CHI3L1 and interstitial lung disease: Plasma biomarkers most commonly linked to differential survival include chemokine (C-C motif) ligand 18 (CCL18) (44, 126, 127, 129, 130), Krebs von den Lungen 6 (KL-6) (131, 133, 138, 142), chitinase-3-like protein 1 (YKL-40) (101, 104, 117), cancer antigen 125 (CA-125) (117–119), and MMP-7, (117, 121, 145, 153) which have been shown to predict this endpoint across diverse forms of ILD.