The frequency of high PD-L1 expression is low in lung adenocarcinoma patients from Northeast Brazil

Antonio V. Alves da SilvaView ORCID ID profile,
Francisco Martins NetoView ORCID ID profile,
Ana Claudia da Silva M. de OliveiraView ORCID ID profile,
Benedito A. CarneiroView ORCID ID profile,
Marclesson AlvesView ORCID ID profile,
Cleto Dantas Nogueira and
Fabio TavoraEmail author View ORCID ID profile

Surgical and Experimental Pathology20192:4

https://doi.org/10.1186/s42047-019-0031-1

Received: 27 July 2018
Accepted: 12 October 2018
Published: 18 February 2019

Abstract

Background

As Immune checkpoint inhibitors (ICPIs) are changing the standard-care in lung cancer with good clinical activities and durable responses, its indication must be based on the appropriate patient selection once only a fraction of patients has a response to these costly drugs. In larger cohorts the expression of programmed cell death–ligand 1 (PD-L1) has been associated with good clinical response of ICPIs in lung adenocarcinoma where the rate of high PD-L1 expression (defined as PD-L1tumor proportion score ≥ 50%) is ~ 30%, but once rare studies are available addressing the frequency of PD-L1 in populations outside those cohorts, we aimed to report the prevalence of PD-L1 and the frequency of patients with high PD-L1 expression utilizing data from a major pathology laboratory in Northeastern Brazil.

Methods

We retrospectively evaluated the PD-L1 expression in 158 surgically resected primary lung adenocarcinoma including 158 with anaplastic lymphoma kinase (ALK) expression. PD-L1 and ALK expression were evaluated by immunohistochemical analysis with the SP263 and D5F3 assays, respectively.

Results

Of the 158 samples analyzed, 94 (59.5%) had a PD-L1 tumor proportion score (TPS) < 1%, 38 (24.0%) had a PD-L1 TPS of 1–49% and 26 (16.5%) had a PD-L1 TPS of ≥50%. ALK expression was detected in 21 (13.3%) of the 158 tumor samples and 5 (3.2%) of them had a PD-L1 TPS of ≥50%.

Conclusion

The frequency of strong PD-L1 expression was lower than that previously reported in the trials where PD-L1 expression was used as a biomarker for patient selection. Also, considering that a subset of patients with ALK positivity had a strong PD-L1 expression, further studies will be required to examine the efficacy of PD-1/PD-L1 inhibitors in such patients.