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Cystic FibrosisNovember 2020Summary reviewed August 2026

A Daily Pill Cut Lung Flare-Ups by 42% in Bronchiectasis Patients

256 people with bronchiectasis took brensocatib, a pill that blocks an enzyme linked to lung inflammation. Those on the pill went twice as long before their next flare-up compared to people on placebo.

What the trial was testing

The WILLOW enrolled 256 patients with cystic fibrosis. The study was sponsored by Insmed Incorporated and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was initial testing (phase 2). Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

Patients taking brensocatib went 134 days before a flare-up, compared to 67 days on placebo.

The New England journal of medicine · 2020 · NCT03218917

These findings — that patients on the 10 mg pill had 42% fewer lung flare-ups than those on placebo — were published in the The New England journal of medicine and represent the headline result of the study.

Researchers tracked outcomes across 256 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with cystic fibrosis, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

This was a mid-stage study and brensocatib is not yet FDA-approved for bronchiectasis. The trial showed promise in reducing flare-ups, but some patients had dental and skin side effects. Ask your doctor about open trials or approved treatments for bronchiectasis.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.