Generalized Myasthenia Gravis (gMG) is a condition where muscles become weak. This study is testing a medicine called efgartigimod PH20 SC to see if it helps adults with new symptoms of gMG. Participants must be at least 18 years old and have had gMG symptoms, like muscle weakness, for less than one year. The study will last for about 58 weeks, with a treatment phase of 51 weeks.

Participants can join if they haven't used certain medicines for gMG, except for a type called AChEI, and have specific blood markers. Those who had surgery called a thymectomy for non-cancer reasons can still join. But, if they've used other specific treatments for gMG, they can't participate.

• The study will take about 58 weeks in total.
• Participants need to be okay with not having certain previous treatments.
• It's important to have gMG symptoms for less than one year to join.