance therapy are needed for boys.

Activated prothrombin complex concentrates have been used to treat bleeding episodes for patients who have developed an inhibitor to factor VIII (FVIII). FEIBA-Vh (FVIII bypassing activity, FEIBA) has been used since 1970 for this purpose and with FVIII for immune tolerance programmes. Studies have not been presented to show the safety and efficacy of FEIBA when given over a long period of time to prevent haemophilic arthropathy with bleeding into the joints of these patients. This study was undertaken to ascertain the outcome of haemophilic arthropathy with FEIBA prophylaxis. Data were collected on seven patients with known long-standing high-titre FVIII inhibitors given FEIBA prophylaxis for 3-6(1/2) years. Patients were given 50-100 units of FEIBA three to four times weekly. A functional joint evaluation revealed some degree of arthropathy already present in all patients at time of prophylaxis initiation. Safety was measured by medical status, evidence of thrombosis, life-threatening bleeding and inhibitor titre. Efficacy was measured for joint outcome by a functional physical therapeutic scale. At the conclusion of the study, efficacy was mixed as all of the joints for which the patients were placed on prophylaxis had progressed and developed synovitis. Two patients had a functional improvement in their arthropathy, and all were functional enough to attend regular school. The product was deemed safe for long-term use, as there were no complications of therapy with no thrombosis, no life-threatening bleeding episodes and no anamnesis caused by FEIBA alone. Inhibitor titres fell in all patients over the course of the study. Total product usage ranged from approximately 9373-15,571 U kg(-1) year(-1). FEIBA is safe for long-term prophylaxis when given in the recommended dosage for an extended period of time. Efficacy to prevent arthropathy could not be seen as all patients had some degree of arthropathy at time of prophylaxis initiation. An additional study needs to be performed using FEIBA before arthropathy has developed.