Phase I, Randomized, Double-Blind, Placebo-Controlled, Single-Dose Escalation Study of the rFVIIa Variant (BAY 86–6150) In Hemophilia A or B with or without Inhibitors.

Abstract 3679

Bleeding episodes in hemophilia A or B patients with inhibitors to factors VIII or IX are commonly managed with bypassing agents such as recombinant factor VIIa (rFVIIa). However, currently available rFVIIa treatment is associated with variable response rates and a short elimination half-life, often necessitating the administration of multiple doses to control bleeding. BAY 86–6150, a human rFVIIa variant, was developed to provide a longer-acting and more potent activated factor VII in the management of bleeding episodes in patients with hemophilia who developed inhibitors.

The safety, tolerability, pharmacodynamic/pharmacokinetic (PD/PK) profiles, and immunogenicity of BAY 86–6150 in nonbleeding patients with hemophilia was investigated in a phase I, randomized, double-blind, placebo-controlled, single-dose escalation study. The patient population comprised nonbleeding men aged 18–65 years with moderate or severe hemophilia A or B with or without inhibitors. 16 patients were randomized 3:1 to escalating doses of BAY 86–6150 at 6.5, 20, 50, or 90 μg/kg (n=3 each) or placebo (n=4). Patients were followed for 50 days postdose. The objective of the trial was to evaluate the safety and tolerability of BAY 86–6150, with adverse events (AEs) as the primary endpoint. Other endpoints included PK parameters, the effects of BAY 86–6150 on hemostasis markers and coagulation, and the immunogenicity of the compound. BAY 86–6150 was not associated with clinically significant AEs or dose-limiting toxicities and the PK parameters were linear over the dose range, with a half-life of 5–7 hours. Patients demonstrated consistent, dose-dependent thrombin generation ex-vivo in platelet-poor plasma (mean peak effect 26–237 nM thrombin from 6.5–90 μg/kg). Peak thrombin levels over time paralleled the presence of BAY 86–6150 by PK analysis, indicating that the drug in circulation retained activity. There were corresponding decreases in time and duration in the activated partial thromboplastin and prothrombin time testing. In contrast, there was no dose response seen in the thrombogenicity markers evaluated including antithrombin III, prothrombin fragment 1+2, TAT, and D-dimer.

One patient demonstrated antibody activity to both BAY 86–6150 and to rVIIa as determined by ELISA testing at baseline. The level of inhibition and titer remained constant when evaluated in follow-up on day 29 and day 49.

The data safety monitoring board recommended progression to the highest proposed dose (90 μg/kg). The phase II/III studies are designed to evaluate the clinical efficacy and safety as well as corresponding laboratory markers. Results of the present study suggest that the novel rFVIIa agent BAY 86–6150 is safe and has increased potency and a longer half-life compared with the currently available rFVIIa therapy. BAY 86–6150 may therefore have the potential to improve the treatment of bleeding episodes in hemophilic patients with inhibitors.