a University of Miami Hemophilia Treatment Center , Miami , Florida , USA. b CSL Behring , King of Prussia , USA. c Department of Transfusion Medicine , Nagoya University Hospital , Nagoya , Japan. d Division of Hematology and Central Hematology Laboratory , Lausanne University Hospital (CHUV) , Lausanne , Switzerland. e Meridian HealthComms , Cheshire , UK. f Foundation IRCCS Ca' Granda Maggiore Hospital Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center , Milan , Italy.
AIMS: Prophylaxis with standard-acting recombinant factor IX (rFIX) in hemophilia B patients requires frequent injections. Extended half-life (EHL) products allow for prolonged dosing intervals and so reduce this treatment burden. Three technologies are employed to extend the half-life of FIX; glycopegylation, Fc-fusion, and albumin fusion. rIX-FP is a novel albumin fusion protein, which allows for a prolonged dosing interval of
up to 14 days. A systematic review and indirect statistical comparison was performed to evaluate the efficacy of both EHL and standard-acting rFIX products compared with rIX-FP in Phase III trials for prophylaxis in adult hemophilia B patients. MATERIALS AND METHODS A systematic search was conducted in both EMBASE and PubMed to identify Phase III trials of prophylactic rFIX treatment in previously treated, hemophilia B patients aged ≥12 years (FIX: ≤2%). Annualized bleeding rate (ABR), spontaneous ABR (AsBR), and joint ABR (AjBR) data were extracted from each study. A z-test was performed using the mean of each parameter, and the mean difference in outcome between studies was calculated. RESULTS Seven articles investigating six rFIX products were identified. Median ABR, AsBR and AjBR ranged from 0-3.0, 0-1.0, and 0-1.1 (means 0.8-4.26, 0.13-2.6, and 0.34-2.85), respectively. rIX-FP achieved lowest median and mean values in all three parameters. Z-tests showed that mean ABR was significantly lower for rIX-FP 7-day prophylaxis compared with the majority of standard-acting and other EHL rFIX products. LIMITATIONS The low number of appropriate trials available for comparison limits the quantity of data available for comparison and restricts the use of methods of adjustment for variance in study design or patient characteristics. However, these limitations are shared with similar analyses published in this field. CONCLUSION This indirect comparison of Phase III trials indicates that rIX-FP efficacy compares favorably versus other rFIX products for prophylaxis in hemophilia B.