Plasma KL-6 reflects pulmonary severity and longitudinal response to enzyme replacement therapy in acid sphingomyelinase deficiency type B.

Acid sphingomyelinase deficiency (ASMD) type B is frequently complicated by interstitial lung disease without validated circulating pulmonary biomarkers. In this retrospective longitudinal study of five patients treated with enzyme replacement therapy, plasma KL-6 was evaluated in relation to CT-based severity, DLCO, and treatment response. Higher pre-treatment KL-6 concentrations were observed with higher exploratory CT severity grades, and KL-6 levels generally decreased or remained stable during follow-up. A transient rise occurred during SARS-CoV-2 infection. KL-6 may reflect dynamic alveolar epithelial injury in ASMD.