The FLEX study is a randomized, blinded, and placebo-controlled study assessing the efficacy and safety of an investigational drug for adults diagnosed with Generalized Myasthenia Gravis (gGM). The injectable investigational drug is being evaluated over a 12-week induction period and a 12-week maintenance period. Based on completion of these periods and a participant's response to the investigational injection, participants may qualify to continue in a 52-week extension study of the investigational drug. If you choose to enter this study, you will participate in the study for up to approximately 84 weeks (1 ½ years) and you will be asked to attend up to 34 study visits; visits can last from 1 to 4 hours.

It is unknown at this time whether the study treatment will improve participant's health. The potential risks of this study include the possibility of infections, low albumin levels, and increases in blood cholesterol.