In a multicenter, open-label, prospective, randomized clinical trial comparing subjects receiving FEIBA for prophylaxis with subjects receiving FEIBA for on-demand treatment, 36 hemophilia A and B subjects with inhibitors to factor VIII or IX were analyzed in the intent-to-treat analysis. Study population included 29 (80.6%) Caucasian, 3 (8.3%) Asian, 2 (5.6%) Black/African American, and 2 (5.6%) other. Inclusion criteria were subjects with a history of high titer inhibitors or low titer refractory to increased factor VIII or IX dosing, age range between 4 and 65, and subjects receiving bypassing agents with ≥12 bleeds in the 12 months prior to trial entry. Subjects with a history of thromboembolic events, symptomatic liver disease, or a platelet count <100,000 per mL, and those receiving immune tolerance induction or routine prophylaxis were excluded.
Subjects were randomized to receive 12 months of prophylactic or on-demand treatment with FEIBA. Seventeen subjects randomized to the prophylaxis arm received 85 units per kg of FEIBA every other day. Nineteen subjects randomized to the on-demand arm received FEIBA for the treatment of acute bleeding episodes per the dose and dosing regimen recommended. Target joints were defined as ≥4 bleeding episodes within 6 months. In this trial, ankles, knees, elbows and hips were target joint locations. Preexisting target joints were not considered as new target joints.
Hemostatic efficacy for treatment of acute bleeds was evaluated at 6 and 24 hours according to a pre-specified four-point scale of excellent, good, fair, or none. An evaluation of "none" was considered a treatment failure. The criteria for evaluation of the effectiveness were relief of pain, cessation of bleeding, and number of infusions required to treat a bleed.
A total of 825 bleeding episodes were reported including 196 that occurred during prophylaxis and 629 that occurred during on-demand therapy. A majority (78%) of the 794 bleeding episodes that were rated for efficacy were treated with 1 or 2 infusions. Hemostatic efficacy was rated as excellent or good for 74% of bleeding episodes rated at 6 hours post infusion and for 87% of the bleeding episodes at 24 hour post infusion. A total of 19 (2.4%) bleeds were rated as "none" at 6 hours post infusion; 1 bleed (0.1%) was rated "none" at 24 hours.
Hemostatic efficacy for routine prophylaxis was evaluated against subjects who received on-demand therapy.
The overall median annual bleed rate (ABR) for the on-demand arm was 28.7 compared to 7.9 for the prophylaxis arm, which represents a 72% reduction in median ABR with prophylaxis. When analyzed by site (e.g. joint, non-joint) and cause of bleed (e.g. spontaneous, traumatic), prophylactic treatment with FEIBA resulted in a greater than 50% reduction in ABR. There were fewer subjects in the prophylaxis arm who developed new target joints (7 new target joints in 5 subjects treated with prophylaxis compared to 23 new target joints in 11 subjects in the on-demand arm). Target joints developed in two subjects in the on-demand arm and three in the prophylaxis arm who did not have reported target joints at trial enrollment. A total of 3 of 17(18%) subjects had no bleeding episodes on prophylaxis. In the on-demand arm, all subjects experienced a bleeding episode.
ABR by age category between on-demand and prophylaxis regimens is provided in Table 4. One adolescent subject on prophylaxis had a higher rate of bleeding possibly due to increased physical activity after study enrollment.
Table 4: ABR by Age Category| Age Category | On-Demand | Prophylaxis |
|---|
| Number of Subjects | ABR Median | Number of Subjects | ABR Median |
|---|
Children (≥7 to <12 years old) | 2 | 39.3 | 2 | 7.7 |
Adolescent (≥12 to <16 years old) | 2 | 30.9 | 3 | 27.5 |
Adult (≥16 years old) | 15 | 23.9 | 12 | 6.9 |