Immunohistochemical Expression of PD-L1 in Core Biopsy Samples of Non Small Cell Lung Cancer and its Association with Histopathological and Clinicoradiological Parameters

Abstract

Introduction: Lung cancer is one of the most common causes of cancer-related mortality worldwide. In addition to chemotherapy, immunotherapy has yielded favourable outcomes in advanced, surgically non resectable Non Small Cell Lung Carcinoma (NSCLC). The inhibition of immune checkpoints by monoclonal antibodies targeting Programmed Death 1 (PD-1) and Programmed Death Ligand 1 (PD-L1) plays a pivotal role in preventing the downregulation of antitumour immunity. Aim: To study the expression of PD-L1 in NSCLC cases from core biopsy specimens and its association with histological types, grades of tumour along with clinicoradiological parameters (age, sex, smoking status, and radiological location of the tumour). Materials and Methods: This ambispective study was done in the Pathology Department of Kalinga Institute of Medical Sciences, Bhubaneshwar, Odisha, India, over two years from October 2020 to August 2022. The authors studied 35 cases of histopathologically and Immunohistochemically (IHC) diagnosed NSCLC. Partial or complete membranous staining of any intensity in ≥1% of tumour cells was considered positive in IHC. The Tumour Proportion Scoring (TPS) used for PD-L1 reporting was as follows: TPS <1%: negative, TPS 1-49%: low positive expression, and TPS ≥50%: high positive expression. Microsoft excel and Statistical Package for Social Sciences (SPSS) version 25.0 software were used for statistical analysis. Results: The most common age group was 61-70 years (12 cases; 34.29%), with a male predominance 24 (68.60). Chronic smokers (16 cases; 45.71%) were commonly affected. Squamous Cell Carcinoma (SCC) was the common histological type (21 cases; 60%). Overall, 14 cases (40.0%) showed low (1-49%) and 5 cases (14.30%) showed high (≥50%) positive TPS of PD-L1 expression, respectively. Three cases (27.3%) of Grade 2 SCC and one case (10%) of Grade 3 SCC expressed high positivity. There was a statistical association between PDL1 expression and male sex (p-value 0.01), positive smoking history (p-value 0.048), and SCC (p-value 0.032). Conclusion: The PD-L1 expression is associated with increased tumour proliferation, aggressiveness, as well as shorter survival period in advanced NSCLC. The present study showed a significant association of PD-L1 expression in males, chronic smokers, and SCC. As per the existing literature, its association with clinicoradiological parameters is not clear. Future research with a larger cohort study, along with other predictive biomarkers, is highly desired to reach conclusive evidence.