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Mitigate Immune-Mediated Loss of Therapeutic Response to Asfotase Alfa (STRENSIQ®) for Hypophosphatasia

NCT ID: NCT06015750

Last Updated: 2025-12-18

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

WITHDRAWN

Clinical Phase

PHASE4

Study Classification

INTERVENTIONAL

Study Start Date

2026-07-29

Study Completion Date

2030-03-13

Brief Summary

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The primary objective of this study is to evaluate the effect of immunosuppressive therapy (IST) in participants treated with asfotase alfa who demonstrate immune-mediated loss of effectiveness (LoE).

Detailed Description

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The administration of biological drugs to patients, especially for chronic conditions, carries a risk of eliciting anti-drug antibodies. Neutralizing antibodies can neutralize the clinical benefit of the agent. In postmarketing safety surveillance, some patients treated with asfotase alfa demonstrated an initial response, but subsequently recurrence and progression of disease. Consequently, the FDA requested a study to assess a potential serious risk of immune-mediated loss of effectiveness.

Conditions

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Hypophosphatasia

Keywords

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Hypophosphatasia HPP Asfotase alfa Strensiq

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Pediatric participants with HPP

Pediatric participants who have been receiving asfotase alfa treatment for their HPP, and who demonstrate immune-mediated LoE.

Group Type EXPERIMENTAL

methotrexate

Intervention Type DRUG

Methotrexate will be administered SC or orally weekly for 104 weeks.

rituximab

Intervention Type DRUG

Rituximab will be administered intravenously (IV) continuously weekly, for up to 74 weeks.

bortezomib

Intervention Type DRUG

Bortezomib will be administered via IV bolus or SC, as needed.

IVIg

Intervention Type DRUG

IVIg will be administered via IV monthly through initial 74 weeks.

Folic Acid

Intervention Type DRUG

Folic acid will be given orally as long as methotrexate is being dosed.

Interventions

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methotrexate

Methotrexate will be administered SC or orally weekly for 104 weeks.

Intervention Type DRUG

rituximab

Rituximab will be administered intravenously (IV) continuously weekly, for up to 74 weeks.

Intervention Type DRUG

bortezomib

Bortezomib will be administered via IV bolus or SC, as needed.

Intervention Type DRUG

IVIg

IVIg will be administered via IV monthly through initial 74 weeks.

Intervention Type DRUG

Folic Acid

Folic acid will be given orally as long as methotrexate is being dosed.

Intervention Type DRUG

Eligibility Criteria

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Inclusion Criteria

* Reoccurrence or worsening of rickets for at least the past 3 months in participants who showed an initial efficacy response to asfotase alfa after at least 6 months of continuous treatment and currently receiving asfotase alfa. RSS will be used to determine severity at Baseline.
* Presence of ADAs, with or without NAbs, irrespective of their titers.
* Confirmation by the TMB that both the clinical evidence and immunogenicity-mediated association noted above are present.
* Female participants of childbearing potential and male participants with partners of childbearing potential must follow protocol-specified contraception guidance as described in Section 10.5.
* Participant, or participant's legal guardian, is capable of signing informed consent or assent as described in Section 10.1.3, which includes compliance with the requirements and restrictions listed in the informed consent or assent form and in this protocol.

Exclusion Criteria

* Known history of human immunodeficiency virus (HIV) infection (evidenced by HIV type 1 or type 2 \[HIV 1, HIV 2\] antibody) or hepatitis B or C viral infection.
* Known or suspected history of drug or alcohol abuse or dependence within 1 year prior to Screening.
* Inability of the participant, or the participant's legal guardian, to provide informed consent.
* Pregnant, breastfeeding, or intending to conceive during the course of the study.
* Inability to travel to the clinic for specified visits during the Treatment Period caused by disease per se or logistics (does not apply to external travel restrictions).
* The participant is at risk of reactivation or has an active significant viral infection such as hepatitis B, cytomegalovirus, herpes simplex, human polyomavirus (also known as John Cunningham \[JC\] virus), parvovirus, or Epstein Barr virus.
* The participant is at risk of reactivation of tuberculosis or has regular contact (eg, in the household) with individuals who are being actively treated for tuberculosis.
* The participant has had or is required to have any live vaccination within 1 month prior to enrollment.
Minimum Eligible Age

2 Years

Maximum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Alexion Pharmaceuticals, Inc.

INDUSTRY

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Countries

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France United Kingdom United States

Other Identifiers

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AA-HPP-407

Identifier Type: OTHER

Identifier Source: secondary_id

2022-502793-17

Identifier Type: EUDRACT_NUMBER

Identifier Source: secondary_id

D8400C00001

Identifier Type: -

Identifier Source: org_study_id