Biologics in Asthma

A detailed guide to assessment, treatment and the major clinical trials

Biologics are targeted antibody medicines for selected people with severe asthma. They can reduce attacks and, for some people, reduce the need for steroid tablets. They are added to carefully optimised asthma care. They are not a cure or a rescue treatment for an acute attack.

At The Chest Clinic, we can assess your asthma, investigate its inflammatory pattern and advise whether referral is appropriate. Most patients who need biologics transfer to an NHS severe asthma service for eligibility assessment, prescribing and ongoing monitoring.

General asthma guide | Arrange an assessment

1. Who might benefit?

Repeated attacks requiring steroid tablets, hospital admissions or a need for daily oral steroids despite appropriate inhaled treatment are reasons for specialist review. Breathlessness alone does not establish eligibility. Before calling asthma severe, the team confirms the diagnosis, checks inhaler technique and regular use, and addresses exposures and other conditions that can make symptoms worse.

Assessment may include spirometry, bronchodilator testing, FeNO, blood eosinophils, total and specific IgE, an attack history and previous steroid prescriptions. Nasal polyps, eczema, allergy, obesity, reflux, sleep apnoea and breathing-pattern disorders can influence the assessment and choice of treatment. Steroids can lower eosinophil counts, so previous results and the timing of tests matter.

Type 2 inflammation is a pattern of immune activity involving pathways such as IgE, interleukins 4, 5 and 13, and eosinophils. Biomarkers help identify the pattern; a single high result is not enough to choose a medicine. Different biologics have different licensed indications and NHS criteria.

GINA: severe asthma guidance | Asthma + Lung UK: severe asthma

2. The main medicines

Omalizumab targets IgE and is used for suitable severe allergic asthma. Allergy testing, IgE and body weight help determine suitability and dosing. Injections are usually every two or four weeks.

Mepolizumab targets interleukin-5 (IL-5), reducing eosinophilic inflammation. It is usually given as an injection every four weeks.

Reslizumab also targets IL-5. For eligible adults, it is given as a weight-based intravenous infusion, usually every four weeks, in a supervised setting.

Benralizumab targets the IL-5 receptor and depletes eosinophils. In asthma it is usually injected every four weeks for the first three doses, then every eight weeks.

Dupilumab blocks the shared receptor pathway for IL-4 and IL-13. It is used in suitable type 2 severe asthma and is usually injected every two weeks. Relevant associated conditions, such as eczema or nasal polyps, may influence selection.

Tezepelumab targets TSLP, a signal released by airway lining cells. It is injected every four weeks and may be an option across a broader range of inflammatory patterns, although response is often greater with raised eosinophils or FeNO.

Asthma + Lung UK: established biologic options

Depemokimab is a longer-acting IL-5 antibody given every 26 weeks. The MHRA approved it in December 2025 for specified inadequately controlled asthma from age 12. A UK licence does not itself establish NHS access: the NICE appraisal and local prescribing arrangements must be checked. It should not be assumed interchangeable with a biologic that is already working.

MHRA: depemokimab approval | NICE: depemokimab appraisal status

3. Benefits, safety and monitoring

Goals are agreed before treatment: fewer attacks, less oral steroid exposure, better daily control and improved quality of life. Response varies. The team reviews attacks, steroid use, symptom scores, lung function and side effects after an initial treatment period and regularly thereafter. A medicine may be continued, changed or stopped if the benefit is insufficient.

Possible side effects include injection-site reactions and drug-specific problems such as headache. Serious allergic reactions are uncommon but possible; supervision and home-injection arrangements depend on the medicine and individual risk. Dupilumab can cause a transient rise in blood eosinophils and eye symptoms in some patients. Discuss pregnancy, other medicines and relevant infection or travel history with the specialist.

Continue prescribed inhalers and your asthma action plan. Do not stop steroid tablets suddenly: a supervised reduction may require assessment of adrenal function. Seek urgent help for a serious reaction or severe asthma attack; call 999 for severe breathing difficulty, collapse or swelling of the tongue or throat.

Asthma + Lung UK: treatment, reviews and side effects

4. How to read the trial evidence

The studies below cover the main pivotal adult and adolescent programmes, steroid-reduction trials and important follow-up studies. Trial participants continued background asthma treatment. A relative reduction in the rate of attacks is not the percentage of patients cured. Studies used different populations, doses, follow-up periods and definitions, so their percentages cannot reliably rank one medicine above another.

Randomised placebo-controlled trials provide stronger evidence of treatment effect than uncontrolled follow-up studies. Extension studies add useful longer-term information but can select people who tolerated or benefited from earlier treatment. Trial entry criteria are also different from current NHS funding rules.

5. Omalizumab: INNOVATE and EXTRA

INNOVATE (2005) studied 419 patients with severe allergic asthma inadequately controlled on high-dose inhaled treatment. The adjusted clinically significant attack rate was 26% lower with omalizumab over 28 weeks. The unadjusted analysis did not reach statistical significance, an important qualification when interpreting the headline result.

EXTRA (2011) enrolled 850 patients over 48 weeks. Protocol-defined attacks were reduced by 25% relative to placebo, with improvements in symptoms and quality of life. These trials support anti-IgE treatment in selected allergic asthma, rather than in all asthma.

INNOVATE publication | EXTRA publication

6. Mepolizumab: DREAM, MENSA, SIRIUS and MUSCA

DREAM (2012) established that selecting patients with recurrent attacks and eosinophilic inflammation was important. Across the intravenous doses studied, clinically significant attacks fell by approximately 39–52% relative to placebo over a year.

MENSA (2014) confirmed benefit in 576 patients with recurrent attacks despite high-dose inhaled treatment. The subcutaneous regimen reduced attack rates by 53% relative to placebo over 32 weeks and improved measures of asthma control.

SIRIUS (2014) addressed a different question: could people dependent on daily steroid tablets reduce their dose while maintaining control? Mepolizumab allowed greater oral steroid reduction than placebo. MUSCA (2017) added evidence of improved health-related quality of life and asthma control.

DREAM | MENSA | SIRIUS | MUSCA

7. Reslizumab: the pivotal phase 3 studies

The two parallel Castro and colleagues phase 3 trials (2015) studied intravenous reslizumab in inadequately controlled asthma with raised blood eosinophils and previous exacerbations. They demonstrated fewer attacks than placebo. A further Bjermer and colleagues trial (2016) demonstrated improvements in lung function, control and quality of life.

The formulation matters: later trials of a fixed-dose subcutaneous preparation did not establish the same efficacy, and should not be confused with the evidence for licensed intravenous treatment.

Two pivotal intravenous trials | Lung-function trial | Subcutaneous trials

8. Benralizumab: SIROCCO, CALIMA and steroid reduction

SIROCCO and CALIMA (2016) demonstrated fewer attacks in severe uncontrolled eosinophilic asthma. In SIROCCO, the every-eight-week regimen after initial loading reduced attack rates by 51% relative to placebo in the primary high-eosinophil population.

ZONDA (2017) demonstrated that maintenance oral steroids could be reduced while maintaining asthma control. PONENTE (2021), a single-arm study, developed an individualised tapering approach that included adrenal-function assessment. It supports careful supervised reduction, not abrupt withdrawal.

SHAMAL (2024) studied selected adults already well controlled on benralizumab. Many could reduce maintenance inhaled corticosteroid/formoterol under a structured protocol. This does not mean that everyone starting a biologic should stop inhaled steroids. BORA provided additional longer-term efficacy and safety follow-up.

9. Dupilumab: QUEST, VENTURE and TRAVERSE

QUEST (2018) studied uncontrolled moderate-to-severe asthma. Dupilumab reduced severe exacerbations and improved lung function; effects were generally larger with raised type 2 biomarkers such as eosinophils and FeNO.

VENTURE (2018) studied 210 people dependent on oral steroids. The oral steroid dose fell by about 70% with dupilumab versus 42% with placebo, while severe attack rates were lower. Steroid withdrawal followed a trial protocol and is not a self-management instruction.

TRAVERSE, an open-label extension, supported sustained benefit and provided longer-term safety information, including in people with associated chronic rhinosinusitis or nasal polyps.

QUEST | VENTURE | TRAVERSE analysis

10. Tezepelumab: PATHWAY, NAVIGATOR and beyond

PATHWAY (2017) provided proof of benefit from blocking TSLP. NAVIGATOR (2021) confirmed reduced exacerbations in severe uncontrolled asthma, including patients with lower eosinophil counts. A broader licence does not guarantee the same response for every inflammatory pattern.

SOURCE (2022) did not meet its main oral-steroid-reduction endpoint in the overall population. This negative finding is important. DESTINATION (2023) extended follow-up to assess longer-term safety and efficacy.

WAYFINDER (2026) reported steroid reduction and discontinuation during structured tapering in an open-label, single-arm study. Without a placebo group, it cannot by itself provide the same causal evidence as a successful randomised steroid-sparing trial.

PATHWAY | NAVIGATOR | SOURCE | DESTINATION | WAYFINDER

11. Depemokimab and newer research

SWIFT-1 and SWIFT-2 (2024) tested injections every 26 weeks in severe asthma with an eosinophilic phenotype. Annualised attack rates were 0.46 versus 1.11 and 0.56 versus 1.08 with depemokimab and placebo respectively—relative reductions of 58% and 48%. The principal established benefit was fewer attacks; this should not be interpreted as proof that every symptom or lung-function measure improves.

NIMBLE (2026) studied switching people already responding to mepolizumab or benralizumab. The overall primary non-inferiority criterion was not established. Fewer injections alone are therefore not a reason to assume that switching will preserve an individual's response.

ABRA investigated benralizumab during selected eosinophilic asthma or COPD exacerbations and found fewer treatment failures than prednisolone alone. This was a relatively small phase 2 study of acute treatment, distinct from routine maintenance prescribing. It does not replace your current emergency action plan.

SWIFT-1 and SWIFT-2 | NIMBLE | ABRA

12. Choosing treatment and arranging NHS care

The best option depends on your inflammatory pattern, attack burden, steroid dependence, associated conditions, previous response, preferences and current eligibility. Your specialist will explain why a particular medicine is being considered and agree a review plan.

Bring a list of inhalers and medicines, previous eosinophil or FeNO results if available, and dates of steroid courses or hospital admissions. We can share our assessment with your GP and NHS severe asthma team. Most patients needing biologics transfer to that NHS service for this part of their care; a private consultation does not guarantee NHS eligibility.

Evidence checked September 2026. This adult-focused guide summarises major studies; it is not an exhaustive bibliography or an individual prescribing recommendation.

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