Efficacy of Human Fibrinogen Concentrate for on-Demand Treatment of Acute Bleeding and to Prevent Bleeding during and after Surgery in Subjects with Congenital Fibrinogen Deficiency

Patients with congenital afibrinogenaemia and hypofibrinogenaemia, frequently experience severe bleeding episodes starting already at birth or during early childhood. Bleeding may occur after a minor trauma or a surgical intervention into the skin, mucosa, muscles, gastrointestinal tract, or the brain. Therapeutic substitution with human fibrinogen concentrate (HFC) corrects the haemostatic defect and arrests bleeding in these patients. Octafibrin (Octapharma OPG, Vienna, Austria) is a plasma-derived, highly purified, lyophilized fibrinogen concentrate with two dedicated virus inactivation/removal steps was used in this study.

This study was prospective, open-label and multinational, in adult and adolescent a- or hypofibrinogenemic patients, to investigate the safety and efficacy of Octafibrin a new HFC in the treatment of on-demand bleeding (BE) and surgical prophylaxis.

A planned interim analysis comprises data of 11 adult and 2 adolescent patients. Efficacy was assessed using a 4 point objective scale completed by the investigator and adjudicated by an independent data monitoring and endpoint adjudication committee (IDMEAC) for each bleeding or surgical episode.

Eleven of the 13 patients experienced a total of 23 minor BEs. Sixteen BEs (69.6%) were spontaneous and 7 (30.4%) were traumatic. A majority of BEs (21/23) required one HFC infusion (91.3%) and 2 (8.7%) BEs required two infusions. The median (range) dose of HFCadministered for the treatment of all BEs was 57.5 mg/kg (33.9-71.4 mg/kg) per infusion and 58.8 mg/kg (33.9-101.7 mg/kg) per BE.

The success rate (efficacy rating of excellent or good) for all BEs was 100% (90% CI: 0.88, 1.00) as adjudicated by the IDMEAC (all excellent).

Maximum clot firmness (MCF) using thromboelastometry (ROTEM^®) performed in plasma was also determined for the first infusions administered for the treatment of all 23 BEs in the 11 BE patients. The mean (±SD) change in MCF from baseline (MCF 0) to 1 hour after the first infusion of HFCwas 6.5 mm (±2.0) (95% CI: 5.65, 7.40; p<0.0001). This significant overall increase in MCF from baseline coincided with the 100% haemostatic efficacy for all BEs.

Four patients underwent 4 surgeries (3 major 1 minor, two of these patients were treated for both BE and surgery). The post-operative success rate (haemostatic efficacy excellent or good) was 100% (90% CI 0.5, 1.0), as assessed by the investigator and the IDMEAC.

There have been no reports of serious adverse events related to the infusion of the HFC.

In conclusion this study showed 100% hemostatic efficacy in on-demand treatment with HFC in bleeding patients with congenital fibrinogen deficiency. Also hemostatic efficacy in surgical prophylaxis in 4 patients was rated excellent/good. Maximum clot firmness values showed a statistically significant increase from baseline to 1 hour post-infusion in all patients after HFCadministrations reflecting the successful treatment of bleeding events. There were no related serious adverse events, no thromboembolic events, no allergic or severe hypersensitivity reactions, and no anti-fibrinogen antibodies that developed during the study.