[Protein expression of PD-L1 and clinico-pathological data in a cohort of 53 patients with resectable non small cell lung cancer (NSCLC). Concordance between clones (22C3 and 28-8) and observers. Correlation and prognostic value of clinico-pathological data].

INTRODUCTION

85% of lung cancers are non-small cell carcinomas (NSCLC), the majority of which are diagnosed in an advanced stage. Immunotherapy has changed the treatment pattern for these tumors and created the need to find a marker for patient selection. Although not ideal, PD-L1 is the biomarker currently used in clinical practice.

MATERIAL AND METHODS

Retrospective review by two pathologists of 53 cases of NSCLC from 2005 to 2007 in Hospital Universitario La Paz, using the WHO 2015 classification studying PD-L1 with clones 22C3 and 28-8. The consistency between observers and clones was assessed and all data studied were correlated with survival rates.

RESULTS

We found a prevalence of PD-L1 expression in tumor cells (TC) similar to that previously reported in the literature and a very good consistency between clones in the evaluation of TC and immune cells (ICC 0.99-0.93, p<.001). Interobserver concordance was very good in the evaluation of TC (ICC 0.902, 95% CI: 0.836-0.942, p<.001 for clone 22C3 and ICC 0.927, 95% CI: 0.877-0.957, p<.001 for clone 28-8) and poor for immune cells (ICC of 0.413, 95% CI: 0.163-0.613, p=.001 with clone 22C3 and ICC of 0.313, 95% CI: 0.053-0.534, p=.010 with clone 28-8). Subtype and histological grade were the only variables related to prognosis.

CONCLUSIONS

The clones of PD-L1 22C3 and 28-8 are equivalent and there is good interobserver consistency in the evaluation of TC but not in immune cells.