Strensiq Drug Information
Generic name: ASFOTASE ALFA
Tissue-nonspecific Alkaline Phosphatase [EPC]
Uses of Strensiq
® is indicated for the treatment of patients with perinatal/infantile- and juvenile-onset hypophosphatasia (HPP). STRENSIQ is a tissue nonspecific alkaline phosphatase indicated for the treatment of patients with perinatal/infantile- and juvenile-onset hypophosphatasia (HPP).
Dosage & Administration of Strensiq
| 3 | 6 mg |
|---|---|
| 4 | 8 mg |
| 5 | 10 mg |
| 6 | 12 mg |
| 7 | 14 mg |
| 8 | 16 mg |
| 9 | 18 mg |
| 10 | 20 mg |
| 15 | 30 mg |
| 20 | 40 mg |
| 25 | 50 mg |
| 30 | 60 mg |
| 35 | 70 mg |
| 40 | 80 mg |
| 50 | 100 mg |
| 60 | 120 mg |
| 70 | 140 mg |
| 80 | 160 mg |
Side Effects of Strensiq
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 practice. The data described below reflect exposure to STRENSIQ in 99 patients with perinatal/infantile- or juvenile onset HPP (age 1 day to 58 years) treated with STRENSIQ, most for more than 2 years (range 1 day to 312 weeks ): 51 patients received at least 96 weeks (24 months) of treatment and 39 patients received 168 weeks (42 months) or more of treatment . Common Adverse Reactions Overall, the most common adverse reactions reported were injection site reactions (63%). Other common adverse reactions included lipodystrophy (28%), ectopic calcifications (14%), and hypersensitivity reactions (12%). Table 4 summarizes the adverse reactions that occurred at a rate of at least 10% in clinical trials following subcutaneous injection of STRENSIQ by patient population and STRENSIQ dosage regimen. The frequency of injection site reactions, lipodystrophy and ectopic calcification were higher in patients with juvenile-onset HPP as compared to perinatal/infantile-onset HPP patients.
The majority of injection site reactions resolved within a week. Two patients experienced injection site reactions that led to reductions of their STRENSIQ dose. One patient switched from six times per week dosing to 3 times per week dosing as a result of injection site reactions.
One other patient experienced a severe injection site reaction of injection site discoloration and withdrew from the trial. Table 4: Adverse Reactions Reported in at Least 10% of Patients with Perinatal/Infantile- or Juvenile-onset HPP Enrolled in STRENSIQ Clinical Trials Perinatal/Infantile-onset HPP Juvenile-onset HPP Adverse Reaction Category or Term STRENSIQ less than or equal to 6 mg/kg per week (N=66) n (%) STRENSIQ more than 6 mg/kg/week Adverse reactions are from the combined period of 6 mg/kg and above (i.e. total drug exposure regardless of starting dose and intermediary doses as long as the patient reached doses > 6 mg/kg) (N=13) n (%) Total (N=79) n (%) STRENSIQ (N=20) n (%) Injection site reactions 38 6 44 18 Erythema 29 3 32 15 Discoloration/ Hypopigmentation 11 1 12 8 Pain/ Tenderness 10 1 11 8 Pruritus/ Itching 10 0 10 7 Swelling 8 0 8 6 Induration 9 1 10 3 Macule 4 0 4 7 Reaction, not otherwise specified 6 1 7 4 Bruising 6 0 6 4 Nodule 2 0 2 2 Other injection site reactions Other injection site reactions include injection site rash, inflammation, papule, hemorrhage, hematoma, urticaria, warmth, calcification, mass, scar and cellulitis. 10 3 13 4 Ectopic calcifications 3 0 3 11 Lipodystrophy 12 2 14 14 Injection site atrophy 4 2 6 8 Injection site hypertrophy 5 0 5 6 Other lipodystrophy Other lipodystrophy includes lipohypertrophy. 4 0 4 1 Hypersensitivity reactions 7 3 10 2 Vomiting/emesis 2 2 4 2 Other hypersensitivity reactions Other hypersensitivity reactions include erythema/redness, pyrexia/fever, irritability, nausea, pain, rigor/chills, hypoesthesia oral, headache, flushing, and anaphylaxis. 6 2 8 2 Less Common Adverse Reactions Adverse reactions that occurred at rates less than 1% included: Hypocalcemia Renal Stones Chronic hepatitis Decreased vitamin B6 Long-Term Safety In long-term extension trials reflecting a median exposure to STRENSIQ of 142 weeks (range 0.1 weeks to 392 weeks) in 112 patients with perinatal/infantile- (n = 89), juvenile- (n = 22), and adult-onset (n = 1) HPP (age at enrollment = 1 day to 66.5 years), the most common adverse reactions were similar to those reported in Table 4.
Immunogenicity As with all therapeutic proteins, there is potential for immunogenicity.
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 the antibodies in the studies described below with the incidence of antibodies in other studies or to other asfotase alfa products may be misleading.
During clinical trials, anti-asfotase alfa antibodies have been detected in patients receiving treatment with STRENSIQ using an electrochemiluminescent (ECL) immunoassay. Antibody positive samples were tested to determine the presence of neutralizing antibodies based on in vitro inhibition of the catalytic activity of STRENSIQ. Among STRENSIQ-treated patients with hypophosphatasia (HPP) in clinical studies who had post-baseline antibody data available, 97/109 (89%) tested positive for anti-asfotase alfa antibodies at some time point during STRENSIQ treatment. Among those 97 patients, 55 (57%) also tested positive for neutralizing antibodies at some time point during STRENSIQ treatment.
No correlation was observed between the anti-asfotase alfa antibody titers and the neutralizing antibody (% inhibition) values. Formation of anti-asfotase alfa antibody resulted in a reduced systemic exposure of asfotase alfa .
Postmarketing Experience
The following adverse reactions have been identified during post-approval use of STRENSIQ. 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. Some STRENSIQ-treated patients with initial therapeutic response to STRENSIQ subsequently developed worsening in disease-associated laboratory and radiographic biomarkers (some in association with neutralizing antibodies) suggesting possible immune-mediated effects on STRENSIQ's pharmacologic action resulting in disease progression.
Warnings & Cautions for Strensiq
Hypersensitivity Reactions Including Anaphylaxis Life-threatening hypersensitivity reactions, including anaphylaxis, have been reported
in patients treated with enzyme replacement therapies, including STRENSIQ. Signs and symptoms consistent with anaphylaxis included difficulty breathing, choking sensation, nausea, periorbital edema, and dizziness. These reactions have occurred within minutes after subcutaneous administration of STRENSIQ and have been observed more than 1 year after treatment initiation. Other hypersensitivity reactions have also been reported in STRENSIQ-treated patients, including vomiting, fever, headache, flushing, irritability, chills, erythema, rash, pruritus and oral hypoesthesia . Anaphylaxis has occurred during the early course of enzyme replacement therapy and after extended duration of therapy.
Initiate STRENSIQ under the supervision of a healthcare provider with appropriate medical monitoring and support measures. If a severe hypersensitivity reaction (e.g., anaphylaxis) occurs, discontinue STRENSIQ and immediately initiate appropriate medical treatment, including use of epinephrine. Consider the risks and benefits of re-administering STRENSIQ to individual patients following a severe reaction.
If the decision is made to re-administer the product, monitor patients for a reoccurrence of signs and symptoms of a severe hypersensitivity reaction. Inform patients of the symptoms of life-threatening hypersensitivity reactions, including anaphylaxis and to seek immediate medical care should symptoms occur.
Lipodystrophy Localized lipodystrophy, including lipoatrophy and lipohypertrophy, has been reported at injection
sites after several months in patients treated with STRENSIQ in clinical trials . Advise patients to follow proper injection technique and to rotate injection sites .
Ectopic Calcifications Patients with
HPP are at increased risk for developing ectopic calcifications. Events of ectopic calcification, including ophthalmic (conjunctival and corneal) and renal (nephrocalcinosis, nephrolithiasis), have been reported in the clinical trial experience with STRENSIQ. There was insufficient information to determine whether or not the reported events were consistent with the disease or due to STRENSIQ. No visual changes or changes in renal function were reported resulting from the occurrence of ectopic calcifications. Ophthalmology examinations and renal ultrasounds are recommended at baseline and periodically during treatment with STRENSIQ to monitor for signs and symptoms of ophthalmic and renal ectopic calcifications and for changes in vision or renal function.
Possible Immune-Mediated Clinical Effects
In clinical trials, most STRENSIQ-treated patients developed anti-asfotase alfa antibodies and neutralizing antibodies which resulted in reduced systemic exposure of asfotase alfa. In postmarketing reports, some STRENSIQ-treated patients with initial therapeutic response subsequently developed recurrence and worsening in disease-associated laboratory and radiographic biomarkers (some in association with neutralizing antibodies) suggesting possible immune-mediated effects on STRENSIQ's pharmacologic action resulting in disease progression . The effect of anti-asfotase alfa antibody formation on the long-term efficacy of STRENSIQ is unknown. There are no marketed anti-asfotase alfa antibody tests.
If patients experience progression of HPP symptoms or worsening of disease-associated laboratory and imaging biomarkers after a period of initial therapeutic response to STRENSIQ, consider obtaining anti-asfotase alfa antibody testing by contacting STRENSIQ Medical Information at Alexion at 1-888-765-4747 or by email at [email protected]. Close clinical follow up is recommended.
Drug Interactions with Strensiq
Drug Interference with Laboratory Tests Laboratory Tests Utilizing Alkaline Phosphatase as a
Detection Reagent Studies have shown that there is analytical interference between asfotase alfa and laboratory tests that utilize an alkaline phosphatase (ALP)-conjugated test system, rendering erroneous test results in patients treated with STRENSIQ. ALP-conjugated test systems are utilized to measure substances such as hormones, bacterial antigens and antibodies. Therefore, it is recommended that laboratory assays which do not have ALP-conjugate technology be used when testing samples from patients who are receiving STRENSIQ. To avoid erroneous test results for patients treated with STRENSIQ, inform laboratory personnel that the patient is being treated with STRENSIQ and discuss the use of a testing platform which does not utilize an ALP-conjugated test system. Serum Alkaline Phosphatase High serum ALP measurements detected through clinical laboratory testing are expected in patients receiving STRENSIQ and reflect circulating concentrations of asfotase alfa.
Do not rely on serum ALP measurements for clinical decision making in patients treated with STRENSIQ.
Pregnancy Safety for Strensiq
Pregnancy Risk Summary There are no available data on STRENSIQ use in pregnant women to inform a drug associated risk. In animal reproduction studies, asfotase alfa administered intravenously to pregnant rats and rabbits during the period of organogenesis showed no evidence of fetotoxicity, embryolethality or teratogenicity at doses causing plasma exposures up to 21 and 24 times, respectively, the exposure at the recommended human dose (see Data ). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Asfotase alfa administered during the period of organogenesis to rats (from gestation Day 6 to Day 19 post-partum) and rabbits (on gestation days 7 to 19) at intravenous doses up to 50 mg/kg/day, approximately 21 and 24 times the human AUC of 65486 ng.h/mL at 2 mg/kg dose administered three times weekly for a 50 kg individual, respectively did not cause any adverse effects on embryofetal development.
A pre- and post-natal development study in pregnant rats showed no evidence of adverse effects on pre- and post-natal development at intravenous doses (from Day 6 of gestation to Day 19 postpartum) of asfotase alfa up to 50 mg/kg/day approximately 21 times the human AUC of 65486 ng.h/mL at 2 mg/kg dose administered three times weekly for a 50 kg individual.
Pediatric Use of Strensiq
Pediatric Use The safety and effectiveness of STRENSIQ for the treatment of perinatal/infantile- and juvenile-onset HPP have been established in pediatric patients. Use of STRENSIQ for this indication is based on 4 prospective, open-label clinical trials conducted in 89 pediatric patients with perinatal/infantile-onset or juvenile-onset HPP.
Clinical Studies of Strensiq
Perinatal/Infantile-Onset
HPP Study 1 was a 24-week prospective single-arm trial in 11 patients with severe perinatal/infantile-onset HPP. In this study, 7/11 (64%) were female and 10/11 (91%) patients were white, and age ranged from 3 weeks to 39.5 months. Severe perinatal/infantile-onset HPP was defined as biochemical, medical history and radiographic evidence of HPP as well as the presence of any of the following: rachitic chest deformity, vitamin B6-dependent seizures, or failure to thrive. Ten of 11 patients completed the 24-week trial and continued treatment in the extension phase.
Nine patients have been treated for at least 216 weeks (54 months) and 4 patients have been treated for over 240 weeks (60 months). Patients received subcutaneous STRENSIQ 3 mg/kg per week for the first month; subsequently, dose increases up to 9 mg/kg per week were allowed for changes in weight and/or for lack of efficacy. All 10 patients required dose increases up to 6 mg/kg per week or higher; 9 patients increased between 4 and 24 weeks after starting treatment and 1 patient increased after 70 weeks due to suboptimal clinical response. One patient's dose was decreased from 9 mg/kg per week to 6 mg/kg per week based on PK data.
Study 2 was a prospective open-label study in 59 patients with perinatal/infantile-onset HPP. In this study, 32/59 (54%) were female, 46/59 (78%) were white, and age ranged from 1 day to 78 months. Patients received subcutaneous STRENSIQ at 6 mg/kg per week for the first 4 weeks. Ten patients received dose increases higher than 6 mg/kg per week due to suboptimal clinical response, with dose increases occurring between 8 and 24 weeks after starting treatment.
The recommended dosage regimen of STRENSIQ for the treatment of perinatal/infantile-onset HPP is up to 9 mg/kg per week administered subcutaneously as 3 mg/kg three times per week. Forty-one patients were treated for at least 24 weeks (6 months) and 15 patients were treated for at least 96 weeks (24 months). Survival and Ventilation-Free Survival in Perinatal/Infantile-Onset HPP Survival and invasive ventilation-free survival were compared in STRENSIQ-treated patients (Studies 1 and 2) with a historical cohort of untreated patients with similar clinical characteristics (Table 7 and Figure 1). Table 7: Survival and Invasive Ventilation-Free Survival in STRENSIQ-Treated versus Historical Control Patients with Perinatal/ Infantile-Onset HPP (Pooled Studies 1 and 2) STRENSIQ-Treated Historical Controls Survival n = 68 n = 48 Alive at Point of Last Contact (%) 91 27 Hazard Ratio (STRENSIQ/Historical Control), 95% Confidence Interval Adjusted for year of diagnosis. 0.14 Kaplan-Meier Estimate and Alive at Age 1 Year (Week 48) (%) 97 42 Invasive Ventilation-Free Survival Alive and not initiating invasive ventilation after start of STRENSIQ treatment. STRENSIQ-treated patients on invasive ventilation at baseline were excluded from this analysis. n = 54 n = 48 Alive and Not on Ventilation at Point of Last Contact (%) 85 25 Hazard Ratio (STRENSIQ/Historical Control), 95% Confidence Interval 0.21 Kaplan-Meier Estimate of Alive and Not on Ventilation at Age 1 Year (Week 48) (%) 96 31 In patients who required any form of respiratory support, 21 of 26 (81%) of the treated patients survived through their last assessment (median age at last assessment was 3.2 years of age), versus 1 of 20 (5%) of historical controls.
Figure 1: Overall Survival in STRENSIQ-Treated versus Historical Control Patients with Perinatal/ Infantile-Onset HPP (Pooled Studies 1 and 2) Figure 1 Skeletal Manifestations in Perinatal/Infantile-Onset HPP Radiographs from 68 STRENSIQ-treated perinatal/infantile-onset HPP patients, including 64 patients in Studies 1 and 2, and 4 patients in Study 3 , were examined to assess HPP-related rickets using the 7-point Radiographic Global Impression of Change (RGI-C) scale. Patients with a minimum RGI-C score of +2 were defined as "responders". Radiologic improvements could be seen by Month 24; at last assessment, 50/68 treated patients were rated as RGI-C responders. No comparative data were available from historical controls.
The mean time interval between the baseline and last RGI-C assessment was 24 months (range was 1 month to 67 months). Eighteen perinatal/infantile-onset HPP patients experienced fractures during the course of treatment. There were insufficient data to determine the effect of STRENSIQ on fractures. Growth in Perinatal/Infantile-Onset HPP Height and weight measurements (as measured by Z-scores) were available post-treatment for 72 perinatal/infantile-onset HPP patients, including 68 patients enrolled in Studies 1 and 2, and 4 patients enrolled in Study 3 (Table 8). Table 8: Perinatal/Infantile-Onset Height and Weight Measurements as Measured by Z-Score (Studies 1 and 2) Height Z-score Weight Z-score Baseline Last Assessment Baseline Last Assessment Mean Min, Max Mean Min, Max Mean Min, Max Mean Min, Max Studies 1 and 2 The mean time interval between baseline and last assessment was 21 months (range was 1 month to 72 months). (N=68) -3.3 -10.1, 0.9 -2.9 -10.6, 0.4 -3.2 -23.8, 0 -2.4 -20.9.
Study 3 (N=4)
The mean time between baseline and last assessment was 56 months (range was 53 months to 60 months). -2.6 -6.6, -0.7 -1.5 -5.8, 0.4 -2.5 -8.2, -1.0 -1.5 -5.4,
Long-Term Extension Trials in Perinatal/Infantile-Onset
HPP Long-term data were collected in 68 STRENSIQ-treated patients with perinatal/infantile onset HPP in Studies 1 and 2 and an additional 10 patients enrolled in Study 2. The longest duration of follow-up in the 78 patients was 7 years (84 months). At point of last contact, 69/78 (88%) STRENSIQ-treated patients had survived.
Juvenile-Onset
HPP Study 3 was a prospective open-label 24-week trial that included 8 juvenile-onset HPP patients and 5 perinatal/ infantile-onset HPP patients; 11/13 (85%) were male and 12/13 (92%) were white . On study entry, patients were 6 to 12 years of age. All 8 juvenile-onset patients entered the extension study and were treated for at least 48 months. At trial entry, patients were randomized to receive subcutaneous STRENSIQ 6 mg/kg per week or 9 mg/kg per week.
Two patients received dose reductions during the primary treatment period, including one patient who experienced a decrease in vitamin B6 levels and one patient who experienced recurrent injection site reactions. During the extension phase, the dosing regimen for all patients was initially changed to 3 mg/kg per week. Dosing was subsequently increased to 6 mg/kg per week, with no patients requiring doses higher than 6 mg/kg per week.
The recommended dosage regimen of STRENSIQ for the treatment of juvenile-onset HPP is 6 mg/kg per week. Growth in Juvenile-Onset HPP Height and weight measurements (as measured by Z-scores) in 8 STRENSIQ-treated juvenile-onset HPP patients were compared with a historical cohort of 32 untreated patients with similar clinical characteristics (Table 9). Height and weight data for historical patients were collected from medical records. Table 9: Juvenile-Onset Height and Weight Measurements as Measured by Z-Score (Study 3) Height Z-score Weight Z-score Baseline Last Assessment Baseline Last Assessment Mean Min, Max Mean Min, Max Mean Min, Max Mean Min, Max STRENSIQ (N=8) The mean time interval between baseline and last assessment was 55 months (range was 53 months to 60 months). -1.5 -3.8, 0 -0.9 -2, 0 -1.1 -3.5, 2.3 0 -1.3,
Control (N=32)
The mean time interval between baseline and last assessment was 61 months (range was 19 months to 109 months). -1.1 -4.9, 2.6 -1.1 -4.9, 1.8 -1.2 -5, 2.1 -1 -5.7,
Skeletal Manifestations in Juvenile-Onset
HPP Radiographs from 8 STRENSIQ-treated juvenile-onset HPP patients and 32 historical controls were compared to assess HPP-related rickets using the 7-point RGI-C (Radiographic Global Impression of Change) scale. Patients who achieved a RGI-C score of 2 or higher (corresponding to substantial healing of rickets) were classified as being responders to treatment. All 8 treated patients were rated as responders by Month 54 of treatment.
The mean duration between the baseline and last RGI-C assessments for control patients was 56 months (range was 8 to 95 months). At last assessment, 2/32 (6%) of control patients were rated as responders. Eight of 20 (40%) patients with juvenile-onset HPP experienced new fractures during the course of treatment. There were insufficient data to assess the effect of STRENSIQ on fractures.
Gait/Mobility in Juvenile-Onset HPP Gait was assessed using a modified Performance Oriented Mobility Assessment-Gait (MPOMA-G) scale in 8 STRENSIQ-treated juvenile-onset HPP patients at 6-month intervals out to 36 months. Mobility was also assessed using the 6 Minute Walk Test (6MWT) in 7 of the 8 patients. Step length improved by at least 1 point in either foot in 6/8 patients compared to 1/6 (17%) control patients.
The proportion of patients who had 6MWT percent predicted values within the normal range for age, sex, and height-matched peers increased from 0/8 patients at baseline to 6/6 patients (100%) by Month 48 and all 6 were also able to walk longer distances at this time point compared to baseline. Long-Term Extension Trials in Juvenile-Onset HPP Long-term data were collected in 8 patients with juvenile-onset HPP treated with STRENSIQ for at least 6 years (72 months). At last assessment, 7 patients with available 6MWT results had maintained improvements in gait/mobility.
Drug information sourced from the FDA. This content is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any medication decisions.
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