Placebo

Remibrutinib (Open Label) active treatment

The Quantitative Myasthenia Gravis (QMG) Score is a 13-item direct physician assessment scoring system that quantifies disease severity, based on impairments of body functions and structures. The total QMG score ranges from 0 to 39, where higher scores indicated greater disease severity. The QMG score is composed of the following items: ocular (2 items), facial (1 item), bulbar (2 items), gross motor (6 items), axial (1 item) and respiratory (1 item).

The MG-ADL is a categorical scale that assesses MG symptoms and their effects on daily activities. MG-ADL is composed of items related to patient's assessment of functional disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or limb (2 items) impairment related to effects from MG.

Each item is assessed on a 4-points scale where a score 0 represents normal function and a score 3 represents loss of ability to perform that function (total score 0 to 24).

The MG-ADL is a categorical scale that assesses MG symptoms and their effects on daily activities. MG-ADL is composed of items related to patient's assessment of functional disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or limb (2 items) impairment related to effects from MG.

Each item is assessed on a 4-points scale where a score 0 represents normal function and a score 3 represents loss of ability to perform that function (total score 0 to 24).

The MGC is a 10-item instrument that measures the symptoms and signs of MG based on physician examination and patient history. Items relate to ptosis, double vision, eye closure, talking, chewing, swallowing, breathing, neck flexion, shoulder abduction, and hip flexion. Each item is scored on an ordinal scale with 4 possible categories and weighted. The total score ranges from 0 to 50, where higher scores indicating more severe impairments.

The revised MG-QoL15 is a 15-item health related quality of life questionnaire completed by participants, designed to measure quality of life in gMG. Items on the MG-QoL15 relate to physical, social, and psychological components and are scored from 0 (not at all) to 2 (very much). The cumulative scores range from 0 to 30, with higher scores representing worse quality of life and dissatisfaction with MG-related dysfunction.

Incidence of adverse events including changes in clinical laboratory values, vital signs, electrocardiograms and suicidality results qualifying and reported as AEs.

The MG-ADL is a categorical scale that assesses MG symptoms and their effects on daily activities. MG-ADL is composed of items related to patient's assessment of functional disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or limb (2 items) impairment related to effects from MG. Each item is assessed on a 4-points scale where a score 0 represents normal function and a score 3 represents loss of ability to perform that function (total score 0 to 24).

The MG-ADL is a categorical scale that assesses MG symptoms and their effects on daily activities. MG-ADL is composed of items related to patient's assessment of functional disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or limb (2 items) impairment related to effects from MG. Each item is assessed on a 4-points scale where a score 0 represents normal function and a score 3 represents loss of ability to perform that function (total score 0 to 24). Participants with a first MG-ADL improvement from baseline of ≥ 2 points occurring by week 4 are considered early responders.

The EQ-5D-5L is a widely used questionnaire designed to assess health status in adults. The measure is divided into two distinct sections, the descriptive system and the EQ visual analogue scale (EQ VAS). The first section includes one item addressing each of five dimensions (mobility, self-care, usual activity, pain/discomfort, and anxiety/depression). Participants rate each of these items from 1 of the 5 levels: no problems, slight problems, moderate problems, severe problems, or unable to/extreme. A composite health state is then defined by combining the levels for each dimension into a 5-digit number. The second section includes the EQ visual analogue scale (EQ VAS) that measures self-rated (global) health status utilizing a vertically oriented visual analogue scale where 100 represents the "best imaginable health state" and 0 represents the "worst imaginable health state." Respondents are asked to rate their current health by placing a mark along this continuum.

The MGC is a 10-item instrument that measures the symptoms and signs of MG based on physician examination and patient history. Items relate to ptosis, double vision, eye closure, talking, chewing, swallowing, breathing, neck flexion, shoulder abduction, and hip flexion. Each item is scored on an ordinal scale with 4 possible categories and weighted. The total score ranges from 0 to 50, where higher scores indicating more severe impairments.

The MG-ADL is a categorical scale that assesses MG symptoms and their effects on daily activities. MG-ADL is composed of items related to patient's assessment of functional disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or limb (2 items) impairment related to effects from MG. Each item is assessed on a 4-points scale where a score 0 represents normal function and a score 3 represents loss of ability to perform that function (total score 0 to 24).

Participants receiving oral corticosteroids are required to be on a stable dose for at least 4 weeks prior to baseline. The dose can be reduced or discontinued during the open label extension period at investigator discretion. Oral corticosteroids use will be recorded.

Incidence of adverse events including changes in clinical laboratory values, vital signs, electrocardiograms and suicidality results qualifying and reported as AEs.