Expression of PD-L1 correlates with pleomorphic morphology and histological patterns of non-small cell lung carcinomas

Abstract

Aims

With immunomodulatory therapy being integrated into treatment regimes for non-small cell carcinoma (NSCLC), we prospectively collected data on the immunohistochemical profile of tumours assessed in our institution and correlated this with morphological tumour features.

Methods and results

Immunohistochemistry for PD-L1 was considered adequate when more than 100 tumour cells were seen microscopically. When adequate, PD-L1 staining was scored as <1%, ≥ 1-49% or ≥ 50% positive membrane staining within tumour cells only. There were 197 assessable cases, of which 87% of those with pleomorphic features (n=39) showed ≥ 50% positivity for PD-L1 expression, compared with only 33% of cases without pleomorphic features (p<0.05) (90% versus 25% in resected cases). Further correlation of PD-L1 expression with architectural patterns within the tumours was performed in 74 adenocarcinoma resections. All invasive mucinous adenocarcinomas scored <1%. All lepidic components in non-mucinous adenocarcinoma resections scored <1%. 35% of the acinar/papillary components and 53% of the solid/micropapillary components were positive for PD-L1 expression.

Conclusions

There are significant differences in PD-L1 expression in relation to histological patterns, with particularly high levels in those with pleomorphic features and low/undetectable levels in invasive mucinous adenocarcinomas and the lepidic components of non-mucinous adenocarcinomas. Assessment of PD-L1 expression in a resected adenocarcinoma with a lepidic component may therefore not be reliable when considering immumodulatory therapy for recurrent disease and either re-biopsy or limiting assessment to the invasive component may be more appropriate.

This article is protected by copyright. All rights reserved.

http://ift.tt/2AOBj02