A Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Safety and Tolerability of Inebilizumab in Children With Generalized Myasthenia Gravis (gMG) (THYME)

A Phase 2 Open-label Multicenter Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Safety and Tolerability of Inebilizumab in Children From 2 Years to Less Than 18 Years of Age With Generalized Myasthenia Gravis (gMG)

The primary objectives of this study are to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of inebilizumab administered in pediatric participants with gMG, and to assess the safety and tolerability of inebilizumab administered in pediatric participants with gMG.

Study Overview

• Status: Recruiting
• Conditions: Generalized Myasthenia Gravis
• Intervention / Treatment: Drug: Inebilizumab

• Study Type: Interventional
• Enrollment (Estimated): 15
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Amgen Call Center; Phone Number: 866-572-6436; Email: medinfo@amgen.com

Study Locations

• France
  • Paris, France, 75012
    • Recruiting
    • Hôpital Armand Trousseau
• Spain
  • Valencia, Spain, 46026
    • Recruiting
    • Hospital Universitari i Politècnic La Fe
• United States
  • Texas
    • Austin, Texas, United States, 78759
      • Recruiting
      • Austin Neuromuscular Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria

• 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.
• Age ≥ 2 to < 18 years of age on the day of enrollment.

• Diagnosis of gMG defined as:

  • Positive serologic test for anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody (Ab) titers as confirmed at screening (1 retest allowed), and

  • At least 1 of the following:

    • History of abnormal neuromuscular transmission test results demonstrated by single-fiber electromyography or repetitive nerve stimulation; or
    • History of positive anticholinesterase test (eg, edrophonium chloride test); or
    • Participant demonstrated improvement in gMG signs on oral cholinesterase inhibitors, as assessed by the treating physician; or
    • Clinical syndrome consistent with a diagnosis of gMG, and not otherwise explained by another condition.
• Myasthenia Gravis Foundation of America Clinical Classification Class II, III, or IV at the time of screening.

• Participants must be on:

  • Corticosteroids only, with no dose increase within 4 weeks prior to screening, or
  • One allowed non-steroidal immunosuppressive therapies (IST) (azathioprine, mycophenolate mofetil, or mycophenolic acid) with continuous use for at least 6 months prior to screening and no dose increase within 4 months prior to screening, or
  • Combination of (1) corticosteroids with no dose increase within 4 weeks prior to screening and (2) one allowed non-steroidal IST with continuous use for at least 6 months prior to screening and no dose increase within 4 months prior to screening.

Tacrolimus is allowed in Japan only, with continued use for ≥ 6 months prior to screening and no dose increase within 4 months prior to screening.

• Participants may enter the study on a stable dose of acetylcholinesterase inhibitors (pyridostigmine dose). The acetylcholinesterase inhibitor dose must have been stable for at least 2 weeks prior to enrollment.
• Vital signs and laboratory parameters within the normal ranges at screening, or, if outside normal ranges, deemed not clinically significant by the investigator.

Exclusion Criteria

• Employees of the Sponsor, contract research organization (CRO), site staff, and their family members.
• Thymectomy within 12 months prior to baseline (Day 1) visit or planned thymectomy during the duration of the treatment period.
• Unresected thymoma- Participants with benign thymoma resected > 12 months prior to screening may enroll.
• History of recurrent significant infections.
• Known immunodeficiency disorder, including current infection or positive test for human immunodeficiency virus (HIV).
• Positive test for chronic hepatitis B infection at screening.
• History of untreated hepatitis C infection, or positive antibody test for hepatitis C virus (HCV).
• 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.
• History of progressive multifocal leukoencephalopathy.
• Participants diagnosed with congenital myasthenic syndromes.
• Receipt of any biologic B-cell-depleting therapy (eg, rituximab, ocrelizumab, obinutuzumab, ofatumumab, inebilizumab) or any experimental B-cell-depleting agent in the 6 months prior to screening.
• Receipt of any other monoclonal antibody (mAb) or large molecule biologic, including but not limited to FcRn inhibitors, anti-TNF mAbs, anti-janus kinase (JAK) Stat mAbs, and complement inhibitors within 6 months prior to screening.
• Receipt of the following medications or treatments at any time prior to randomization: alemtuzumab, total lymphoid irradiation, bone marrow transplant, T-cell vaccination therapy, natalizumab.
• Participants who are pregnant or breastfeeding or planning to get pregnant.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Inebilizumab; Inebilizumab will be administered intravenously (IV).	Drug: Inebilizumab; Inebilizumab will be administered IV.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Maximum Observed Concentration (Cmax) of Inebilizumab	Up to Week 52
Area Under the Concentration-time Curve (AUC) of Inebilizumab	Up to Week 52
Half-life (t1/2) of Inebilizumab	Up to Week 52
Clearance (CL) of Inebilizumab	Up to Week 52
Volume of Distribution at Steady State (Vss) of Inebilizumab	Up to Week 52
Change from Baseline in Cluster of Differentiation 20 (CD20)+ B-cell Counts	Baseline and Week 78
Number of Participants Experiencing Treatment-emergent Adverse Events	Up to Week 78
Number of Participants Experiencing Clinically Significant Changes in Laboratory Parameters	Up to Week 78
Number of Participants Experiencing Clinically Significant Changes in Vital Signs	Up to Week 78

Secondary Outcome Measures

Outcome Measure	Time Frame
Change from Baseline in Quantitative Myasthenia Gravis (QMG) Score	Baseline and Week 78
Change from Baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) Score	Baseline and Week 78
Change from Baseline in Euro Quality of Life-5 Dimension Youth (EQ-5D-Y) Score	Baseline and Week 78
Number of Participants with Anti-drug Antibodies (ADAs) Present	Up to Week 78
Change from Baseline in Neurological Quality of Life (Neuro-QoL) Pediatric Fatigue Score	Baseline and Week 78

Collaborators and Investigators

• Sponsor: Amgen
• Investigators: Study Director: MD, Amgen

Publications and helpful links

Helpful Links

• AmgenTrials clinical trials website

Study record dates

Study Major Dates

• Study Start (Estimated): August 31, 2026
• Primary Completion (Estimated): March 13, 2030
• Study Completion (Estimated): March 13, 2030

Study Registration Dates

• First Submitted: May 16, 2025
• First Submitted That Met QC Criteria: May 16, 2025
• First Posted (Actual): May 23, 2025

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 27, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Generalized Myasthenia Gravis; Inebilizumab; Uplizna; AMG 335
• Additional Relevant MeSH Terms: Nervous System Diseases; Neoplasms by Site; Neoplasms; Neuromuscular Diseases; Autoimmune Diseases; Immune System Diseases; Autoimmune Diseases of the Nervous System; Neurodegenerative Diseases; Paraneoplastic Syndromes, Nervous System; Nervous System Neoplasms; Paraneoplastic Syndromes; Neuromuscular Junction Diseases; Myasthenia Gravis; inebilizumab
• Other Study ID Numbers: 20240236; 2025-520993-20 (Other Identifier: EU CT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.
• IPD Sharing Time Frame: Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication (or other new use) have been granted marketing authorization in both the US and Europe, or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.
• IPD Sharing Access Criteria: Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors, and if not approved, may be further arbitrated by a Data Sharing Independent Review Panel. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No