Asfotase Alfa

HPP is caused by a deficiency in TNSALP enzyme activity, which leads to elevations in several TNSALP substrates, including inorganic pyrophosphate (PPi). TNSALP is a metallo-enzyme that catalyzes the hydrolysis of phosphomonoesters with release of inorganic phosphate and alcohol.

• 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).

• None. None.contraindicated

Perinatal/Infantile-Onset HPP ( 2.2 ) Recommended dosage regimen is 2 mg/kg administered subcutaneously three times per week, or 1 mg/kg administered six times per week. Injection site reactions may limit the tolerability of the six times per week regimen. The dose may be increased to 3 mg/kg three times per week for insufficient efficacy. Juvenile-Onset HPP ( 2.3 ) Recommended dosage regimen is 2 mg/kg administered subcutaneously three times per week, or 1 mg/kg administered six times per week. Injection site reactions may limit the tolerability of the six times per week regimen. Preparation and Weight-Based Dosing ( 2.4 ): Caution: Do not use the 80 mg/0.8 mL vial in pediatric patients weighing less than 40 kg because the systemic asfotase alfa exposure achieved with the 80 mg/0.8 mL vial (higher concentration) is lower than that achieved with the other strength vials (lower concentration). A lower exposure may not be adequate for this subgroup of patients. See full prescribing information for tables of weight-based dosing by treatment regimen. Administration ( 2.5 ): For subcutaneous injection only. Rotate injection sites. Do not administer to areas that are reddened, inflamed or swollen. 2.1 Recommendations Prior to STRENSIQ Treatment Initiate STRENSIQ under the supervision of a healthcare provider with appropriate medical monitoring and support measures [see Warnings and Precautions (5.1) ].

Lipodystrophy: Localized reactions were reported after several months of treatment; follow proper injection technique and rotate injection sites. ( 5.2 ) Ectopic Calcifications (eye and kidneys): Monitor using ophthalmologic examinations and renal ultrasounds at baseline and periodically during treatment. ( 5.3 ) Possible Immune-Mediated Clinical Effects: Evaluate patients for antibody formation if clinically indicated. ( 5.4 ) 5.1 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 [see Adverse Reactions (6.1) ] . 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.

The following adverse reactions are described below and elsewhere in the labeling: Hypersensitivity Reactions [see Warnings and Precautions (5.1) ] Lipodystrophy [see Warnings and Precautions (5.2) ] Ectopic Calcifications [see Warnings and Precautions (5.3) ] Possible Immune-Mediated Clinical Effects [see Warnings and Precautions (5.4) ] Most common adverse reactions (≥ 10%) are injection site reactions, lipodystrophy, ectopic calcifications and hypersensitivity reactions. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Alexion Pharmaceuticals, Inc. at 1-844-259-6783 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 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 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 [78 months]): 51 patients received at least 96 weeks (24 months) of treatment and 39 patients received 168 weeks (42 months) or more of treatment [see Clinical Studies (14) ] . 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%).

8.1 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.

Metabolism

Based on data in 38 HPP patients, the pharmacokinetics of asfotase alfa exhibit dose proportionality across the dose range of 0.3 mg/kg to 3 mg/kg once every other day (three times a week) and appear to be time-independent. Steady state exposure was achieved as early as three weeks after the administration of the first dose.

• Oct 23, 2015BLABLA125513Alexion Pharm

1. 1Injection Site Pain1,27914%
2. 2Fatigue8629.2%
3. 3Injection Site Erythema8449.0%
4. 4Pain7528.0%
5. 5Injection Site Reaction7027.5%
6. 6Arthralgia5996.4%
7. 7Pain In Extremity5035.3%
8. 8Injection Site Bruising4815.1%
9. 9Injection Site Swelling4274.5%
10. 10Headache3703.9%
11. 11Injection Site Pruritus3233.4%
12. 12Blood Alkaline Phosphatase Increased2933.1%
13. 13Injection Site Mass2843.0%
14. 14Nausea2833.0%
15. 15Malaise2823.0%

The 10 most recently updated of 20 ClinicalTrials.gov registrations naming Asfotase Alfa as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPP
  Active not recruiting · Phase 3 · Interventional · 30 enrolled · Alexion Pharmaceuticals, Inc.
  NCT06079359updated 2026-05-28
• Phase 3 Study of ALXN1850 Versus Placebo in Adolescent and Adult Participants With HPP Who Have Not Previously Been Treated With Asfotase Alfa
  Active not recruiting · Phase 3 · Interventional · 124 enrolled · Alexion Pharmaceuticals, Inc.
  NCT06079281updated 2026-05-28
• Phase 3 Study of ALXN1850 in Pediatric Participants With HPP Previously Treated With Asfotase Alfa
  Active not recruiting · Phase 3 · Interventional · 43 enrolled · Alexion Pharmaceuticals, Inc.
  NCT06079372updated 2026-05-05
• A Prospective Sub-Study of the Global Hypophosphatasia Registry
  Recruiting · Observational · 30 enrolled · Alexion Pharmaceuticals, Inc.
  NCT05234567updated 2026-02-09
• Mitigate Immune-Mediated Loss of Therapeutic Response to Asfotase Alfa (STRENSIQ®) for Hypophosphatasia
  Withdrawn · Phase 4 · Interventional · 0 enrolled · Alexion Pharmaceuticals, Inc.
  NCT06015750updated 2025-12-18
• Patient Reported Outcomes in Adults With Pediatric-onset Hypophosphatasia Treated With Strensiq® (Asfotase Alfa)
  Completed · Observational · 50 enrolled · Alexion Pharmaceuticals, Inc.
  NCT04195763updated 2024-07-10
• Safety and Efficacy Study of ENB-0040 in Juvenile Patients With Hypophosphatasia (HPP)
  Withdrawn · Phase 2 · Interventional · 0 enrolled · Alexion Pharmaceuticals, Inc.
  NCT00894075updated 2023-08-04
• Evaluate and Monitor Physical Performance of Adults Treated With Asfotase Alfa for Hypophosphatasia
  Completed · Observational · 23 enrolled · Dr. Lothar Seefried
  NCT03418389updated 2022-07-12
• Relieving Burden of Hypophosphatasia in Adults With Functional Impairment Due to Chronic Disease
  Withdrawn · Phase 4 · Interventional · 0 enrolled · Alexion Pharmaceuticals, Inc.
  NCT04189315updated 2020-06-04
• Pharmacokinetic and Dose Response Study of Asfotase Alfa in Adult Patients With Pediatric-Onset Hypophosphatasia (HPP)
  Completed · Phase 2 · Interventional · 27 enrolled · Alexion Pharmaceuticals, Inc.
  NCT02797821updated 2019-09-17

Frequently asked questions

How does Asfotase Alfa work?

HPP is caused by a deficiency in TNSALP enzyme activity, which leads to elevations in several TNSALP substrates, including inorganic pyrophosphate (PPi). TNSALP is a metallo-enzyme that catalyzes the hydrolysis of phosphomonoesters with release of inorganic phosphate and alcohol.

What is Asfotase Alfa used for?

According to FDA labeling, Asfotase Alfa carries indications including: 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).. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Asfotase Alfa?

Asfotase Alfa is classified as Enzymes, Tissue-nonspecific Alkaline Phosphatase, Enzymatic Activity, Bone Formation Stimulation.

What are the brand names for Asfotase Alfa?

Asfotase Alfa is marketed under brand names including Strensiq.

What are the contraindications for Asfotase Alfa?

Asfotase Alfa labeling lists contraindications including: None. None.. Always consult the full prescribing information and a clinician.