Transcriptomic Responses to Lumacaftor/Ivacaftor Therapy in Cystic Fibrosis

Cystic fibrosis (CF) remains a life-shortening disease without a definitive cure. Novel therapeutics targeting the causative defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are now in clinical use.  Lumacaftor/ivacaftor is a CFTR modulator approved for patients homozygous for the CFTR mutation p.Phe508del, but there are wide variations in treatment responses preventing prediction of patient responses. We aimed to determine changes in gene expression related to treatment initiation and response. Whole-blood transcriptomics was performed using RNA-Seq in 20 patients with CF pre- and 6 months post-lumacaftor/ivacaftor (drug) initiation and 20 non-CF healthy controls.  Correlation with clinical variables was performed by stratification via clinical responses.  We identified 491 genes that were differentially expressed in CF patients (pre-drug) compared with non-CF controls. In addition, 36 genes were differentially expressed when comparing pre-drug to post-drug profiles within CF patients. Transcriptomics revealed novel pathways in CF patients at baseline compared to non-CF, and in clinical responders to lumacaftor/ivacaftor. Overall changes in gene expression post-lumacaftor/ivacaftor were modest compared to pre-drug CF profiles. 20 control non-CF samples,  20 CF samples pre-drug,  20 samples from the same CF patients 6 months-post drug