A Multi-center, Open-label Extension, Safety Study of Mepolizumab in Subjects With Hypereosinophilic Syndrome (HES) From Study 200622

Exclusion Criteria

• •Subjects with any history of hypersensitivity to any monoclonal antibody (including mepolizumab).
• •Subjects with current malignancy or malignancy that developed during Study 200622.
• •Subjects who is pregnant or breastfeeding.
• •Subjects who has other clinically significant medical conditions uncontrolled with SoC therapy not associated with HES, example (e. g.), unstable liver disease, uncontrolled cardiovascular disease, ongoing active infectious disease.
• •Subjects with QT interval corrected (QTc) greater than 450 millisecond (msec) or QTc greater than 480 msec in subjects with bundle branch block based on local Electrocardiogram (EGC) reading.
• •Subjects who discontinue study treatment based on liver chemistry stopping criteria during Study 200622.
• •Current active liver or biliary disease (with the exception of Gilbert's syndrome or asymptomatic gallstones or otherwise stable chronic liver disease per investigator assessment).
• •Subjects who have received treatment with an investigational agent (biologic or non-biologic) within the past 30 days or 5 drug half-lives whichever is longer, prior to the first dose, other than Study 200622 study treatment. The term "investigational" applies to any drug not approved for sale for the disease/indication to treat in the country in which it is being used or investigational formulations of marketed products.
• •Subjects who are currently participating in any other interventional clinical study.
• •Subjects had an AE (serious or non-serious) considered related to study treatment while participating in Study 200622 which resulted in permanent withdrawal of study treatment.