Correlation of clinical characteristics and immunologic profile of stage III NSCLC patients.

Abstract

e20552 Background: Recently, immunotherapy has significantly increased mPFS and mOS in unresectable stage III NSCLC whom completed concurrent chemoradiation (CCRT). Predictive biomarker for immunotherapy in this setting has not been established yet. Methods: This is a retrospective study in stage III NSCLC patients in Ramathibodi hospital between year of 2013 and 2019. Clinical data of 176 patients were retrieved from electronic medical record. Only 64 patients had adequate tissue for tissue array for immunohistochemistry (IHC) staining of protein expression in CD3, CD4, CD8, FOXP3, PDL-1, CD163, CD 138, CD20 in stroma and tumor cells. We also performed IHC staining for Microsatellite Instability (MSI). Optimum cut point for each protein expression was performed by C-statistic. Survival analysis was performed. All statistical analysis was performed by Stata version 15. Results: Of 176 patients, majority of patient were male (63.6%), age ≥65 years (63.6%), never-smoker (40.9%), stage IIIB (44.9%) and adenocarcinoma (67.6%). EGFR-positive patients were 47.7%. Most of the patients underwent CCRT (32.4%), only 11.9% underwent trimodality treatment. Doublet-carboplatin based chemotherapy was the most common regimen (61.5%). The mOS was 2.9 years and mPFS was 1.6 years. Multivariable analysis showed stage IIIB patients, patients whom received only systemic treatment or best palliative care had significantly shorter OS. Trimodality treatment showed significantly longer OS compared to bimodality (CCRT) (HR = 0.18, P= 0.02), as well as cisplatin-based chemotherapy had significantly longer OS compared to carboplatin-based regimen (HR = 0.47, P= 0.005). Of 64 patients whom had tissue testing in our study, majority of patients had of MSI-low (81.25%), PD-L1 negative (78.13%). Regarding tumor microenvironment, patients with high protein expression of CD3, CD4, CD8 and CD20 in stromal cells showed significantly longer OS, whereas MSI and PD-L1 were not significantly associated with survival outcomes. Conclusions: OS in stage III NSCLC in our population (2.9 years) is comparable with other studies (2.4 years). Trimodalities treatment significantly increased OS compared to CCRT. High protein expression of CD3, CD4, CD8 and CD20 in stroma probably potential prognostic and predictive biomarkers for immunotherapy in stage III NSCLC. Larger cohort is needed to explore.