Hazel Ozuna ^1,2 Dinesh Bojja ³ Santiago Partida Sanchez ⁴ Luanne Hall-Stoodley ⁵ Amal Amer ⁵ Rodney Britt ^4,6 Shahid Sheikh ⁴ David Frank ⁷ Weiyuan Wang ⁷ Bum-Yong Kang ^1,2 Irina Miralda ^1,2 Samantha L Durfey ^1,2 Benjamin T Kopp ^1,2*

• ¹ Center for Cystic Fibrosis and Airways Disease Research (CF-AIR), Emory University School of Medicine, Atlanta, United States
• ² Division of Pulmonology, Asthma, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory University School of Medicine, Atlanta, United States
• ³ Yale College, Yale University, New Haven, Connecticut, United States
• ⁴ Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, Georgia, United States
• ⁵ Department of Microbial Infection and Immunity, College of Medicine, The Ohio State University, Columbus, Ohio, United States
• ⁶ Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, Ohio, United States
• ⁷ Winship Cancer Institute, Emory University School of Medicine, Atlanta, United States

Background: CFTR modulator therapies have positive clinical outcomes, yet chronic inflammation and bacterial infections persist in people with CF (pwCF). How elexacaftor-tezacaftor-ivacaftor (ETI) fails to improve innate immune signaling responsible for bacterial clearance and inflammation resolution remains unknown. Methods: We used an unbiased proteomics approach to measure the effect of ETI on inflammatory proteins. Plasma from 20 pediatric pwCF and 20 non-CF (NCF) was collected during routine examinations and 3 months after ETI initiation. Protein screening was performed with an inflammation panel (Target 96, Olink®). Bioinformatics analysis was used to determine changes in protein expression. Results: There were significantly fewer pulmonary exacerbations after ETI initiation, along with sustained improvement in lung function and reduced bacterial colonization. Unpaired analysis of CF-Pre ETI and NCF resulted in 34 significantly different proteins. Of these CCL20, MMP-10, EN-RAGE, and AXIN1 had a log2 fold-change of 1.2 or more. There was a modest shift in overall CF protein profiles post-ETI towards the NCF cluster. Unpaired analysis of protein differential expression between NCF and CF-Post identified a total of 24 proteins significantly impacted by ETI therapy (p – value ≤ 0.05), with only CCL20 with a log2 fold-change higher than 1.2. Paired analysis (CF-Pre and CF-Post ETI) of differential protein expression demonstrated significant expression changes of MMP-10, EN-RAGE and IL-17A. Pathway analysis identified significantly impacted pathways such as NF-κB pathway. Conclusions: This study showed that in a pediatric cohort, ETI had a modest effect on several inflammatory proteins with potential as biomarkers. Pathways significantly impacted by ETI can be further studied for future therapies to combat persistent inflammation and dysregulated immunity.