Percentage of patients with relapsing or refractory EGPA, achieving remission, defined as BVAS = 0 and OCS dose ≤ 4 mg/day (main remission definition) at both Weeks 36 and 48.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Supportive endpoint: Proportion of patients with relapsing or refractory EGPA, achieving remission, defined as BVAS = 0 and OCS dose ≤ 7.5 mg/day (supportive remission definition) at both Weeks 36 and 48.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Total accrued duration of remission for the following categories: 0 week, > 0 to < 12 week, 12 to < 24 week, 24 to < 36 week, ≥ 36 week.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Total accrued duration of sustained remission for the following categories: 0 week, > 0 to < 12 week, 12 to < 24 week, 24 to < 36 week, ≥ 36 week.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Time from randomization to first Eosinophilic Granulomatosis with Polyangiitis (EGPA) relapse, where relapse is defined as any of the following:

• Active vasculitis (BVAS > 0); OR
• Active asthma symptoms and/or signs with a corresponding worsening in ACQ-6 score; OR
• Active nasal and/or sinus disease, with a corresponding worsening in at least one of the sino-nasal symptom questions; warranting any of the following:
• An increased dose of OCS therapy to > 4 mg/day prednisolone total daily dose; OR
• An increased dose or addition of immunosuppressive therapy; OR
• Hospitalization related to EGPA worsening Calculated using the Kaplan-Meier technique.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Annualized Eosinophilic Granulomatosis with Polyangiitis (EGPA) relapse rate through end of DB treatment period. The estimate of annualized relapse rate (relapses per year) and the corresponding 95% CIs were calculated using a negative binomial model. The response variable in the model is the number of relapses experienced by a subject up to Week 52. The logarithm of the subject's corresponding follow-up time up to Week 52 was used as an offset variable to adjust for subjects having different follow-up times during which the events occur. The covariates in the model include treatment arm, baseline dose of prednisone, baseline BVAS and region.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Average daily dose of prednisolone/prednisone and change from baseline during Week 48 through 52, or last 28 days prior to last double-blind assessment for those that withdrew

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Proportion of patients with average daily dose of prednisolone/prednisone during Week 48 through 52 in each category: 0 mg; >0 to ≤ 4 mg; > 4 to ≤ 7.5 mg and > 7.5 mg

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Percentage reduction from baseline in average daily dose of prednisolone/prednisone during Week 48 through 52 in each category: no reduction or withdrawal from treatment; < 25% reduction; 25 to < 50% reduction; 50 to <75% reduction; 75 to < 100% reduction; 100% reduction.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Proportion of subjects with reduction from baseline in average daily dose of prednisolone/prednisone during Week 48 through 52 in each category: >= 50% reduction; 100% reduction; OCS dose <= 4 mg/day.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Proportion of subjects who achieved any clinical benefit definition 1 (defined as any of the following:

• Main remission at any time in DB period
• >= 50% reduction in OCS dose in Weeks 48 to 52
• EGPA relapse free in DB period) and subjects who achieved complete response definition 1 (defined as meeting all the definition 1 criteria above.)

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Proportion of patients who have achieved remission within the first 24 weeks and remained in remission for remainder of the double-blind treatment period

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Birmingham Vasculitis Activity Score (BVAS) change from baseline by timepoint up to week 52. The BVAS form is divided into 9 organ-based systems, with each section including symptoms/signs that are typical of that particular organ involvement in systemic vasculitis. The total score on all 9 organ systems gives an indication of the disease activity of each patient at the time of scoring. Total scores range from 0 to 63, with higher scores indicating more active vasculitis.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Pre-bronchodilator (BD) Forced Expiratory Volume during first second (FEV1) change from baseline by timepoint up to week 52

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Pre-bronchodilator (BD) Forced vital capacity (FVC) change from baseline by timepoint up to week 52

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Vasculitis Damage Index (VDI) change from baseline by timepoint up to week 52. The VDI is divided into 11 organ systems and records items of damage, due to vasculitis, treatment or unrelated, that have occurred since the onset of vasculitis. Completion of the form provides a numerical score, ranging from 0 to 64, with a higher score indicating more damage.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Asthma Control Questionnaire (6-item version) (ACQ-6) change from baseline by timepoint up to week 52. The ACQ-6 score is calculated by taking the mean of 6 equally weighted domains, with a range of 0 (well controlled) to 6 (extremely poorly controlled).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Short Form 36-item health survey (version 2, acute recall) (SF-36v2) component Physical Component Summary (PCS) change from baseline by timepoint up to week 52. PCS score ranges from 10.8 to 75.5, where a higher score indicates better health.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Short Form 36-item health survey (version 2, acute recall) (SF-36v2) component Mental Component Summary (MCS) change from baseline by timepoint up to week 52. MCS score ranges from 5.6 to 69.7, where a higher score indicates better health.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Outcome Test-22 (SNOT-22) total score change from baseline by timepoint up to week 52. Patient reported symptom severity and symptom impact over the previous 2 weeks on 22 items are captured via a 6-point scale (0 = no problem to 5 = problem as bad as it can be). The total score is the sum of item scores and ranges from 0 to 110 (higher scores indicate poorer outcomes).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Symptoms Questionnaire (SSQ) scores : symptom runny nose by timepoint. For the SSQ, participants rate each symptom against the following categories: very severe, severe, moderate, mild, none. Higher scores indicate greater severity (0 = none to 4 = very severe).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Symptoms Questionnaire (SSQ) scores : symptom Post-nasal discharge by timepoint. For the SSQ, participants rate each symptom against the following categories: very severe, severe, moderate, mild, none. Higher scores indicate greater severity (0 = none to 4 = very severe).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Symptoms Questionnaire (SSQ) scores: symptom Facial pain/pressure by timepoint. For the SSQ, participants rate each symptom against the following categories: very severe, severe, moderate, mild, none. Higher scores indicate greater severity (0 = none to 4 = very severe).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Symptoms Questionnaire (SSQ) scores: symptom Loss or reduction in sense of taste/smell by timepoint. For the SSQ, participants rate each symptom against the following categories: very severe, severe, moderate, mild, none. Higher scores indicate greater severity (0 = none to 4 = very severe).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Sino-nasal Symptoms Questionnaire (SSQ) scores: symptom Blockage/congestion of nose by timepoint. For the SSQ, participants rate each symptom against the following categories: very severe, severe, moderate, mild, none. Higher scores indicate greater severity (0 = none to 4 = very severe).

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Patient Global Impression of Severity (PGIS) category by timepoint

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Patient Global Impression of Change (PGIC) category by timepoint

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

The Work Productivity and Activity Impairment questionnaire (WPAI-GH) has 6 questions which address absenteeism, presenteeism (reduced effectiveness while working), overall work productivity loss (absenteeism plus presenteeism), and activity impairment for the 7 days prior to the assessment. WPAI outcomes are presented as impairment percentages (a higher percentage indicating greater impairment and less productivity). Subscale: Absenteeism (work time missed) (%) score, range 0-100.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

The Work Productivity and Activity Impairment questionnaire (WPAI-GH) has 6 questions which address absenteeism, presenteeism (reduced effectiveness while working), overall work productivity loss (absenteeism plus presenteeism), and activity impairment for the 7 days prior to the assessment. WPAI outcomes are presented as impairment percentages (a higher percentage indicating greater impairment and less productivity). Presenteeism (%) score.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

The Work Productivity and Activity Impairment questionnaire (WPAI-GH) has 6 questions which address absenteeism, presenteeism (reduced effectiveness while working), overall work productivity loss (absenteeism plus presenteeism), and activity impairment for the 7 days prior to the assessment. WPAI outcomes are presented as impairment percentages (a higher percentage indicating greater impairment and less productivity). Work productivity loss (%) score, range 0-100.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

The Work Productivity and Activity Impairment questionnaire (WPAI-GH) has 6 questions which address absenteeism, presenteeism (reduced effectiveness while working), overall work productivity loss (absenteeism plus presenteeism), and activity impairment for the 7 days prior to the assessment. WPAI outcomes are presented as impairment percentages (a higher percentage indicating greater impairment and less productivity). Activity impairment (%) score, range 0-100.

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.

Absolute eosinophil count, change from baseline by timepoint up to week 52

Full Analysis Set: All patients randomized and receiving at least one (1) dose of IP are included in the full analysis set, irrespective of their protocol adherence and continued participation in the study.