High-Purity Factor IX Concentrates for Treatment of Hemophilia B: Relative Purity and Thrombogenic Potential

Abstract

Constituents other than factor IX have been implicated as etiologic agents for thrombotic complications in patients receiving prothrombin complex concentrates (PCCs). In vitro studies, in vivo animal models, and clinical evaluations in patients with hemophilia B indicate that high-purity factor IX concentrates contain significantly fewer potentially thrombogenic contaminants than PCCs. A recent in vitro study from our laboratory used highly sensitive assays to analyze the relative purity of these newer products. The following products were studied using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and immunoblotting: Aimafix, AlphaNine-SD, Factor IX VHP, Immunine, Mononine, Nanotiv, and 9MC (now known as Replinine). The mean specific activity of the high-purity factor IX products ranged from 68 IU factor IX/mg (Aimafix) to 246 IU factor IX/mg (Mononine). SDS-PAGE analysis under reducing and nonreducing conditions showed that Mononine had the fewest contaminating bands. The immunoblot to detect factor IX showed a dominant factor IX band for all products, visible light chain of factor IX for all products except Aimafix, and another contaminating band visible at 49,500 daltons for all products except 9MC. High molecular weight contaminants were apparent for some products. Factor Vila was detected in some lots of Immunine, Nanotiv and 9MC. Factor X and prothrombin contaminated Aimafix, AlphaNine-SD, Factor IX VHP, Immunine, Nanotiv and 9MC. Thus, Mononine, Nanotiv and 9MC demonstrated the highest purity but no product was totally free of contaminants.

An open clinical study assessing the efficacy and safety of Factor IX Grifols®, a high‐purity Factor IX concentrate, in patients with severe haemophilia B

“…There was also no evidence that Factor IX Grifols Ò possesses an increased thrombogenicity as no clinical evidence of thrombotic events was noted in the patients during the follow-up period. Very probably, this can be ascribed to the high level of purity of Factor IX Grifols Ò and the absence of clotting factors other than FIX [1,2,23]. No anaphylactic reactions were reported and the product was observed to be effective throughout the study, with no inhibitor development during the entire follow-up.…”

Kinetics of factor IX activity differ from that of factor IX antigen in patients with haemophilia B receiving high‐purity factor IX replacement

“…Although these studies failed to demonstrate a signi®cant FIX receptor pool, they did demonstrate a phenomenon of progressive loss of biologic activity of the FIX protein after infusion of FIX concentrates. puri®cation steps have eliminated the thrombotic complications associated with their use [15,16].…”

Unusual case of coronary artery disease in a patient with severe hemophilia B

“…Hematologists should be aware of the fact that severe atherosclerosis can still occur in severe hemophilia [4]. Even high-purity factor IX can still contain pro-thrombotic activated factor impurities and can cause paradoxical venous thrombosis [11]. Vascular interventions, however, can be routinely undertaken with full factor replacement as for any normal patient [6].…”