ER positivity was associated with significant PFS benefit in both the ICI monotherapy group (11.9 vs. 0.63 months, p=0.061) and the group that received ICI/TKI combination (11.3 vs. 1.75 months, p=0.001)….ER-positivity remained an independent predictive factor favoring PFS in the Multivariate Cox regression analysis when adjusting for immunotherapy type, histology, and previous lines of therapy (HR=0.216, p=0.013)....ER expression proved to be an independent prognostic factor regarding PFS in our cohort of patients.