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Cystic FibrosisOctober 2018Summary reviewed July 2026

What Researchers Found Testing VX-659 Triple Therapy for Cystic Fibrosis

Scientists tested a three-drug combination (VX-659, tezacaftor, and ivacaftor) in people with cystic fibrosis caused by specific genetic mutations. Patients saw significant improvements in lung function—up to 13 percentage points in some groups—with mild to moderate side effects.

What the trial was testing

The trial enrolled 124 patients with cystic fibrosis. The study was sponsored by Vertex Pharmaceuticals 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

Lung function improved by up to 13 percentage points in patients with certain cystic fibrosis gene mutations.

The New England journal of medicine · 2018 · NCT03224351

These findings — that patients with certain gene mutations saw major gains in breathing ability — were published in the The New England journal of medicine and represent the headline result of the study.

Researchers tracked outcomes across 124 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 an initial testing study. The triple combination later became FDA-approved as Trikafta in 2019 and is now a standard treatment for people with cystic fibrosis who have at least one Phe508del gene mutation. If you have cystic fibrosis, ask your doctor if Trikafta or similar treatments are right for you.

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.