Programmed death-ligand 1 (PD-L1) is used to predict response to immunotherapy. Temporal variability in the expression of PD-L1 in tumor cells has been reported; we wanted to assess the prevalence and prognostic role of PD-L1 expression in patients with resected non-small cell lung carcinoma (NSCLC) in initial stages with negative ganglia.
We analyzed tumor tissue of 170 patients with NSCLC stages I and II (pN0), no adjuvant or neoadjuvant therapy. Immunohistochemical staining of PD-L1 (Dako PD-L1 IHC 22C3 pharmDx) was performed on sections of tissue microarrays (TMAs), being able to be carried out in 165 cases (97%). The results were correlated (Ji Square and Fisher test) with clinicopathological variables (gender, age, smoking, pathological stage, histological type, nuclear grade, Ki67). For the analysis of survival (disease-free (DFS) and overall (OS) survival), the curves of Kaplan-Meier were used with the test of the logarithmic ranges (log rank test), and the proportional method of Cox taking the negative values as reference.
The median age was 66 years (IQR 60-73), 135 men and 35 women. Eighty-eight per cent of them were smokers. The median follow-up was 64 months (range 1-163). The distribution by stages was: 51% of pathological stage IA, 31% of IB stage and 18% corresponded to stage II with pN0. Regarding histology there were 57% adenocarcinomas, 34% squamous cell carcinomas and 7% large cell carcinomas. PD-L1 expression was detected in 28.8% of the cases: 19.8% of the adenocarcinoma tumours and 41.3% of the squamous subtypes. We found a PD-L1 expression greater than 5% in 24.7% of cases and 11.8% of the total showed a PD-L1 expression ≥ 50%. The median DFS was 59.6 months (IQR 27-85) and OS 64.2 months (IQR 39.9-94.9). A statistically significant association was observed between expression of PD-L1 and younger age (inverse relationship, p = 0,033) and histologic subtype (lower expression in squamous type, p = 0,029). Kaplan-Meier analysis showed less DFS in positive PD-L1 patients. No significant differences were observed in relation to overall survival.
The expression of PD-L1 is associated with morphological data of greater aggressiveness and is a risk factor for relapse in NSCLC in early stages without positive ganglia.
Clinical trial identification
Legal entity responsible for the study
Hospital General de Alicante.
Has not received any funding.
All authors have declared no conflicts of interest.