AFSTYLA(Antihemophilic Factor (Recombinant))
HIGHLIGHTS OF PRESCRIBING INFORMATION
These highlights do not include all the information needed to use AFSTYLA safely and effectively. See full prescribing information for AFSTYLA.
AFSTYLA ®, Antihemophilic Factor (Recombinant), Single Chain
For Intravenous Injection, Powder and Solvent for Injection
Initial U.S. Approval: 2016
INDICATIONS AND USAGE
AFSTYLA, Antihemophilic Factor (Recombinant), Single Chain, is a recombinant, antihemophilic factor indicated in adults and children with hemophilia A (congenital Factor VIII deficiency) for:
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On-demand treatment and control of bleeding episodes,
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Routine prophylaxis to reduce the frequency of bleeding episodes,
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Perioperative management of bleeding.
Limitation of Use
AFSTYLA is not indicated for the treatment of von Willebrand disease (1).
DOSAGE AND ADMINISTRATION
For intravenous use after reconstitution only.
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Each vial of AFSTYLA is labeled with the amount of recombinant Factor VIII in international units (IU or unit). One unit per kilogram body weight will raise the Factor VIII level by 2 IU/dL. (2.1)
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Plasma Factor VIII levels can be monitored using either a chromogenic assay or a one-stage clotting assay – routinely used in US clinical laboratories. If the one-stage clotting assay is used, multiply the result by a conversion factor of 2 to determine the patient's Factor VIII activity level. (2.1, 5.3)
Calculating Required Dose: (2.1)
Dose (IU) = Body Weight (kg) × Desired Factor VIII Rise (IU/dL or % of normal) × 0.5 (IU/kg per IU/dL)
Routine Prophylaxis: (2.1)
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Adults and adolescents (≥12 years): The recommended starting regimen is 20 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly.
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Children (<12 years): The recommended starting regimen is 30 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly. More frequent or higher doses may be required in children <12 years of age to account for the higher clearance in this age group.
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The regimen may be adjusted based on patient response.
Perioperative Management: (2.1)
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Ensure the appropriate Factor VIII activity level is achieved and maintained.
DOSAGE FORMS AND STRENGTHS
AFSTYLA is available as a white or slightly yellow lyophilized powder supplied in single-use vials containing nominally 250, 500, 1000, 2000, or 3000 International Units (IU). (3)
CONTRAINDICATIONS
Do not use in patients who have had life-threatening hypersensitivity reactions, including anaphylaxis to AFSTYLA or its excipients, or hamster proteins. (4)
WARNINGS AND PRECAUTIONS
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Hypersensitivity reactions, including anaphylaxis, are possible. Should symptoms occur, immediately discontinue AFSTYLA and administer appropriate treatment. (5.1)
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Development of Factor VIII neutralizing antibodies (inhibitors) can occur. If expected plasma Factor VIII activity levels are not attained, or if bleeding is not controlled with an appropriate dose, perform an assay that measures Factor VIII inhibitor concentration. (5.2)
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If the one-stage clotting assay is used, multiply the result by a conversion factor of 2 to determine the patient's Factor VIII activity level. (5.3)
ADVERSE REACTIONS
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The most common adverse reactions reported in clinical trials (>0.5% of subjects) were dizziness and hypersensitivity. (6)
To report SUSPECTED ADVERSE REACTIONS, contact the CSL Behring Pharmacovigilance Department at 1-866-915-6958 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
USE IN SPECIFIC POPULATIONS
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Pediatric: Clearance (based on per kg body weight) is higher in pediatric patients 0 to <12 years of age. Higher and/or more frequent dosing may be needed. (8.4)
See 17 for PATIENT COUNSELING INFORMATION and FDA-approved patient labeling.
Revised: 5/2016
FULL PRESCRIBING INFORMATION: CONTENTS*
1 INDICATIONS AND USAGE
AFSTYLA, Antihemophilic Factor (Recombinant), Single Chain is a recombinant, antihemophilic factor indicated in adults and children with hemophilia A (congenital Factor VIII deficiency) for:
-
On-demand treatment and control of bleeding episodes,
-
Routine prophylaxis to reduce the frequency of bleeding episodes,
-
Perioperative management of bleeding.
Limitation of Use
AFSTYLA is not indicated for the treatment of von Willebrand disease.
2 DOSAGE AND ADMINISTRATION
For intravenous use after reconstitution only.
2.1 Dosing Guidelines
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Dose and duration of treatment depend on the severity of the Factor VIII deficiency, the location and extent of bleeding, and the patient's clinical condition.
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Each vial of AFSTYLA states the actual amount of Factor VIII activity in International Units (IU) as determined by chromogenic assay. One IU corresponds to the activity of Factor VIII contained in 1 milliliter (mL) of normal human plasma.
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Plasma Factor VIII levels can be monitored using either a chromogenic assay or a one-stage clotting assay – routinely used in US clinical laboratories. If the one-stage clotting assay is used, multiply the result by a conversion factor of 2 to determine the patient's Factor VIII activity level [see Warnings and Precautions (5.3)].
Calculating Required Dose
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The calculation of the required dose of Factor VIII is based on the empirical finding that 1 IU Factor VIII per kg body weight raises the plasma Factor VIII level by 2 IU/dL.
The expected in vivo peak increase in Factor VIII level expressed as IU/dL (or % of normal) is estimated using the following formula:
Estimated Increment of Factor VIII (IU/dL or % of normal) = [Total Dose (IU)/body weight (kg)] × 2 (IU/dL per IU/kg)
The dose to achieve a desired in vivo peak increase in Factor VIII level may be calculated using the following formula:
Dose (IU) = body weight (kg) × Desired Factor VIII rise (IU/dL or % of normal) × 0.5 (IU/kg per IU/dL)
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The amount of AFSTYLA to be administered and the frequency of administration should always be oriented to the clinical effectiveness in the individual case.
On-demand Treatment and Control of Bleeding Episodes
A guide for dosing AFSTYLA in the treatment and control of bleeding episodes is provided in Table 1. Consideration should be given to maintaining a Factor VIII activity at or above the target range.
Routine Prophylaxis
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Adults and adolescents (≥12 years): The recommended starting regimen is 20 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly.
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Children (<12 years): The recommended starting regimen is 30 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly. More frequent or higher doses may be required in children <12 years of age to account for the higher clearance in this age group [see Clinical Pharmacology (12.3)].
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The regimen may be adjusted based on patient response.
Perioperative Management of Bleeding
A guide for dosing AFSTYLA during surgery (perioperative management of bleeding) is provided in Table 2. Consideration should be given to maintaining a Factor VIII activity at or above the target range.
2.2 Preparation and Reconstitution
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Reconstitute AFSTYLA using aseptic technique with diluent provided in the kit.
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Visually inspect the reconstituted solution for particulate matter prior to administration. The solution should be free from visible particles. Do not use if particulate matter is observed.
The procedures provided in Table 3 are general guidelines for the preparation and reconstitution of AFSTYLA.
2.3 Administration
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Use aseptic technique when administering AFSTYLA.
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Do not mix AFSTYLA with other medicinal products.
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Administer by intravenous injection. The rate of administration should be determined by the patient's comfort level. Do not exceed infusion rate of 10 mL per minute.
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Administer AFSTYLA at room temperature within 4 hours after reconstitution.
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AFSTYLA is for single use only. Following administration, discard any unused solution and all administration equipment in an appropriate manner as per local requirements.
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If a central venous access device (CVAD) is required, risk of CVAD-related complications including local infections, bacteremia and catheter site thrombosis should be considered.
3 DOSAGE FORMS AND STRENGTHS
AFSTYLA is available as a white or slightly yellow lyophilized powder supplied in single-use vials containing nominally 250, 500, 1000, 2000, or 3000 IU. The actual potency is labeled on each AFSTYLA vial and carton.
4 CONTRAINDICATIONS
AFSTYLA is contraindicated in patients who have had life-threatening hypersensitivity reactions, including anaphylaxis to AFSTYLA or its excipients (e.g., polysorbate 80) [see Description (11)], or hamster proteins [see Warnings and Precautions (5.1)].
5 WARNINGS AND PRECAUTIONS
5.1 Hypersensitivity Reactions
Allergic-type hypersensitivity reactions, including anaphylaxis, are possible with AFSTYLA. Inform patients of the early signs of hypersensitivity reactions that may progress to anaphylaxis (including hives, generalized urticaria, tightness of the chest, wheezing, hypotension and pruritus). Immediately discontinue administration and initiate appropriate treatment if hypersensitivity reactions occur.
For patients with previous hypersensitivity reactions, consider premedication with antihistamines.
5.2 Neutralizing Antibodies
Formation of neutralizing antibodies (inhibitors) to Factor VIII can occur following administration of Factor VIII products. Monitor patients for the development of neutralizing antibodies (inhibitors) by appropriate clinical observations and laboratory tests. If expected plasma Factor VIII activity levels are not attained, or if bleeding is not controlled after AFSTYLA administration, the presence of an inhibitor (neutralizing antibody) should be suspected [see Warnings and Precautions (5.3)].
Contact a specialized hemophilia treatment center if a patient develops an inhibitor.
5.3 Monitoring Laboratory Tests
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Monitor plasma Factor VIII activity in patients receiving AFSTYLA using either the chromogenic assay or the one-stage clotting assay, which is routinely used in US clinical laboratories. The chromogenic assay result most accurately reflects the clinical hemostatic potential of AFSTYLA and is preferred. The one-stage clotting assay result underestimates the Factor VIII activity level compared to the chromogenic assay result by approximately one-half. If the one-stage clotting assay is used, multiply the result by a conversion factor of 2 to determine the patient's Factor VIII activity level. Incorrect interpretation of the Factor VIII activity obtained by the one-stage clotting assay could lead to unnecessary additional dosing, higher chronic dosing, or investigations for an inhibitor.
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Monitor for the development of Factor VIII inhibitors. Perform a Bethesda inhibitor assay if expected plasma Factor VIII activity levels are not attained or if bleeding is not controlled with the expected dose of AFSTYLA. Use Bethesda Units (BU) to report inhibitor levels.
6 ADVERSE REACTIONS
The most common adverse reactions (>0.5% of subjects) reported in clinical trials were dizziness and hypersensitivity.
6.1 Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of one drug cannot be directly compared to rates in clinical trials of another drug and may not reflect the rates observed in practice.
The safety, efficacy and pharmacokinetics of AFSTYLA have been eva luated in 258 previously treated patients (PTPs) with severe hemophilia A (<1% endogenous Factor VIII activity) who received at least one dose of AFSTYLA as part of either routine prophylaxis, on-demand treatment of bleeding episodes or perioperative management in two completed clinical trials (an adult/adolescent study [≥12 to 65 years of age] and a pediatric study [<12 years of age]), and an ongoing extension study (0 to ≤65 years of age). Patients with a history of, or current FVIII inhibitors, or any first order family history of FVIII inhibitors, patients with known hypersensitivity (allergic reaction or anaphylaxis) to any FVIII product or hamster protein, and patients with evidence of thrombosis, including deep vein thrombosis, stroke, pulmonary embolism, myocardial infarction and arterial embolus within 3 months prior to Day 1 of the study were excluded from study participation.
Eighty-four (32.6%) subjects were children <12 years of age (35 [13.6%] 0 to <6 years and 49 [19.0%] ≥6 to <12 years), 14 (5.4%) were adolescents (≥12 to <18 years), and 160 (62.0%) were adults (≥18 to ≤65 years). There have been a total of 28,418 exposure days (EDs), with at least 28,492 injections of AFSTYLA administered. In the completed studies, a total of 185 subjects achieved at least 50 EDs, of whom 60 subjects achieved ≥100 EDs.
Adverse reactions (ARs) (summarized in Table 4) were reported for 14 of 258 (5.4%) subjects in all studies. An adverse reaction of hypersensitivity resulted in the withdrawal of one subject. No subject developed neutralizing antibodies (inhibitors) to Factor VIII or antibodies to host cell proteins. No events of anaphylaxis or thrombosis were reported.
6.2 Immunogenicity
All subjects were monitored for inhibitory and binding antibodies to AFSTYLA, and binding antibodies to chinese hamster ovary (CHO) host cell proteins prior to the first infusion of AFSTYLA, at defined intervals during the studies and at the end of study visit.
No subjects developed neutralizing antibodies (inhibitors) to Factor VIII or antibodies against CHO host cell proteins at any time during the clinical studies. Four subjects in the adult/adolescent study and 10 subjects in the pediatric study were negative for non-neutralizing anti-drug antibodies (ADAs) at screening and turned positive during the clinical study. Two of the adult/adolescent subjects and 3 of the pediatric subjects who developed ADAs were negative at end of study visit. No adverse events were associated with the development of ADAs. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of 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, it may be misleading to compare the incidence of antibodies to AFSTYLA with the incidence of antibodies to other products.
8 USE IN SPECIFIC POPULATIONS
8.1 Pregnancy
Risk Summary
There are no data with AFSTYLA use in pregnant women to inform on drug-associated risk. No developmental or animal reproduction toxicity studies were conducted with AFSTYLA. Thus, the risk of developmental toxicity including, structural abnormalities, embryo-fetal and/or infant mortality, functional impairment, and alterations to growth is not known. In the US general population, the estimated background risk of major birth defects occurs in 2-4% of the general population and miscarriage occurs in 15-20% of clinically recognized pregnancies. AFSTYLA should be given to a pregnant woman only if clearly needed.
8.2 Lactation
Risk Summary
There is no information regarding the excretion of AFSTYLA in human milk, the effect on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for AFSTYLA and any potential adverse effects on the breastfed infant from AFSTYLA or from the underlying maternal condition.
8.4 Pediatric Use
Safety and efficacy studies with AFSTYLA have been performed in 98 previously treated pediatric patients <18 years of age. Fourteen adolescent subjects ≥12 to <18 years were enrolled in the adult/adolescent safety and efficacy study. Thirty-five subjects 0 to <6 years and 49 subjects ≥6 to <12 years were enrolled in a pediatric safety and efficacy study [see Adverse Reactions (6.1), Clinical Pharmacology (12.3), and Clinical Studies (14)]. Because clearance (based on per kg body weight) has been shown to be higher in the pediatric population 0 to <12 years, more frequent or higher doses of AFSTYLA based on body weight may be needed [see Clinical Pharmacology (12.3)].
8.5 Geriatric Use
Clinical studies of AFSTYLA did not include subjects over 65 years to determine whether or not they respond differently from younger subjects.
11 DESCRIPTION
AFSTYLA is a single-chain recombinant Factor VIII produced in chinese hamster ovary (CHO) cells. It is a construct where the B-domain occurring in wild type full-length Factor VIII has been truncated and 4 amino acids of the adjacent acidic a3 domain were removed (amino acids 765 to 1652 of full-length Factor VIII). AFSTYLA is expressed as a single-chain Factor VIII molecule with covalent linkage between heavy and light chains; thereby keeping the molecule in the single-chain form resulting in increased stability and increased von Willebrand Factor (VWF) affinity. Except for a new N-glycosylation site at the junction between heavy and light chains, the post-translational modifications are comparable to endogenous Factor VIII.
AFSTYLA is purified by a controlled multi-step process including two virus reduction steps complementing each other in their mode of action. No human or animal derived proteins are used in the purification or formulation processes.
AFSTYLA is a preservative-free, sterile, non-pyrogenic, lyophilized powder to be reconstituted with sterile water for injection (sWFI) for intravenous injection. AFSTYLA is available in single-use vials containing the labeled amount of Factor VIII activity, expressed in IU. Each vial contains nominally 250, 500, 1000, 2000 or 3000 IU of AFSTYLA. The actual potency is labeled on each AFSTYLA vial and carton. After reconstitution of the lyophilized powder, all dosage strengths yield an almost colorless to slightly opalescent solution. The concentrations of excipients based on the vial size, as well as the amount of sWFI for reconstitution are provided in the table below.
The number of units of Factor VIII administered is expressed in IU, which are related to the current WHO standard for Factor VIII products. One IU of Factor VIII activity in plasma is equivalent to that quantity of Factor VIII in 1 mL of normal plasma. Factor VIII activity in plasma is expressed either as a percentage (relative to normal human plasma) or in IU (relative to an International Standard for Factor VIII in plasma).
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
AFSTYLA is a recombinant protein that replaces the missing Coagulation Factor VIII needed for effective hemostasis. AFSTYLA is a single polypeptide chain with a truncated B-domain that allows for a covalent bridge to link the Factor VIII heavy and light chains. AFSTYLA has demonstrated a higher VWF affinity relative to full-length rFVIII.1 VWF stabilizes Factor VIII and protects it from degradation. Activated AFSTYLA has an amino acid sequence identical to endogenous FVIIIa.
12.2 Pharmacodynamics
Hemophilia A is an X-linked hereditary disorder of blood coagulation due to decreased levels of Factor VIII and results in bleeding into joints, muscles or internal organs, either spontaneously or as result of accidental or surgical trauma. Replacement therapy increases the plasma levels of Factor VIII enabling a temporary correction of the factor deficiency and correction of the bleeding tendencies.
12.3 Pharmacokinetics
Subjects ≥12 years
The pharmacokinetics (PK) of AFSTYLA were eva luated in 91 (81 adults ≥18 years and 10 adolescents ≥12 to <18 years) previously treated subjects following an intravenous injection of a single dose of 50 IU/kg.
The PK parameters (Table 5) were based on plasma Factor VIII activity measured by the chromogenic assay after the first dose (initial PK assessment). The PK profile obtained 3 to 6 months after the initial PK assessment was comparable with the PK profile obtained after the first dose.
Children <12 years
Pharmacokinetic parameters of AFSTYLA were eva luated in 39 previously treated children (0 to <12 years) in open-label, multicenter studies following a 50 IU/kg intravenous injection of AFSTYLA.
Table 6 summarizes the PK parameters calculated from the pediatric data. These parameters were estimated based on the plasma Factor VIII activity over time profile.
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