CO18 - Clinical Significance of Serum KL-6 in Fibrotic Interstitial Lung Diseases
Maria Kokosi (UK)1; Eirini Vasarmidi (Greece)2 3; Athina Trachalaki (UK)1; Carmel Stock (UK)1; Vasileios Kouranos (UK)1; Felix Chua (UK)1; Simon Bax (UK)1; Richard Hewitt (Greece)1; Elisabetta Renzoni (UK)1; Nikolaos Tzanakis (Greece)2; Peter George (UK)1; Athol Wells (UK)1; Katerina Antoniou (Greece)2 3;
1 - Royal Brompton Hospital, London; 2 - Medical University of Crete; 3 - General University Hospital of Crete;
Keywords: biomarker; progressive fibrosis; interstitial lung disease;
Select the theme: Progressive Pulmonary Fibrosis
Type: Original Papers
Presentation: Oral Communication

Introduction: Fibrotic interstitial lung diseases (fILDs) are a heterogeneous group of conditions with variable clinical courses and outcomes. Idiopathic pulmonary fibrosis (IPF) is the prototypical progressive fibrotic disease, though other fILD subtypes may also demonstrate similar progression. Reliable biomarkers are needed to better assess disease severity, guide management, and predict outcomes. KL-6, a glycoprotein expressed by type II alveolar epithelial cells, is released following epithelial injury and has shown promise as a biomarker in this context.

Objectives: To evaluate the role of serum KL-6 in predicting progressive fibrosis.

Materials and Methods: Baseline serum KL-6 levels were measured in 305 patients with fILDs from two centres: Royal Brompton Hospital (UK) and the University Hospital of Heraklion (Crete). Longitudinal lung function data and mortality outcomes were collected. The cohort comprised IPF (n=156), chronic hypersensitivity pneumonitis (n=39), connective tissue disease-associated ILD (n=48), other fILDs (n=36), and unclassifiable ILD (n=26).

Results: The mean age was 70.5 years (SD 9.3); 64.5% were male, and 62% had a history of smoking. Mean baseline KL-6 was 1317.6 U/mL (SD 988.7). Baseline lung function included mean FVC 78.7% predicted (SD 20.4), DLCO 48.9% predicted (SD 21.3), and CPI 45.13 (SD 17.1). During follow-up, 53% of patients died. Higher baseline KL-6 levels were significantly associated with greater disease severity, showing strong correlations with FVC, DLCO, and CPI (all p<0.0001). Mixed linear effects modelling demonstrated a significant decline in FVC over time (p<0.0005).

Conclusions: Serum KL-6 is strongly associated with baseline disease severity in fILDs and may serve as a useful biomarker. Ongoing analyses are evaluating its prognostic value and relationship with quantitative imaging biomarkers.