An Open-label Study to Investigate the Clinical Efficacy of Different Dosing Regimens of Efgartigimod IV in Patients With Generalized Myasthenia Gravis (ADAPT NXT)

A Phase 3b, Randomized, Open-label, Parallel-Group Study to Evaluate Different Dosing Regimens of Intravenous Efgartigimod to Maximize and Maintain Clinical Benefit in Patients With Generalized Myasthenia Gravis

The purpose of this open-label study is to investigate the efficacy, safety, and tolerability of a continuous regimen of efgartigimod compared with a cyclic regimen in participants with Generalized Myasthenia Gravis (gMG).

Participants will receive efgartigimod throughout the study. The participants will be randomized to the continuous regimen arm or to the cyclic regimen arm. The study consists of a part A (regimen comparison period) where participants will continue the treatment based on the treatment regimen arm they were assigned at randomization. Following part A, participants will enter part B (extension period) where all participants will receive efgartigimod in the continuous regimen. The study duration for participants is up to 138 weeks.

Study Overview

• Status: Completed
• Conditions: Generalized Myasthenia Gravis; gMG; MG - Myasthenia Gravis
• Intervention / Treatment: Biological: Efgartigimod IV

• Study Type: Interventional
• Enrollment (Actual): 69
• Phase: Phase 3

Contacts and Locations

Study Locations

• Austria
  • Innsbruck, Austria, 6020
    • Investigator Site 26 - AT0430002
  • Vienna, Austria, 1090
    • Investigator Site 27 - AT0430001
• Belgium
  • Leuven, Belgium, 3000
    • Investigator Site 28 - BE0320001
• Canada
  • London, Canada, N6A 5A5
    • Investigator Site 29 - CA0019003
  • Québec, Canada, H3A 2B4
    • Investigator site 37 - CA0019002
• France
  • Bordeaux, France, 33604
    • Investigator Site 23 - FR0330005
  • Lille, France, 59000
    • Investigator Site 24 - FR0330004
  • Marseille, France, 13385
    • Investigator Site 20 - FR0330001
  • Nice, France, 06001
    • Investigator Site 25 - FR0330003
  • Paris, France, 75013
    • Investigator site 38 - FR0330002
• Georgia
  • Tbilisi, Georgia, 0112
    • Investigator Site 2 - GEO9950002
  • Tbilisi, Georgia, 0114
    • Investigator Site 1 - GEO9950001
  • Tbilisi, Georgia, 0114
    • Investigator Site 3 - GEO9950003
• Germany
  • Berlin, Germany, 10117
    • Investigator Site 33 - DE0490004
  • Bochum, Germany, 44791
    • Investigator Site 36 - DE0490002
  • Essen, Germany, 45147
    • Investigator Site 32 - DE0490001
  • Hanover, Germany, 30625
    • Investigator Site 34 - DE0490005
• Italy
  • Bologna, Italy, 40139
    • Investigator Site 31 - IT0390005
  • Genova, Italy, 16132
    • Investigator Site 30 - IT0390004
  • Milan, Italy, 20133
    • Investigator Site 21 - IT0390002
  • Pisa, Italy, 56126
    • Investigator site 39 - IT0390006
  • Roma, Italy, 00168
    • Investigator Site 22 - IT0390001
• Netherlands
  • Amsterdam, Netherlands, 1105
    • Investigator Site 35 - NL0310001
• Poland
  • Krakow, Poland, 31-426
    • Investigator Site 5 - PL0480002
  • Lubin, Poland, 20-093
    • Investigator Site 4 - PL0480001
• Spain
  • Barcelona, Spain, 08041
    • Investigator Site 19 - ES0340001
  • A Coruña
    • Santiago de Compostela, A Coruña, Spain, 15706
      • Investigator Site 18 - ES0340002
• United States
  • California
    • Carlsbad, California, United States, 92011
      • Investigator Site 10 - US0010007
    • Orange, California, United States, 92868
      • Investigator Site 7 - US0010001
  • Florida
    • Boca Raton, Florida, United States, 33487
      • Investigator Site 9 - 0010006
    • Coral Springs, Florida, United States, 33067
      • Investigator Site 15 - US0010014
  • Georgia
    • Augusta, Georgia, United States, 30910
      • Investigator Site 16 - US0010009
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Investigator Site 8 - US0010003
    • Meadows, Illinois, United States, 60008
      • Investigator Site 6 - US0010008
  • Kansas
    • Kansas City, Kansas, United States, 66160
      • Investigator Site 12 - US0010004
  • Oregon
    • Portland, Oregon, United States, 97239
      • Investigator Site 13 - US0010013
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104
      • Investigator Site 17 - US0010012
  • Texas
    • Austin, Texas, United States, 78756
      • Investigator Site 11 - US0010011
  • Virginia
    • Richmond, Virginia, United States, 23219
      • Investigator Site 14 - US0010010

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• At least 18 years of age, at the time of signing the informed consent.
• Diagnosed with Generalized Myasthenia Gravis (gMG) with confirmed documentation and supported by a physical exam and confirmed seropositivity for anti-acetylcholine receptor antibodies (AChR-Abs).
• Meets the clinical criteria as defined by the Myasthenia Gravis Foundation of America (MGFA) class II, III, or IV

Exclusion Criteria:

• Any other condition that, in the opinion of the investigator, would interfere with an accurate assessment of the clinical symptoms of gMG and/or put the participant at undue risk
• A thymectomy within 3 months of screening

• Use of the following prior or concomitant therapies:

  1. intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg) within 14 days of day 1
  2. Rituximab within 6 months of day 1
  3. Eculizumab within 1 month of day 1
  4. Other monoclonal antibodies (eg, adalimumab, tocilizumab, ixekizumab)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Efgartigimod IV - continuous regimen; Participants receiving efgartigimod IV on a continuous regimen	Biological: Efgartigimod IV; Intravenous infusions of efgartigimod
Experimental: Efgartigimod IV - cyclic regimen; Participants receiving efgartigimod IV on a cyclic regimen	Biological: Efgartigimod IV; Intravenous infusions of efgartigimod

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean of the Average MG-ADL Total Score Change From Baseline During the Visit of Week 1 Through Week 21 by Regimen Arm	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 21 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of AEs, SAEs and AESIs	AE : adverse event; SAE: serious adverse event; AESI: adverse event of special interest	Up to 135 weeks
Change From Baseline in the MG-ADL Total Score Over Time	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 126 weeks
Normalized Area Under the Effect Curve (AUEC) of MG-ADL Total Score Improvement From Baseline	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 21 weeks
Characterization of MG-ADL Total Score Change From Baseline	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 21 weeks
Percentage of Participants Who Have a ≥ 2, 3, 4, or 5 Points Improvement in MG-ADL Total Score From Baseline	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 21 weeks
Percentage of Time Participants Have a Change in MG-ADL Total Score of at Least 2 Points From Baseline During Week 4 Through Week 21	The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	From week 4 to week 21
Percentage of Participants Who Achieve MSE, Defined as a MG-ADL Total Score of 0 or 1	MSE = minimal symptom expression; The MG-ADL (Myasthenia Gravis Activities of Daily Living) scale assesses MG symptoms and their effects on daily activities. The total score varies between 0 and 24, with higher total scores indicating more impairment.	Up to 21 weeks

Collaborators and Investigators

• Sponsor: argenx

Study record dates

Study Major Dates

• Study Start (Actual): December 16, 2021
• Primary Completion (Actual): August 24, 2023
• Study Completion (Actual): October 6, 2025

Study Registration Dates

• First Submitted: July 19, 2021
• First Submitted That Met QC Criteria: July 27, 2021
• First Posted (Actual): July 28, 2021

Study Record Updates

• Last Update Posted (Actual): May 27, 2026
• Last Update Submitted That Met QC Criteria: May 1, 2026
• Last Verified: November 1, 2025

More Information

Terms related to this study

• 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; Pharmaceutical Solutions
• Other Study ID Numbers: ARGX-113-2003; 2024-510932-36-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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