Vimentin expression correlates with immune checkpoint inhibitor efficacy in non-small cell lung cancer.

BACKGROUND: Although vimentin is often expressed in non-small cell lung cancer (NSCLC), the association between vimentin expression and immune-checkpoint inhibitor (ICI) efficacy remains unclear. METHODS: This retrospective multicenter study enrolled patients with NSCLC who received ICI treatment between December 2015 and July 2020. The authors constructed tissue microarrays and performed immunohistochemical staining with vimentin. They analyzed the relationship between vimentin expression rate and objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: Immunohistochemically evaluable specimens on microarray blocks were available for 397 patients, of whom 343 (86%) were negative (<10%), 30 (8%) were positive (10%-49%), and 24 (6%) were highly positive (≥50%) for vimentin expression. Both rates of programmed death-ligand 1 (PD-L1) tumor proportion score ≥1% and ≥50% were significantly higher in the vimentin-positive group (≥10%) than the vimentin-negative group (<10%) (96% vs. 78%, p = .004; 64% vs. 42%, p = .006, respectively). In patients treated with ICI monotherapy, ORR, PFS, and OS were significantly better in the vimentin-positive group (10%-49%) than in the vimentin-negative group (<10%) (54% vs. 25%, p = .003, median = 7.9 vs. 3.2 months, p = .011; median = 27.0 vs. 13.6 months, p = .015, respectively), whereas there was no significant difference in PFS and OS between the vimentin highly positive group (≥50%) and the vimentin-negative group (<10%) (median = 3.4 vs. 3.2 months, p = .57; median = 7.2 vs. 13.6 months, p = .086, respectively). CONCLUSIONS: Vimentin expression correlated with PD-L1 expression and ICI efficacy. PLAIN LANGUAGE SUMMARY: We constructed tissue microarrays and performed immunohistochemical staining with vimentin on 397 patients with advanced non-small cell lung cancer who were treated with immune-checkpoint inhibitor (ICI). The vimentin-positive group who were treated with ICI monotherapy showed significantly better objective response rate, progression-free survival, and overall survival than the vimentin negative group. The measurement of vimentin expression will aid in determining appropriate immunotherapy strategies.