Brensocatib is making waves in respiratory medicine. Following the full publication of its Phase 3 ASPEN trial in The New England Journal of Medicine in May 2025, this new oral treatment is being hailed as a breakthrough for people living with non-cystic fibrosis bronchiectasis (NCFBE). On 12 August 2025, the U.S FDA approved Brensocatib for the treatment of NCFBE.
In the UK, healthcare professionals and patients now wait with growing anticipation as the drug moves through the regulatory process in the UK. In this article, we explore what brensocatib is, how it works, what the clinical trials show, and when it might become available in the UK.
What Is Brensocatib?
Brensocatib is a first-in-class oral medicine developed by Insmed Incorporated. It is designed to treat adults with non-cystic fibrosis bronchiectasis, a chronic lung disease characterised by permanent airway damage, mucus build-up, and frequent chest infections.
Brensocatib targets one of the causes of inflammation in bronchiectasis, rather than just treating the symptoms. It works by inhibiting dipeptidyl peptidase I (DPP1), an enzyme responsible for activating neutrophil serine proteases, which are powerful proteins released by white blood cells (neutrophils) that can damage lung tissue when overactive.
By blocking DPP1, brensocatib aims to reduce harmful inflammation and slows the destructive cycle of infection and lung damage that defines bronchiectasis.
Understanding Bronchiectasis
Bronchiectasis affects over 300,000 people in the UK, particularly older adults and women. It leads to symptoms such as:
- Persistent cough
- Daily sputum (phlegm) production
- Frequent chest infections
- Fatigue and breathlessness
Treatment has traditionally focused on antibiotics, chest physiotherapy, and inhaled medications. However, these manage symptoms and kill bacteria without addressing the underlying inflammatory disease process. Brensocatib offers a new approach by directly targeting inflammation.
Clinical Trials of Brensocatib
Brensocatib has been evaluated in two major clinical trials: WILLOW (Phase 2) and ASPEN (Phase 3). Both trials tested its ability to reduce pulmonary exacerbations, which are flare-ups of bronchiectasis that often require hospital care or antibiotics.
Phase 2: The WILLOW Trial
- Participants: 256 adults with NCFBE and ≥2 exacerbations in the past year.
- Design: Randomised, double-blind, placebo-controlled.
- Treatment: Brensocatib 10 mg or 25 mg once daily vs placebo.
- Duration: 24 weeks.
Key findings (published in The Lancet Respiratory Medicine, 2021):
- Both doses of brensocatib significantly reduced the frequency of exacerbations.
- Patients had longer time to their first exacerbation.
- Marked reductions in neutrophil protease activity confirmed the drug’s biological effect.
Adverse events included tooth discolouration, rash, and mild gastrointestinal issues, but the treatment was generally well tolerated.
Phase 3: The ASPEN Trial
In May 2025, the full results of the pivotal ASPEN trial were published in The New England Journal of Medicine. This was a larger, longer study that confirmed the benefits of brensocatib.
- Participants: 1,680 adults with NCFBE and ≥2 exacerbations in the previous year.
- Design: International, randomised, double-blind, placebo-controlled.
- Treatment: Brensocatib 10 mg once daily vs Bresocatib 25 mg once a day vs placebo.
- Duration: 52 weeks.
Results:
- Annualised rate of exacerbations:
- Brensocatib: 0.78 exacerbations/year
- Placebo: 1.03 exacerbations/year
- Rate ratio: 0.75 (P < 0.001)
- Time to first exacerbation: Significantly longer in the brensocatib group.
- Neutrophil enzyme activity: Substantially reduced, confirming the drug’s mechanism of action.
- Quality of life (St. George’s Respiratory Questionnaire):
- Improvements observed, but did not reach statistical significance.
Adverse Effects:
- Common side effects:
- Tooth and gum discolouration (Periodontal disease)
- Skin rash
- Nausea and diarrhoea
- Serious adverse events: Occurred at similar rates in both groups.
The trial confirmed that brensocatib reduces exacerbations, delays their onset, and is generally well tolerated.
Reference:
Chalmers JD, et al. Brensocatib in Non–Cystic Fibrosis Bronchiectasis. N Engl J Med. 2025
FDA Approval: A Landmark Moment
The U.S. Food and Drug Administration (FDA) granted priority review for brensocatib for adults with NCFBE who have had two or more exacerbations in the past 12 months.n
On 12 August 2025 they made available the first licensed therapy to directly address the inflammatory mechanisms in bronchiectasis, rather than just controlling infections.
When Will Brensocatib Be Available in the UK?
Brensocatib is not yet available in the UK or on the NHS, but steps are in motion. It is understood that:
In February 2026, the Medicines and Healthcare products Regulatory Agency (MHRA) granted marketing authorisation for brensocatib, marking a historic step in the treatment of Non‑cystic fibrosis bronchiectasis. This decision makes brensocatib the first medicine specifically developed to treat this long-term lung condition, offering new hope for patients who experience repeated infections, persistent cough and progressive lung damage.
The approval allows the medicine to be prescribed in the UK for patients aged 12 years and older who suffer from recurrent exacerbations of non-cystic fibrosis bronchiectasis.
Although the MHRA licence means brensocatib can legally be prescribed in the UK, widespread access will depend on several additional steps.
For patients receiving care through the NHS, the medicine must first undergo evaluation by the National Institute for Health and Care Excellence (NICE). This process assesses the clinical effectiveness and cost-effectiveness of new treatments before recommending whether they should be funded by the NHS. Until NICE publishes its final guidance, routine NHS access is unlikely.
Private prescribing may become possible sooner because licensed medicines can be prescribed outside the NHS once they are commercially available. However, the manufacturer must first complete the UK commercial launch and distribution of the drug.
If approved, brensocatib could be made available in the UK by 2027. Experts are hopeful, given the high unmet need.
Why Brensocatib Is a Breakthrough for Patients
For the first time, bronchiectasis patients have a licensed treatment that:
- Reduces the number of exacerbations
- Targets the underlying inflammation
- Offers once-daily oral dosing
Conclusion
Approval of brensocatib represents a major milestone in bronchiectasis treatment. Its expected UK launch is highly anticipated by both patients and clinicians.
As we await NICE decisions, brensocatib stands out as the first drug to address the root cause of this under-recognised respiratory condition, offering hope to thousands of people living with bronchiectasis. Once available, and people living with bronchiectasis are using it, we will be able to see what the effect is outside of the clinic trials.Hopefully, it will have an effect on delaying disease progression.
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