Last reviewed 2026-05-26 · How we verify

Strensiq (ASFOTASE ALFA)

Strensiq (generic name: ASFOTASE ALFA) is a Tissue-nonspecific Alkaline Phosphatase [EPC] Enzyme drug developed by AstraZeneca. It is currently FDA-approved (first approved 2015) for Hypophosphatasia.

Strensiq works by replacing the deficient tissue-nonspecific alkaline phosphatase enzyme in patients with hypophosphatasia.

Asfotase Alfa is a medication used to treat Hypophosphatasia (HPP), a rare genetic disorder. It works as a pyrophosphate hydrolytic enzyme, which is a type of hydrolytic enzyme.

At a glance

Mechanism of action

HPP is caused by deficiency in TNSALP enzyme activity, which leads to elevations in several TNSALP substrates, including inorganic pyrophosphate (PPi). TNSALP is metallo-enzyme that catalyzes the hydrolysis of phosphomonoesters with release of inorganic phosphate and alcohol. Elevated extracellular levels of PPi block hydroxyapatite crystal growth which inhibits bone mineralization and causes an accumulation of unmineralized bone matrix which manifests as rickets and bone deformation in infants and children and as osteomalacia (softening of bones) once growth plates close, along with muscle weakness. Replacement of the TNSALP enzyme upon STRENSIQ treatment reduces the enzyme substrate levels.

Approved indications

• Hypophosphatasia

Boxed warnings

• WARNING: HYPERSENSITIVITY REACTIONS INCLUDING ANAPHYLAXIS Patients treated with enzyme replacement therapies have experienced life-threatening hypersensitivity reactions, including anaphylaxis. 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. Inform patients of the symptoms of life-threatening hypersensitivity reactions, including anaphylaxis and to seek immediate medical care should symptoms occur [see Warnings and Precautions (5.1) ] . WARNING: HYPERSENSITIVITY REACTIONS INCLUDING ANAPHYLAXIS See full prescribing information for complete boxed warning. Anaphylaxis has occurred during the early course of enzyme replacement therapy and after extended duration of therapy. ( 5.1 ) Initiate STRENSIQ under the supervision of a healthcare provider with appropriate medical monitoring and support measures. ( 5.1 ) If a severe hypersensitivity reaction (e.g., anaphylaxis) occurs, discontinue STRENSIQ and immediately initiate appropriate medical treatment, including use of epinephrine. ( 5.1 )

Common side effects

• Injection site reactions
• Lipodystrophy
• Ectopic calcifications
• Hypersensitivity reactions
• Erythema
• Discoloration/Hypopigmentation
• Pain/Tenderness
• Pruritus/Itching
• Swelling
• Induration
• Macule
• Reaction, not otherwise specified

Key clinical trials

• Phase 3 Study of ALXN1850 Versus Placebo in Adolescent and Adult Participants With HPP Who Have Not Previously Been Treated With Asfotase Alfa (PHASE3)
• Phase 3 Study of ALXN1850 in Pediatric Participants With HPP Previously Treated With Asfotase Alfa (PHASE3)
• Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPP (PHASE3)
• A Prospective Sub-Study of the Global Hypophosphatasia Registry
• Mitigate Immune-Mediated Loss of Therapeutic Response to Asfotase Alfa (STRENSIQ®) for Hypophosphatasia (PHASE4)
• Patient Reported Outcomes in Adults With Pediatric-onset Hypophosphatasia Treated With Strensiq® (Asfotase Alfa)
• Safety and Efficacy Study of ENB-0040 in Juvenile Patients With Hypophosphatasia (HPP) (PHASE2)
• Evaluate and Monitor Physical Performance of Adults Treated With Asfotase Alfa for Hypophosphatasia

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Strensiq CI brief — competitive landscape report
• Strensiq updates RSS · CI watch RSS
• AstraZeneca portfolio CI

Frequently asked questions about Strensiq

Related

• Drug class: All Tissue-nonspecific Alkaline Phosphatase [EPC] drugs
• Manufacturer: AstraZeneca — full pipeline
• Therapeutic area: All drugs in Bone
• Indication: Drugs for Hypophosphatasia

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing