BeneFix

Limitation of Use

BeneFIX is not indicated for induction of immune tolerance in patients with hemophilia B [see Warnings and Precautions (5.3)].

Dose

Preparation and Reconstitution

The procedures below are provided as general guidelines for the preparation and reconstitution of BeneFIX.

Administration

For intravenous use after reconstitution only.

The safety and efficacy of administration by continuous infusion have not been established [see Warnings and Precautions (5.2)].

•

Inspect BeneFIX solution for particulate matter and discoloration prior to administration, whenever solution and container permit.

•

Administer BeneFIX using the tubing provided in this kit, and the pre-filled diluent syringe provided, or a single sterile disposable plastic syringe.

•

Do not mix or administer BeneFIX in the same tubing or container with other medicinal products.

Pregnancy

Lactation

Pediatric Use

Safety, efficacy, and pharmacokinetics of BeneFIX have been evaluated in previously treated (PTP) and previously untreated pediatric patients (PUP) [see Clinical Studies (14) and Adverse Reactions (6)]. On average, lower recovery, shorter half-life and higher clearance (based on kg body weight) have been observed in children younger than 12 years old [see Clinical Pharmacology (12.3)]. Dose adjustment may be needed [see Dosage and Administration (2.1)].

Geriatric Use

Clinical trials of BeneFIX did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Dose selection for an elderly patient should be individualized [see Dosage and Administration (2.1)].

Hypersensitivity Reactions

Hypersensitivity reactions, including anaphylaxis, have been reported with BeneFIX and have manifested as pruritus, rash, urticaria, hives, facial swelling, dizziness, hypotension, nausea, chest discomfort, cough, dyspnea, wheezing, flushing, discomfort (generalized) and fatigue. Frequently, these events have occurred in close temporal association with the development of factor IX inhibitors.

Closely monitor patients for signs and symptoms of acute hypersensitivity reactions, particularly during the early phases of initial exposure to product. Because of the potential for allergic reactions with factor IX concentrates, perform the initial (approximately 10 – 20) administrations of factor IX under medical supervision where proper medical care for allergic reactions could be provided. Advise patients to discontinue use of the product and contact their physician and/or seek immediate emergency care. Immediately discontinue the administration and initiate appropriate treatment if symptoms occur.

BeneFIX contains trace amounts of hamster (CHO) proteins. Patients treated with this product may develop hypersensitivity to these non-human mammalian proteins.

Thromboembolic Complications

There have been post-marketing reports of thrombotic events in patients receiving continuous-infusion BeneFIX through a central venous catheter, including life-threatening superior vena cava (SVC) syndrome in critically ill neonates [see Adverse Reactions (6.2)]. The safety and efficacy of BeneFIX administration by continuous infusion have not been established [see Dosage and Administration (2.1, 2.3)].

Nephrotic Syndrome

Nephrotic syndrome has been reported following immune tolerance induction with factor IX products in hemophilia B patients with factor IX inhibitors and a history of allergic reactions to factor IX. The safety and efficacy of using BeneFIX for immune tolerance induction have not been established.

Neutralizing Antibodies (Inhibitors)

Neutralizing antibodies (inhibitors) have been reported following administration of BeneFIX [see Adverse Reactions (6.1)]. Evaluate patients using BeneFIX for the development of factor IX inhibitors by appropriate clinical observations and laboratory tests. If expected plasma factor IX activity levels are not attained, or if bleeding is not controlled with an expected dose, perform an assay that measures factor IX inhibitor concentration.

Patients with factor IX inhibitors are at an increased risk of severe hypersensitivity reactions or anaphylaxis upon subsequent challenge with factor IX.2 Evaluate patients experiencing allergic reactions for the presence of an inhibitor and closely monitor patients with inhibitors for signs and symptoms of acute hypersensitivity reactions, particularly during the early phases of initial exposure to product [see Warnings and Precautions (5.1)].

Monitoring Laboratory Tests

•

Monitor patients for factor IX activity levels by the one-stage clotting assay to confirm that adequate factor IX levels have been achieved and maintained, when clinically indicated [see Dosage and Administration (2.1)].

•

Monitor patients for the development of inhibitors if expected plasma factor IX activity levels are not attained, or if bleeding is not controlled with the recommended dose of BeneFIX. Determine plasma factor IX inhibitor levels in Bethesda Units (BUs).

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

During uncontrolled, open-label clinical trials with BeneFIX conducted in PTPs, 113 adverse reactions with known or unknown relation to BeneFIX therapy were reported among 38.5% (25 of 65) of subjects (with some subjects reporting more than one event) who received a total of 7,573 infusions. These adverse reactions are summarized in Table 2.

In the 63 PUPs, who received a total of 5,538 infusions, 10 adverse reactions were reported among 9.5% of the patients (6 out of 63) having known or unknown relationship to BeneFIX. These events are summarized in Table 3.

In a multi-center, prospective, open-label clinical trial with BeneFIX administered at 100 IU/kg once weekly, 25 PTPs (exposed to a factor IX containing product for ≥100 exposure days) were evaluated, with 25 subjects treated for approximately 52 weeks. Common (≥5%) adverse reactions were headache (36%), fever (20%), and cough (8%). No subject was withdrawn from the trial due to an adverse reaction. In the trial, no inhibitors were detected and no thrombotic events or anaphylactic reactions were reported.

Postmarketing Experience

The following post-marketing adverse reactions have been reported for BeneFIX: inadequate factor IX recovery, inadequate therapeutic response, inhibitor development [see Clinical Pharmacology (12)], anaphylaxis [see Warnings and Precautions (5.1)], angioedema, dyspnea, hypotension, and thrombosis.

Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

There have been post-marketing reports of thrombotic events, including life-threatening SVC syndrome in critically ill neonates, while receiving continuous-infusion BeneFIX through a central venous catheter. Cases of peripheral thrombophlebitis and DVT have also been reported. In some, BeneFIX was administered via continuous infusion, which is not an approved method of administration [see Dosage and Administration (2)]. The safety and efficacy of BeneFIX administration by continuous infusion have not been established [see Warnings and Precautions (5.2)].

Mechanism of Action

BeneFIX temporarily replaces the missing clotting factor IX that is needed for effective hemostasis.

Pharmacodynamics

The activated partial thromboplastin time (aPTT) is prolonged in people with hemophilia B. Treatment with factor IX concentrate may normalize the aPTT by temporarily replacing the factor IX. The administration of BeneFIX increases plasma levels of factor IX, and can temporarily correct the coagulation defect in these patients.

Pharmacokinetics

In a randomized, cross-over pharmacokinetic study, BeneFIX reconstituted in 0.234% sodium chloride diluent was shown to be pharmacokinetically equivalent to the previously marketed BeneFIX (reconstituted with Sterile Water for Injection) in 24 previously treated patients (≥12 years) at a dose of 75 IU/kg. In addition, pharmacokinetic parameters were followed up in 23 previously treated patients after repeated administration of BeneFIX for six months and found to be unchanged compared with those obtained at the initial evaluation. A summary of pharmacokinetic data are presented in Table 4:

Pediatric Patients (<12 years)

A population pharmacokinetic model was developed using data collected in patients aged 7 months to 60 years who received single doses of BeneFIX ranging from 50 to 75 IU/kg. The parameters estimated using the final 2-compartment model are shown in Table 5. Infants and children had higher clearance, larger volume of distribution, shorter half-life and lower recovery than adolescents and adults.

Table 5: Mean ± SD Pharmacokinetic Parameters Derived from Population Pharmacokinetic Analysis

Age Group	Infants (<2 years)	Children 2 to <6 yr	Children 6 to <12 yr	Adolescents and Adults (≥12 years)
Abbreviations: SD = standard deviation; Vss = volume of distribution at steady-state.
Number of subjects	7	16	1	43
Clearance (mL/h/kg)	13.1 ± 2.1	13.1 ± 2.8	15.5	8.4 ± 2.4
Vss (mL/kg)	252 ± 35	257 ± 25	303	229 ± 57
Half-life (h)	15.6 ± 1.2	16.7 ± 1.9	16.3	23.1 ± 4.4
Recovery (IU/dL per IU/kg)	0.61 ± 0.10	0.60 ± 0.08	0.47	0.72 ± 0.19

Data from 57 PUP subjects who underwent repeat recovery testing for up to 60 months demonstrated that the average recovery was consistent over time, as shown in Figure 1.

Figure 1. Average Recovery over Time

Carcinogenesis, Mutagenesis, Impairment of Fertility

BeneFIX has been shown to be nonmutagenic in the Ames assay and non-clastogenic in a chromosomal aberrations assay. No investigations on carcinogenesis or impairment of fertility have been conducted.

On-demand Treatment and Control of Bleeding Episodes

Fifty-six PTPs and sixty-three PUPs were treated for bleeding episodes on an on-demand treatment and control of bleeds (see Tables 6 and 7). The PTPs were followed over a median interval of 24 months (mean 23.4 ± 5.3 months) and for a median of 83.5. The PUPs were followed over a median interval of 37 months (mean 38.1 ± 16.4 months) and for a median of 89 exposure days.

Fifty-five PTPs and fifty-four PUPs received BeneFIX for the treatment of bleeding episodes (see Table 6). Bleeding episodes that were managed successfully included hemarthrosis and bleeding in soft tissue and muscle. Data concerning the severity of bleeding episodes were not reported. In the PTPs, 88% of total infusions administrated for on-demand treatment were rated as an "excellent" or "good" response.

A total of 20 PTPs were treated with BeneFIX for secondary prophylaxis (the regular administration of FIX replacement therapy to prevent bleeding in patients who may have already demonstrated clinical evidence of hemophilic arthropathy or joint disease) at some regular interval during the trial with a mean of 2 infusions per week (see Table 7). Thirty-two PUPs were administered BeneFIX for routine (primary and secondary) prophylaxis (see Table 7). Twenty-four PUPs were administered BeneFIX at least twice weekly, and eight PUPs were administered BeneFIX once weekly. Seven PTPs experienced a total of 26 spontaneous bleeding episodes within 48 hours after an infusion. Six spontaneous bleeds within 48 hours after an infusion were reported in 5 PUPs. Prophylaxis therapy was rated as "excellent" or "effective" in 93% of PTPs receiving prophylaxis one to two times per week.

Perioperative Management

Management of hemostasis was evaluated in the surgical setting in both PTPs and PUPs (see Table 8 and Table 9). Thirty-six surgical procedures have been performed in 28 PTPs with 23 major surgical procedures performed (including 6 complicated dental extractions). Thirty surgical procedures have been performed in 23 PUPs. Twenty-eight of these procedures were considered minor. Hemostasis was maintained throughout the surgical period; however, one PTP subject required evacuation of a surgical wound-site hematoma, and another PTP subject who received BeneFIX after a tooth extraction required further surgical intervention due to oozing at the extraction site. There was no clinical evidence of thrombotic complications in any of the subjects.

Among the PTP surgery subjects, the median increase in circulating factor IX activity was 0.7 IU/dL per IU/kg infused (range 0.3–1.2 IU/dL; mean 0.8 ± 0.2 IU/dL per IU/kg). The median elimination half-life for the PTP surgery subjects was 19.4 hours (range 10–37 hours; mean 21.3 ± 8.1 hours).

Nine of the major surgical procedures were performed in 8 PUPs using a continuous-infusion regimen. Five of the surgical procedures were performed in PUPs using a continuous-infusion regimen over 3 to 5 days. Although circulating factor IX levels targeted to restore and maintain hemostasis were achieved with both pulse replacement and continuous infusion regimens, clinical trial experience with continuous infusion of BeneFIX for perioperative management in hemophilia B has been too limited to establish the safety and clinical efficacy of administration of the product by continuous infusion.

Routine Prophylaxis

In an open-label trial of 25 patients (age range 12–54 years) comparing on-demand treatment versus prophylaxis when administered at a dose of 100 IU/kg once weekly, the annualized bleed rate (ABR) for the prophylaxis period was significantly lower (p < 0.0001) than the ABR for the on-demand period (mean ± standard deviation (SD): 3.6 ± 4.6, median: 2.0, min–max: 0–13.8 versus mean: 32.9 ± 17.4, median: 33.6, min–max: 6.1–69.0, respectively).

In an open-label crossover trial in patients aged 6–64 years, of 100 IU/kg once weekly (44 patients) and 50 IU/kg twice weekly (43 patients) with 4-month treatment periods, the ABR for the 100 IU/kg once-weekly prophylaxis period was mean 4.4 ± 10.0 episodes per year (median: 0.0, min–max: 0 – 50.5) and mean 2.8 ± 5.7 (median: 0.0, min–max: 0 – 24.1) for the 50 IU/kg twice-weekly period. Six patients aged <12 years had mean ABR of 1.6 ± 1.7 (median: 1.5, min–max: 0–3.3) in the 100 IU/kg once-weekly period, and mean ABR of 0 ± 0 (median: 0, min–max: 0–0) in the 50 IU/kg twice-weekly period.