AFSTYLA是目前首个，也是唯一一个获FDA批治疗A型血友病的重组单链凝血因子VIII
2016年5月31日，FDA批准了其长效血友病药物Afstyla用于治疗血友病A。
血友病为一组遗传性凝血功能障碍的出血性疾病，其共同的特征是活性凝血活酶生成障碍，凝血时间延长，终身具有轻微创伤后出血倾向，重症患者没有明显外伤也可发生“自发性”出血。血友病主要分为A、B、C三型，A型血友病是一种X染色体连锁的凝血因子VIII量和分子结构异常引起的隐性遗传性出血性疾病，多发于男性。通常是由体内VIII因子缺乏引起，可引起关节点的反复出血，从而导致关节严重受损。
Afstyla是一种新型的重组单链凝血因子VIII，是第一个也是目前唯一一个获批的治疗血友病A的单链凝血因子，能够长效预防出血事件，使用频率为每周两至三次。
Afstyla可以用于成人和儿童血友病A患者的常规出血预防，能够有效预防患者出血的频率、按需要控制患者出血以及用于围手术期的出血管理等。临床试验数据显示，使用Afstyla预防出血的血友病患者，其中位年自发出血率为0，表现出极强的预防出血效果，此前几乎没有同类的出血抑制剂能够达到同样的效果。Rush血友病及血栓研究中心的负责人Lisa Boggio表示，Afstyla作为首个被FDA批准的长效单链重组凝血因子，不仅具有极强的预防出血效果，其稳定性和效果的持续性也增强了。此外，Afstyla每周使用两至三次，对患者而言比较方便，极大地提高了血友病A患者的生活质量。

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:
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 (1).
DOSAGE AND ADMINISTRATION
For intravenous use after reconstitution only.
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)
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)
Adults and adolescents (≥12 years): The recommended starting regimen is 20 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly.
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.
The regimen may be adjusted based on patient response.
Perioperative Management: (2.1)
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
Hypersensitivity reactions, including anaphylaxis, are possible. Should symptoms occur, immediately discontinue AFSTYLA and administer appropriate treatment. (5.1)
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)
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
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
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
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.
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.
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
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)
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.
Table 1. Dosing for On-demand Treatment and Control of Bleeding Episodes

Type of Bleeding Episode	Factor VIII Activity Level Required (% or IU/dL)	Frequency of Doses (hours)
Minor Uncomplicated hemarthrosis, minor muscle bleeding or oral bleeding	20-40	Repeat injection every 12-24 hours until the bleeding is resolved.
Moderate Muscle bleeding (except iliopsoas), hemarthrosis, or mild trauma	30-60	Repeat injection every 12-24 hours until the bleeding is resolved.
Major/Life-threatening Limb threatening hemorrhage, deep muscle bleeding (including iliopsoas), intracranial and retropharyngeal bleeding, fractures or head trauma	60-100	Repeat injection every 8-24 hours until bleed is resolved.

Routine Prophylaxis
Adults and adolescents (≥12 years): The recommended starting regimen is 20 to 50 IU per kg of AFSTYLA administered 2 to 3 times weekly.
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)].
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.
Table 2. Target Factor VIII Activity Levels for Perioperative Management of Bleeding

Type of Surgery	Factor VIII Activity Level Required (% or IU/dL)	Frequency of Doses (hours) / Duration of Therapy (days)
Minor (including tooth extraction)	30-60	Repeat injection every 24 hours for at least 1 day, until healing is achieved.
Major (intracranial, intra-abdominal, intrathoracic, or joint-replacement)	80-100	Repeat injection every 8-24 hours until adequate wound healing, then continue therapy for at least another 7 days to maintain a Factor VIII activity of 30-60% (IU/dL).

2.2 Preparation and Reconstitution
Table 3. AFSTYLA Reconstitution Instructions

1. Ensure that the AFSTYLA vial and diluent vial are at room temperature. Prepare and administer using aseptic technique.
2. Place the AFSTYLA vial, diluent vial, and Mix2Vial ® transfer set on a flat surface.
3. Remove AFSTYLA and diluent vial flip caps. Wipe the stoppers with the sterile alcohol swab provided and allow the stoppers to dry prior to opening the Mix2Vial transfer set package.
4. Open the Mix2Vial transfer set package by peeling away the lid (Fig. 1). Leave the Mix2Vial transfer set in the clear package.	Fig. 1
5. Place the diluent vial on a flat surface and hold the vial tightly. Grip the Mix2Vial transfer set together with the clear package and push the plastic spike at the blue end of the Mix2Vial transfer set firmly through the center of the stopper of the diluent vial (Fig. 2).	Fig. 2
6. Carefully remove the clear package from the Mix2Vial transfer set. Make sure that you pull up only the clear package, not the Mix2Vial transfer set (Fig. 3).	Fig. 3
7. With the AFSTYLA vial placed firmly on a flat surface, invert the diluent vial with the Mix2Vial transfer set attached and push the plastic spike of the transparent adapter firmly through the center of the stopper of the AFSTYLA vial (Fig. 4). The diluent will automatically transfer into the AFSTYLA vial.	Fig. 4
8. With the diluent and AFSTYLA vial still attached to the Mix2Vial transfer set, gently swirl the AFSTYLA vial to ensure that the AFSTYLA is fully dissolved (Fig. 5). Do not shake the vial.	Fig. 5
9. With one hand, grasp the AFSTYLA side of the Mix2Vial transfer set and with the other hand grasp the blue diluent-side of the Mix2Vial transfer set, and unscrew the set into two pieces. (Fig. 6).	Fig. 6
10. Draw air into an empty, sterile syringe. While the AFSTYLA vial is upright, screw the syringe to the Mix2Vial transfer set. Inject air into the AFSTYLA vial. While keeping the syringe plunger pressed, invert the system upside down and draw the concentrate into the syringe by pulling the plunger back slowly. (Fig. 7).	Fig. 7
11. Now that the concentrate has been transferred into the syringe, firmly grasp the barrel of the syringe (keeping the plunger facing down) and unscrew the syringe from the Mix2Vial transfer set (Fig. 8).	Fig. 8
12. After reconstitution, infuse immediately or within 4 hours. Reconstituted AFSTYLA may be stored at room temperature, not to exceed 25°C (77°F), for up to 4 hours. Do not freeze. Protect from direct sunlight.
13. Record treatment – Remove the peel-off portion of the label from each vial used, and affix it to the patient's treatment diary/log book or scan the vial if recording the infusion electronically.
14. If the dose requires more than one vial, use a separate, unused Mix2Vial ® transfer set for each product vial. Repeat step 10 to pool the contents of the vial into one syringe.

2.3 Administration
Use aseptic technique when administering AFSTYLA.
Do not mix AFSTYLA with other medicinal products.
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.
Administer AFSTYLA at room temperature within 4 hours after reconstitution.
AFSTYLA is for single use only. Following administration, discard any unused solution and all administration equipment in an appropriate manner as per local requirements.
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
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.
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 evaluated 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.
Table 4. Adverse Reactions Reported for AFSTYLA (N=258)

MedDRA System Organ Class	Adverse Reactions	Number of Subjects n (%)
Immune system disorders	Hypersensitivity	4 (1.6)
Nervous system disorders	Dizziness	2 (0.8)
	Paresthesia	1 (0.4)
Skin and subcutaneous tissue disorders	Rash	1 (0.4)
	Erythema	1.(0.4)
	Pruritus	1 (0.4)
General disorders and administration site conditions	Pyrexia	1 (0.4)
	Injection-site pain	1 (0.4)
	Chills	1 (0.4)
	Feeling hot	1 (0.4)

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.
Nominal Composition after Reconstitution with sWFI

Ingredient	250 IU vial	500 IU vial	1000 IU vial	2000 IU vial	3000 IU vial
rVIII-Single Chain	100 IU/mL	200 IU/mL	400 IU/mL	400 IU/mL	600 IU/mL
L-Histidine	3.1 mg/mL	3.1 mg/mL	3.1 mg/mL	3.1 mg/mL	3.1 mg/mL
Polysorbate 80	0.2 mg/mL	0.2 mg/mL	0.2 mg/mL	0.2 mg/mL	0.2 mg/mL
Calcium chloride	0.4 mg/mL	0.4 mg/mL	0.4 mg/mL	0.4 mg/mL	0.4 mg/mL
Sodium chloride	16.4 mg/mL	16.4 mg/mL	16.4 mg/mL	16.4 mg/mL	16.4 mg/mL
Sucrose	6 mg/mL	6 mg/mL	6 mg/mL	6 mg/mL	6 mg/mL
Water for Injection	2.5 mL	2.5 mL	2.5 mL	5 mL	5 mL

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 evaluated 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.
Table 5. Pharmacokinetic Parameters (Arithmetic Mean, Coefficient of Variation [CV%]) in Adults and Adolescents Following a Single Injection of 50 IU/kg of AFSTYLA - Chromogenic Assay

PK Parameters	≥18 years (N=81)	≥12 to <18 years (N=10)
IR (IU/dL)/(IU/kg)	2.00 (20.8)	1.69 (24.8)
Cmax (IU/dL)	106 (18.1)	89.7 (24.8)
AUC0-inf (IU*h/dL)	1960 (33.1)	1540 (36.5)
t1/2 (h)	14.2 (26.0)	14.3 (33.3)
MRT (h)	20.4 (25.8)	20.0 (32.2)
CL (mL/h/kg)	2.90 (34.4)	3.80 (46.9)
Vss (mL/kg)	55.2 (20.8)	68.5 (29.9)

IR = incremental recovery recorded at 30 minutes after injection; Cmax = observed maximum plasma concentration; AUC0-inf = area under the Factor VIII activity time curve extrapolated to infinity; t1/2 = half-life; MRT = mean residence time; CL = body weight adjusted clearance; Vss = body weight adjusted volume of distribution at steady-state.
Children <12 years
Pharmacokinetic parameters of AFSTYLA were evaluated 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.
Table 6. Comparison of Pharmacokinetic Parameters in Children by Age Category (Arithmetic Mean, Coefficient of Variation [CV%]) Following a Single Injection of 50 IU/kg of AFSTYLA - Chromogenic Assay

PK Parameters	0 to <6 years (N=20)	≥6 to <12 years (N=19)
IR (IU/dL)/(IU/kg)	1.60 (21.1)	1.66 (19.7)
Cmax (IU/dL)	80.2 (20.6)	83.5 (19.5)
AUC0-inf (IU*h/dL)	1080 (31.0)	1170 (26.3)
t1/2 (h)	10.4 (28.7)	10.2 (19.4)
MRT (h)	12.4 (25.0)	12.3 (16.8)
CL (mL/h/kg)	5.07 (29.6)	4.63 (29.5)
Vss (mL/kg)	71.0 (11.8)	67.1 (22.3)

IR = incremental recovery recorded at 30 minutes after injection for subjects 12 to <18 years and at 60 minutes after injection for subjects 1 to <12 years; Cmax = observed maximum plasma concentration; AUC = area under the Factor VIII activity time curve extrapolated to infinity; t1/2 = half-life; MRT = mean residence time; CL = body weight adjusted clearance; Vss = body weight adjusted volume of distribution at steady-state.
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term animal studies investigating the carcinogenic effects of AFSTYLA have not been conducted. In vitro and in vivo testing of AFSTYLA for mutagenicity or effects on fertility were not performed.
14 CLINICAL STUDIES
The safety and efficacy of AFSTYLA were evaluated in two studies: an Open-label, Multicenter, Crossover Safety, Efficacy and Pharmacokinetic Study in adults/adolescents as well as in an Open Label Pharmacokinetic, Efficacy and Safety study in children. These studies characterized the PK of AFSTYLA and determined hemostatic efficacy in the control of bleeding events, the prevention of bleeding events in prophylaxis and in the adult/adolescent study determined hemostatic efficacy during perioperative management of bleeding in subjects undergoing surgical procedures.
The adult/adolescent study enrolled a total of 175 previously treated male subjects with severe hemophilia A (<1% endogenous Factor VIII activity). Subjects ranged in age from 12 to 65 years, including 14 adolescent subjects (≥12 to <18 years). Of the 175 enrolled subjects, 174 received at least one dose of AFSTYLA and 173 (99%) were evaluable for efficacy. A total of 161 subjects (92.5%) completed the study. A total of 120 (69.0%) subjects were treated for at least 50 EDs and 52 (29.9%) of those subjects were treated for at least 100 EDs. Subjects received a total of 14,592 injections with a median of 67.0 (range 1 to 395) injections per subject.
The pediatric study enrolled 84 previously treated male subjects with severe hemophilia A (35 subjects 0 to <6 years and 49 subjects ≥6 to <12 years). Of the 84 enrolled subjects, all received at least one dose of AFSTYLA and 83 (99%) were evaluable for efficacy. A total of 65 (77.4%) subjects were treated for at least 50 EDs and 8 (9.5%) of those subjects were treated for at least 100 EDs. Subjects received a total of 5,313 injections with a median of 59 (range 4 to 145) injections per subject.
On-demand Treatment and Control of Bleeding Episodes
In the adult/adolescent study a total of 848 bleeding episodes were treated with AFSTYLA and 835 received an efficacy assessment by the investigator. The majority of the bleeding episodes occurred in joints. The median dose per injection used to treat a bleeding episode was 31.7 IU/kg (range 6 to 84 IU/kg). Of the 848 bleeding episodes, 686 (81%) were controlled with a single AFSTYLA injection and another 107 (13%) were controlled with 2 injections. Fifty-five (6%) of the 848 bleeding episodes required 3 or more injections. For 94% of bleeding episodes the hemostatic efficacy rating by the investigator was either excellent or good.
In the pediatric study a total of 347 bleeding episodes were treated with AFSTYLA all of which received an efficacy assessment by the investigator. The majority of the bleeding episodes occurred in joints. The median dose per injection used to treat a bleeding episode was 27.3 IU/kg (range 16 to 76 IU/kg). Of the 347 bleeding episodes, 298 (86%) were controlled with a single AFSTYLA injection and another 34 (10%) were controlled with 2 injections. Fifteen (4%) of the 347 bleeding episodes required 3 or more injections. For 96% of bleeding episodes the hemostatic efficacy rating by the investigator was either excellent or good.
Assessment of response to treatment of bleeds by the investigator was as follows:
Excellent: Pain relief and/or improvement in signs of bleeding (i.e., swelling, tenderness, and/or increased range of motion in the case of musculoskeletal hemorrhage) within approximately 8 hours after the first infusion
Good: Pain relief and/or improvement in signs of bleeding at approximately 8 hours after the first infusion, but requires two infusions for complete resolution
Moderate: Probable or slight beneficial effect within approximately 8 hours after the first infusion; requires more than two infusions for complete resolution
No response: No improvement at all or condition worsens (i.e., signs of bleeding) after the first infusion and additional hemostatic intervention is required with another FVIII product, cryoprecipitate, or plasma for complete resolution.
Efficacy in control of bleeding episodes in both studies is summarized in Table 7.
Table 7. Efficacy of AFSTYLA in Control of Bleeding

Bleeding Episodes Treated	Adult and Adolescent (≥12 to 65 years of age) (N=848)	Pediatric (0 to <12 years of age) (N=347)
Number of injections
1 injection, n (%)	686 (81%)	298 (85.9%)
2 injections, n (%)	107 (13%)	34 (9.8%)
3 injections, n (%)	29 (3%)	8 (2.3%)
>3 injections, n (%)	26 (3%)	7 (2.0%)
Efficacy evaluation by investigator	(N=835)	(N=347)
Excellent or Good, n (%)	783 (94%)	334 (96.3%)
Moderate, n (%)	52 (6%)	12 (3.5%)
No response, n (%)	0	1 (0.3%)

Routine Prophylaxis
Adult and Adolescent Study
In the adult/adolescent and pediatric studies, subjects received prophylaxis in a regimen that was determined by the investigator, taking into account the subject's Factor VIII treatment regimen used prior to enrollment and the subject's bleeding phenotype.
In the adult/adolescent study, 54% of the 146 subjects on prophylaxis received AFSTYLA 3 times weekly; 32% of subjects received AFSTYLA 2 times weekly; 6% received AFSTYLA every other day, and 8% of subjects received other regimens.
The annualized bleeding rate (ABR) was comparable between subjects on a 3 times weekly regimen (median ABR of 1.53) and those on a 2 times weekly regimen (median ABR of 0.00). The annualized spontaneous bleeding rate (AsBR) was also comparable between subjects on a 3 times weekly regimen (median AsBR of 0.0) and those on a 2 times weekly regimen (median AsBR of 0.0). The number of subjects who needed dose adjustments was comparable between the two groups (34.2% [27 subjects] for three times weekly and 27.7% [13 subjects] for twice weekly).
The median prescribed dose for subjects on a 3 times weekly prophylaxis regimen was 30 IU/kg (12 to 50 IU/kg). The median prescribed dose for subjects on a 2 times weekly regimen was 35 IU/kg (17 to 50 IU/kg).
The ABR in prophylaxis (median of 1.14) was significantly lower (p <0.0001) than the ABR that was observed in subjects treated on-demand (median of 19.64). Sixty-three of 146 subjects (43%) experienced no bleeding episodes while on prophylaxis. There were no severe or life-threatening bleeds (e.g., intracranial hemorrhage) in subjects receiving prophylaxis.
Pediatric Study
In the pediatric study, 54% of the 80 subjects on prophylaxis received AFSTYLA 2 times a week; 30% of subjects received AFSTYLA 3 times a week; 4% received AFSTYLA every other day; and 12% of subjects received other regimens.
Twenty-one of 80 subjects (26%) experienced no bleeding episodes while on prophylaxis. There was one severe bleed (hip joint hemorrhage) in the pediatric study that was successfully treated.
For subjects on prophylaxis the overall ABR was 3.69, with a median ABR of 2.30 for subjects on a 3 times a week regimen and 4.37 for subjects on a 2 times a week regimen. The median AsBR (0.00) was identical between subjects on the 3 times a week and 2 times a week regimens.
The median prescribed dose for subjects on a 3 times a week regimen was 32 IU/kg (19 to 50 IU/kg) and for subjects on a 2 times a week regimen was 35 IU/kg (20 to 57 IU/kg).
The ABRs for prophylaxis and on-demand in both studies are summarized in Table 8.
Table 8. Summary of Annualized Bleeding Rate (ABR) by AFSTYLA Treatment Regimen

Phase I/III Adult/Adolescent Study		Phase III Pediatric Study
	Prophylaxis (N=146)	On-demand (N=27)	Prophylaxis (N=80)	On-demand (N=3)
Overall ABR   Median (IQR*)	1.14 (0–4.2)	19.64 (6.2–46.5)	3.69 (0–7.2)	78.56 (35.1–86.6)
Annualized Spontaneous Bleeding Rate (AsBR) Median (IQR*)	0 (0–2.4)	11.73 (2.8–36.5)	0 (0–2.2)	31.76 (0–42.7)
Number of subjects with zero bleeding episodes	63 (43.2%)	1 (3.7%)	21 (26.3%)	0

IQR = interquartile range, 25 th percentile to 75 th percentile
Perioperative Management of Bleeding
Thirteen subjects in the adult/adolescent study underwent a total of 16 surgical procedures. Overall, investigators assessed hemostatic efficacy of AFSTYLA in perioperative management of bleeding as excellent in 15 of 16 surgeries and as good in 1 of 16 surgeries (see Table 9). Median factor consumption pre- and intra-operatively was 89.4 IU/kg (range 40.5 to 108.6 IU/kg).
Assessment of hemostasis during surgical procedures by the investigator was as follows:
Excellent: Hemostasis clinically not significantly different from normal (e.g., achieved hemostasis comparable to that expected during similar surgery in a non-factor deficient patient) in the absence of other hemostatic intervention and estimated blood loss during surgery is not more than 20% higher than the predicted blood loss for the intended surgery
Good: Normal or mildly abnormal hemostasis in terms of quantity and/or quality (e.g., slight oozing, prolonged time to hemostasis with somewhat increased bleeding compared to a non-factor deficient patient in the absence of other hemostatic intervention) or estimated blood loss is >20%, but ≤30% higher than the predicted blood loss for intended surgery
Moderate: Moderately abnormal hemostasis in terms of quantity and/or quality (e.g., moderate hemorrhage that is difficult to control) with estimated blood loss greater than what is defined as good
Poor/No Response: Severely abnormal hemostasis in terms of quantity and/or quality (e.g., severe hemorrhage that is difficult to control) and/or additional hemostatic intervention required with another FVIII product, cryoprecipitate, or plasma for complete resolution.
Table 9. Efficacy of AFSTYLA in Perioperative Management of Bleeding

Procedure	Efficacy Evaluation	Factor Consumption (IU/kg) (pre- and intra-operatively)
Extraction of wisdom teeth	Excellent	51.09
Abdominal hernia repair	Excellent	47.89
Elbow replacement	Excellent	108.58
Ankle arthroplasty	Excellent	76.83
Knee replacement (5)	Excellent (4), Good (1)	92.49 100.9 67.26 105.79 86.09
Cholecystectomy and Lengthening of the Achilles tendon combined with: Straightening of the right toes	Excellent Excellent	105.95
Circumcision (3)	Excellent (3)	99.04 92.74 81.5
Open reduction internal fixation (ORIF) right ankle	Excellent	89.36
Hardware removal, Right ankle	Excellent	40.45

15 REFERENCES
1 Zollner S, Raquet E, Claar Ph, Müller-Cohrs J, Metzner HJ, Weimer Th, Pragst I, Dickneite G, Schulte S. Non-clinical pharmacokinetics and pharmacodynamics of rVIII-SingleChain, a novel recombinant single-chain factor VIII, Thrombosis Research 2014; 134: 125-131.
16 HOW SUPPLIED/STORAGE AND HANDLING
How Supplied
AFSTYLA is supplied in a kit containing a lyophilized powder in a single-use vial labeled with the amount of Factor VIII activity, expressed in international units (IU). Actual Factor VIII activity in International Units (IU) is stated on the AFSTYLA carton and vial label.
AFSTYLA is packaged with Sterile Water for Injection, USP (2.5 mL for reconstitution of 250, 500 or 1000 IU or 5 mL for reconstitution of 2000 or 3000 IU AFSTYLA), one Mix2Vial filter transfer set, and one sterile alcohol swab. Components are not made of natural rubber latex.

Nominal Strength	Fill Size Color Indicator	Kit NDC
250 IU	Orange	69911-474-02
500 IU	Blue	69911-475-02
1000 IU	Green	69911-476-02
2000 IU	Purple	69911-477-02
3000 IU	Yellow	69911-478-02

Storage and Handling
Store AFSTYLA in the original package to protect the AFSTYLA vials from light.
Store AFSTYLA in powder form at 2°C to 8°C (36°F to 46°F). Do not freeze to avoid damage to the diluent vial. AFSTYLA can be stored at room temperature, not to exceed 25°C (77°F), for a single period of up to 3 months, within the expiration date printed on the carton and vial labels.
Record the starting date of room temperature on the unopened product carton. Once stored at room temperature, do not return the product to the refrigerator. The shelf-life then expires after storage at room temperature for 3 months, or after the expiration date on the product vial, whichever is earlier.
Do not use AFSTYLA after the expiration date indicated on the vial.
The reconstituted product (after mixing dry product with diluent) can be stored at 2°C to 8°C (36°F to 46°F), or at room temperature, not to exceed 25°C (77°F), for up to 4 hours.
Protect from direct sunlight.
After reconstitution, if the product is not used within 4 hours, it must be discarded.
Do not use AFSTYLA if the reconstituted solution is cloudy or has particulate matter.
Discard any unused AFSTYLA.
17 PATIENT COUNSELING INFORMATION
Advise patients to:
Read the FDA-approved Patient Labeling (Patient Product Information and Instructions for Use).
Discontinue use of AFSTYLA in case of a hypersensitivity reaction and contact their healthcare provider and/or seek emergency care, depending on the severity of the reaction. Early signs of hypersensitivity reactions may include hives, itching, facial swelling, tightness of the chest, and wheezing [see Warnings and Precautions (5.1)].
Contact their healthcare provider or hemophilia treatment facility for further treatment and/or assessment if they experience a lack of a clinical response to Factor VIII replacement therapy, as in some cases this may be a manifestation of an inhibitor [see Warnings and Precautions (5.2)].
Report any adverse reactions or problems following AFSTYLA administration to their healthcare provider.
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=51f19873-a63f-4229-9477-5da4ecf31cde