Clinical characteristics and PD-L1 expression in primary lung squamous cell carcinoma: A case series

BACKGROUND: Squamous cell lung carcinoma(SCLC), accounts for 20% of lung cancer(LC). The binding of programmed cell death 1(PD-1) to its ligand PD-L1 is a key checkpoint regulator of immune response, and overexpression of the latter leads to immune surveillance escape. This might represent an important oncogenic mechanism, as well as a predictor for immunotherapy treatment success in SCLC. METHODS: A retrospective series of 24 patients with SCLC was included(2009–2013). These patients presented with a single pulmonary lesion and no history of previous cancer. Expression of PD-L1 was evaluated on tumoral biopsies with immunohistochemistry. PD-L1 tumor proportion score(TPS) was considered high when ≥50%. Clinical characteristics regarding diagnosis were reviewed and recorded. Data were analysed in STATA v.14®. RESULTS: Twenty four patients were included in this series. Mean age was 67 + 14 years, and 62.5% were men. Smoking status was positive in 54%. Cancer stage IV was present in 54%. PD-L1 was positive in 13(54%). (+)PD-L1 was more frequent in smokers than in non-smokers(11 vs 2)(p = 0.001), as well as in COPD patients(p = 0.006). General overall survival was 21.8% at 5 years. Overall survival at one year in PD-L1(+) was 30.7% and 72.7% for PD-L1(-) patients. Survival median for PD-L1(+) patients was 10.5mo, as well as for the whole series. CONCLUSION: Patients with primary SCLC who have a high PD-L1 TPS, had a worse overall survival than their counterparts. PD-L1 expression in SCLC in a Colombian sample lies between the one found in the literature.