Open-label, Uncontrolled Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Inebilizumab in Pediatric Participants with Immunoglobulin G4-related Disease (IgG4-RD)

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Amgen Inc.

Participant type

Pediatric, Patients

Age range

0-17 years

Gender

Male and Female

Therapeutic area

Diseases [C] - Immune System Diseases [C20]

Trial duration

15 May 2026 → ongoing

Decision date (initial)

2026-02-25

Transition trial

No

Low-intervention

No

Rare-disease indication

Yes

Vulnerable population

Yes

Funding sources

Amgen Inc.

External identifiers

EU CT number

2025-520988-41-00

WHO UTN

U1111-1328-9492

ClinicalTrials.gov

NCT07222553

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Pharmacodynamic, Pharmacokinetic, Others, Safety

• To characterize the pharmacokinetics (PK) of inebilizumab administered in pediatric participants with Immunoglobulin G4-related Disease (IgG4-RD)
• To characterize the pharmacodynamics (PD) of inebilizumab administered in pediatric participants with IgG4 RD
• To assess the safety and tolerability of inebilizumab administered in pediatric participants with IgG4-RD

Secondary objectives 3

1. •To assess efficacy of inebilizumab in pediatric participants with IgG4-RD
2. • To characterize the immunogenicity of inebilizumab administered in pediatric participants with IgG4-RD
3. • To assess the effects of inebilizumab on steroid treatment for IgG4-RD

Conditions and MedDRA coding

Immunoglobulin G4 related Disease (IgG4-RD)

Study design 1 period

Regulatory references

EMA paediatric investigation plan (PIP)

EMEA-001911-PIP03-23

Plan to share IPD

Yes

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 8

1. 101 Participants must weigh ≥ 17 kg to be eligible for enrollment.
2. 102 Participant has provided informed consent/assent before initiation of any study specific activities/procedures. Participant’s legally authorized representative has provided informed consent when the participant is legally too young to provide informed consent, and the participant has provided written assent based on local regulations and/or guidelines before any study-specific activities/procedures being initiated.
3. 103 Age 2 to < 18 years at the time of screening. For participants who reach the age of legal consent during the clinical study, notification will be required, and a new consent form must be signed by the participant for continuation in the study.
4. 104 Clinical diagnosis of IgG4-RD.
5. 105 Fulfillment of the 2019 American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) classification criteria as determined by the principal investigator (PI) at screening. Specifically, participants must meet the classification criteria entry requirements (including involvement of one of the following organs: pancreas, bile ducts/biliary tree, orbits, lungs, kidneys, lacrimal glands, major salivary glands, retroperitoneum, aorta, pachymeninges, or thyroid gland [Riedel’s thyroiditis]), must not meet any of the classification criteria exclusions, and must achieve at least 20 classification criteria inclusion points.
6. 106 Receipt of all age-appropriate and locally-required vaccinations before screening.
7. 107 Participants requiring treatment in addition to or other than GCs for IgG4 RD according to PI’s assessment at screening.
8. 108 Participants who are on GCs for the treatment of IgG4-RD should remain on a stable dose for at least 2 weeks before enrollment (day 1). Tapering post enrollment will be at PI’s discretion.

Exclusion criteria 35

1. 201 Participants with any of the following abnormal liver function tests in the presence of hepatobiliary IgG4-RD activity: • aspartate aminotransferase (AST) > 10 × upper limit of normal (ULN) • alanine aminotransferase (ALT) > 10 × ULN • total bilirubin (TBL) > 5 × ULN Screening liver function tests may be repeated before day 1 to permit abnormal values due to hepatobiliary IgG4-RD activity to respond to glucocorticoid treatment.
2. 210 Known history of congenital or acquired immunodeficiency (eg, due to human immunodeficiency virus [HIV] infection, splenectomy, immunosuppression-related or idiopathic T-cell deficiencies) that predisposes the participant to infection.
3. 211 Positive test for chronic hepatitis B infection at screening, defined as either: (1) positive hepatitis B surface antigen (HBsAg); or (2) a positive hepatitis B core antibody (anti-HBc) PLUS negative hepatitis B surface antibody (anti-HBs). Note: Participants with a positive anti-HBs only, or a positive anti-HBc plus positive anti-HBs and negative HBsAg, are eligible to enroll.
4. 212 History of untreated hepatitis C infection, or positive antibody test for hepatitis C virus (HCV) unless the participant is considered to be cured following antiviral therapy and has an HCV viral load below the limit of detection at least 24 weeks after completion of treatment at site or central lab.
5. 213 History of active or latent tuberculosis (TB), or a positive QuantiFERON-TB Gold test at screening, unless treatment for TB was completed per local guidelines.
6. 214 Negative test for varicella zoster virus (VZV)-IgG.
7. 215 Participants with any of the following abnormal liver function tests in the absence of hepatobiliary IgG4-RD activity: • AST > 2 × ULN • ALT > 2 × ULN • TBL > 2 × ULN unless AST, ALT, and hemoglobin are within central laboratory normal range and the participant has a known history of Gilbert syndrome
8. 216 History of alcohol or drug abuse that, in the opinion of the Investigator, might affect participant safety or compliance with visits or interfere with safety or other study assessments
9. 217 Known positive anti-neutrophil cytoplasmic antibodies targeted against proteinase 3 or myeloperoxidase if done based on participant records.
10. 218 Receipt of any of the following before day 1: alemtuzumab, total lymphoid irradiation, bone marrow transplant, T-cell vaccination therapy.
11. 202 Malignancy (except any of the following nonmelanoma skin cancers, or cervical or breast ductal carcinoma in situ) within the last 5 years.
12. 219 Receipt of any of the following within 2 months before day 1: azathioprine, mycophenolate mofetil, cyclosporine, methotrexate, cyclophosphamide, tocilizumab, satralizumab, eculizumab, and mitoxantrone.
13. 220 Receipt of rituximab or any experimental B-cell depleting agent (eg, ocrelizumab, obinutuzumab, ofatumumab, inebilizumab), or any non-depleting B-cell-directed therapy (eg, belimumab), abatacept, within 6 months before screening unless B cell counts have returned to ≥ one-half the LLN.
14. 221 Receipt of intravenous immunoglobulin (IVIG) within 1 month before day 1.
15. 222 Receipt of natalizumab within 6 months before day 1.
16. 223 Severe drug allergic history or anaphylaxis to 2 or more food products or medicines (including known sensitivity to acetaminophen/paracetamol, diphenhydramine or equivalent antihistamine, and methylprednisolone or equivalent glucocorticoid).
17. 224 Receipt of any live or attenuated vaccine (administration of inactivated [killed] vaccine is acceptable) within 4 weeks before day 1, Bacillus Calmette-Guérin vaccine within 1 year of screening, or blood transfusion within 4 weeks before screening or during screening.
18. 225 Currently receiving treatment in another investigational device or drug study, or less than 5 half-lives since ending treatment in another investigational device or drug study. This does not apply to other investigational procedures or participation in observational research studies.
19. 226 Participants of childbearing potential unwilling to use protocol-specified method of contraception (see Section 11.5 [Appendix 5]) during treatment and for an additional 6 months after the last dose of inebilizumab.
20. 227 Participants who are breastfeeding or who plan to breastfeed while on study through 6 months after the last dose of investigational product.
21. 228 Participants planning to become pregnant while on study through 6 months after the last dose of investigational product.
22. 203 Major surgery within 8 weeks before screening.
23. 229 Participants of childbearing potential with a positive pregnancy test assessed at screening by a highly sensitive urine or serum pregnancy test.
24. 230 Participants with a partner of childbearing potential who are unwilling to practice sexual abstinence (refrain from heterosexual intercourse) or use contraception during treatment and for an additional 6 months after the last dose of investigational product. Refer to Section 11.5 (Appendix 5) for additional contraceptive information.
25. 231 Participants assigned male at birth with a pregnant partner who are unwilling to practice abstinence or use a condom during treatment and for an additional 6 months after the last dose of investigational product.
26. 232 Participants unwilling to abstain from donating sperm during treatment and for an additional 6 months after the last dose of investigational product.
27. 233 Participant has known sensitivity to any of the products to be administered during dosing.
28. 234 Participant likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures (eg, Clinical Outcome Assessments) to the best of the participant’s and investigator’s knowledge.
29. 235 History or evidence of any other clinically significant disorder, condition, or disease (except for those outlined above) that, in the opinion of the investigator or Amgen physician, if consulted, would pose a risk to participant’s safety, or interfere with the study evaluation, procedures, or completion.
30. 204 Spontaneous or induced abortion, still or live birth, or pregnancy ≤ 4 weeks before screening.
31. 205 Evidence of significant hepatic, renal, or metabolic dysfunction or significant hematological abnormality, including any of the following at screening (one repeat test may be conducted to confirm results within the same screening period): • platelet count < 75000/μL (or < 75 × 109/L) • absolute neutrophil count < 1200 cells/μL • total Ig < 600 mg/dL • CD4 T lymphocyte count < 300 cells/µL • hemoglobin < 8 g/dL (or < 80 g/L)
32. 206 Estimated glomerular filtration rate < 45 mL/min/1.73 m2.
33. 207 B-cell counts < one-half of the lower limit of normal (LLN) for age according to the central laboratory.
34. 208 Diagnosed with a concurrent autoimmune disease that is uncontrolled or requires any prohibited medication (unless approved by the medical monitor).
35. 209 Clinically significant serious active or chronic viral, bacterial, or fungal infection that requires treatment with anti-infectives, hospitalization, or, in the investigator’s opinion, represents an additional risk to the participant, within 2 months before day 1 of study.

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 3

1. • PK parameters, including maximum plasma concentration (Cmax), area under the plasma concentration-time curve (AUC), terminal half-life (t½), clearance (CL), and volume of distribution at steady-state (Vss)
2. • Change from baseline in CD20+ B cell counts
3. • Incidence of adverse events, serious adverse events, events of interest (EOIs), and change from baseline in laboratory parameters and vital signs

Secondary endpoints 3

1. • Disease activity endpoints include: - Time-to-first treated flare across 52 weeks - Proportion of flare-free participants across 52 weeks - Annualized flare rate across 52 weeks
2. • Presence of antidrug antibodies (ADA) before and after initiation of treatment
3. • Percent reduction from baseline in daily glucocorticoid dose at week 52 taken for the purpose of IgG4 RD control

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Amgen Inc.

Sponsor organisation

Amgen Inc.

Address

1 Amgen Center Drive

City

Thousand Oaks

Postcode

91320-1730

Country

United States

Scientific contact point

Organisation

Amgen Inc.

Contact name

Medical Information

Public contact point

Organisation

Amgen Inc.

Contact name

Medical Information

Third parties 6

Locations

4 EU/EEA countries · 7 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Application history

2 submissions — initial application plus substantial / non-substantial modifications