Safety Study of Ivacaftor in Subjects With Cystic Fibrosis

Cystic Fibrosis Clinical Trial

Official title: A Phase 2a, Randomized, Double-Blind, Placebo-Controlled Study of VX-770 to Evaluate Safety, Pharmacokinetics, and Biomarkers of CFTR Activity in Cystic Fibrosis (CF) Subjects With Genotype G551D

Status Completed

Clinical Trial Summary

The purpose of this study was to evaluate the safety and tolerability of ivacaftor in patients with cystic fibrosis (CF) who were aged 18 years or older and have a G551D mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Ivacaftor is a potent and selective CFTR potentiator of wild-type, G551D, F508del, and R117H forms of human CFTR protein. Potentiators are pharmacological agents that increase the chloride ion transport properties of the channel in the presence of cyclic AMP-dependent protein kinase A (PKA) activation.

Clinical Trial Description

This was a double-blind, placebo-controlled, cross-over, multiple dose study of up to 28 days of dosing, in subjects with cystic fibrosis (CF) who have a G551D-CTFR gene mutation. Enrollment of 39 subjects occurred at 15 centers in the US, Canada, and Germany.

The study was conducted in 2 parts:

• Part 1 consisted of Group A and Group B. Subjects in Group A (10 subjects) were randomized to receive 25 mg of ivacaftor every 12 hours [q12h] (4 subjects), 75 mg of ivacaftor q12h (4 subjects), or placebo (2 subjects) for 14 days. Following a 7- to 28-day washout period, subjects who received active study drug crossed over to the alternate dose strength of ivacaftor for an additional 14 days. Placebo subjects continued to receive placebo for an additional 14 days. Subjects in Group B (10 subjects) were randomized to receive 75 mg of ivacaftor q12h (4 subjects), 150 mg of ivacaftor q12h (4 subjects), or placebo (2 subjects) for 14 days. Following a 7- to 28-day washout period, the subjects who received active study drug crossed over to the alternate dose strength of ivacaftor for an additional 14 days. Placebo subjects continued to receive placebo for an additional 14 days.

• Part 2 consisted of Group C; these subjects did not participate in Part 1. Subjects were randomized to receive 150 mg of ivacaftor q12h (7 subjects), 250 mg of ivacaftor q12h (7 subjects), or placebo (4 subjects) for a total of 28 days. Ivacaftor doses studied in Part 2 were selected following an interim pharmacokinetic/pharmacodynamic (PK/PD) and statistical analyses of data from Part 1. The 2 doses selected for Part 2 were anticipated to enable better definition of the optimal therapeutic dose. ;

Study Design

Allocation: Randomized, Endpoint Classification: Safety Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Cystic Fibrosis
• Fibrosis

• NCT number: NCT00457821
• Study type: Interventional
• Source: Vertex Pharmaceuticals Incorporated
• Status: Completed
• Phase: Phase 2
• Start date: May 2007
• Completion date: August 2008