Patient description: The patient is a 15-year-old boy with asthma diagnosed a year ago. He presents with shortness of breath, chest tightening and cough. According to his mother, he didn't respond to the usual corticosteroid inhaler. He was admitted to the emergency department with diagnosis of severe asthma exacerbation. He is a candidate for general corticosteroid therapy. Spirometry revealed a forced expiratory volume in the first second (FEV1) of 60% of the predicted. His past medical history is non-significant. His family history is significant for asthma in his mother and his uncle. He used to be treated with combination of inhaled corticosteroids and Zafirlukast.

Clinical trial eligibility criteria: eligible ages (years): 12.0-999.0,  Asthma Key for study Adults and adolescents >=12 years of age, at the time of signing the informed consent/assent Participants must have a documented physician diagnosis of asthma for >=2 years that meets the National Heart, Lung, and Blood Institute guidelines (NHLBI, 2007) or Global Initiative for Asthma (GINA) guidelines (GINA, 2020) and (a) Eosinophilic phenotype: participants who have, or with high likelihood of having, asthma with an eosinophilic phenotype as per randomization and (b) Exacerbation history: participants who have previously confirmed history of >=2 exacerbations requiring treatment with systemic corticosteroid (CS) (Intramuscular [IM], Intravenous [IV], or oral), in the 12 months prior to Visit 1, despite the use of medium to high-dose ICS. For participants receiving maintenance CS, the CS treatment for the exacerbations must have been a two-fold dose increase or greater Persistent airflow obstruction as indicated by (i) For participants >=18 years of age at Visit 1, a pre-bronchodilator FEV1 <80 percent predicted National Health and Nutrition Examination Survey (NHANES III) recorded at Visit 1 (ii)For participants 12-17 years of age at Visit 1: A pre-bronchodilator FEV1 <90 percent predicted (NHANES III) recorded at Visit 1 or FEV1: Forced Vital Capacity (FVC) ratio <0.8 recorded at Visit 1 A well-documented requirement for regular treatment with medium to high dose ICS (in the 12 months prior to Visit 1 with or without maintenance OCS). The maintenance ICS dose must be >=440 micrograms fluticasone propionate (FP) hydrofluoroalkane product (HFA) daily, or clinically comparable (GINA, 2020). Participants who are treated with medium dose ICS will also need to be treated with LABA to qualify for inclusion Current treatment with at least one additional controller medication, besides ICS, for at least 3 months (e.g., LABA, LAMA, leukotriene receptor antagonist [LTRA], or theophylline). Key for randomization An elevated peripheral blood eosinophil count of >=300 cells per microliter demonstrated in the past 12 months prior to Visit 1 that is related to asthma or an elevated peripheral blood eosinophil count of >=150 cells per microliter at Screening Visit 1 that is related to asthma Evidence of airway reversibility or responsiveness as documented by either: (i) Airway reversibility (FEV1>=12 percent and 200 milliliter [mL]) demonstrated at Visit 1 or Visit 2 using the Maximum Post Bronchodilator Procedure or (ii)Airway reversibility (FEV1>=12 percent and 200 mL) documented in the 12 months prior to Visit 2 (randomization visit) or (iii) Airway hyperresponsiveness (methacholine: Provocative concentration causing a 20 percent fall in FEV1 [PC20] of <8 milligrams per milliliter (mg/mL), histamine: Provocative dose that decreases FEV1 by 20 percent [PD20] of <7.8 micromoles, mannitol: decrease in FEV1 as per the labelled product instructions) documented in the 12 months prior to Visit 2 (randomization visit). Key  for study Presence of a known pre-existing, clinically important lung condition other than asthma. This includes (but is not limited to) current infection, bronchiectasis, pulmonary fibrosis, bronchopulmonary aspergillosis, or diagnoses of emphysema or chronic bronchitis (chronic obstructive pulmonary disease other than asthma) or a history of lung cancer Participants with other conditions that could lead to elevated eosinophils such as hyper-eosinophilic syndromes including (but not limited to) Eosinophilic Granulomatosis with Polyangiitis (EGPA, formerly known as Churg-Strauss Syndrome) or Eosinophilic Esophagitis A current malignancy or previous history of cancer in remission for less than 12 months prior to screening (Participants that had localized carcinoma of the skin which was resected for cure will not be excluded) Cirrhosis or current unstable liver or biliary disease per investigator assessment defined by the presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia, esophageal or gastric varices, persistent jaundice Participants who have known, pre-existing, clinically significant cardiac, endocrine, autoimmune, metabolic, neurological, renal, gastrointestinal, hepatic, hematological or any other system abnormalities that are uncontrolled with standard treatment Participants with current diagnosis of vasculitis. Participants with high clinical suspicion of vasculitis at screening will be evaluated and current vasculitis must be excluded prior to enrolment Participants who have received mepolizumab, reslizumab, or benralizumab within 12 months prior to Visit 1 or who have a previous documented failure with Anti-Interleukin-5/ Anti-Interleukin-5 receptor (anti-IL-5/5R) therapy Participants who have received omalizumab or dupilumab within 130 days prior to Visit 1 Participants who have received any monoclonal antibody (mAb) within 5 half-lives of Visit 1