5 WARNINGS AND PRECAUTIONS
5.1 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.
5.2 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)].
5.3 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.
5.4 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)].
5.5 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 factor IX activity plasma levels are not attained, or if bleeding is not controlled with the recommended dose of BeneFIX. Determine factor IX inhibitor levels in Bethesda Units (BUs).
6 ADVERSE REACTIONS
The most serious adverse reactions are systemic hypersensitivity reactions, including bronchospastic reactions and/or hypotension and anaphylaxis and the development of high-titer inhibitors necessitating alternative treatments to factor IX replacement therapy.
The most common adverse reactions observed in clinical trials (frequency > 5% of PTPs or PUPs) were headaches, dizziness, nausea, injections site reaction, injection site pain and skin-related hypersensitivity reactions (e.g., rash, hives).
6.1 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 studies with BeneFIX conducted in previously treated patients (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.
|Body System||Adverse Reaction||Number of patients (%)|
|Blood and lymphatic system disorders||Factor IX inhibition†||1 (1.5%)|
|Eye disorders||Blurred vision||1 (1.5%)|
|Gastrointestinal disorders||Nausea||4 (6.2%)|
|General disorders and administration site conditions||Injection site reaction||5 (7.7%)|
|Injection site pain||4 (6.2%)|
|Infections and infestations||Cellulitis at IV site||1 (1.5%)|
|Phlebitis at IV site||1 (1.5%)|
|Nervous system disorders||Headache||7 (10.8%)|
|Taste perversion (altered taste)||3 (4.6%)|
|Renal and urinary disorders||Renal infarct‡||1 (1.5%)|
|Respiratory, thoracic and mediastinal disorders||Dry cough||1 (1.5%)|
|Chest tightness||1 (1.5%)|
|Skin and subcutaneous disorders||Rash||4 (6.2%)|
|Vascular disorders||Flushing||2 (3.1%)|
In the 63 previously untreated patients (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.
|Body System||Adverse Reaction||Number of Patients (%)|
|Blood and lymphatic system disorders||Factor IX inhibition†||2 (3.2%)|
|General disorders and administration site conditions||Injection site reaction||1 (1.6%)|
|Respiratory, thoracic and mediastinal disorders||Dyspnea (respiratory distress)||2 (3.2%)|
|Skin and subcutaneous disorders||Hives||3 (4.8%)|
In clinical studies with 65 PTPs (defined as having more than 50 exposure days), a low-titer inhibitor was observed in one patient. The inhibitor was transient, the patient continued on study and had normal factor IX recovery pharmacokinetics at study completion (approximately 15 months after inhibitor detection).
In clinical studies with pediatric PUPs, inhibitor development was observed in 2 out of 63 patients (3.2%), both were high-titer (> 5 BU) inhibitors detected after 7 and 15 exposure days, respectively. Both patients were withdrawn from the study.
The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to BeneFIX with the incidence of antibodies to other products may be misleading.
All subjects participating in the PTP, PUP and surgery studies were monitored for clinical evidence of thrombosis. No thrombotic complications were reported in PUPs or surgery subjects. One PTP subject experienced a renal infarct (see Table 2). Laboratory studies of thrombogenecity (fibrinopeptide A and prothrombin fragment 1 + 2) were obtained in 41 PTPs and 7 surgery subjects prior to infusion and up to 24 hours following infusion. The results of these studies were inconclusive. Out of 29 PTP subjects noted to have elevated fibrinopeptide A levels post-infusion of BeneFIX, 22 also had elevated levels at baseline. Surgery subjects showed no evidence of significant increase in coagulation activation.
6.2 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)].
1 INDICATIONS AND USAGE
BeneFIX®, Coagulation Factor IX (Recombinant), is a human blood coagulation factor indicated in adult and pediatric patients with hemophilia B (congenital factor IX deficiency or Christmas disease) for:
- control and prevention of bleeding episodes
- peri-operative management
Limitations of Use
BeneFIX is NOT indicated for:
- treatment of other factor deficiencies (e.g., factors II, VII, VIII, and X),
- treatment of hemophilia A patients with inhibitors to factor VIII,
- reversal of coumarin-induced anticoagulation,
- treatment of bleeding due to low levels of liver-dependent coagulation factors.