Open-label Uncontrolled Trial to Evaluate Pharmacokinetics, Pharmacodynamics, Safety, and Activity of Efgartigimod in Children From 2 to Less Than 18 Years of Age With Generalized Myasthenia Gravis

Trial status: Authorised Incidence and severity of AEs, incidence of serious AEs (SAEs), incidence of AEs of special interest (AESIs), and changes in laboratory test results, physical examination results, vital sign measurements, and electrocardiogram (ECG) (part B only for ECGs), Efgartigimod serum concentrations, Levels of total IgG and AChR-Ab: absolute values, change from baseline and percent (%) change from baseline, Incidence and prevalence of antidrug antibodies (ADAs) against efgartigimod, MG-ADL total score: absolute value and change from baseline total MG-ADL score, Total QMG score: absolute value and change from baseline, Total score EQ-5D-Y: absolute value and change from baseline, Quality of Life in Neurological Disorders (Neuro-QoL) Pediatric Fatigue Score: values and change from baseline, Change in protective antibody titers to vaccines received before or received during the trial Efgartigimod concentrations as input for compartmental, model-driven analysis to determine age and size dependency of clearance and volume of distribution, PD parameters: total IgG levels and anti-acetylcholine receptors antibodies (AChR-Ab) as input for PK/PD modeling analysis

Incidence and severity of AEs, incidence of serious AEs (SAEs), incidence of AEs of special interest (AESIs), and changes in laboratory test results, physical examination results, vital sign measurements, and electrocardiogram (ECG) (part B only for ECGs), Efgartigimod serum concentrations, Levels of total IgG and AChR-Ab: absolute values, change from baseline and percent (%) change from baseline, Incidence and prevalence of antidrug antibodies (ADAs) against efgartigimod, MG-ADL total score: absolute value and change from baseline total MG-ADL score, Total QMG score: absolute value and change from baseline, Total score EQ-5D-Y: absolute value and change from baseline, Quality of Life in Neurological Disorders (Neuro-QoL) Pediatric Fatigue Score: values and change from baseline, Change in protective antibody titers to vaccines received before or received during the trial

Age group: 0-17 years Gender: Female, Male Target enrollment: 12 participants