Retrospective evaluation of PD-L1 expression in tumor tissue of patients with lung carcinoma and correlation with clinical and demographical data from a tertiary care institute of northern India

Abstract

Background: It has been widely recognized that response rates of immunotherapy drugs correlates with PD-L1 (Programmed Death-Ligand 1) expression with higher response rates with higher PD-L1 expression. As there is extreme paucity of PD-L1 expression data from the Indian perspective, we studied the clinical and demographical profile of PD-L1 in lung cancer patients. Methods: 134 cases of lung cancer patients from June 2017 to June 2018, in whom, membranous PD-L1 expression testing was done by using rabbit Anti-Human PD-L1 monoclonal antibody (clone SP263) on VENTANA BENCHMARK XT were retrospectively evaluated in terms of histological and demographical profile. PD-L1 expression of > =1% was regarded as positive. All statistical analysis were done using SPSS Version 23.0. p value < = 0.05 was considered to be significant. Results: The median age was 62 Years (Range 27-89). PD-L1 positivity was seen in 53.3% and 38.6% with age < =60 years and >60 years respectively (p = 0.09). 51% of male and 33.4% of female patients had PD-L1 > =1% (p = 0.08). Out of 134 cases, 63 (47%) had PD-L1 > =1%.On further stratification, 20.1%, 3% and 23.9% PD-L1 positivity was noted in subgroups of 1 – 24, 25-49 and > =50% PD-L1 expression respectively. PD-L1 positivity was commoner in non smokers (52.1%) than in active or former smokers (44.2%) but the difference was statistically insignificant (p = 0.37). PD-L1 positivity in Non squamous NSCLC and squamous histology was 50.5% and 47.7% respectively (p = 0.812). None of the SCLC cases had PD-L1 positivity. PD-L1 positivity in brain, skeletal only, extra thoracic visceral and intra thoracic metastasis was 47.9%, 53.6%, 51.3% and 41.4% respectively (p = 0.803).35% of EGFR mutant cases had PD-L1 positivity. There were 2 ALK positive cases and both had PD-L1 > =1%. Conclusions: In this first analysis of PD-L1 expression in lung cancer patients from India, we found a PD-L1 positivity rate of 47%. There was no statistically significant difference in PD-L1 expression in respect to age, gender, smoking, histology, sites of metastasis and molecular profile, although more studies with larger sample sizes will be necessary to fill in the knowledge gaps. Legal entity responsible for the study: Rajiv Gandhi Cancer Institute & Research Centre, Delhi. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.