Combination lumacaftor and ivacaftor therapy for cystic fibrosis

The safety of lumacaftor and ivacaftor for the treatment of cystic fibrosis

INTRODUCTION

Lumacaftor-ivacaftor is indicated for treatment of cystic fibrosis (CF) in patients homozygous for the Phe-508del cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations. In clinical trials, treated patients showed improved pulmonary function, reduced pulmonary exacerbations, and other benefits. This article reviews safety of this therapy. Areas covered: Safety findings in ivacaftor, lumacaftor and combined therapy trials, and reported subsequently through post-approval evaluation, were accessed by PubMed and Google searches using key words 'VX-770', 'ivacaftor', 'VX-809', and 'lumacaftor'. Transaminitis was seen in ivacaftor and combination trials. Non-congenital cataracts were seen in pre-clinical animal studies and in children taking ivacaftor and combined therapy. Dyspnea occurs in some patients taking lumacaftor and combined therapy and usually resolves without stopping treatment. Lumacaftor is a strong inducer of CYP3A while ivacaftor is a CYP3A sensitive substrate. Combination therapy can decrease systemic exposure of medications that are substrates of CYP3A, decreasing therapeutic effect. Co-administration of lumacaftor-ivacaftor with sensitive CYP3A substrates or CYP3A substrates with narrow therapeutic index is not recommended. Expert opinion: Lumacaftor-ivacaftor therapy may be associated with ocular and hepatic side effects. Specific recommendations for monitoring are available. Dyspnea occurs, especially during initiation of treatment. Potential drug interactions should be evaluated in patients taking combination therapy. The risk benefit ratio of lumacaftor-ivacaftor favors therapy.

A safety evaluation of ivacaftor for the treatment of cystic fibrosis

INTRODUCTION

Ivacaftor is indicated for treatment of cystic fibrosis (CF) mediated by 10 mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene that causes gating or partial function abnormalities. In placebo-controlled and open-label studies, ivacaftor-treated subjects showed improved pulmonary function, nutrition and quality of life measures. This article reviews ivacaftor safety.

AREAS COVERED

Safety findings in ivacaftor clinical trials, and reported subsequently, were accessed by a PubMed search using key words "VX-770" or "ivacaftor". Additional information was accessed via Google Search. Transaminitis was noted in ivacaftor and combination lumacaftor-ivacaftor trials. Ivacaftor was associated with cataracts in juvenile rat pups in pre-clinical studies; non-congenital cataracts have been found in children taking ivacaftor. Ivacaftor is a CYP3A substrate; CYP3A inhibitors and inducers should be avoided during its administration. Ivacaftor and its M1 metabolite may inhibit CYP3A and P-gp; therefore, ivacaftor may increase systemic exposure to drugs which are substrates of CYP3A and/or P-gp, increasing the potential for adverse events.

EXPERT OPINION

Ivacaftor therapy may be associated with ocular and hepatic side effects; specific recommendations for monitoring are available. Potential drug interactions should be evaluated in patients taking ivacaftor. High clinical efficacy suggests that the risk benefit ratio of ivacaftor favors therapy.