Trial Outcomes & Findings for A Phase 3 Study to Evaluate the Efficacy and Safety of Efgartigimod IV in Patients With Acetylcholine Receptor Binding Antibody Seronegative Generalized Myasthenia Gravis (NCT NCT06298552)
NCT ID: NCT06298552
Last Updated: 2026-08-10
Results Overview
The Myasthenia Gravis Activities of Daily Living (MG-ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (no symptoms) to 24 (most severe symptoms).
Recruitment status
ACTIVE_NOT_RECRUITING
Study phase
PHASE3
Target enrollment
119 participants
Primary outcome timeframe
Up to 29 days in part A
Results posted on
2026-08-10
Participant Flow
This study was conducted at 109 sites across 20 countries. A total of 245 participants were screened, of whom 119 were randomized following approval by a diagnostic adjudication committee. Participants who were historically MuSK seropositive were not adjudicated. As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion.
Participant milestones
| Measure |
Efgartigimod IV
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
|---|---|---|
|
Overall Study
STARTED
|
58
|
61
|
|
Overall Study
COMPLETED
|
54
|
60
|
|
Overall Study
NOT COMPLETED
|
4
|
1
|
Reasons for withdrawal
| Measure |
Efgartigimod IV
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
|---|---|---|
|
Overall Study
Withdrawal by Subject
|
2
|
0
|
|
Overall Study
Meeting a protocol-specified criterion
|
1
|
0
|
|
Overall Study
WIthdrawal of consent
|
1
|
0
|
|
Overall Study
Death
|
0
|
1
|
Baseline Characteristics
Data for one participant was not collected
Baseline characteristics by cohort
| Measure |
Efgartigimod IV
n=58 Participants
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
n=61 Participants
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Total
n=119 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Continuous
|
50.6 Years
STANDARD_DEVIATION 13.44 • n=58 Participants
|
51.7 Years
STANDARD_DEVIATION 12.97 • n=61 Participants
|
51.2 Years
STANDARD_DEVIATION 13.16 • n=119 Participants
|
|
Sex: Female, Male
Female
|
44 Participants
n=58 Participants
|
46 Participants
n=61 Participants
|
90 Participants
n=119 Participants
|
|
Sex: Female, Male
Male
|
14 Participants
n=58 Participants
|
15 Participants
n=61 Participants
|
29 Participants
n=119 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
4 Participants
n=58 Participants • Data for one participant was not collected
|
2 Participants
n=60 Participants • Data for one participant was not collected
|
6 Participants
n=118 Participants • Data for one participant was not collected
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
53 Participants
n=58 Participants • Data for one participant was not collected
|
55 Participants
n=60 Participants • Data for one participant was not collected
|
108 Participants
n=118 Participants • Data for one participant was not collected
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
1 Participants
n=58 Participants • Data for one participant was not collected
|
3 Participants
n=60 Participants • Data for one participant was not collected
|
4 Participants
n=118 Participants • Data for one participant was not collected
|
|
Race/Ethnicity, Customized
Asian
|
8 Participants
n=58 Participants • Data for one participant was not collected
|
8 Participants
n=60 Participants • Data for one participant was not collected
|
16 Participants
n=118 Participants • Data for one participant was not collected
|
|
Race/Ethnicity, Customized
Black or African American
|
1 Participants
n=58 Participants • Data for one participant was not collected
|
2 Participants
n=60 Participants • Data for one participant was not collected
|
3 Participants
n=118 Participants • Data for one participant was not collected
|
|
Race/Ethnicity, Customized
White
|
48 Participants
n=58 Participants • Data for one participant was not collected
|
46 Participants
n=60 Participants • Data for one participant was not collected
|
94 Participants
n=118 Participants • Data for one participant was not collected
|
|
Race/Ethnicity, Customized
Other
|
1 Participants
n=58 Participants • Data for one participant was not collected
|
4 Participants
n=60 Participants • Data for one participant was not collected
|
5 Participants
n=118 Participants • Data for one participant was not collected
|
PRIMARY outcome
Timeframe: Up to 29 days in part APopulation: Intent to treat analysis set - Part A
The Myasthenia Gravis Activities of Daily Living (MG-ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (no symptoms) to 24 (most severe symptoms).
Outcome measures
| Measure |
Efgartigimod IV
n=58 Participants
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
n=61 Participants
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
|---|---|---|
|
MG-ADL Total Score Change From Baseline
|
-3.35 points on a scale
Interval -3.98 to -2.72
|
-1.90 points on a scale
Interval -2.51 to -1.28
|
SECONDARY outcome
Timeframe: Up to 29 days in part AThe Quantitative Myasthenia Gravis (QMG) score includes 13 items that measure endurance or fatigability and accounts for fluctuations in disease state. The total score ranges from 0 (no symptoms) to 39 (highest disease severity).
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A)A participant was an MG-ADL responder if there was a ≥2-point reduction in the MG-ADL total score compared with baseline that was maintained for at least 4 consecutive weeks (ie, at least 5 consecutive visits total), with the first reduction occurring no later than 1 week after the last administration of IMP in part A. A participant was a QMG responder if there was a ≥3-point reduction in the QMG total score compared with baseline that was maintained for at least 4 consecutive weeks (ie, at least 5 consecutive visits total), with the first reduction occurring no later than 1 week after the last administration of IMP in part A.
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A) + 3 years (part B)Minimal symptom expression (MSE) is defined as an MG-ADL total score of 0 or 1
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A)The Myasthenia Gravis Activities of Daily Living (MG- ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (no symptoms) to 24 (most severe symptoms). A participant was an MG-ADL responder if there was a ≥2-point reduction in the MG-ADL total score compared with baseline that was maintained for at least 4 consecutive weeks (ie, at least 5 consecutive visits total), with the first reduction occurring no later than 1 week after the last administration of IMP in part A.
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A)The Quantitative myasthenia gravis (QMG) includes 13 items that measure endurance or fatigability and accounts for fluctuations in disease state. The total score ranges from 0 (no symptoms) to 39 (highest disease severity). A participant was a QMG responder if there was a ≥3-point reduction in the QMG total score compared with baseline that was maintained for at least 4 consecutive weeks (ie, at least 5 consecutive visits total), with the first reduction occurring no later than 1 week after the last administration of IMP in part A.
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A)The Myasthenia Gravis Activities of Daily Living (MG- ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (no symptoms) to 24 (most severe symptoms). An Early MG-ADL responder is an MG-ADL responder who had an onset of an MG-ADL response no later than 2 weeks after the first administration of IMP in part A.
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A) + 3 years (part B)The Myasthenia Gravis Activities of Daily Living (MG- ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (no symptoms) to 24 (most severe symptoms).
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A) + 3 years (part B)The Myasthenia Gravis Quality of Life-15 revised (MG-QoL15r) is a patient-reported instrument that measures the impact of MG symptoms on quality of life. The total scores range from 0 (best outcome) to 30 (worst outcome).
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A) + 3 years (part B)The EQ-5D-5L is a participant-reported measure of health status developed by the EuroQol Group. The questionnaire comprises 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Current health status is rated on vertical visual analog score (VAS) from 0 to 100, with a score of 0 corresponding to "the worst health you can imagine" and 100 corresponding to "the best health you can imagine."
Outcome measures
Outcome data not reported
SECONDARY outcome
Timeframe: Up to 8 weeks (part A) + 3 years (part B)Outcome measures
Outcome data not reported
Adverse Events
Efgartigimod IV
Serious events: 3 serious events
Other events: 16 other events
Deaths: 1 deaths
Placebo
Serious events: 1 serious events
Other events: 14 other events
Deaths: 1 deaths
Serious adverse events
| Measure |
Efgartigimod IV
n=58 participants at risk
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
n=61 participants at risk
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
|---|---|---|
|
Blood and lymphatic system disorders
ANAEMIA
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Gastrointestinal disorders
DIVERTICULUM INTESTINAL
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Gastrointestinal disorders
LOWER GASTROINTESTINAL HAEMORRHAGE
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Gastrointestinal disorders
UPPER GASTROINTESTINAL HAEMORRHAGE
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Infections and infestations
LOWER RESPIRATORY TRACT INFECTION
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Nervous system disorders
MYASTHENIA GRAVIS
|
1.7%
1/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
0.00%
0/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Nervous system disorders
MYASTHENIA GRAVIS CRISIS
|
0.00%
0/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
1.6%
1/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
Other adverse events
| Measure |
Efgartigimod IV
n=58 participants at risk
Participants receiving infusions of efgartigimod IV once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
Placebo
n=61 participants at risk
Participants receiving infusions of placebo once weekly for 3 weeks per treatment period (4 infusions total), followed by a 5-week follow-up period
|
|---|---|---|
|
Gastrointestinal disorders
NAUSEA
|
6.9%
4/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
4.9%
3/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
General disorders
FATIGUE
|
3.4%
2/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
8.2%
5/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Infections and infestations
UPPER RESPIRATORY TRACT INFECTION
|
8.6%
5/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
4.9%
3/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Infections and infestations
URINARY TRACT INFECTION
|
5.2%
3/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
4.9%
3/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
|
Nervous system disorders
HEADACHE
|
5.2%
3/58 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
11.5%
7/61 • Available data included for Part A (up to 8 weeks).
As the study is ongoing at the time of the results reporting deadline, the submitted results are limited to primary outcome and part A safety data. Remaining results (part B) will be reported within a year of global study completion. Adverse events are reported for all participants who received at least part of an IMP dose in part A. Any clinically significant changes occurring during the study were reported as adverse events.
|
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place