The use of ivacaftor in CFTR mutations resulting in residual functioning protein.

INTRODUCTION: Ivacaftor, a cystic fibrosis transmembrane regulator (CFTR) potentiator is currently approved for use in individuals with class III gating mutations and the R117H mutation, a non-gating mutation with residual functioning CFTR. Nevertheless, ivacaftor may also be effective in individuals who have CF mutations giving rise to a residual functioning protein. However, aside from case reports involving a single patient, little data exist on the use of ivacaftor in such individuals.

METHODS: A real life pragmatic report wherein seven adults with mutations resulting in a CFTR with residual function were prescribed ivacaftor. Four individuals with similar mutations acted as comparison. We assessed lung function, body mass index, sweat chloride; the number of acute respiratory exacerbations and health related quality of life.

RESULTS: Patients with residual functioning CFTR showed significant improvement or stabilization in all parameters up to 3 years following the start of ivacaftor. Those with similar mutations and who did not receive ivacaftor worsened.

CONCLUSION: We report the use of ivacaftor in seven adults with various Class IV and V non-gating CFTR mutation with residual functioning protein and we demonstrate improvement in several clinical parameters.