Alexion Pharmaceuticals, a wholly‑owned subsidiary of AstraZeneca plc (NYSE: AZN), announced that the U.S. Food and Drug Administration (FDA) has accepted the Biologics License Application (BLA) and granted Priority Review for efzimfotase alfa (ALXN1850), an investigational enzyme replacement therapy (ERT) for patients aged 2 years and older with hypophosphatasia (HPP). The FDA is expected to reach a decision in the first half of 2027.
Regulatory Milestone
| Item | Detail |
|---|---|
| Agency | FDA (United States) |
| Filing Type | BLA accepted with Priority Review designation |
| Product | Efzimfotase alfa (ALXN1850), subcutaneous ERT |
| Proposed Indication | HPP in patients aged 2 years and older |
| PDUFA Target | First half of 2027 |
| Ex‑US Filings | Marketing applications under review in Japan and other major markets; China’s CDE accepted the country’s first marketing application on 24 Aug 2026 |
Drug Profile & Mechanism of Action
- Disease Background: HPP is a rare inherited metabolic disorder caused by deficient alkaline phosphatase (ALP) activity, leading to abnormal bone mineralization and disturbed calcium and phosphate metabolism, alongside muscle weakness, chronic pain, fatigue and neurological symptoms.
- Molecule: ALXN1850 is an ERT designed to replace the deficient ALP activity at the root of the disease.
- Route & Regimen: Subcutaneous injection planned once every two weeks, combining treatment convenience with support for self‑administration — a key unmet need in HPP care.
- Differentiation vs. Incumbent: Compared with Strensiq® (asfotase alfa), the existing bone‑targeted ERT, ALXN1850 showed an approximately 5‑fold lower annualized rate of injection‑site reactions, according to Alexion.
- Potential First: If approved, ALXN1850 could become the first HPP therapy not restricted by age of onset, simultaneously addressing both skeletal abnormalities and functional impairment.
- Patient Population: Alexion estimates roughly 13,800 potential HPP patients across eight major markets (U.S., Germany, France, U.K., Italy, Spain, Japan and China), about 80 % of whom are adults.
Clinical Evidence – Phase III Program (MULBERRY / CHESTNUT / HICKORY)
| Study | Population | Design | Primary Endpoint | Results |
|---|---|---|---|---|
| MULBERRY | 29 pediatric patients aged 2–12, Strensiq‑naïve | Double‑blind, placebo‑controlled | Skeletal RGI‑C at Day 169 | Not disclosed in this announcement |
| CHESTNUT | 43 pediatric patients aged 2–12 with ≥6 months prior Strensiq exposure | Open‑label, active‑controlled | Safety & tolerability after switching to ALXN1850 | Favorable safety and tolerability reported |
| HICKORY | 124 adolescents and adults aged ≥12, Strensiq‑naïve | – | Change from baseline in 6‑minute walk test (6MWT) distance at Day 169 | Not disclosed in this announcement |
The BLA is supported by one of the largest Phase III clinical development programs in HPP, spanning pediatric, adolescent and adult patients. All three studies demonstrated favorable safety and tolerability, per Alexion. Patients completing the randomized assessment period are eligible to continue in the ongoing open‑label extension studies.
Market Impact & Outlook
- Rare Disease Landscape: With an estimated 13,800 identifiable patients across major markets — predominantly adults — a therapy addressing both skeletal and functional outcomes across all ages could redefine the HPP treatment standard.
- Convenience Edge: A once‑every‑two‑weeks, self‑administered subcutaneous regimen directly targets treatment‑burden pain points, a meaningful advantage over more frequent bone‑targeted ERT dosing.
- Tolerability Profile: The ~5‑fold lower annualized injection‑site reaction rate versus Strensiq strengthens the label’s potential competitiveness on tolerability.
- Global Regulatory Momentum: Concurrent reviews at the FDA (1H 2027 decision), Japan and other major markets, plus CDE acceptance in China, position Alexion for a coordinated multi‑region launch if approvals are granted.
Forward‑Looking Statements
This brief contains forward‑looking statements regarding regulatory timelines (including the FDA’s anticipated 1H 2027 decision and pending reviews in Japan, China and other markets), clinical outcomes of the ongoing open‑label extension studies, and commercial expectations for efzimfotase alfa (ALXN1850). Actual results may differ materially due to risks including regulatory decisions, approval conditions, market adoption, and competitive dynamics. Investors should not place undue reliance on these statements.-Fineline Info & Tech
