Evaluating the Long-Term Safety and Tolerability of Efgartigimod PH20 SC Administered Subcutaneously in Patients With Generalized Myasthenia Gravis (ADAPTSC+)

A Long-Term, Single-Arm, Open-label, Multicenter Phase 3 Study to Evaluate the Safety and Tolerability of Multiple Subcutaneous Injections of Efgartigimod PH20 SC in Patients With Generalized Myasthenia Gravis

The purpose of this study is to evaluate the long-term safety and tolerability of efgartigimod PH20 SC 1000 mg, and the clinical efficacy, PD, pharmacokinetics (PK), immunogenicity, impact on the quality of life (QoL) of the participants, treatment satisfaction, and administration method preference, and the feasibility of self- and caregiver-supported administration of the SC injection.

Treatment duration: 3-week treatment periods, repeated as needed with at least 28 days in between treatment periods

Health measurements: total levels of immunoglobulin G (IgG), Acetylcholine receptor binding autoantibodies (AChR-Ab) levels, Myasthenia Gravis Activities of Daly Living (MG-ADL).

Study Overview

• Status: Completed
• Conditions: Generalized Myasthenia Gravis
• Intervention / Treatment: Biological: efgartigimod PH20 SC

• Study Type: Interventional
• Enrollment (Actual): 184
• Phase: Phase 3

Contacts and Locations

Study Locations

• Belgium
  • Ghent, Belgium, 9000
    • Investigator site 5 - BE0320007
• Czechia
  • Brno, Czechia, 625 00
    • Investigator site 24 - CZ4200005
• Georgia
  • Tbilisi, Georgia, 0112
    • Investigator Site 2 - GEO9950002
  • Tbilisi, Georgia, 0114
    • Investigator Site 1 - GEO9950001
  • Tbilisi, Georgia, 0114
    • Investigator Site 3 - GEO9950003
  • K'alak'i T'bilisi
    • Tbilisi, K'alak'i T'bilisi, Georgia, 0160
      • Investigator Site 32 - GEO9950004
    • Tbilisi, K'alak'i T'bilisi, Georgia, 016
      • Investigator Site 33 - GEO9950016
• Germany
  • Berlin, Germany, 10117
    • Investigator Site 25 - DE490006
  • Münster, Germany, 48149
    • Investigator Site 26 - DE490009
• Hungary
  • Budapest, Hungary, 1082
    • Investigator site 10 - HU0360013
  • Budapest, Hungary, 1204
    • Investigator site 9 - HU0360012
• Italy
  • Milan, Italy, 20133
    • Investigator site 11 - IT0390003
  • Napoli, Italy, 80138
    • Investigator Site 34 - IT0390007
  • Roma, Italy, 00189
    • Investigator Site 35 - IT0390008
• Japan
  • Osaka, Japan, 565-0871
    • Investigator site 14 - JP0810007
  • Sapporo, Japan, 060 8542
    • Investigator Site 27 - JP0810008
  • Sendai, Japan, 983-8520
    • Investigator site 13 - JP0810005
  • Tokyo, Japan, 160-0023
    • Investigator site 15 - JP0810009
  • Chiba-Shi
    • Chiba, Chiba-Shi, Japan, 260-8677
      • Investigator site 12 - JP0810002
  • Hokkaido
    • Sapporo, Hokkaido, Japan, 063-0005
      • Investigator Site 36 - JP0810055
  • Iwate
    • Hanamaki, Iwate, Japan, 025-0082
      • Investigator site 8 - JP0810004
  • Tokyo
    • Ōta-ku, Tokyo, Japan, 143-8541
      • Investigator Site 28- JP0810059
• Netherlands
  • Leiden, Netherlands, 2333
    • Investigator site 16 - NL0310001
• Poland
  • Gdansk, Poland, 80-952
    • Investigator site 17 - PL0480001
  • Katowice, Poland, 40-123
    • Investigator site 19 - PL0480007
  • Krakow, Poland, 31-426
    • Investigator site 22 - PL0480065
  • Krakow, Poland, 31-505
    • Investigator site 18 - PL0480005
  • Lublin, Poland, 20-093
    • Investigator site 20 - PL0480018
  • Warsaw, Poland, 02-097
    • Investigator site 21 - PL0480022
• Russia
  • Novosibirsk, Russia, 630087
    • Investigator Site 29- RU0070002
  • Saint Petersburg, Russia, 194354
    • Investigator Site 30 - RU0070014
• Spain
  • Barcelona, Spain, 08035
    • Investigator Site 37 - ES0340021
  • Barcelona, Spain, 08041
    • Investigator Site 31 - ES0340038
  • Valencia, Spain, 46026
    • Investigator site 23 - ES0340039
• United States
  • California
    • Carlsbad, California, United States, 92011
      • Investigator site 6 - US0010032
    • Palo Alto, California, United States, 94304
      • Investigator Site 47 - US0010021
  • Florida
    • Boca Raton, Florida, United States, 33428
      • Investigator Site 45 - US0010108
    • Port Charlotte, Florida, United States, 33952
      • Investigator site 4 - US0010110
    • Tampa, Florida, United States, 41076
      • Investigator Site 39 - US0010006
  • Kansas
    • Kansas City, Kansas, United States, 66160
      • Investigator Site 41 - US0010015
  • New York
    • Amherst, New York, United States, 14226
      • Investigator Site 46 - US0010111
  • North Carolina
    • Chapel Hill, North Carolina, United States, 27514
      • Investigator Site 38 - US0010003
    • Durham, North Carolina, United States, 27710
      • Investigator Site 44 - US0010077
  • Ohio
    • Cleveland, Ohio, United States, 44195
      • Investigator Site 42 - US0010019
  • Tennessee
    • Cordova, Tennessee, United States, 38018
      • Investigator site 7 - US0010008
  • Texas
    • Austin, Texas, United States, 78759
      • Investigator Site 43 - US0010066
    • San Antonio, Texas, United States, 78229
      • Investigator Site 40 - US0010009

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Must be capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
2. Previously participated in antecedent studies ARGX-113-2001 or ARGX-113-1705 and are eligible for roll over.

3. Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies and:

   • Women of Child bearing potential (WOCBP) must have a negative urine pregnancy test at baseline before investigational medicinal product (IMP) can be administered.

Exclusion Criteria:

1. The participant was discontinued early from studies ARGX-113-2001 or ARGX-113-1705, unless the reason for discontinuation from study ARGX-113-1705 was to roll over into study ARGX-113-2002.

   a. Participants who, in the investigator's judgment, are not benefiting from efgartigimod IV in study ARGX-113-1705 Part B are not eligible for roll over into ARGX-113-2002.

2. Are pregnant or lactating, or intend to become pregnant during the study or within 90 days after the last dose of investigational medicinal product (IMP)

3. Has any of the following medical conditions:

   1. Clinically significant uncontrolled chronic bacterial, viral, or fungal infection at roll-over
   2. Any other known autoimmune disease that, in the opinion of the investigator, would interfere with accurate assessment of clinical symptoms of myasthenia gravis or put the participant at undue risk

   3. History of malignancy unless deemed cured by adequate treatment with no evidence of reoccurrence for ≥3 years before the first administration of investigational medicinal product (IMP).

      Participants with the following cancers can be included at any time:

      • adequately treated basal cell or squamous cell skin cancer
      • carcinoma in situ of the cervix
      • carcinoma in situ of the breast
      • incidental histological findings of prostate cancer (TNM classification of malignant tumors stage T1a or T1b)
   4. Clinical evidence of other significant serious diseases, or the participant has had a recent major surgery, or who have any other condition that, in the opinion of the investigator, could confound the results of the study or put the participant at undue risk
4. Received a live-attenuated vaccine within 28 days prior to study entry or plan to receive a live-attenuated vaccine during the study
5. A known hypersensitivity reaction to efgartigimod, rHuPH20, or any of its excipients

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: efgartigimod PH20 SC; Patients receiving efgartigimod PH20 subcutaneous (SC) treatment	Biological: efgartigimod PH20 SC; Subcutaneous injection with efgartigimod PH20 SC

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of AEs, SAEs and AESIs	Adverse events, Serious Adverse event and Adverse events of special interest. Adverse events in the 'Infections and infestations' SOC were defined as AESIs because efgartigimod causes a transient reduction in total IgG levels.	Up to 3.5 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
MG-ADL Total Score Changes From Baseline	The Myasthenia Gravis Activities of Daily Living (MG-ADL) is an 8-item patient-reported scale that assesses MG symptoms and their effects on daily activities. It evaluates a participant's capacity to perform different activities in their daily life. The total score ranges from 0 to 24 with higher scores indicating more impairment.	Up to week 4 of the first cycle
Percent Change in Total IgG Levels From Baseline	IgG: immunoglobulin G	Up to week 4 of the first cycle
Percent Change in AChR-Ab From Baseline in AChR-Ab Seropositive Participants	AchR-Ab: anti-acetylcholine receptor antibodies.	Up to week 4 of the first cycle
Efgartigimod Serum Concentrations		Up to week 4 of the first cycle
Incidence of ADAs Against Efgartigimod Over Time	ADA: Anti-drug antibodies.	Up to 3.5 years
Incidence of NAbs Against Efgartigimod Over Time	NAbs: neutralizing antibodies	Up to 3.5 years
Incidence of Antibodies Against rHuPH20 Over Time		Up to 3.5 years
Incidence of NAbs Against rHuPH20 Over Time	NAbs: neutralizing antibodies	Up to 3.5 years
Changes in Total MG-QoL15r From Baseline	Myasthenia Gravis Quality of Life 15 item scale revised (MG-QoL 15r) scores range from 0 to 30 with a higher score representing more severe symptoms.	Up to week 4 of the first cycle
Changes in EQ-5D-5L VAS Score From Baseline	EuroQoL 5 Dimensions 5-Level (EQ-5D-5L) visual analog scale (VAS) scores range from 0 to 100 with a higher score representing better health.	Up to week 4 of the first cycle
Percent of Participants or Caregivers by Number of Training Visits Needed to be Competent to Start Self- or Caregiver-Supported Administration		Up to 3.5 years
Percent of Self- or Caregiver-supported Study Drug Administration Among All Study Treatment Visits at Home		Up to 3.5 years

Collaborators and Investigators

• Sponsor: argenx

Study record dates

Study Major Dates

• Study Start (Actual): April 26, 2021
• Primary Completion (Actual): December 31, 2024
• Study Completion (Actual): December 31, 2024

Study Registration Dates

• First Submitted: March 11, 2021
• First Submitted That Met QC Criteria: March 25, 2021
• First Posted (Actual): March 26, 2021

Study Record Updates

• Last Update Posted (Actual): January 22, 2026
• Last Update Submitted That Met QC Criteria: January 20, 2026
• Last Verified: January 1, 2026

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
• Other Study ID Numbers: ARGX-113-2002

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
• product manufactured in and exported from the U.S.: No