What are the indications for biologics in bronchial asthma?

Indications for Biologics in Bronchial Asthma

Biologics are indicated for patients aged 6 years and older with severe asthma that remains uncontrolled despite high-dose inhaled corticosteroid-long-acting beta agonist (ICS-LABA) therapy, specifically targeting those with eosinophilic or allergic phenotypes. 1

Primary Indication Criteria

Biologics should be considered at Step 5 or Step 6 of asthma management when patients meet the following criteria:

• Severe persistent asthma uncontrolled on high-dose ICS-LABA combination therapy 1
• Frequent exacerbations despite optimal inhaled therapy 1
• Need for systemic corticosteroids (either maintenance or frequent bursts) 1, 2
• Significantly impaired quality of life due to asthma symptoms 1

Critical Pre-Biologic Assessment

Before initiating biologics, you must verify:

• Adherence to current medications has been confirmed 1, 3
• Inhaler technique has been optimized and verified 1
• Comorbidities (GERD, rhinosinusitis, obesity) have been treated 1, 3
• Environmental triggers (smoking, allergens, occupational exposures) have been addressed 1, 3
• Alternative diagnoses (COPD, bronchiectasis, vocal cord dysfunction) have been excluded 1

Phenotype-Based Biologic Selection

The choice of biologic depends on endotyping the patient's asthma:

Allergic Asthma

• Omalizumab (anti-IgE) for patients with elevated IgE levels and documented allergic sensitization 1, 4
• Most effective in those with elevated Type 2 biomarkers despite the allergic indication 4
• FDA-approved for ages 6 years and older 5

Eosinophilic Asthma

• Blood eosinophil count ≥150 cells/μL with frequent exacerbations defines this phenotype 1, 4
• Mepolizumab (anti-IL-5): FDA-approved for ages 6 years and older, subcutaneous administration 5, 4
• Benralizumab (anti-IL-5Rα): FDA-approved for ages 6 years and older, causes rapid eosinophil depletion within 24 hours 6, 7, 4
• Reslizumab (anti-IL-5): Intravenous administration, weight-based dosing 4, 2
• All three reduce exacerbations and demonstrate steroid-sparing efficacy 4, 2

Type 2 Asthma (Broader Phenotype)

• Dupilumab (anti-IL-4Rα) for patients with elevated eosinophils and/or elevated FeNO 1, 4
• Particularly valuable when nasal polyposis or atopic dermatitis coexist 1, 4
• Reduces exacerbations and oral corticosteroid requirements 4, 2

Non-Type 2 Asthma

• Tezepelumab (anti-TSLP) is the only biologic effective in non-Type 2 asthma after excluding other chronic obstructive airway diseases 1
• Effective even at lower Type 2 biomarker thresholds 4

Key Biomarkers for Patient Selection

Essential Laboratory Testing

• Blood eosinophil count: Critical for anti-IL-5/IL-5R therapies (threshold ≥150 cells/μL, though higher counts predict better response) 1, 4, 8
• Fractional exhaled nitric oxide (FeNO): Useful for dupilumab and general Type 2 inflammation assessment 1, 8
• Total IgE and specific IgE: Required for omalizumab eligibility 9, 4
• Nasal endoscopy and CT sinuses: When chronic rhinosinusitis with nasal polyps is suspected 1

Special Populations and Considerations

Pediatric Patients (Ages 6-11 Years)

• Omalizumab is the only biologic with extensive pediatric data in this age range 1
• Mepolizumab and benralizumab are FDA-approved for ages 6 years and older 7, 5
• Specialist consultation is strongly recommended at Step 4 or higher 1

Pregnancy Planning

• Omalizumab is preferred for females planning pregnancy in the near future 1

Comorbid Conditions

• Chronic rhinosinusitis with nasal polyps (CRSwNP): Dupilumab or mepolizumab 1, 5, 4
• Atopic dermatitis: Dupilumab 1, 4
• Eosinophilic granulomatosis with polyangiitis (EGPA): Mepolizumab or benralizumab 7, 5

Common Pitfalls to Avoid

• Do not initiate biologics without first optimizing basic asthma management and confirming adherence 1, 3
• Do not use biologics for acute bronchospasm or status asthmaticus—they are maintenance therapies only 7, 5
• Do not assume all severe asthma is refractory—most cases are "difficult asthma" due to modifiable factors 3
• Do not delay specialist referral when patients reach Step 4 therapy 1
• Do not ignore overlapping eligibility—many patients qualify for multiple biologics, requiring phenotype-guided selection 1, 4, 8

Monitoring and Response Assessment

Initial Response Evaluation

• Assess clinical response at 8-12 weeks using symptom control, exacerbation frequency, and lung function 9
• Continue monitoring every 3-6 months with clinical review, biomarkers, and spirometry 9

Treatment Goals

• Reduction in exacerbations is the most consistent outcome across all biologics 4, 2
• Oral corticosteroid sparing (reduction or elimination of maintenance steroids) 4, 2
• Improved asthma control and quality of life 2
• Stabilization or improvement in lung function 2