An Efficacy and Safety Study of Intravenous Anifrolumab to Treat Systemic Lupus Erythematosus in Pediatric Participants (BLOSSOM)

May 26, 2026 updated by: AstraZeneca

A Phase III, Randomized, Double-blind, Parallel-group, Placebo-controlled Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Efficacy, and Safety of IV Anifrolumab in Pediatric Participants 5 to < 18 Years of Age With Moderate to Severe Active Systemic Lupus Erythematosus While on Background Standard of Care Therapy

A Study to Evaluate the Pharmacokinetics (PK), Pharmacodynamics (PD), Efficacy, and Safety of Anifrolumab in Children with Moderate to Severe Active Systemic Lupus Erythematosus (SLE)

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This study aims to characterize the pharmacokinetics, pharmacodynamics, efficacy, and safety of anifrolumab solution for infusion compared with placebo solution for infusion in pediatric participants with severe active systemic lupus erythematosus who are on background standard of care therapy.

The study duration for a participant will be approximately 116 weeks, which includes:

  • Screening period of up to 30 days.
  • Part A consists of a four-week, double-blind, placebo-controlled, randomised, pharmacokinetic period.
  • Part B is a double-blind, placebo-controlled, randomised, safety/efficacy period lasting 48 weeks (for rollover participants from Part A) or 52 weeks (for de novo participants).
  • Part C is a 52-week open-label extension period.
  • Part D is a safety follow-up period. One safety visit at 12 weeks post last dose.

Study Type

Interventional

Enrollment (Estimated)

100

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Argentina
      • Buenos Aires, Argentina, C1270
        • Withdrawn
        • Research Site
      • Córdoba, Argentina, 5000
        • Recruiting
        • Research Site
      • Rosario, Argentina, S2000PBJ
        • Recruiting
        • Research Site
      • San Miguel de Tucumán, Argentina, T4000AXL
        • Not yet recruiting
        • Research Site
  • Brazil
      • Belo Horizonte, Brazil, 30130-100
        • Not yet recruiting
        • Research Site
      • Porto Alegre, Brazil, 90035-903
        • Recruiting
        • Research Site
      • Ribeirão Preto, Brazil, 14048-900
        • Recruiting
        • Research Site
      • São Paulo, Brazil, 04024-002
        • Recruiting
        • Research Site
      • São Paulo, Brazil, 05403 000
        • Recruiting
        • Research Site
  • Canada
    • British Columbia
      • Calgary, British Columbia, Canada, T2N 4N1
        • Not yet recruiting
        • Research Site
      • Vancouver, British Columbia, Canada, V6H 3N1
        • Recruiting
        • Research Site
    • Ontario
      • Toronto, Ontario, Canada, M5G 1X8
        • Recruiting
        • Research Site
  • China
      • Beijing, China, 100730
        • Recruiting
        • Research Site
      • Beijing, China, 100032
        • Not yet recruiting
        • Research Site
      • Beijing, China, 100020
        • Withdrawn
        • Research Site
      • Changchun, China, 130021
        • Recruiting
        • Research Site
      • Changsha, China, 410007
        • Recruiting
        • Research Site
      • Nanjing, China, 210008
        • Not yet recruiting
        • Research Site
      • Shanghai, China, 201102
        • Recruiting
        • Research Site
      • Suzhou, China, 215002
        • Recruiting
        • Research Site
      • Wenzhou, China, 325027
        • Recruiting
        • Research Site
      • Zhengzhou, China, 450018
        • Recruiting
        • Research Site
  • Colombia
      • Barranquilla, Colombia, 01800
        • Recruiting
        • Research Site
      • Medellín, Colombia, 050034
        • Withdrawn
        • Research Site
  • France
      • Bordeaux, France, 33076
        • Recruiting
        • Research Site
      • Bron, France, 69677
        • Recruiting
        • Research Site
      • Le Kremlin-Bicêtre, France, 94275
        • Recruiting
        • Research Site
      • Lille, France, 59037
        • Recruiting
        • Research Site
      • Toulouse, France, 31300
        • Recruiting
        • Research Site
  • Germany
      • Berlin, Germany, D-13353
        • Recruiting
        • Research Site
      • Freiburg im Breisgau, Germany, 79106
        • Recruiting
        • Research Site
      • Sankt Augustin, Germany, 53757
        • Recruiting
        • Research Site
  • Italy
      • Genova, Italy, 16148
        • Recruiting
        • Research Site
      • Milan, Italy, 20122
        • Not yet recruiting
        • Research Site
      • Milan, Italy, 20122
        • Recruiting
        • Research Site
      • Padova, Italy, 35128
        • Recruiting
        • Research Site
      • Roma, Italy, 00165
        • Recruiting
        • Research Site
  • Japan
      • Bunkyō City, Japan, 113-8519
        • Recruiting
        • Research Site
      • Bunkyō City, Japan, 113-8603
        • Recruiting
        • Research Site
      • Chiba, Japan, 266-0007
        • Recruiting
        • Research Site
      • Fuchu-shi, Japan, 183-8561
        • Recruiting
        • Research Site
      • Kawasaki-shi, Japan, 216-8511
        • Recruiting
        • Research Site
      • Kobe, Japan, 650-0047
        • Recruiting
        • Research Site
      • Obu-shi, Japan, 474-8710
        • Recruiting
        • Research Site
      • Shinjuku-ku, Japan, 162-8666
        • Recruiting
        • Research Site
      • Yokohama, Japan, 236-0004
        • Recruiting
        • Research Site
      • Yokohama, Japan, 232 8555
        • Recruiting
        • Research Site
  • Mexico
      • Atizapán de Zaragoza, Mexico, 52937
        • Not yet recruiting
        • Research Site
      • Guadalajara, Mexico, 44620
        • Recruiting
        • Research Site
      • Monterrey, Mexico, 64460
        • Recruiting
        • Research Site
      • Mérida, Mexico, 97070
        • Recruiting
        • Research Site
      • México, Mexico, 06720
        • Recruiting
        • Research Site
  • Poland
      • Lodź, Poland, 91-738
        • Recruiting
        • Research Site
      • Warsaw, Poland, 02-637
        • Recruiting
        • Research Site
      • Wroclaw, Poland, 52-114
        • Recruiting
        • Research Site
  • Portugal
      • Lisbon, Portugal, 1169-045
        • Withdrawn
        • Research Site
      • Lisbon, Portugal, 1649-035
        • Withdrawn
        • Research Site
      • Porto, Portugal, 4200-319
        • Withdrawn
        • Research Site
  • South Africa
      • Cape Town, South Africa, 7700
        • Withdrawn
        • Research Site
  • Spain
      • Esplugues de Llobregat, Spain, 8950
        • Recruiting
        • Research Site
      • Madrid, Spain, 28034
        • Recruiting
        • Research Site
      • Madrid, Spain, 28046
        • Not yet recruiting
        • Research Site
      • Madrid, Spain, 28009
        • Recruiting
        • Research Site
      • Málaga, Spain, 29011
        • Recruiting
        • Research Site
      • Santiago de Compostela, Spain, 15706
        • Not yet recruiting
        • Research Site
      • Valencia, Spain, 46026
        • Recruiting
        • Research Site
  • Turkey (Türkiye)
      • Ankara, Turkey (Türkiye), 06230
        • Recruiting
        • Research Site
      • Istanbul, Turkey (Türkiye), 34098
        • Recruiting
        • Research Site
      • Kayseri, Turkey (Türkiye), 38039
        • Recruiting
        • Research Site
      • Umraniye, Turkey (Türkiye), 34760
        • Recruiting
        • Research Site
  • United Kingdom
      • Birmingham, United Kingdom, B4 6NH
        • Recruiting
        • Research Site
      • Bristol, United Kingdom, BS2 8BJ
        • Recruiting
        • Research Site
      • Liverpool, United Kingdom, L12 2AP
        • Recruiting
        • Research Site
      • London, United Kingdom, NW1 2PG
        • Recruiting
        • Research Site
      • London, United Kingdom, WC1N 3JH
        • Recruiting
        • Research Site
      • Manchester, United Kingdom, M13 9WL
        • Recruiting
        • Research Site
      • Southampton, United Kingdom, SO16 6YD
        • Recruiting
        • Research Site
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85016
        • Recruiting
        • Research Site
    • California
      • Los Angeles, California, United States, 90027
        • Recruiting
        • Research Site
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20010
        • Recruiting
        • Research Site
    • Illinois
      • Chicago, Illinois, United States, 60637
        • Recruiting
        • Research Site
      • Chicago, Illinois, United States, 60611
        • Recruiting
        • Research Site
    • Louisiana
      • New Orleans, Louisiana, United States, 70118
        • Not yet recruiting
        • Research Site
    • Maryland
      • Bethesda, Maryland, United States, 20889
        • Withdrawn
        • Research Site
    • Minnesota
      • Saint Paul, Minnesota, United States, 55125
        • Recruiting
        • Research Site
    • New York
      • New Hyde Park, New York, United States, 11042
        • Recruiting
        • Research Site
      • New York, New York, United States, 10032
        • Recruiting
        • Research Site
      • The Bronx, New York, United States, 10467
        • Recruiting
        • Research Site
      • Valhalla, New York, United States, 10595
        • Recruiting
        • Research Site
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Recruiting
        • Research Site
    • Ohio
      • Cincinnati, Ohio, United States, 45229
        • Recruiting
        • Research Site
      • Cleveland, Ohio, United States, 44109
        • Recruiting
        • Research Site
      • Columbus, Ohio, United States, 43203
        • Recruiting
        • Research Site
    • Oregon
      • Portland, Oregon, United States, 97227
        • Recruiting
        • Research Site
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Recruiting
        • Research Site
    • South Carolina
      • Greenville, South Carolina, United States, 29605
        • Withdrawn
        • Research Site
    • Texas
      • El Paso, Texas, United States, 79902
        • Recruiting
        • Research Site
      • Houston, Texas, United States, 77030
        • Recruiting
        • Research Site
    • Utah
      • Salt Lake City, Utah, United States, 84108
        • Recruiting
        • Research Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participant's parent/caregiver/legally authorized representative and participant (if required per local country regulation) capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the ICF and in this protocol. Informed assent is to be provided by the participant per local country regulation.
  • Diagnosis of SLE according to the 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) criteria for at least 3 months prior to signing the ICF.
  • Participant should meet all of following tuberculosis (TB) criteria:

A. No signs or symptoms of active TB B. No medical history or past physical examinations suggestive of active TB C. No recent contact with a person with active TB or if there has been such contact, referral to a TB specialist for evaluation and initiation of treatment for latent TB, if warranted, prior to the first administration of study intervention in accordance with local SoC D. No history of latent TB without documented completion of treatment prior to initial screening visit

  • Female participants of childbearing potential must have a negative serum pregnancy test at screening and negative urine pregnancy test at randomization.
  • Female participants of childbearing and male participants must adhere to the contraception methods.

Exclusion Criteria:

  • Known diagnosis of an IFN-mediated autoinflammatory interferonopathy.
  • History of, or current diagnosis of, clinically significant non-SLE-related vasculitides.
  • In participants aged 11 years and above: history or evidence of suicidal ideation.
  • History of any non-SLE disease that has required treatment with oral or parenteral corticosteroids for more than a total of 2 weeks within the last 24 weeks prior to signing the ICF.
  • Any positive result on screening for human immunodeficiency virus.
  • Active hepatitis B surface antigen OR hepatitis B core antibody (HBcAb), hepatitis C virus (HCV) antibody and detectable HCV ribonucleic acid (RNA) or any active or recent case of Herpes Zoster infection.
  • Any clinical cytomegalovirus or Epstein-Barr virus infection that has not completely resolved within 12 weeks prior to signing the ICF.
  • History of severe COVID-19 infection requiring hospitalization, intensive care unit care, or assisted ventilation or any prior COVID-19 infection with unresolved sequelae. Any mild/asymptomatic COVID-19 infection (laboratory confirmed or suspected based on clinical symptoms).
  • Prior use of anifrolumab.
  • Prior treatment with directly acting cytotoxic B-cell depleting therapeutics (eg, rituximab) < 26 weeks prior to ICF signature.
  • Blood transfusion or receipt of blood products except albumin within 4 weeks prior to signing the ICF.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Randomized participants will receive matching placebo via IV infusion
Drug: Placebo
Participants will receive matching placebo via IV infusion
Experimental: Anifrolumab
Randomized participants will receive anifrolumab via intravenous (IV) infusion every 4 weeks
Biological: Anifrolumab
Participants will receive anifrolumab via IV infusion.
Other Names:
  • (MEDI-546)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part B - Number of participants who are British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA) responders (yes/no)
Time Frame: At Week 52

BICLA response is defined as:

  • Reduction of all baseline British Isles Lupus Assessment Group BILAG-2004 A to B/C/D and B to C/D, and no BILAG-2004 worsening in other organ systems, as defined by ≥ 1 new BILAG-2004 A or ≥ 2 new BILAG- 2004 B.
  • No worsening from baseline in SLEDAI-2K, defined as an increase from baseline of > 0 points.
  • No worsening from baseline in participant's lupus disease activity, defined by an increase ≥ 0.30 points on a PGA 3-point visual analogue scale (VAS).
At Week 52
Part A - Maximum observed serum (peak) drug concentration (Cmax)
Time Frame: Up to Day 29
The serum PK will be characterised and the dose of anifrolumab will be defined in pediatric participants with moderate to severely active SLE.
Up to Day 29
Part A - Area under the serum concentration curve (AUC)
Time Frame: Up to Day 29
The serum PK will be characterised and the dose of anifrolumab will be defined in pediatric participants with moderate to severe active SLE.
Up to Day 29
Part A - Minimum observed serum concentration (Cmin)
Time Frame: Up to Day 29
The serum PK will be characterised and the dose of anifrolumab will be defined in pediatric participants with moderate to severe active SLE.
Up to Day 29
Part A- Anifrolumab serum concentration
Time Frame: Pre-dose Day 29
The serum concentration will be characterised and the dose of anifrolumab will be defined in pediatric participants with moderate to severely active SLE.
Pre-dose Day 29

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part B - Number of participants who are Systemic Lupus Erythematosus Responder Index of ≥ 4 SRI(4) responders (yes/no)
Time Frame: At Week 52

SRI-4 response is defined as:

  • ≥ 4-point reduction from baseline in Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score.
  • No new organ systems affected as defined by ≥ 1 new BILAG-2004 A or ≥ 2 new BILAG-2004 B items compared to baseline.
  • No worsening from baseline in participant's lupus disease activity, defined by an increase ≥ 0.30 points on a PGA 3-point VAS.
At Week 52
Number of participants who are Pediatric Rheumatology International Trials Organization/American College of Rheumatology (PRINTO/ACR) childhood-onset systemic lupus erythematosus (cSLE) responders (yes/no)
Time Frame: At Week 52

PRINTO/ACR cSLE responders are defined as participants with at least 50% improvement from baseline in any 2 of 5 core set outcome measures and no more than one of the remaining worsening more than 30%, where the core set measures are:

  • ParentGA 21-circle VAS
  • PGA 3-point VAS
  • SLEDAI-2K
  • PedsQL Generic Core (Physical Functioning Domain)
  • Proteinuria
At Week 52
Part B - Time to first flare
Time Frame: Through Week 52
Time to first flare, where flare is defined as either ≥ 1 new BILAG-2004 A, or ≥ 2 new BILAG-2004 B items compared with the previous visit.
Through Week 52
Part B - Anifrolumab serum concentration
Time Frame: Pre-dose Week 12, Pre-dose Week 24, Pre-dose Week 52
The PK of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
Pre-dose Week 12, Pre-dose Week 24, Pre-dose Week 52
Part - B Change from baseline through Week 52 in antidrug antibody (ADA)
Time Frame: Up to Week 52
The immunogenicity of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
Up to Week 52
Part - B Change from baseline in anti-double stranded deoxyribonucleic acid antibodies
Time Frame: At Week 12 and Week 52
The PD of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
At Week 12 and Week 52
Part - B Change from baseline in total hemolytic complement (CH50)
Time Frame: At Week 12 and Week 52
The PD of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
At Week 12 and Week 52
Part - B Change from baseline in complement component (C3)
Time Frame: At Week 12 and Week 52
The PD of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
At Week 12 and Week 52
Part - B Change from baseline in complement component (C4)
Time Frame: At Week 12 and Week 52
The PD of anifrolumab in pediatric participants with moderate to severe active SLE will be characterized.
At Week 12 and Week 52
Part B - The mean percentage reduction from Baseline through Week 52 in oral corticosteroid(s) (OCS) background dose
Time Frame: At Week 52
The efficacy of anifrolumab vs placebo on OCS background dose in pediatric participants with moderate to severe active SLE will be characterized.
At Week 52
Part B - Change from baseline through Week 52 in type I interferon (IFN) 21-gene signature
Time Frame: At Week 52
Type 1 IFN 21 gene signatures in pediatric patients with moderate to active SLE will be characterized.
At Week 52

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
All parts - Number of participants reporting suicidal ideation and/or suicidal behavior as per Columbia Suicide Severity Rating Scale (C-SSRS)
Time Frame: From Week 0 until the follow-up visit (12 weeks post-last dose)
The safety and tolerability of anifrolumab in pediatric participants with moderate to severe active SLE will be assessed.
From Week 0 until the follow-up visit (12 weeks post-last dose)
All parts - Number of participants with adverse events
Time Frame: From Week 0 until the follow-up visit (12 weeks post-last dose)
The safety and tolerability of anifrolumab in pediatric participants with moderate to severe active SLE will be assessed.
From Week 0 until the follow-up visit (12 weeks post-last dose)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

AstraZeneca

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 14, 2024

Primary Completion (Estimated)

October 5, 2028

Study Completion (Estimated)

January 9, 2030

Study Registration Dates

First Submitted

April 18, 2023

First Submitted That Met QC Criteria

April 18, 2023

First Posted (Actual)

April 28, 2023

Study Record Updates

Last Update Posted (Actual)

May 27, 2026

Last Update Submitted That Met QC Criteria

May 26, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • D3461C00030
  • 2022-502289-25-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All requests will be evaluated as per the AZ disclosure commitment:

https://astrazenecagrouptrials.pharmacm.com /ST/Submission/Disclosure.

Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.

IPD Sharing Time Frame

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please refer to our disclosure commitment at:

https://astrazenecagrouptrials.pharmacm.com /ST/Submission/Disclosure.

IPD Sharing Access Criteria

When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool. Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at:

https://astrazenecagrouptrials.pharmacm.com /ST/Submission/Disclosure.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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