Clinicopathological characteristics and tumor infiltrating immune cells associations of PD-L1 tumor expression in non-small cell lung cancer patients

Abstract

Aim: Our study aimed to perform on Moroccan patients non-small cell lung carcinoma (NSCLC) concerning the relationship between PD-L1 tumor expression, clinicopathological features and tumor infiltrating immune cells (ICs). Methods: This is a retrospective study (2019 to 2021) conducted on samples from Moroccan patients with NSCLC at the Pathological Anatomy Laboratory of Ibn Rochd University Hospital in Casablanca. Eligible participants for our study had to meet the following predefined criteria: Age 18 years, histologically confirmed NSCLC, no prior therapeutic interventions, availability of clinical and pathological data, and a usable tumor sample for determining PD-L1 status. Exclusion criteria applied to patients with other types of lung cancer and unusable tumor samples. The evaluation of tumor and immune expression of PD-L1 was performed using immunohistochemistry (IHC), with the 22C3 clone on the Dako Autostainer Link 48 platform. Tumor PD-L1 expression was categorized into 3 levels: TPS 1% (negative expression), TPS 1-49% (low expression), and TPS 50% (high expression). ICs infiltrating the tumor expressing PD-L1 were considered positive when more than 1% of positive ICs were present. Results: Among the 316 analyzed samples, 56.6% showed a negative expression of PD-L1, 16.8% displayed a low expression of PD-L1, and 26.6% exhibited a strong expression. Regarding the histological type, among patients with TPS 50%, 25.8% had adenocarcinoma. Among patients with TPS 50%, 24.81% were smokers. PD-L1 was also strongly expressed in the lung (28.2%) and bronchi (26.5%). PD-L1 expression (TPS 50%) was observed in 35.29% of early-stage patients. Concerning tumor cells (TCs), 27.5% of tumors infiltrated by ICs had TPS 50%. Furthermore, coexpression of PD-L1 on both TCs and ICs infiltrating the tumor was found in 27.8% of tumors. Statistical analysis demonstrated a significant association between tumor PD-L1 expression and smoking status (P=0.019). However, no significant difference was observed between PD-L1 expression and the presence of ICs infiltrating the tumor (P=0.652), as well as the IHC expression of PD-L1 on ICs (P=0.259). Conclusion: Our results demonstrate a significant association between PD-L1 expression and smoking status. However, no significant association was observed between PD-L1 expression and the presence of infiltrating ICs, nor with the IHC expression of PD-L1 on ICs. Our data underscore the importance of participating in the study of specific factors influencing PD-L1 expression in patients with NSCLC.