Introduction: Data from the INBUILD trial in subjects with progressive fibrosing ILDs other than IPF suggested that nintedanib may have effects on circulating biomarkers of epithelial injury.

Aim: To investigate the effects of nintedanib on circulating biomarkers of epithelial injury in the INBUILD trial in subgroups by fibrotic pattern on HRCT.

Methods: Fold changes from baseline in adjusted mean levels of biomarkers were analysed in subjects with a usual interstitial pneumonia (UIP)-like fibrotic pattern on HRCT or other fibrotic patterns on HRCT. Data were log10 transformed before analysis and estimates of change from baseline were back-transformed.

Results: Of 663 subjects, 412 (62.1%) had a UIP-like fibrotic pattern on HRCT. Over 52 weeks, the effect of nintedanib on fold changes in CA-125 was consistent between subjects with a UIP-like fibrotic pattern and other fibrotic patterns on HRCT, whereas the effects of nintedanib on SP-D and CA19-9 were larger in subjects with a UIP-like pattern than other fibrotic patterns (Figure). Compared with placebo, nintedanib appeared to reduce KL-6 at week 52 in subjects with a UIP-like fibrotic pattern but not in subjects with other fibrotic patterns.

Conclusions: The effect of nintedanib on reducing levels of CA-125 in subjects with progressive pulmonary fibrosis other than IPF did not differ between subgroups by fibrotic pattern on HRCT.