Cessation Versus Continuation of Long-term Mepolizumab in Severe Eosinophilic Asthma Patients

Inclusion Criteria:

- Informed Consent: Prior to commencing any study related activities, subjects must be
able and willing to provide written informed consent, and an assent for subjects under
18 years of age, at Visit 0 (or Visit 1 if these Visits are conducted on the same
day).

- MEA115666 or 201312 Study Participation: Participation (through the Follow Up/Exit
Visit or Early Withdrawal) in either study with documented evidence of at least 6
months of continuous mepolizumab treatment prior to Visit 1. Continuous treatment with
mepolizumab is defined as no more than 2 consecutive missed doses (no treatment gaps
of more than 12 weeks [84 days] between any two doses).

- Current Anti-Asthma Therapy: Asthma is currently being treated with a controller
medication and the subject has been on a controller medication for the past 12 weeks.
Subjects will be expected to continue controller therapy for the duration of the
study.

- Male or Eligible Female Subjects: A female is eligible to enter and participate in the
study if she is of: Non-child bearing potential (i.e., physiologically incapable of
becoming pregnant, including any female who is post-menopausal or surgically sterile).
Surgically sterile females are defined as those with a documented hysterectomy and/or
bilateral oophorectomy or tubal ligation. Post-menopausal females are defined as being
amenorrhoeic for greater than 1 year with an appropriate clinical profile, e.g., age
appropriate, > 45 years, in the absence of hormone replacement therapy.

OR Child bearing potential, has a negative pregnancy test at screening, and agrees to
acceptable contraceptive methods approved in their local country, when used consistently
and correctly (i.e., in accordance with the approved product label and the instructions of
the physician) for the duration of the study and for 4 months after the last study drug
administration.

A urine pregnancy test is required of all females of child-bearing potential at each
scheduled study visit prior to the injection of study treatment, and at the Exit Visit,
Early Withdrawal (EW) or Discontinuation of IP Visit.

- French subjects: In France, a subject will be eligible for inclusion in this study
only if either affiliated to or a beneficiary of a social security category.

Exclusion Criteria:

- MEA115666 or 201312 IP Discontinuation: Subjects withdrawn from IP or withdrawn from
study participation from either MEA115666 or 201312 for safety reasons.

- Health Status: Clinically significant deterioration in health status at the completion
of participation or EW from either the MEA115666 or 201312 trials which in the opinion
of the investigator would make the subject unsuitable for participation in this study.

- Pregnancy: Subjects who are pregnant or breastfeeding. Subjects should not be enrolled
if they plan to become pregnant during the time of study participation.

- Cardiovascular: Subjects who have severe or clinically significant cardiovascular
disease uncontrolled with standard treatment. Including but not limited to:

known ejection fraction of <30% OR severe heart failure meeting New York Heart Association
Class IV classification OR hospitalised in the 12 months prior to Visit 1 for severe heart
failure meeting New York Heart Association Class III OR angina diagnosed less than 3 months
prior to Visit 1 or at Visit 1.

- 12-Lead Electrocardiogram (ECG): ECG which has a clinically significant abnormality
observed at the Screening Visit as determined by the investigator. Subjects with the
following abnormalities are excluded from study participation: QT interval corrected
for heart rate by Fridericia's formula (QTcF) > 450 milliseconds (msec), or QTcF >480
msec for subjects with Bundle Branch Block.

- Malignancy: A current malignancy or previous history of cancer in remission for less
than 12 months prior to screening (Subjects that had localized carcinoma of the skin
which was resected for cure will not be excluded).

Note for South Korea: Korean subjects with a diagnosis of malignancy within 5 years are
excluded.

- Other Monoclonal Antibodies: Subjects who have received any monoclonal antibody (other
than XOLAIR®) to treat inflammatory disease within 5 half-lives of Visit 1.

XOLAIR is a registered trademark of Genentech USA, Inc. and Novartis Pharmaceuticals
Corporation.

- Adherence: Subjects who have known evidence of lack of adherence within studies
MEA115666 or 201312 (less than 80%) to controller medications, scheduled study visits
and/or ability to follow physician's recommendations.

- Smoking status: Current smokers

- Inability to read: In the opinion of the Investigator, any subject who is unable to
read and/or would not be able to complete a questionnaire.