Pharmacotherapy of haemophilia A.

INTRODUCTION: Haemophilia A is due to factor VIII (FVIII) deficiency. The main treatment is replacement therapy with FVIII concentrates. However, these concentrates carried a high risk of blood-borne viral infections and still have a high risk of inducing anti-FVIII inhibitors. AREAS COVERED: An overview of products available and therapeutic options for haemophilia A management in order to help in decision making. A literature search using Medline with the keywords: 'haemophilia', 'factor VIII', 'therapy', 'inhibitor', 'concentrate', 'bleeding', 'prophylaxis', 'on demand', 'plasma-derived', 'recombinant', 'coagulation factors', 'immunotolerance' was performed. The years 1960 - 2010 are included. EXPERT OPINION: Progress in management of patients with haemophilia A has allowed increased life expectancy and quality of life. There is evidence that prophylaxis prevents or, at least, slows down arthropathy development when started early in childhood. FVIII concentrates have achieved high levels of blood-borne pathogen safety. However, treatment is frequently complicated by development of FVIII-neutralizing inhibitors, which prevent control of bleeding and predispose to a high morbidity and mortality risk. Bypassing agents are effective in bleeding treatment in a high percentage of cases. Prophylaxis with bypassing agents and their use in combination are offering opportunities in management of inhibitor patients. More evidence is necessary to understand how to prevent and manage this complication.

Long-term safety and feasibility of arteriovenous fistulae as vascular accesses in children with haemophilia: a prospective study.

Infectious and thrombotic complications limit the long-term use of subcutaneous ports as venous accesses for children with haemophilia. This study has evaluated for the first time the safety and feasibility of internal arteriovenous fistulae (AVF) as alternative accesses. During the 3-year study period, 27 severe haemophiliacs, 14 with factor VIII inhibitors (52%), underwent the creation of 31 proximal AVF in the forearm. Mild forearm haematomas were observed after five procedures (16%) in five patients who had or developed inhibitors after surgery. Inadequate AVF maturation was observed after five of 31 procedures (16%) in four children. AVF were first accessed after a median of 42 d and regularly used at home by 26 patients (96%) for a median follow-up period of 29 months. Thrombosis of a venous branch occurred in one AVF (3%) after 9 months of uncomplicated use in a child with inhibitor who spontaneously recovered from the symptoms and still used AVF for nine additional months. Mild symptoms, referable to distal ischaemia, were transiently reported by two children (7%) who needed no remedial intervention. This study demonstrates that the use of AVF in haemophiliacs enabled long-term treatment at home in all patients but one.

Identification of immunodominant epitopes in inactivated Tat-vaccinated healthy and HIV-1-infected volunteers.

We analyzed the epitopes and the molecular forms of Tat recognized by the antibodies raised by Tat-toxoid vaccination in both healthy and HIV-infected volunteers. Tat-toxoid-vaccinated healthy volunteer sera reacted predominantly with peptides covering amino acids 1 through 24 and 46 through 60, corresponding to the N-terminus and basic domains of Tat. In contrast, whereas all sera from vaccinated HIV-1-positive patients reacted with the N-terminus and (with a single exception) with the basic domain, most of these sera also recognized peptides encompassing distinct domains of Tat, particularly the C-terminus (79-86). The sera of vaccinated individuals recognized both monomeric and oligomeric forms of Tat 1 through 86 or of Tat 1 through 101 and also blocked the ability of cell-released extracellular Tat to transactivate the HIV-1 LTR promoter. Synthetic Tat preincubated with sera from vaccinated individuals lost its functional activity as well. This is probably because of its inability to enter the cells as a result of immune complex formation with anti-Tat IgG. These data demonstrate that Tat-toxoid vaccination induces an efficient antibody response blocking the functional activity of Tat.