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\begin{document}

\title{Elexacaftor/tezacaftor/ivacaftor Treatment Reduces Airway Inflammation
in Cystic Fibrosis}



\author[1]{Richard C. De Vuyst}%
\author[1]{Erin Bennard}%
\author[2]{Charissa Kam}%
\author[2]{Cameron McKinzie}%
\author[1]{Charles Esther}%
\affil[1]{The University of North Carolina at Chapel Hill Department of Pediatrics}%
\affil[2]{University of North Carolina Medical Center}%


\vspace{-1em}



  
  \date{May 21, 2024}


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\selectlanguage{english}
\begin{abstract}
ETI treatment reduces inflammatory markers and positive bacterial
cultures on BAL in PwCF. These findings suggest that ETI has a greater
impact on chronic infection and inflammation than ivacaftor alone.
However, airway inflammation persists in a fraction of treated
individuals, indicating an ongoing need to optimize other treatments in
a subset of patients.%
\end{abstract}%



\sloppy


To the editor,

Airway mucus dehydration from loss of cystic fibrosis transmembrane
conductance regulator (CFTR) activity leads to excessive airway
muco-inflammation that drives the onset and progression of lung disease
in cystic fibrosis (CF.)\textsuperscript{1,2} Previous studies with the
highly effective modulator therapy (HEMT) ivacaftor have demonstrated
improvement in CFTR function and substantial clinical benefits. However,
clinical studies of ivacaftor therapy in people with CF (PwCF) with
eligible genotypes have not consistently demonstrated a significant
reduction in markers of airway inflammation.\textsuperscript{3,4} This
somewhat unanticipated result suggests that airway inflammation may
persist in PwCF on HEMT and could benefit from anti-inflammatory
therapies.

Recently, elexacaftor-tezacaftor-ivacaftor (ETI, Trikafta) was approved
as a HEMT available to a larger fraction of PwCF. While \emph{in
vitro}evidence suggests that ETI treatment may alter inflammatory
pathways in CF\textsuperscript{5}, there is little information regarding
the impact of ETI on airway inflammation in treated individuals. To
address this issue, we identified PwCF who underwent bronchoscopy with
bronchoalveolar lavage (BAL) after starting ETI therapy. To avoid
confounding by indication, the study population was limited to those who
had surveillance procedures before and after starting ETI therapy. BAL
markers of inflammation and infection obtained during these procedures
were then compared.

\textbf{Methods}

A database of all PwCF on ETI therapy was cross-referenced to a
bronchoscopy database to identify individuals who underwent bronchoscopy
with BAL while on ETI therapy. Procedures performed while the individual
was on intravenous antibiotics were excluded, as were procedures where
pulmonary exacerbation was the indication. Individuals were excluded
from further analysis if they did not have at least one bronchoscopy
performed while not on ETI therapy within 5 years of the index
procedure. Clinical information including demographics and CFTR
genotype, indication for bronchoscopy, as well as BAL findings including
culture data, cell count, neutrophil count and neutrophil percentage
were abstracted from the medical record. Pathogen positive cultures were
defined as growth of any potentially pathogenic organism on culture.
Statistical analysis was performed using GraphPad Prism using paired
T-tests (continuous data) or Fisher exact test (dichotomous data).
Neutrophil cells counts were log transformed prior to analysis. The
study was approved by the UNC IRB (\#21-1137).

\textbf{Results}

To assess whether ETI therapy affected lower airway inflammation, we
identified 16 patients who had bronchoscopy and BAL performed while on
ETI therapy. Two individuals were excluded who did not have comparison
bronchoscopies performed while not on ETI therapy within five years, and
a further 6 were excluded due to pre or post ETI bronchoscopy being
performed for suspected bronchopneumonia. The study population consisted
of 8 subjects, all white, and was 75\% male with an average age of
12.7\selectlanguage{ngerman}±5.3 years at the time of the bronchoscopy on ETI therapy. The
locations of bronchoalveolar lavage were determined clinically. In 42\%
of subjects lavage was performed in different lobes in the matched
procedures.

BAL markers of neutrophilic inflammation were significantly reduced in
the samples obtained from PwCF while on ETI, including both \%
neutrophils and neutrophil counts (\textbf{Fig. 1A-B} ). While pathogens
were recovered from 5 of 8 PwCF not on ETI, no pathogens were recovered
from any procedure performed on an individual on ETI (\textbf{Fig. 1D}
).

\textbf{Discussion}

The Use of ETI in eligible PwCF was associated with a marked decrease in
markers of inflammation in BAL and fewer positive cultures from BAL
fluid. While consistent with the known pathophysiology of CF, this
result differs from prior studies of ivacaftor alone that have not shown
a clear impact on airway inflammation or infection despite substantial
clinical benefit.\textsuperscript{4} It is possible that ETI results in
greater restoration of CFTR activity than ivacaftor alone in eligible
genotypes, and clinical studies have suggested a clinical benefit of ETI
in patients previously treated with
ivacaftor.\textsuperscript{6}However, further investigation will be
necessary to confirm these findings and better understand the
differences between ETI therapy and ivacaftor alone.

The failure of ivacaftor alone to substantially reduce airway
inflammation in treated patients has suggested that individuals on HEMT
may still benefit from anti-inflammatory therapies. Our findings suggest
that anti-inflammatory therapies may be less effective for many treated
with ETI, although substantial levels of airway inflammation remained in
some PwCF on ETI. It is not clear if this reflects therapeutic failure
of ETI to effectively improve CFTR activity or the presence of
established structural lung disease that led to continued inflammation
and infection despite normal levels of CFTR. Regardless, the findings
indicate that individualized strategies will be needed to optimize
efficacy of ETI and/or identify those who continue to need
anti-inflammatory or other treatments despite HEMT.

Strengths of this study include use of bronchoscopy with BAL as the gold
standard measure of airway inflammation. Limitations include the small
size and reliance on clinically indicated procedures and findings for
analysis. Therefore, measures such as neutrophil elastase or cytokines
that are not routinely performed clinically were not available.

In conclusion, ETI treatment reduces inflammatory markers and positive
bacterial cultures on BAL in PwCF. These findings suggest that ETI has a
greater impact on chronic infection and inflammation than ivacaftor
alone. However, airway inflammation persists in a fraction of treated
individuals, indicating an ongoing need to optimize other treatments in
a subset of patients.

\textbf{Conflict of interest statement}

The authors have no conflicts of interest to report.

1. Ghigo A, Prono G, Riccardi E, De Rose V. Dysfunctional inflammation
in cystic fibrosis airways: From mechanisms to novel therapeutic
approaches. \emph{Int J Mol Sci} . 2021;22(4):1-23.
doi:10.3390/ijms22041952

2. Roesch EA, Nichols DP, Chmiel JF. Inflammation in cystic fibrosis: An
update. \emph{Pediatr Pulmonol} . 2018;53(June):S30-S50.
doi:10.1002/ppul.24129

3. Rowe SM, Heltshe SL, Gonska T, et al. Clinical mechanism of the
cystic fibrosis transmembrane conductance regulator potentiator
ivacaftor in G551D-mediated cystic fibrosis. \emph{Am J Respir Crit Care
Med} . 2014;190(2):175-184. doi:10.1164/rccm.201404-0703OC

4. McNally P, Butler D. Ivacaftor and Airway Inflammation in Preschool
Children with Cystic Fibrosis. \emph{Am J Respir Crit Care Med} .
2021;204(5):605-607.

5. Veltman M, De Sanctis JB, Stolarczyk M, et al. CFTR Correctors and
Antioxidants Partially Normalize Lipid Imbalance but not Abnormal Basal
Inflammatory Cytokine Profile in CF Bronchial Epithelial
Cells.\emph{Front Physiol} . 2021;12(February).
doi:10.3389/fphys.2021.619442

6. Nichols DP, Paynter AC, Heltshe SL, et al. Clinical Effectiveness of
Elexacaftor/Tezacaftor/Ivacaftor in People with Cystic Fibrosis: A
Clinical Trial. \emph{Am J Respir Crit Care Med} . 2022;205(5):529-539.
doi:10.1164/rccm.202108-1986oc

\textbf{Elexacaftor/tezacaftor/ivacaftor Treatment Reduces Airway
Inflammation in Cystic Fibrosis}

Richard C. De Vuyst\textsuperscript{1}, Erin Bennard\textsuperscript{1},
Charissa W. Kam\textsuperscript{2}, Cameron J.
McKinzie\textsuperscript{2}, and Charles R. Esther Jr\textsuperscript{1}

1. Division of Pediatric Pulmonology, Department of Pediatrics,
University of North Carolina School of Medicine, Chapel Hill, North
Carolina.

2. Department of Pharmacy, University of North Carolina Medical Center,
Chapel Hill, North Carolina.

\textbf{Hosted file}

\verb`Figure 1 A-C.docx`  available at \url{https://authorea.com/users/569033/articles/614625-elexacaftor-tezacaftor-ivacaftor-treatment-reduces-airway-inflammation-in-cystic-fibrosis}

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\end{document}

