Conditions: Cystic Fibrosis
Keywords: Cystic fibrosis Nonsense mutation Premature stop codon
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 30
Healthy volunteers: no

Brief summary:
In some participants with cystic fibrosis (CF), the disease is caused by a nonsense mutation (premature stop codon) in the gene that makes the cystic fibrosis transmembrane regulator (CFTR) protein. Ataluren has been shown to partially restore CFTR production in animals with CF due to a nonsense mutation. The main purpose of this study is to understand whether ataluren can safely increase functional CFTR protein in the cells of participants with CF due to a nonsense mutation.

Detailed description:
In this study, participants with CF due to a nonsense mutation will be treated with a new investigational drug called ataluren. Evaluation procedures (history, physical examination, blood and urine tests to assess organ function, electrocardiogram \[ECG\], chest x-ray, and CF-specific tests) to determine if a participant qualifies for the study will be performed within 21 days prior to the start of treatment. Eligible participants with nonsense-mutation-mediated CF will receive 2 repeated 28-day cycles, each comprising of 14 days on therapy and 14 days off therapy. In a crossover design, participants will be randomized to receive ataluren treatment in Cycle 1 by either of the following regimens:

* Ataluren, given 3 times per day (TID) with a regimen of 4 milligrams/kilograms (mg/kg) at breakfast, 4 mg/kg at lunch, and 8 mg/kg at dinner, or
* Ataluren, given 3 TID with a regimen of 10 mg/kg at breakfast, 10 mg/kg at lunch and 20 mg/kg at dinner.

In Cycle 2, participants will then receive the drug according to the regimen opposite from that given in Cycle 1.

There will be a 2-night stay at the clinical research center at the beginning and at the end of each 14 days of ataluren treatment, which means that there will be four 2-night stays at the clinical research center during the study. During the study, ataluren efficacy, safety, and pharmacokinetics (PK) will be evaluated periodically with measurements of transepithelial potential difference (TEPD), nasal mucosal brushing to assess for cellular CFTR messenger ribonucleic acid (mRNA) and protein, medical history, physical examinations, blood tests, sputum test, urinalysis, ECGs, chest x-ray, and pulmonary function tests.

The measurement of TEPD, also known as nasal potential difference, provides a sensitive evaluation of sodium and chloride transport directly in secretory epithelial cells. TEPD assessments are made on the nasal epithelium cells lining the inferior turbinate because these cells are easier to access than the respiratory epithelial cells lining the lower airways and have been shown to have the same ion transport characteristics. As an endpoint, TEPD has the advantage that it can detect chloride transport changes that are a quantitative integration of the presence, functional activity, and apical location of the CFTR in airway cells. Furthermore, it is a direct measure of CFTR activity that is not likely to be affected by supportive or palliative treatments for CF (with the possible exception of systemically administered aminoglycoside antibiotics).

Arms:
arm 1: During Cycle 1, participants will receive ataluren at 4 mg/kg in the morning, 4 mg/kg at midday, and 8 mg/kg in the evening for 14 days, followed by a 14-day follow-up period without treatment. Then, the participants will crossover to the other ataluren dose regimen (ataluren 10, 10, and 20 mg/kg) for Cycle 2. arm 2: During Cycle 1, participants will receive ataluren at 10 mg/kg in the morning, 10 mg/kg at midday, and 20 mg/kg in the evening for 14 days, followed by a 14-day follow-up period without treatment. Then, the participants will crossover to the other ataluren dose regimen (ataluren 4, 4, and 8 mg/kg) for Cycle 2.

Interventions: intervention 1: Ataluren
Intervention descriptions: intervention 1: Ataluren will be provided as a vanilla-flavored powder to be mixed with water, milk, or apple juice. Participants are to receive a total of 42 doses of ataluren during each cycle, for a total of 84 doses of ataluren in both cycles.

Protocol document: