This is a prospective, real-world, single arm, global, multi-centre study to evaluate the effect of timely treatment with mepolizumab (NUCALA) to achieve clinical remission in adult participants with severe asthma with an eosinophilic phenotype (SA-EP).

Inclusion Criteria:

• Participant has a confirmed asthma diagnosis and has been prescribed NUCALA by their physician for the treatment of asthma, as per local label. NUCALA can be initiated up to 7 days prior to study enrollment.
• No NUCALA use in the 6 months prior to enrollment.
• Participants with greater than or equal to (≥)60 percentage (%) predicted forced expiratory volume in 1 second (FEV1) and less than or equal to (≤)4 exacerbations per year, as confirmed by the physician.
• Other local prescription criteria of NUCALA not described above at NUCALA initiation (e.g., local reimbursement criteria).
• Written informed consent

Exclusion Criteria:

• Investigator concerns about participant's willingness to adhere to biologic treatment for any reason (e.g., cost, behavior, difficulty with access to healthcare)
• Participants currently on maintenance OCS or intramuscular corticosteroids.
• Participants using omalizumab, reslizumab, dupilumab, tezepelumab, or benralizumab within the 6 months prior to enrollment
• Participants participating in an interventional study with a treatment intervention

Qualified researchers may request access to anonymized individual patient-level data (IPD) and related study documents of the eligible studies via the Data Sharing Portal. Details on GSK's data sharing criteria can be found at: https://www.gsk.com/en-gb/innovation/trials/data-transparency/

Anonymized IPD will be made available within 6 months of publication of primary, key secondary and safety results for studies in product with approved indication(s) or terminated asset(s) across all indications.

Anonymized IPD is shared with researchers whose proposals are approved by an Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months but an extension may be granted, when justified, for up to 6 months.

There will be no masking in this study.