TTF-1 expression is associated with survival in patients with non-squamous non-small cell lung cancer treated with immune checkpoint inhibitor therapy.

Thyroid transcription factor-1 (TTF-1) expression has been associated with the prognosis of patients with non-small cell lung cancer treated with immune checkpoint inhibitor (ICI) therapy; however, it has also been suggested that there is no such link. The present study analyzed the association of TTF-1 expression, evaluated using a cocktail antibody (TTF-1/napsin A; clone, SPT24/TMU-Ad02), with survival after the initiation of ICI therapy in patients with EGFR/ALK wild-type non-squamous non-small cell lung cancer receiving first-line treatment with ICI monotherapy or chemoimmunotherapy. A total of 49 patients were enrolled to the present study. Multivariate analysis using the Cox proportional hazard model showed that TTF-1 expression was associated with progression-free survival (PFS) after the initiation of treatment with ICI monotherapy or chemoimmunotherapy (hazard ratio: 0.18, 95% confidence interval: 0.06-0.54). Subset analysis showed that the TTF-1-positive group exhibited significantly longer PFS than the negative group in both the ICI monotherapy (median PFS, 17.6 months vs. 2.9 months, P<0.001, log-rank test) and chemoimmunotherapy (median PFS, 10.4 months vs. 5.2 months, P=0.021, log-rank test) groups. In conclusion, the current study observed an association between TTF-1 expression evaluated using a cocktail antibody and the effectiveness of treatment with ICI monotherapy or chemoimmunotherapy.